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Stability of implants placed at sites treated with bone allograft Tuckey, Tanya Danielle 2012

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 STABILITY
OF
IMPLANTS
PLACED
AT
SITES
TREATED
WITH
BONE
ALLOGRAFT

by

TANYA
DANIELLE
TUCKEY

B.Sc.,
The
University
of
British
Columbia,
2003
D.D.S.,
University
of
Toronto,
2008


A
THESIS
SUBMITTED
IN
PARTIAL
FULFILLMENT
OF

THE
REQUIREMENTS
FOR
THE
DEGREE
OF

MASTER
OF
SCIENCE

in

THE
FACULTY
OF
GRADUATE
STUDIES

(Craniofacial
Science)

THE
UNIVERSITY
OF
BRITISH
COLUMBIA
(Vancouver)


July
2012
©
Tanya
Danielle
Tuckey,
2012
 
 ii
 ABSTRACT

 Objective:
A
retrospective
chart
review
was
performed
to
assess
the
stability
of
implants
in
a
variety
of
clinical
situations,
including
placement
at
sites
with
a
history
of
bone
augmentation
using
bone
allograft.


 Methods:
The
study
included
286
implants
placed
by
an
experienced
practitioner
and
by
Graduate
Periodontics
residents
at
the
University
of
British
Columbia.
Implants
included
a
variety
of
Nobel
Biocare,
Straumann,
and
Astra
Tech
designs.
The
Osstell
ISQ
device
was
used
to
measure
implant
stability
(RFA)
by
emitting
magnetic
pulses
that
cause
a
SmartPeg
attached
to
the
implant
to
resonate
according
to
the
stability

of
the
implant.
Results
were
displayed
in
Implant
Stability
Quotient
(ISQ)
units
and
were
recorded
in
triplicate,
from
the
buccal,
lingual,
mesial,
and
distal.
Measurements
obtained
at
second
surgery
were
compared
with
factors
related
to
bone
grafting,
as
well
as
patient
demographics,
implant
site,
and
physical
implant
characteristics
(significance
p<0.05).

 Results:
The
overall
implant
survival
rate
was
98.9%
with
3
implant
failures.
There
was
good
reproducibility
of
measurements
taken
in
triplicate
and
measurements
taken
from
the
buccal
were
significantly
lower
than
those
taken
from
either
the
mesial
or
distal.
A
significantly
higher
ISQ
was
obtained
in
the
mandible
than
the
maxilla,
with
significantly
lower
values
at
incisor
sites
compared
with
both
premolar
and
molar
sites.
A
higher
ISQ
was
obtained
for
short
implants
and
this
reached
statistical
significance
in
the
mandible,
where
shorter
implants
tended
to
be
wider.
Significantly
lower
ISQ
values
were
obtained
for
narrow
implants
in
both
arches.
ISQ
values
in
soft
bone
were
significantly
lower,
as
were
values
at
sites
with
a
 
 iii
 history
of
lateral
ridge
augmentation
using
xenograft.
No
significant
difference
was
observed
between
ISQ
and
age,
gender,
Type
2
diabetes,
smoking,
implant
type,
insertion
torque,
buccal
bony
dehiscence,
surgeon’s
level
of
experience,
or
whether
the
site
had
a
history
of
lateral
ridge
augmentation,
socket
preservation,
or
sinus
lifting.


 Conclusions:
Implant
stability,
as
measured
using
the
Osstell
ISQ
device,
is
not
significantly
affected
by
a
history
of
bone
grafting
using
bone
allograft.
Stability
is,
however,
affected
by
implant
dimensions,
implant
site,
and
bone
density.

 
 
 iv
 
 PREFACE

The
Clinical
Research
Ethics
Board
(the
University
of
British
Columbia)
approved
the
present
study
(Approval
number
H10‐00464).

 
 v
 
 TABLE
OF
CONTENTS
 Table
of
Contents
 ABSTRACT ..................................................................................................................................ii
 PREFACE ....................................................................................................................................iv
 TABLE
OF
CONTENTS.............................................................................................................. v
 LIST
OF
TABLES .................................................................................................................... viii
 LIST
OF
FIGURES .....................................................................................................................ix
 LIST
OF
ILLUSTRATIONS ......................................................................................................xi
 ACKNOWLEDGEMENTS ....................................................................................................... xii
 1.
INTRODUCTION ...................................................................................................................1
 2.
REVIEW
OF
THE
LITERATURE.........................................................................................3
 2.1
Measurement
of
Implant
Stability ....................................................................................... 3
2.1.1
Radiography ...........................................................................................................................................4
2.1.2
Insertion
torque....................................................................................................................................4
2.1.3
Reverse
and
removal
torque...........................................................................................................5
2.1.5
Percussion...............................................................................................................................................5
2.1.6
Damping
capacity
assessment........................................................................................................6
2.1.7
Pulsed
oscillation
waveform...........................................................................................................7
2.1.8
Resonance
frequency
analysis
(RFA) ..........................................................................................7
 2.2
Agreement
Between
RFA
and
Other
Measurement
Techniques .............................12
2.2.1
RFA
versus
histology ....................................................................................................................... 12
2.2.2
RFA
versus
insertion
torque ........................................................................................................ 15
2.2.3
RFA
versus
radiography ................................................................................................................ 17
2.2.4
RFA
versus
removal
torque.......................................................................................................... 18
2.2.5
RFA
versus
Periotest™ .................................................................................................................... 19
 2.3
Variables
Influencing
Implant
Stability
and
Resonance
Frequency ......................21
2.3.1
Transducer
orientation .................................................................................................................. 22
2.3.2
Bone
density........................................................................................................................................ 24
2.3.3
Implant
site.......................................................................................................................................... 27
2.3.4
Bone
quantity
and
effective
implant
length .......................................................................... 30
2.3.5
Healing
time ........................................................................................................................................ 33
2.3.6
Patient
characteristics:
age,
gender,
and
nicotine .............................................................. 37
2.3.7
Implant
dimensions ......................................................................................................................... 39
2.3.8
Implant
geometry
and
surface
characteristics..................................................................... 42
2.3.9
Implant
design.................................................................................................................................... 46
 2.4
Clinical
Use
of
Resonance
Frequency
Analysis ..............................................................50
2.4.1
Immediately
placed
implants ...................................................................................................... 51
2.4.2
Immediate
and
early
loading ....................................................................................................... 52
2.4.3
Sinus
augmentation ......................................................................................................................... 56
 
 vi
 2.4.4
Guided
bone
regeneration ............................................................................................................ 58
2.4.5
Predictive
value
of
RFA .................................................................................................................. 60
 3.
OBJECTIVES ........................................................................................................................ 67
 4.
MATERIALS
AND
METHODS.......................................................................................... 68
 5.
RESULTS .............................................................................................................................. 71
 5.1
Population
and
Implant
Distribution ...............................................................................71
 5.2
Osstell­Related
Factors..........................................................................................................72
5.2.1
Orientation
of
transducer.............................................................................................................. 72
5.2.2
Repeatability
of
measurements .................................................................................................. 74
 5.3
Patient­Related
Factors.........................................................................................................74
5.3.1
Patient
age............................................................................................................................................ 74
5.3.2
Patient
gender .................................................................................................................................... 75
5.3.3
Diabetic
status .................................................................................................................................... 76
5.3.4
Smoking
status ................................................................................................................................... 76
 5.4
Implant
Design­Related
Factors .........................................................................................77
5.4.1
Implant
system................................................................................................................................... 77
5.4.2
Implant
dimensions
‐
length ........................................................................................................ 81
5.4.3
Implant
dimensions
‐
diameter................................................................................................... 85
5.4.4
Implant
dimensions
‐
surface
area ............................................................................................ 88
 5.5
Implant
Placement­Related
Factors..................................................................................89
5.5.1
Insertion
torque
value .................................................................................................................... 89
5.5.2
Bone
density........................................................................................................................................ 90
5.5.3
Number
of
implants ......................................................................................................................... 91
 5.6
Anatomic
Site­Related
Factors............................................................................................92
5.6.1
Arch......................................................................................................................................................... 92
5.6.2
Location
in
arch ................................................................................................................................. 92
 5.7
Bone
Grafting­Related
Factors............................................................................................97
5.7.1
Lateral
ridge
augmentation .......................................................................................................... 98
5.7.2
Socket
preservation .......................................................................................................................102
5.7.3
Sinus
lift...............................................................................................................................................104
5.7.4
Presence
of
dehiscence
at
implant
placement ...................................................................106
 5.8
Factors
Related
to
Timing
of
Implant
Placement ...................................................... 108
5.8.1
Healing
time ......................................................................................................................................108
5.8.2
Immediate
placement ...................................................................................................................108
5.8.3
Staging
protocol...............................................................................................................................109
 5.9
Level
of
Training
of
the
Surgeon ..................................................................................... 110
 5.10
Linear
Multiple
Regression
Coefficients .................................................................... 110
 6.
DISCUSSION ......................................................................................................................111
 6.1
Osstell­Related
Factors....................................................................................................... 111
6.1.1
Direction
of
measurement ..........................................................................................................111
6.1.2
Repeatability
of
measurements ................................................................................................112
 6.2
Patient­Related
Factors...................................................................................................... 112
6.2.1
Age
and
gender ................................................................................................................................112
6.2.2
Diabetic
status ..................................................................................................................................113
6.2.3
Smoking
status .................................................................................................................................113
 6.3
Implant
Design­Related
Factors ...................................................................................... 114
6.3.1
Implant
type ......................................................................................................................................114
6.3.2
Implant
dimensions .......................................................................................................................114
 
 vii
 6.4
Implant
Placement­Related
Factors............................................................................... 116
6.4.1
Insertion
torque
value ..................................................................................................................116
6.4.2
Bone
density......................................................................................................................................117
6.4.3
Number
of
implants .......................................................................................................................117
 6.5
Anatomic
Site­Related
Factors......................................................................................... 118
6.5.1
Arch
and
location
in
arch.............................................................................................................118
 6.6
Bone
Grafting­Related
Factors......................................................................................... 119
6.6.1
Guided
bone
regeneration ..........................................................................................................119
6.6.2
Sinus
lift...............................................................................................................................................120
6.6.3
Presence
of
buccal
dehiscence
at
implant
placement .....................................................120
 6.7
Factors
Related
to
Implant
Timing................................................................................. 121
6.7.1
Immediate
placement ...................................................................................................................121
 6.8
Experience
of
Surgeon ........................................................................................................ 122
 6.9
Prediction
of
Failure............................................................................................................ 122
 6.10
Limitations
of
Study .......................................................................................................... 125
 7.
CONCLUSION ....................................................................................................................126
 BIBLIOGRAPHY....................................................................................................................127
 APPENDIX
1 ..........................................................................................................................146


 
 
 viii
 LIST
OF
TABLES

 Table
1.
Distribution
and
mean
ISQ
for
types
of
implants
placed…………………………78
 Table
2.
Surface
area
specifications
of
Nobel
Active
implants…………………………….146
 Table
3.
Surface
area
specifications
of
Nobel
Replace
Straight
Groovy
implants…146
 Table
4.
Surface
area
specifications
of
Nobel
Replace
Tapered
Groovy
implant….147

 
 ix
 LIST
OF
FIGURES
 Figure
1.
Distribution
of
implants………………………………………………………………………71
 Figure
2.
ISQ
values
for
measurements
taken
from
the
buccal,
lingual,
mesial,
and
distal…………………………………………………………………………………………………………………73
 Figure
3.
ISQ
values
for
measurements
taken
from
the
buccal/lingual
and
mesial/distal……………………………………………………………………………………………………..73
 Figure
4.
Distribution
of
age
groups…………………………………………………………………..74
 Figure
5.
Distribution
of
patients
according
to
gender……………………..…………………75
Figure
6.
Distribution
of
implants
according
to
gender………………………………………..75
 Figure
7.
ISQ
depending
on
diabetic
status
of
patient
(patient‐level
analysis)………76
 Figure
8.
ISQ
depending
on
smoking
status
of
patient
(patient‐level
analysis)……..77
 Figure
9.
Distribution
of
implants
according
to
implant
system…………………………..78
 Figure
10.
ISQ
values
for
each
implant
type
placed……………………………………………..79
 Figure
11.
Mean
ISQ
for
Nobel
Biocare,
Straumann,
and
Astra
Tech
implants………80
 Figure
12.
Mean
ISQ
values
for
Straumann
SP
and
Straumann
BL
implants…….……80
 Figure
13.
Distribution
of
implants
according
to
implant
length………………………….81
 Figure
14.
ISQ
of
implants
based
on
length…………………………………………………………81
 Figure
15.
ISQ
of
maxillary
implants
based
on
length………………………………………….82
 Figure
16.
ISQ
of
mandibular
implants
based
on
length………………………………………83
 Figure
17.
ISQ
of
short
implants
(<10mm)
placed
in
the
maxilla
and
mandible……84
 Figure
18.
Mean
ISQ
of
short
implants
placed
in
anterior
or
posterior
sites…………84
 Figure
19.
ISQ
according
to
implant
diameter……………………………………………………..86
 Figure
20:
Distribution
of
implants
according
to
diameter…………………………………..86
 Figure
21:

Maxillary
ISQ
values
according
to
implant
diameter…………………………..87
 Figure
22:

Mandibular
ISQ
according
to
implant
diameter………………………………….87
 Figure
23.
Mean
ISQ
for
Nobel
Active
implants,
compared
with
all
other
Nobel
Biocare
implants………………………………………………………………………………………………..88
 Figure
24:
ISQ
according
to
implant
surface
area
(Nobel
Biocare
implants
only)….89
 Figure
25:
ISQ
of
implants
based
on
insertion
torque
(Ncm)……………………………….90
 Figure
26.
ISQ
of
implants
based
on
bone
density……………………………………………….91
 Figure
27.
ISQ
according
to
arch
(maxilla
or
mandible)……………………………………….92
 Figure
28.
ISQ
according
to
implant
site……………………………………………………………..93
 Figure
29.
ISQ
according
to
implant
site
in
the
mandible
only……………………………..94
 Figure
30.
ISQ
according
to
implant
site
in
the
maxilla
only………………………………...94
 Figure
31.
ISQ
value
for
incisor
implants
placed
in
the
maxilla
and
mandible………95
 Figure
32.
ISQ
value
for
canine
implants
placed
in
the
maxilla
and
mandible……….96
 Figure
33.
ISQ
value
for
premolar
implants
placed
in
the
maxilla
and
mandible…...96
 Figure
34.
ISQ
value
for
molar
implants
placed
in
the
maxilla
and
mandible………..97
 Figure
35.
Mean
ISQ
of
implants
placed
in
native
bone,
compared
to
those
placed
at
sites
treated
with
GBR………………………………………………………………………………………..98
 Figure
36.
ISQ
based
on
whether
or
not
the
site
was
treated
with
lateral
ridge
augmentation…………………………………………………………………………………………………….99
 
 x
 Figure
37.
Buccal
ISQ
based
on
whether
or
not
the
site
was
treated
with
lateral
ridge
augmentation…………………………………………………………………………………………..99
 Figure
38.
ISQ
based
on
type
of
lateral
ridge
augmentation
material
used…………100
 Figure
39.
ISQ
based
on
timing
of
lateral
ridge
augmentation……………………………101
 Figure
40.
Buccal
ISQ
based
on
timing
of
lateral
ridge
augmentation…………………102
 Figure
41.
ISQ
based
on
whether
or
not
socket
preservation
was
performed…….103
 Figure
42.
ISQ
based
on
socket
preservation
material
used……………………………….103
 Figure
43.
ISQ
based
on
timing
of
socket
preservation………………………………………104
 Figure
44.
ISQ
based
on
whether
or
not
sinus
lift
was
performed………………………105
 Figure
45.
ISQ
based
on
sinus
graft
material…………………………………………………….105
 Figure
46.
ISQ
based
on
sinus
graft
timing……………………………………………………….106
 Figure
47.
Overall
ISQ
based
on
presence
and
size
of
buccal
dehiscence……………107
 Figure
48.
Buccal
ISQ
based
on
presence
and
size
of
buccal
dehiscence…………….107
 Figure
49.
Scatter
plot
demonstrating
no
consistent
pattern
between
the
overall
ISQ
value
and
the
months
of
implant
healing
prior
to
measurement
of
the
ISQ…………108
 Figure
50.
ISQ
based
on
placement
timing………………………………………………………..109
 Figure
51.
ISQ
based
on
placement
protocol…………………………………………………….110



 
 xi
 LIST
OF
ILLUSTRATIONS

 
 Illustration
1.
Box
plot
representation………………………………………………………………70
 Illustration
2:
Implants
at
sites
32
and
42,
with
advanced
bone
loss
at
42…………123
 Illustration
3:
Circumferential
bone
loss
at
site
45…………………………………………...123
 
 xii
 ACKNOWLEDGEMENTS
 
I
would
like
to
thank
my
thesis
committee,
Dr.
Tassos
Irinakis,
Dr.
Chris
Wyatt
and
Dr.
Colin
Wiebe,
for
their
time
commitment
and
guidance
in
the
production
of
this
document,
and
Dr.
Jolanta
Aleksejuniene
for
her
indispensable
assistance
with
statistical
analysis.
A
special
thank
you,
as
well,
to
my
husband
Mike
Tuckey,
who
has
supported
me
during
many
more
years
of
education
than
was
ever
anticipated.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1
 1.
INTRODUCTION
Dental
implants
are
a
common
treatment
option
to
replace
missing
teeth
and
have
been
shown
to
have
a
high
degree
of
predictability
and
clinical
success.
One
of
the
key
factors
in
implant
success
is
achieving
osseointegration
with
the
surrounding
bone1,
2.
Establishment
of
osseointegration
relates
to
the
stability
of
implants,
since
stable
implants
have
been
shown
to
have
increasing
bone‐to‐implant
contact
over
a
9‐month
period,
whereas
unstable
implants
showed
no
true
osseointegration3.
Several
methods
are
available
to
measure
implant
stability
clinically,
including
insertion
torque,
reverse
torque,
radiography,
percussion,
damping
capacity
assessment
and
resonance
frequency
analysis
(RFA).
RFA
is
a
relatively
new
technology
and
was
introduced
commercially
in
1994
as
the
Osstell
device.
Using
this
device,
the
implant
stability
is
reported
in
Implant
Stability
Quotient
(ISQ)
units.




For
successful
implant
therapy,
an
adequate
bone
volume
is
also
needed.
Exposed
implant
surfaces
can
increase
the
risk
of
recession,
thus
compromising
esthetics
and
making
proper
oral
hygiene
more
difficult1.
In
order
to
achieve
this,
bone
augmentation
may
be
performed
prior
to,
or
in
conjunction
with,
implant
placement.
A
variety
of
graft
materials
are
available
to
perform
bone
augmentation,
including
autogenous
bone,
allograft,
xenograft,
and
alloplast.


Very
few
studies
have
specifically
investigated
the
impact
of
bone
augmentation
on
implant
stability,
as
measured
by
RFA.
Further,
the
majority
of
the
studies
have
included
only
autogenous
bone
and
these
have
generally
reported
no
significant
difference
in
ISQ
from
non‐grafted
sites4‐6.
Bone
allograft
is
another
common
product
used
prior
to
implant
placement
but
no
studies
have
compared
ISQ
values
of
sites
grafted
with
bone
allograft
with
non‐grafted
sites.
The
primary
objective
of
the
present
study
was
to
measure
the
effect
of
bone
augmentation
using
bone
allograft
on
implant
stability
(ISQ
values).
Secondary
objectives
included
evaluation
 
 2
 of
other
clinical,
implant‐
or
patient‐related
factors,
which
may
impact
implant
stability,
as
measured
with
RFA.

 
 3
 2.
REVIEW
OF
THE
LITERATURE
 2.1
Measurement
of
Implant
Stability
Ostman
et
al
(2006)
7
defines
implant
stability
as
the
“capacity
to
withstand
loading
in
the
axial,
lateral,
and
rotational
directions.”
The
result
of
any
test
of
stability
therefore
depends
on
the
direction
in
which
the
force
is
applied8.
Resonance
frequency
analysis,
for
example,
reflects
the
lateral
stability,
which
is
thought
to
mimic
normal
bending
forces
on
dental
implants7.
In
contrast,
reverse
torque
is
a
measure
of
shear
force8.
Implant
stability
is
described
as
primary
or
secondary.
Primary
stability
relates
to
the
level
of
bone
contact9,
which
is
influenced
by
the
shape
of
the
implant,
the
surgical
technique,
and
the
quantity
and
quality
of
the
bone10‐12.
Bone
quality
involves
mechanical
physiologic
properties,
including
the
bone
density,
hardness,
and
stiffness,
as
well
as
the
bone’s
capacity
for
healing
and
regeneration10.
Secondary
stability
results
from
contact
of
woven
bone
and
then
lamellar
bone
with
the
implant9
and
is
affected
by
primary
stability,
bone
remodeling
and
implant
surface
characteristics12.
Secondary
stability
influences
the
time
of
functional
loading12
and
is
necessary
to
facilitate
stress
distribution
during
loading13.
Implant
stability
is
expected
to
be
at
its
lowest
several
weeks
after
implant
placement,
at
which
time
secondary
stability
begins
to
increase12.
The
healing
pattern,
however,
depends
on
many
factors
so
implant
stability
shows
considerable
inter‐individual
variation12.


Lioubavina‐Hack
et
al
(2006)
3
investigated
the
significance
of
initial
(primary)
stability
for
implant
osseointegration
in
the
mandibular
ramus
of
16
rats.
One
side
had
implant
placement
that
ensured
primary
stability
but
the
other
side
did
not
achieve
primary
stability
and
implants
were
easily
movable.
The
animals
were
sacrificed
at
1,
3,
6,
and
9
months
for
histometric
analysis.
The
stable
implants
showed
increasing
bone‐to‐implant
contact
(BIC)
over
the
observation
period,
from
28.1%
at
1
month
to
69.6%
at
9
months.
Although
peri‐implant
bone
formed
around
the
mobile
implants,
histology
showed
that
there
was
no
actual
osseointegration
of
 
 4
 the
implants.
The
results
indicated
that
achievement
of
primary
stability
is
essential
for
successful
osseointegration.
When
the
implants
did
not
have
primary
stability,
the
histologic
evaluation
showed
a
layer
of
connective
tissue
between
the
bone
and
implant.


Several
methods
have
been
used
to
measure
implant
stability
and
osseointegration
but
the
clinical
usefulness
of
many
testing
modalities
is
limited
due
to
their
destructive
or
technique‐sensitive
nature.
Some
methods
that
have
been
used,
either
in
experimental
studies
or
in
clinical
practice
are
the
pull‐out
or
push‐out
technique,
insertion
or
removal
torque,
radiography,
histology
and
histomorphometry,
percussion,
damping
capacity
assessment,
and
resonance
frequency
analysis.


 2.1.1
Radiography
Radiographs
are
often
used
pre‐operatively
to
assess
the
implant
site
and
post‐operatively
to
count
the
number
of
exposed
threads
above
the
bone
level14.
However,
radiography
has
unreliable
reproducibility
and
the
radiograph
must
be
taken
at
the
exact
same
angle
each
time
for
comparison15.
Standard
radiography
also
does
not
allow
assessment
of
the
3‐dimensional
structure
of
the
bone,
which
could
affect
implant
stability13,
15,
and
does
not
provide
information
on
demineralization
until
at
least
40%
of
the
bone
mineral
has
been
lost12.
Further,
buccal
bone
loss
is
likely
to
precede
mesiodistal
bone
loss
but
is
not
visible
on
standard
intraoral
radiographs12.

 2.1.2
Insertion
torque
Insertion
torque
has
also
been
used
to
quantify
bone
density16.
In
this
method,
the
torque
needed
to
thread
the
implant
site
or
place
a
self‐threading
implant
is
measured,
thus
providing
an
indication
of
the
site’s
capacity
for
primary
stability14.
While
this
method
provides
information
about
bone
density
and
is
simple
to
use
in
clinical
practice,
it
can
only
provide
information
at
the
time
of
implant
placement12.
 
 5
 
 2.1.3
Reverse
and
removal
torque
Reverse
torque
refers
to
the
application
of
torque
in
a
reverse
direction
at
the
time
of
abutment
connection,
to
ensure
a
minimum
level
of
stability
has
been
achieved14
and
to
provide
indirect
information
regarding
the
bone‐implant
contact
area12.
However,
measuring
reverse
torque
to
assess
osseointegration
is
potentially
quite
damaging
to
the
interface
between
the
implant
and
surrounding
bone17.
Rotational
mobility
may
indicate
incomplete
healing
of
the
bone
surrounding
the
implant,
rather
than
soft
tissue
encapsulation14.
Additionally,
the
threshold
torque
value
that
should
be
used
is
unclear
and
is
likely
to
depend
on
the
bone
density
and
implant‐related
factors12.


Removal
torque
is
an
invasive
test
used
in
research
and
refers
to
the
shear
force
needed
to
disrupt
the
bone‐implant
interface18.
Removal
torque
depends
on
the
bond
strength
between
the
implant
and
bone
and
also
on
the
geometry
and
size
of
the
implant,
meaning
that
comparisons
should
not
be
made
between
different
implant
designs
or
dimensions18.


There
are
a
number
of
less
invasive
tools
for
assessment
of
the
bone‐implant
interface.
Some
of
these
are
based
on
measurement
of
the
natural
frequency
of
a
system
in
resonance12.
The
displacement
of
the
system
can
be
initiated
by
steady‐state
waves
or
by
a
transient
impulse
force,
and
the
response
is
detected
and
used
to
evaluate
implant
mobility12.
Specific
techniques
include
percussion,
impact
hammer
methods
(Periotest
and
Dental
Mobility
Checker),
pulsed
oscillation
waveform,
and
resonance
frequency
analysis.


 2.1.5
Percussion
A
simple
clinical
tool
is
percussion
of
the
implant
to
listen
for
a
characteristic
sound
indicating
stability,
but
this
is
quite
subjective17
and
does
not
allow
discrimination
between
extremes
of
stability14.
In
this
method,
the
clinician
listens
for
a
clear
 
 6
 ringing
sound,
indicating
that
the
implant
has
osseointegrated
or
a
dull
sound
indicating
a
lack
of
osseointegration12.


 2.1.6
Damping
capacity
assessment
The
Periotest
(Siemens,
Bensheim,
Germany)
is
an
electronic
instrument,
which
was
designed
to
measure
mobility
of
natural
teeth.
In
this
method,
an
8
gram
rod
taps
the
implant
4
times
per
second
for
4
seconds19.
The
contact
time
of
the
slug
with
the
tooth
relates
to
the
tooth’s
mobility17.
Results
range
from
‐8
(indicating
stability)
to
+50
(indicating
mobility).
When
this
instrument
is
used
for
implants,
rather
than
natural
teeth,
values
typically
have
a
narrow
range
(for
example,
‐5
to
+5
for
ITI
implants)
13,
17.
The
low
Periotest
values
(PTV)
are
not
surprising,
given
the
stiffness
of
the
bone‐implant
interface
compared
with
the
periodontal
ligament
surrounding
a
tooth17.
Further,
the
difference
between
implants
placed
in
soft
and
dense
bone
has
been
shown
to
be
less
than
2
units18.
Meredith
and
others
have
discussed
how
the
Periotest
can
be
technique
sensitive,
with
differences
found
depending
on
the
position
and
angle
of
the
device,
the
height
of
the
abutment,
the
jaw
position,
and
the
distance
between
the
handpiece
and
the
implant15,
18,
20.
The
Periotest
has
been
widely
used
in
experimental
and
clinical
research
but
the
prognostic
value
has
not
been
determined20.
Negative
PTV
indicate
implant
stability,
whereas
high
positive
values
suggest
a
loss
of
stability
and
possible
bone
resorption.
Unfortunately,
PTV
changes
are
delayed
and
occur
once
clinical
changes
have
already
taken
place20.
The
sensitivity
of
PTV
is
therefore
quite
low
but
it
does
have
a
high
specificity20.
Clinical
usefulness
is
limited
to
repeated
measurements
of
a
given
implant
and,
considering
there
is
no
consensus
on
normal
values
and
a
range
of
PTV
likely
indicates
stability,
routine
use
of
the
Periotest
is
not
justified20.


Both
the
DMC
and
the
Periotest
are
impact
hammer
methods,
in
which
excitation
is
provided
by
an
impact
force
to
the
implant.
With
the
DMC,
the
transient
force
is
generated
by
impact
of
a
small
hammer
and
the
response
is
detected
by
a
 
 7
 microphone12.
It
is
possible,
however,
that
the
physical
contact
with
the
implant
could
damage
the
interface
and
interfere
with
osseointegration12.


 2.1.7
Pulsed
oscillation
waveform
Kaneco21‐23
has
described
another
non‐invasive
method
to
assess
the
bone‐implant
interface.
A
high
frequency
mechanical
vibration
is
transmitted
to
the
implant
through
a
transmucosal
piezoelectric
puncture
needle
and
the
resulting
resonance
is
measured
by
another
needle
and
displayed.
The
sensitivity
of
this
method,
however,
has
been
questioned17
and
it
is
likely
that
results
depend
on
the
direction
of
loading12,
18.

 2.1.8
Resonance
frequency
analysis
(RFA)
Clinical
use
of
resonance
frequency
was
developed
by
Neil
Meredith
and
Peter
Cawley
(http://www.osstell.com/about­us.aspx)
and
introduced,
in
relation
to
implant
stability,
by
Meredith
in
199424.
In
this
method,
a
stainless
steel
or
titanium
transducer
is
screwed
to
the
implant
fixture.
The
transducer
consists
of
a
beam
and
two
piezoceramic
elements.
A
computer‐generated
sinusoidal
signal
with
amplitude
of
1
volt
excites
one
of
the
elements,
which
causes
the
transducer
to
vibrate17.
An
extremely
small
bending
force
is
transferred
to
the
implant
in
order
to
mimic
conditions
of
clinical
loading8.
The
purpose
of
the
second
element
is
to
receive
and
measure
the
response
as
resonance
frequency
(RF)
17,
18.


Meredith
et
al
(1996)
17
used
the
following
equation
to
describe
the
variables
affecting
RF.
Based
on
the
equation,
it
was
expected
that,
with
a
transducer
of
constant
length,
bone
loss
or
an
increased
effective
implant
length
would
result
in
decreased
RF25.
The
stiffness
of
the
surrounding
bone
would
also
impact
the
RF,
with
lower
values
obtained
with
lower
stiffness25.
The
design
of
the
transducer
itself
is
the
third
factor
influencing
RF8
but

the
torque
with
which
the
transducer
is
attached
to
the
implant
fixture
has
been
shown
to
have
an
insignificant
effect
on
RF
values,
once
a
moderate
torque
has
been
reached25.
 
 8
 
 Rf:
resonance
frequency
(Hz)
 l:
effective
length
of
the
beam
 m:
mass
of
the
beam(g)
 E:
Young’s
modulus
(GNm‐2)
 I:
moment
of
inertia

The
potential
of
resonance
frequency
to
measure
changes
at
the
bone‐implant
interface
was
tested
by
Meredith
et
al
(1996)
17.
Nobelpharma
implants
of
various
lengths
(7,
8.5,
10,
15,
18,
and
20mm)
and
3.75mm
diameter
were
placed
in
an
aluminum
block
at
various
depths
to
examine
the
effect
of
changes
in
exposed
implant
height.
Resonance
frequency
was
measured
for
each
implant
and
was
repeated
5
times
for
3
implants
to
assess
repeatability.
Since
it
was
expected
that
there
would
be
a
difference
in
stiffness
of
the
system
depending
how
tightly
the
screws
were
placed,
an
electronic
torque
controller
was
used
to
compare
RF
at
different
torques
(10,
20,
32,
and
45Ncm).
To
assess
the
sensitivity
of
the
transducer
to
changes
in
stiffness,
an
implant
was
placed
in
a
hole
filled
with
polymethyl
methacrylate
(PMMA)
and
the
RF
was
measured
every
30
seconds
during
setting.
Clinical
use
was
also
assessed
by
measuring
the
RF
for
4
implants
in
one
patient.
It
appeared
that
the
length
of
the
fixture
had
no
effect
on
RF,
as
long
as
the
same
height
was
exposed
above
the
aluminum
block.
A
likely
explanation
for
this
finding
was
the
use
of
a
very
stiff
model
system
–
an
aluminum
block
with
an
epoxy
adhesive.
A
statistically
significant
difference
was,
however,
found
between
implants
of
the
same
length
placed
with
varying
heights
of
exposed
fixture.
Repeatability
was
better
than
1%
based
on
the
5
measurements
taken
for
each
of
3
implants.
The
experiment
with
PMMA
indicated
that
the
system
was
sensitive
to
changes
in
stiffness.
Results
from
the
torque
experiment
demonstrated
that,
as
long
as
a
torque
of
at
least
10Ncm
was
used,
the
RF
would
not
be
significantly
affected.
These
types
of
in
vitro
tests
are
simple
and
reproducible
ways
to
analyze
the
effect
 
 9
 of
a
change
in
system
stiffness;
however,
the
findings
are
not
entirely
transferable
to
bone8.

The
clinical
test
showed
that
the
procedure
was
well‐tolerated
but
the
values
were
lower
than
those
found
in
aluminum.


Disadvantages
of
this
first‐generation
RFA
system
included
the
high
cost
and
size/weight
of
the
instrument,
as
well
as
the
time
needed
to
perform
the
test
(over
1
minute)
8.
Heo
et
al
(1998)
26,
however,
noted
that
measurements
were
simple
and
quick,
taking
less
than
one
minute
to
attach,
measure
and
remove
the
transducer
for
each
implant.
The
second‐generation
RF
instruments
were
connected
to
a
computer,
which
programmed
the
frequencies
and
collected/stored
data.

Both
this
and
the
first‐generation
system
were
flawed
in
that
each
individual
transducer
had
a
different
resonance
frequency
and
the
machines
needed
to
be
calibrated
to
a
standard
prior
to
comparing
measurements8.
Adjustments
were
also
needed
for
implants
with
different
abutment
lengths
and
this
was
possible
since
there
was
a
linear
relationship
between
RF
and
abutment
length20.

The
third‐generation
system
(Osstell,
Integration
Diagnostics
AB,
Savedalen,
Sweden)
was
introduced
to
address
some
of
these
concerns.
This
device
was
designed
to
be
used
chair‐side,
avoiding
the
cumbersome
attachment
of
a
computer,
and
was
run
on
battery
power8.
Additionally,
Osstell
was
pre‐calibrated
by
the
manufacturer
to
provide
a
measurement
known
as
the
Implant
Stability
Quotient
(ISQ).
The
ISQ
values
are
based
on
the
stiffness
(N/µm)
of
the
system,
which
is
composed
of
the
transducer,
the
implant
and
the
bone,
and
on
the
calibration
of
the
transducer9.
The
ISQ
is
expressed
in
values
ranging
from
1
to
100,
with
a
value
of
1
indicating
the
lowest
stability
and
a
value
of
100
indicating
the
highest
stability8.
These
devices
are
available
with
transducers
adapted
for
various
implant
designs
so
that
ISQ
values
can
be
compared
among
systems8.
With
the
third‐generation
system,
it
is
still
possible
to
transfer
data
to
a
computer.


A
more
recent
version
(Osstell
Mentor)
is
magnetic
and
wireless.
With
this
device,
a
metal
peg
(rod),
with
a
magnet
at
its
top,
is
screwed
to
the
implant8.
Magnetic
pulses
 
 10
 are
sent
from
a
computer,
causing
this
Smart
Peg
to
vibrate
in
two
perpendicular
directions.
The
ISQ
is
reported
in
two
numbers
–
the
higher
number
represents
the
direction
that
resulted
in
the
highest
RF,
and
the
lower
number
represents
the
direction
that
gave
lowest
RF8.
Therefore,
if
bone
was
missing
on
one
side
of
the
implant,
application
of
the
vibrations
in
this
direction
should
lead
to
a
low
ISQ8.
The
newest
Osstell
device
is
called
the
Osstell
ISQ
Instrument.
According
to
the
manufacturer,
this
device
provides
a
faster
measurement,
a
more
attractive
design
and
reduced
sensitivity
to
electromagnetic
noise.
A
cow
rib
model
was
used
to
compare
RF
measurements
taken
with
the
Osstell
Mentor
and
the
Osstell
ISQ
devices27.
No
significant
difference
was
found
between
the
devices,
however
the
inter‐observer
reliability
was
poor,
meaning
repeated
measurements
should
be
performed
by
the
same
examiner.
This
likely
relates
to
differences
in
positioning
of
the
probe
or
tightness
of
the
Smartpeg27.
One
major
drawback
of
all
RFA
devices
is
that
they
cannot
be
used
on
cemented
restorations28.

Valderama
et
al
(2007)
29
conducted
a
clinical
trial
to
determine
whether
electronic
and
magnetic
RFA
devices
provided
similar
findings
and
whether
they
were
able
to
detect
changes
in
stability
during
healing.
Seventeen
patients
were
included
and
each
received
2
Straumann
implants.
ISQ
was
measured
at
the
time
of
implant
placement,
as
well
as
at
1,
2,
3,
4,
5,
6,
and
12
weeks.
Electronic
RFA
was
used
first
and
recordings
taken
in
triplicate.
The
Osstell
Mentor
was
then
used
and
three
measurements
were
taken
and
averaged.
Both
methods
were
found
to
detect
changes
in
stability
over
time
and
correlated
well
with
each
other.
On
average,
the
magnetic
ISQ
values
were
8‐12
units
higher
than
the
electronic
ISQ
values,
meaning
that
the
two
devices
should
not
be
directly
compared.
The
authors
proposed
that
the
difference
was
due
to
the
design
of
the
devices,
with
the
electronic
one
screwed
on
top
of
the
implant
and
the
peg
of
the
wireless
magnetic
device
screwed
inside
the
internal
hex
of
the
implant.
Electronic
RFA
had
less
variance
in
repeated
measurements
than
the
magnetic
device.
There
was
more
variability
in
measurements
at
earlier
time
points,
which
could
indicate
that
an
exact
value
is
difficult
to
obtain
when
the
stability
is
low,
or
that
there
is
learning
curve
for
the
 
 11
 examiners.
Alternately,
the
variance
could
indicate
that
the
implant
is
displaced
slightly
each
time
the
transducer
is
attached
and
tightened.
Increased
height
of
exposed
implant
above
the
marginal
bone
resulted
in
a
significantly
lower
ISQ
with
the
magnetic,
but
not
with
the
electronic,
device29.


Tözüm
et
al
(2010)
30
compared
three
devices
designed
to
assess
implant
stability
in
human
cadavers.
These
included
the
previous
RFA
with
cable
(Osstell),
Osstell
Mentor,
and
the
Periotest.
All
teeth
were
extracted
from
eight
dried
human
mandibles
and
thirty
11mm
long
tapered
implants
were
placed
into
the
premolar
sockets.
Circular
vertical
bone
defects
were
created
incrementally
(0‐5mm)
to
mimic
different
sized
areas
of
peri‐implant
bone
loss.
Osstell,
Osstell
Mentor,
and
Periotest
measurements
were
taken
after
implant
placement,
and
after
each
incremental
increase
in
defect
size
up
to
5mm.
ISQ
measurements
decreased
significantly
as
defect
size
was
increased,
meaning
that
both
RFA
devices
were
capable
of
detecting
peri‐implant
bone
loss.
The
Periotest
was
less
sensitive
to
detect
these
changes
and
could
not
distinguish
mobility
changes
for
2,
3,
and
4mm
defects.
The
three
devices
were
all
found
to
have
significant
correlation.
The
RFA
with
cable
consistently
showed
lower
ISQs
than
the
wireless
version.
The
overall
mean
ISQ
(including
defect
measurements)
found
with
cable
was
46.5
±
1,
compared
with
57.8
±
9
for
the
wireless
device.
It
is
important
to
acknowledge,
however,
that
these
results
were
obtained
in
non‐vital
cadaver
bone
and
vital
bone
may
produce
different
results.


A
synthetic
bone
model
was
used
to
measure
the
repeatability
of
measurements
taken
with
the
Osstell31.
Synthetic
jawbones
of
high
and
low
density
were
used
and
12
different
Brånemark
System
implants
(Nobel
Biocare,
Göteborg,
Sweden)
were
placed
in
each
type.
ISQ
values
were
measured
in
triplicate
and,
to
determine
if
there
were
differences
between
the
transducers,
the
tests
were
repeated
with
a
separate
transducer.
Once
these
transducers
were
sterilized,
the
measurements
were
repeated.
A
final
test
was
done
by
securing
various
abutments
on
the
fixtures
 
 12
 and
measuring
ISQ
at
the
abutment‐level.
The
transducers
were
found
to
be
interchangeable
and
the
sterilization
process
did
not
reduce
accuracy.
In
a
study
of
32
implants
placed
in
dry
human
mandibles32,
Osstell
measurements
were
repeated
by
1
examiner
at
2
separate
occasions
and
then
repeated
a
third
time
by
another
examiner
to
assess
intra‐
and
inter‐observer
reliability.
The
intra‐observer
reliability
was
fair‐to‐good
and
the
inter‐observer
reliability
was
between
fair‐to‐good
and
excellent.
Nedir
et
al
(2004)
33
calculated
the
repeatability
of
the
RFA
device
as
1.14%
with
38
repeat
measurements.
In
this
experiment,
84.2%
of
the
measurements
were
either
identical
or
within
1
ISQ
unit
and
only
5.3%
had
a
3‐unit
difference.
Reproducibility
was
also
investigated
by
Lachmann
et
al
(2006)
28,
who
placed
8
implants
into
blocks
of
bovine
bone
and
used
Osstell
to
determine
the
primary
stability.
Multiple
measurements,
taken
after
loosening
and
retightening
the
screws,
did
not
lead
to
significantly
different
values.
RF
measurements
were
about
1%
higher
when
a
torque
control
instrument
was
used
at
10
Ncm,
compared
to
hand
tightening,
but
this
was
considered
clinically
insignificant.
Reliability
of
the
Osstell
was
good
and
variations
in
repetitions
did
not
exceed
2%
of
the
overall
range
of
measurements.
Lachmann28
also
found
a
standard
deviation
below
2%
of
the
overall
mean,
when
implants
were
polymerized
into
acrylic
blocks.
This
is
similar
to
the
1%
difference
found
by
Meredith34,
Barewal9,
and
Nedir33.
 
 2.2
Agreement
Between
RFA
and
Other
Measurement
Techniques
With
all
these
possible
measurement
techniques,
many
studies
have
been
conducted
to
compare
results
and
assess
their
validity.
RFA
has
been
compared
with
histological
and
radiologic
findings,
as
well
as
insertion
or
removal
torque
and
the
Periotest.


 2.2.1
RFA
versus
histology
Inflammation
around
an
implant
eventually
leads
to
loss
of
peri‐implant
bone
and
osseointegration;
the
final
stage
in
this
process
of
peri‐implantitis
is
mobility,
which
 
 13
 corresponds
to
a
loss
of
direct
BIC35.
Histomorphometry
is
considered
to
be
the
‘gold
standard’
for
evaluating
BIC36.
While
some
studies
have
shown
a
correlation
between
ISQ
values
and
histological
BIC,
others
have
failed
to
find
such
a
correlation;
this
may
be
since
bone
stiffness
is
not
necessarily
reflective
of
the
BIC,
particularly
because
a
thin
layer
of
bone
may
not
contribute
significantly
to
implant
stability8.

Scarano
et
al
(2006)
37
found
a
significant
correlation
between
ISQ
and
BIC.
They
conducted
a
retrospective
histological
and
histomorphometrical
study
of
7
implants,
which
had
been
retrieved
after
6
months
for
various
reasons,
including
nerve
pathology,
psychological
reasons,
malalignment,
hygiene
problems,
and
restorative
difficulty.
All
were
stable
with
no
mobility
and
were
clinically
osseointegrated.
Osstell
was
used
to
determine
the
ISQ
and
then
implants
were
retrieved
with
a
5‐mm
trephine
bur
and
processed
for
histology.
Mean
reported
ISQ
ranged
from
69
to
81,
with
a
statistically
significant
positive
correlation
between
ISQ
and
BIC.
Histomorphometric
BIC
was
58.6%
in
one
implant
with
an
ISQ
of
69,
68.1%
for
three
implants
with
an
ISQ
of
71,
73.2%
in
one
implant
with
an
ISQ
of
74,
78.2%
for
one
implant
with
an
ISQ
of
79
and
87.5%
for
one
implant
with
an
ISQ
of
81.
In
2007,
Scarano
et
al35
again
compared
ISQ
(Osstell)
with
histological
findings
for
37
implants
that
were
removed,
this
time
due
to
failure.
The
mean
ISQ
for
these
failed
implants
was
37,
and
histological
evaluation
revealed
that
there
was
no
bone
in
close
contact
with
the
implants.
In
fact,
there
was
a
statistically
significant
correlation
between
the
ISQ
and
replacement
of
BIC
with
soft
tissue‐implant
contact.
Strnad
et
al
(2008)
38
followed
implants
placed
in
the
tibiae
of
3
dogs,
with
ISQ
values
(Osstell)
obtained
at
0,
1,
3,
9,
and
12
weeks,
before
sacrifice
for
histological
analysis.
The
BIC
and
ISQ
values
were
proportional
to
each
other
only
during
the
first
5
weeks
of
the
study.

Kunnekel
et
al
(2011)
39
determined
the
ISQ
for
10
implants
placed
in
goat
femurs,
either
tightly
or
with
a
lack
of
primary
stability.
The
distance
between
the
bone
and
implant
surface
was
measured
histomorphometrically
and
compared
to
the
 
 14
 resultant
ISQ
value.
A
negative
relationship
was
found,
with
the
ISQ
decreasing
as
the
implant
to
bone
distance
increased.
Implants
with
primary
stability
were
found
to
have
higher
ISQ
values
than
those
placed
without
primary
stability.

In
contrast
to
these
studies,
which
found
a
correlation
between
histological
findings
and
ISQ,
other
investigators
have
found
that
RFA
does
not
reflect
changes
in
histological
parameters.

Schliephake
et
al
(2006)
36
compared
ISQs
with
histomorphometric
data
(BIC
and
volume
density
of
peri‐implant
bone)
obtained
for
80
implants
placed
in
dogs.
There
was
no
significant
increase
in
ISQ
from
1
to
3
months,
despite
a
significant
increase
in
bone
volume
density
and
BIC
during
this
time.
The
authors
questioned
the
validity
of
RFA
and
concluded
that
caution
is
needed
when
using
RFA
to
determine
implant
stability.
Abrahamsson
et
al
(2009)
40
also
failed
to
find
correlations
between
histological
parameters
(BIC
and
bone
density)
and
ISQ
(Osstell),
for
160
implants
placed
in
the
premolar
region
of
20
dogs
and
followed
for
up
to
3
months.
When
interpreting
the
results
from
animal
studies,
it
is
important
to
consider
that,
whereas
rabbits
may
show
increased
stiffness
and
RF
values
over
time,
dog
mandibles
tend
to
have
higher
initial
stability
and
fewer
changes
over
time8.


Degidi
et
al
(2010)
41
failed
to
find
a
correlation
between
ISQ
(Osstell)
and
BIC
in
humans.
Sixteen
clinically
stable
implants
that
had
been
removed
from
the
posterior
mandible
during
the
first
4‐8
weeks
of
healing
were
assessed
histomorphometrically.
No
statistically
significant
correlation
was
found
between
ISQ
and
mineralized
BIC.
Proposed
reasons
for
the
lack
of
correlation
included
the
dynamic
nature
of
bone
healing
and
the
two‐dimensional
nature
of
histology.


Ito
et
al
(2008)
42
conducted
2
related
experiments
to
investigate
and
explain
the
reported
discrepancy
between
RFA
and
other
parameters
of
implant
stability.
In
a
simulation
experiment,
an
implant
was
placed
in
a
box
and
fixed
with
small
screws
at
different
heights.
RF
values
decreased
when
screws
were
loosened
at
the
neck,
but
not
the
middle
or
apical
regions,
of
the
implant.
A
second
experiment
was
 
 15
 conducted
in
the
tibiae
of
mini‐pigs
who
received
a
total
of
24
implants.
RF
of
each
implant
was
measured
and
the
animals
were
sacrificed
at
1,
2,
and
4
weeks
to
determine
BIC.
There
was
no
significant
correlation
between
overall
BIC
and
RF
values
but,
when
only
the
neck
of
the
implant
was
considered,
the
correlation
between
the
BIC
and
RF
values
was
stronger
(although
still
not
statistically
significant).
From
these
results,
it
was
concluded
that
RF
values
are
most
affected
by
the
BIC
in
the
neck
region
of
the
implant.


 2.2.2
RFA
versus
insertion
torque
The
relationship
between
cutting
torque
and
RF
was
investigated
by
Friberg
et
al
(1999)
16,
who
followed
maxillary
TiUnite
Brånemark
implants
up
to
1‐year.
There
was
a
significant
correlation
between
the
patient
mean
torque
and
RF
values,
but
only
for
the
upper/crestal
third
of
the
implant
and
only
for
the
initial
RF
readings.
Turkyilmaz
et
al
(2006)
43
also
found
a
significant
correlation
between
insertion
torque
and
RF
when
30
edentulous
patients
each
had
2
Brånemark
TiUnite
implants
placed
in
the
anterior
mandible.
The
mean
ISQ
(Osstell)
at
time
of
fixture
placement
was
74
and
there
was
a
statistically
significant
correlation
between
this
value
and
the
insertion
torque
(OsseoCare,
Nobel
Biocare
AB,
Göteborg,
Sweden).
Similarly,
Tözüm
et
al
(2008)
44
found
a
significant
correlation
when
the
ISQ
(Osstell
Mentor)
was
compared
to
maximum
insertion
torque
for
12
implants
placed
in
resin
models.
A
significant
correlation
was,
again,
found
with
the
wireless
Osstell,
when
Kahraman
et
al
(2009)
45
followed
42
implants
placed
in
13
subjects.


Becker
et
al
(2006)
46
found
that,
for
a
1‐unit
increase
in
insertion
torque,
the
baseline
ISQ
increased
by
0.3,
and
the
3‐month
ISQ
decreased
by
0.2.
In
other
words,
greater
insertion
torque
led
to
reduced
implant
stability
after
3
months.
They
suggested
that
this
may
be
due
to
pressure
necrosis
when
implants
are
overtightened
in
an
undersized
osteotomy
site.

Nkenke
et
al47
also
suggested
that
high
insertion
torque
might
cause
microfractures
or
pressure
necrosis
of
the
surrounding
bone
and
ultimately
lead
to
failure.
Al‐Nawas
et
al48
found
that
ISQ
 
 16
 values
at
time
of
fixture
placement
were
significantly
higher
for
successful
implants
but
this
was
not
reflected
in
the
insertion
torque
values.


Peri‐implant
bone
levels
were
compared
with
implant
stability
parameters
(RF
and
insertion
torque)
for
84
Neoss
implants
placed
immediately
after
extraction
of
mandibular
teeth
in
6
human
cadavers49.
A
statistically
significant
correlation
was
found
between
insertion
torque
(OsseoSet,
Nobel
Biocare
AB,
Göteborg,
Sweden)
and
RFA,
and
both
testing
modalities
were
sensitive
to
changing
marginal
bone
levels.


Several
studies
have
investigated
the
relationship
between
insertion
torque
and
RF,
with
bone
density,
as
determined
radiographically.
In
a
series
of
related
studies,
Turkyilmaz
et
al50‐52
found
significant
correlations
between
the
bone
density
(measured
on
CT
scans),
insertion
torque,
and
ISQ
(Osstell)
values.
In
contrast,
Akça
et
al
(2006)
53
conducted
a
study
of
Straumann
and
Astra
Tech
implants,
placed
in
human
cadaver
jaws,
and
found
that
the
correlation
between
insertion
torque
and
bone
parameters
(volume
and
micro‐architecture),
as
determined
using
micro‐computed
tomography,
was
greater
than
that
between
ISQ
and
the
bone
parameters.
It
was
suggested
that
insertion
torque
is
a
more
sensitive
test
than
RFA
when
considering
biomechanical
properties
of
the
bone‐implant
interface.

Some
investigators
have
found
no
significant
correlation
between
RFA
and
insertion
torque,
including
da
Cunha
et
al
(2004)
10
with
single
tooth
Brånemark
implants,
Çehreli
et
al
(2005
and
2009)
54,
55
with
2
human
cadaver
studies,
and
dos
Santos
et
al
(2009)
56,
who
sometimes
even
found
dichotomous
results,
depending
on
the
implant
design.
Karl
et
al
(2008)
57
questioned
the
utility
of
insertion
torque,
however,
since
most
implant
protocols
do
not
involve
bone
tapping.
Further,
the
insertion
torque
only
provides
information
at
the
time
of
implant
placement,
whereas
RFA
can
be
used
to
monitor
changes
in
implant
stability
over
time.

 
 17
 2.2.3
RFA
versus
radiography
For
comparisons
of
radiographic
parameters
and
ISQ
values,
the
reported
results
are
not
consistent.
Song
et
al
(2009)
58
found
strong
correlations
between
RFA
(Osstell
Mentor)
and
the
quality
and
thickness
of
the
compact
bone
(cone
beam
computed
tomography).
Roze
et
al
(2009)
59
also
found
a
correlation
between
RFA
and
cortical
bone
thickness,
but
no
other
parameters,
when
implants
placed
in
human
cadavers
were
analyzed
with
micro‐computed
tomography
(CT).
Cortical
thickness
was,
therefore,
suggested
as
an
important
factor
leading
to
implant
stability,
as
the
thickness
of
cortical
bone
was
significantly
higher
in
a
specimen
that
displayed
higher
ISQ
values.
In
a
preliminary
clinical
trial
of
10
patients60,
bone
density
(CT
scan),
ISQ
(Osstell
Mentor),
tactile
sense,
and
histological
measurements
of
bone
cores
were
obtained
for
23
implants.
There
was
a
significant
correlation
between
ISQ
and
tactile
sense
for
male
patients
and
between
ISQ
values,
trabecular
bone
volume,
and
tactile
sense
for
female
patients.
The
authors
concluded
that
CT
measurements
of
bone
density
(in
Hounsfield
units)
could
be
helpful
in
predicting
primary
stability,
prior
to
implant
placement.


Other
investigators
have
found
no
correlation
between
various
radiographic
parameters
and
ISQ
values.
Huwiler
et
al
(2007)
61
found
no
correlation
when
the
bone
volume
density
and
trabecular
nature
(micro
CT)
of
bone
cores
were
compared
to
RF
measurements
(Osstell)
taken
up
to
12
weeks.
Yang
et
al
(2008)
62
investigated
the
relationship
between
ISQ
values
and
bone
loss
during
early
healing
of
43
Nobel
Biocare
implant
in
19
patients.
RFA
measurements
were
taken
at
the
time
of
surgery
and
then
weekly
for
12
weeks.
Values
were
compared
to
findings
from
periapical
radiographs
taken
at
surgery,
and
at
4,
8,
and
12
weeks.
No
correlation
was
found
between
marginal
bone
loss
and
ISQ
changes.
Lachmann
et
al
(2006)
63
reported
that
the
change
in
bone
height
must
be
at
least
2mm
in
order
for
the
ISQ
to
show
significant
differences.
Since
the
marginal
bone
resorption
was
only
approximately
1.3mm
in
Yang’s
study,
it
is
not
surprising
that
no
statistically
significant
changes
were
found
in
the
ISQ
values.

 
 18
 2.2.4
RFA
versus
removal
torque
Removal
torque
measures
the
shear
strength
of
the
bone‐implant
interface
and
values
for
removal
torque
appear
to
vary
with
changes
in
implant
shape
and
topography64.
This
test
has
been
used
in
human
cadaver
or
animal
studies
and
is
sometimes
compared
to
RF
values.
While
the
relationship
between
these
two
tests
is
not
fully
understood,
RFA
provides
a
clear
advantage
in
that
it
is
non‐invasive
and
can
be
used
to
monitor
changes
in
stability
over
time64.


The
stability
of
implants
placed
in
rabbit
tibiae
was
monitored
using
RFA
and
removal
torque64.
There
was
no
statistically
significant
difference
in
either
test,
regardless
of
bone
coverage
of
the
implants.
The
inability
of
the
RFA
to
pick
up
on
the
newly
formed
bone
may
mean
that
the
bone
was
not
yet
supporting
the
implant.
The
authors
suggested
that
this
could
be
due
to
the
bone
not
contacting
the
implant,
to
the
immaturity
of
the
bone
or
to
the
magnitude
of
the
change
not
being
sufficient
to
be
registered
by
RFA.

In
other
animal
studies,
where
RFA
was
compared
to
removal
torque
and
histological
findings,
increases
in
RF
values
have
been
reflected
in
greater
bone
formation
at
the
bone‐implant
interface.
In
one
study,
Brånemark
implants
were
placed
bilaterally
in
the
tibiae
of
10
rabbits,
in
either
grafted
or
un‐grafted
sites65.
RF
measurements
were
taken
at
0,
4,
8,
16,
and
24
weeks
and
then
removal
torque
and
histomorphometric
analysis
were
performed.
Both
the
removal
torque
and
RF
values
were
higher
for
implants
placed
in
grafted
bone.
The
increase
in
stability
over
time
was
attributed
to
bone
formation
and
maturation
at
the
bone‐implant
interface,
as
was
observed
histologically.
In
a
similar
rabbit
study,
where
implants
were
placed
either
simultaneously
with
bone
grafting
or
after
8
weeks
of
healing66,
the
RF
values
for
delayed
implants
were
significantly
higher
at
all
times
but
the
removal
torque
showed
no
significant
difference.
Higher
RF
values
in
the
delayed
group
were
supported
by
the
histological
finding
of
greater
BIC
in
this
group,
at
the
coronal
part
of
the
implant,
which
appears
to
be
the
region
with
the
greatest
impact
 
 19
 on
RF.
The
difference
between
removal
torque
and
RFA
in
studies
such
as
these
has
been
attributed
to
the
fact
that
they
measure
different
parameters
‐
the
stiffness
of
the
bone‐implant
interface
under
bending
forces
for
RFA,
versus
the
shear
strength
of
this
interface
for
removal
torque65.


More
recent
studies
have
also
failed
to
find
a
correlation
between
removal
torque
and
RFA.
Akkocaoglu
et
al
(2005)
67
used
RFA,
as
well
as
insertion
and
removal
torques,
to
assess
the
stability
of
implants
placed
immediately
into
extraction
sockets
of
premolars
in
four
human
cadavers.
There
was
no
statistically
significant
correlation
between
ISQ
and
insertion
or
removal
torque.
These
same
parameters,
as
well
as
radiography
and
histomorphometry,
were
used
to
evaluate
the
stability
of
implants
placed
in
various
bones
of
fresh
human
cadavers68.
The
ISQ
values
were
similar
for
all
bones
but
differences
were
noted
for
insertion
and
removal
torques,
as
well
as
for
the
histomorphometric
and
radiographic
measurements,
meaning
that
the
RFA
was
not
as
sensitive
as
the
other
tests.
Brouwers
et
al
(2009)
32
compared
16
tapered
and
16
cylindrical
implants,
placed
in
dry
human
mandibles
and,
again,
found
a
significant
difference
in
removal
torque
but
not
ISQ.


 2.2.5
RFA
versus
Periotest™
Sakoh
et
al
(2006)
69
evaluated
the
primary
stability
of
implants
placed
in
fresh
porcine
iliac
bone
blocks,
using
various
placement
techniques.
Several
stability
tests
were
conducted,
including
insertion
torque,
Periotest,
RFA,
and
push‐out
testing
(applying
force
to
the
apical
end
of
the
implant
in
an
axial
direction).
A
significant
correlation
was
found
for
Periotest
and
insertion
torque
with
the
push‐out
test
but
no
correlation
was
found
between
RFA
and
the
push‐out
test.
Additionally,
RFA
and
Periotest
were
not
able
to
detect
differences
that
were
found
with
insertion
torque.
The
authors
speculated
that
the
inability
of
RFA
to
detect
differences
which
were
found
with
other
testing
modalities
could
be
due
to
the
fact
that
all
implants
had
sufficiently
high
primary
stability
and
RFA
is
not
sufficiently
sensitive
to
detect
such
small
differences.

 
 20
 
In
contrast,
Alsaadi
et
al
(2007)
70
found
a
significant
relationship
between
ISQ
(Osstell
Mentor),
Periotest,
and
bone
quality
assessment
(Lekholm
&
Zarb
index)
as
well
as
between
ISQ,
Periotest,
and
the
surgeons’
subjective
tactile
sensation.
Oh
et
al
(2009)
71
also
found
a
strong
association
between
the
Periotest
and
ISQ
(Osstell
Mentor),
when
48
implants
were
placed
in
the
posterior
jaws
of
4
dogs,
with
follow‐up
at
3
and
6
weeks.
The
rate
of
new
bone
formation
was
assessed
histologically
and
both
measurement
devices
were
found
to
be
effective
at
evaluating
the
level
of
osseointegration.
At
6
weeks,
the
ISQ
value
had
increased
and
the
PTV
had
decreased,
compared
to
the
3‐week
values
–
both
of
these
changes
indicate
that
the
measurement
devices
correlated
with
the
degree
of
osseointegration.
Nkenke
et
al
(2003)
72
found
a
higher
correlation
between
RFA
and
histomorphometric
parameters
than
between
the
Periostest
and
histomorphometry,
when
48
implants
were
placed
in
3
human
cadavers.
In
particular,
RFA
correlated
with
the
BIC
on
the
oral
aspect
and
with
the
height
of
the
cortical
crestal
bone
surrounding
the
implants.
However,
no
significant
differences
were
found
in
RF
values
between
the
maxilla
and
mandible,
despite
differences
found
for
Periotest.


Zix
et
al
(2008)
73
also
compared
the
ability
of
Periotest
and
RFA
to
measure
implant
stability.
Sixty‐five
edentulous
patients
received
213
Straumann
implants.
Osstell
and
Periotest
measurements
were
both
taken
in
triplicate.
The
average
ISQ
for
all
implants
was
57.7
(range
23‐73)
and
the
average
PTV
was
‐5.1
(range
+5
to
‐7.7).
The
two
parameters
showed
a
moderate
correlation
with
each
other.
The
Periotest
appeared
to
be
less
precise
than
the
Osstell,
likely
due
to
the
susceptibility
of
the
Periotest
to
technical
variables;
however,
the
authors
did
find
the
Periotest
to
be
less
expensive
and
easier
to
use
than
the
Osstell.
Lachmann
et
al
(2006)
63
placed
4
implants
in
each
of
2
blocks
of
bovine
bone
(class
2
and
3
bone)
and
found
a
statistically
significant
difference
in
mean
stability
between
the
blocks
and
a
good
correlation
between
the
Osstell
and
Periotest
values.
In
a
related
study28,
implants
were
polymerized
into
acrylic
blocks
and
material
was
removed
successively
around
the
implants
to
simulate
peri‐implant
bone
loss
of
0‐9mm.
The
results
 
 21
 obtained
with
the
Periotest
and
Osstell
devices
were
similar
and
showed
linear
correlation.
The
increasing
loss
of
implant
support
was
reflected
in
statistically
significant
changes
in
values
for
both
tests.
The
Osstell
was
more
precise
than
the
Periotest,
with
a
threshold
of
about
2‐3mm.
Merheb
et
al
(2010)
74
found
that
neither
test
was
very
sensitive
in
identifying
peri‐implant
bone
loss,
other
than
in
the
marginal
region.
Both
devices
were
able
to
detect
marginal
bone
loss
of
2mm
or
greater
during
staged
removal
of
bone
around
32
implants
in
6
human
cadavers.
Winter
et
al
(2010)
75
performed
a
simulated
experiment
(finite
element
analysis)
comparing
the
Osstell
Mentor
and
Periotest
and
found
that
values
correlated
when
no
bone
loss
was
present.


Considering
their
respective
drawbacks,
the
decision
about
whether
to
use
the
Periotest
or
RFA
could
be
based
on
the
potential
damage
caused
to
the
implant.
Seong
et
al
(2009)
76
found
that
repeated
use
of
the
Periotest
could
damage
the
bone‐implant
interface
of
implants
placed
in
jawbones
of
human
cadavers.
Six
RF
measurements
were
taken
for
each
implant
and
all
indicated
stable
measurements.
The
Periotest
was
then
used
9
times
for
each
implant
(3
times
from
the
BL,
MD,
and
axial
direction)
and
some
specimens
showed
values
indicating
increasing
mobility
as
measurements
were
repeated.
The
authors
caution
against
using
the
Periotest,
particularly
when
repeated
or
in
low‐quality
bone.


 2.3
Variables
Influencing
Implant
Stability
and
Resonance
Frequency
A
number
of
factors
have
been
found
to
influence
ISQ
values.
These
are
mainly
related
to
the
bone‐implant
interface,
the
distance
from
the
transducer
to
the
first
bone
contact,
and
the
orientation
of
the
transducer8.
RFA
is
also
affected
by
factors
such
as
the
characteristics
of
bone,
implant
morphology
and
implant
surface
treatments.
 
 
 22
 2.3.1
Transducer
orientation
Meredith
et
al
(1996)
77
found
that
RF
measurements
are
affected
by
the
orientation
of
the
transducer.
In
a
rabbit
study34,
RF
measurements
were
taken
in
both
parallel
and
perpendicular
directions.
Clearer
resonance
peaks
were
obtained
with
the
transducer
perpendicular
to
the
bone.
In
a
synthetic
bone
model,
Balshi
et
al
(2005)
31
also
found
that
the
orientation
of
the
transducer
influenced
the
recorded
ISQ
value.
Some
of
the
measurements
taken
perpendicular
to
the
ridge
resulted
in
higher
ISQ
readings
than
the
corresponding
measurements
taken
in
a
parallel
orientation.
For
this
reason,
the
authors
recommend
maintaining
the
same
orientation
for
all
measurements.


Kramer
et
al
(2005)
78
used
serial
ISQ
values
to
monitor
the
stability
of
implants.
ISQ
values
were
significantly
lower
when
the
transducer
was
used
in
a
bucco‐lingual
orientation,
compared
to
a
mesio‐distal
orientation.
In
the
bucco‐lingual
direction,
values
increased
from
66.0
at
implant
placement,
to
67.4
at
exposure,
to
72.1
by
12
months.
The
corresponding
values
for
the
mesio‐distal
direction
were
74.1,
75.4,
and
79.9.
The
orientation
of
the
transducer
was
found
to
have
a
large
influence
on
the
RF
values
measured
with
Osstell
in
a
guinea
pig
model79,
with
higher
RF
values
obtained
when
the
transducer
was
placed
parallel
to
the
long
axis
of
the
bone.
Capek
et
al
(2009)
80
used
finite
element
analysis
to
investigate
the
effect
of
transducer
orientation
on
RFA
values
obtained
with
Osstell.
Results
indicated
that,
if
RFA
measurements
are
taken
with
the
transducer
perpendicular
to
the
alveolar
crest,
ISQ
values
are
not
changed
significantly
by
a
rotation
of
less
than
30°,
and
the
first
resonance
frequency
is
obtained.
If,
however
the
rotation
is
between
30°
and
80°,
the
second
resonance
frequency
is
recorded.
Similarly,
if
a
parallel
orientation
is
used
then
the
deviation
must
be
less
than
10°.

The
effect
of
transducer
orientation
was
also
assessed
by
Veltri
et
al
(2007)
81,
by
measuring
the
ISQ
(Osstell)
of
55
clinically
stable
implants
from
the
buccal,
palatal,
mesial
and
distal.
Significant
differences
were
found
between
measurements
taken
 
 23
 with
a
perpendicular
or
parallel
orientation
but
no
significant
differences
were
found
between
buccal
(61)
and
palatal
(63),
or
between
mesial
and
distal
(both
71).
When
the
transducer
is
oriented
perpendicular
to
the
bone
crest,
ISQ
values
appear
to
be
up
to
8‐10
ISQ
units
lower
than
in
a
parallel
orientation.
As
such,
it
has
been
recommended
to
standardize
transducer
orientation
so
that
ISQ
values
can
be
compared.
Fischer
et
al
(2008)
82
also
found
a
difference
of
about
10
ISQ
units
‐
with
a
buccal‐palatal
(perpendicular)
transducer
orientation,
the
early
and
delayed
values
were
56.7
and
56.2
versus
with
a
mesial‐distal
(parallel)
orientation,
the
values
were
66.6
and
65.0.
It
was
suggested
that
the
lower
ISQ
value
in
the
buccal‐lingual
direction
was
due
thinner
bone
in
this
direction.


Park
et
al
(2010)
83
conducted
a
prospective
clinical
trial
to
determine
if
it
is
necessary
to
take
measurements
from
both
the
mesiodistal
and
buccolingual
directions
when
using
the
wireless
Osstell
Mentor.
Fifty‐three
patients
were
included,
and
received
71
implants
in
the
posterior
mandible.
Two
measurements
were
taken
from
each
direction
with
the
buccolingual
measurements
from
the
buccal
and
the
mesiodistal
measurements
from
the
mesial.
There
were
no
significant
differences
between
the
buccolingual
and
mesiodistal
measurements
but
there
were
significant
differences
between
the
ISQs
representing
the
higher
and
lower
values.
This
is
supported
by
the
claim
that
the
peg
vibration
in
this
system
is
equal
in
all
directions,
with
the
higher
and
lower
ISQ
values
representing
the
most
and
least
stable
directions8.
The
authors
discuss
the
advantage
of
having
both
the
upper
and
lower
values
with
the
Osstell
Mentor,
which
may
be
more
useful
to
detect
a
change
in
the
ISQ
pattern
compared
with
having
only
one
measurement.
Ohta
et
al
(2010)
84
also
investigated
the
effect
transducer
orientation
with
the
Osstell
Mentor,
using
a
pig
cortical
bone
model
and
6
measurements
for
each
implant
–
parallel,
perpendicular
and
at
45°
to
the
smart
peg,
as
well
as
parallel,
perpendicular
and
45°
to
the
long
axis
of
the
bone.
No
significant
differences
were
found
between
the
different
probe
orientations.
The
authors
discussed
the
limitations
of
the
model
system
used
and
indicated
that
the
shape
and
length
of
the
model
was
different
 
 24
 from
human
jaws.
Similarly,
Merheb
et
al74
found
no
significant
differences
between
measurements
taken
in
the
mesiodistal
and
buccolingual
directions,
using
the
Osstell
Mentor.
The
manufacturer,
however,
recommends
taking
2
measurements,
with
the
probe
perpendicular
and
parallel
to
the
jaw
line,
to
ensure
that
both
the
highest
and
lowest
stability
values
are
detected.

 2.3.2
Bone
density
Lekholm
&
Zarb
(1985)
85
define
type
I
bone
as
homogenous
compact
bone
occupying
nearly
the
entire
jaw.
Type
II
bone
has
a
thick
layer
of
compact
bone
surrounding
a
core
of
dense
trabecular
bone.
Type
III
bone
has
a
thin
layer
of
cortical
bone
surrounding
a
core
of
dense
trabecular
bone.
Type
IV
bone
has
a
thin
layer
of
cortical
bone
surrounding
a
core
of
low‐density
trabecular
bone.
Lower
success
rates
have
been
reported
for
implants
placed
in
type
IV
bone,
which
is
often
found
in
the
posterior
areas
of
the
jaws86.
In
a
prospective
human
clinical
trial,
Barewal
et
al
(2003)
9
placed
27
posterior
implants
in
20
patients
in
order
to
monitor
early
healing.
Bone
was
classified
according
to
Lekholm
and
Zarb;
30%
of
the
implants
were
placed
in
type
1,
37%
in
types
2
and
3
(combined
due
to
difficulty
distinguishing
the
types),
and
33%
in
type
4
bone.
RF
(Osstell)
was
measured
in
triplicate
at
placement,
1,
2,
3,
4,
5,
6,
8,
and
10
weeks.
The
lowest
mean
RF
value
was
obtained
at
3
weeks
for
implants
placed
in
all
types
of
bone
and,
at
this
time,
implants
placed
in
type
1
bone
were
significantly
more
stable
than
those
placed
in
type
4
bone.
Type
4
bone
had
the
largest
drop
(8.6%)
in
RF
value
from
baseline
to
3
weeks
but
this
was
followed
by
a
large
increase
from
3
to
10
weeks
(26.9%).
The
low
values
for
type
4
bone
were
not
surprising,
considering
that
most
of
the
implant
was
surrounded
by
low‐density
bone.
In
contrast,
there
were
no
significant
differences
in
stability
for
type
1
bone
at
any
point.
At
5
weeks,
there
were
no
longer
any
significant
differences
between
groups.


Balshi
et
al
(2005)
31
followed
344
immediately
loaded
Brånemark
implants
up
to
90
days
and
found
successful
osseointegration
with
all
4
bone
types.
Significantly
 
 25
 different
ISQ
values
were
obtained
between
types
2
and
3
and
between
types
3
and
4
bone
but
not
between
types
1
and
2
bone.
Type
1
bone
had
the
highest
initial
stability
but
also
had
the
biggest
decrease
over
the
first
30
days.
The
ISQ
of
type
2
bone
decreased
initially
and
then
returned
to
baseline
values
by
60
days.
For
type
3
bone,
the
return
to
baseline
values
took
90
days.
The
finding
that
implants
placed
in
different
bone
qualities
have
similar
RF
values
after
a
period
of
healing
supports
the
idea
that
an
extended
period
of
healing
is
beneficial
when
implants
are
placed
in
less
dense
bone86.
The
stability
of
implants
placed
in
the
anterior
mandible,
however,
has
been
shown
to
be
similar
over
time,
implying
that
maximal
stability
is
reached
at
the
time
of
fixture
placement
in
this
area87.


Sençimen
et
al
(2011)
88
used
CT
scanning
software
to
classify
bone
at
implant
sites.
ISQ
values
decreased
for
the
first
21
days
after
implant
placement,
but
by
60
days
were
shown
to
have
increased
to
the
initial
placement
values.
The
bone
density,
however,
did
not
appear
to
impact
the
ISQ
values
at
any
stage
up
to
60
days
post‐placement.

Friberg
et
al
(1999)
87
found
significantly
lower
initial
RF
values
for
implants
placed
in
soft
and
medium,
compared
to
dense
bone.
The
subsequent
measurements
(at
abutment
connection
and
1
year),
however,
showed
no
significant
differences
between
the
groups,
indicating
that
the
stability
of
all
implants
equalized
over
time,
regardless
of
bone
density
or
initial
stability.
Sennerby
et
al
(2010)
89
also
found
that,
despite
a
significant
correlation
between
bone
quality
and
ISQ
at
placement
and
abutment
connection,
there
was
no
longer
a
significant
difference
in
ISQ
for
different
bone
densities
at
1‐year.
Even
at
12
weeks,
Bischof
et
al90
no
longer
found
a
difference
in
stability
based
on
bone
density,
despite
differences
found
at
0,
1,
2,
4,
6,
8,
and
10
weeks.
This
was
supported
by
Sim
&
Lang
(2010)
91
who
longitudinally
monitored
the
stability
of
Straumann
implants
placed
in
the
posterior
jaws
of
32
patients.
Implants
placed
in
types
III
and
IV
bone
had
similar
ISQ
readings
(Osstell
Mentor),
which
were
significantly
lower
than
those
for
type
II
bone
at
0,
1,
2,
3,
4,
5,
6,
and
8
weeks.
At
the
end
of
the
study,
the
difference
was
no
longer
significant.
 
 26
 
Turkyilmaz
et
al
(2008)
92,
placed
300
implants
in
111
patients
and
evaluated
RF
at
implant
placement,
6
and
12
months.
Bone
density
was
assessed
from
CT
scans,
and
a
significant
correlation
was
found
with
ISQ
value.
In
a
similar
study,
Turkyilmaz
et
al
(2008)
52
again
found
a
statistically
significant
correlation
between
RF
and
bone
density.
Pre‐operative
CT
determination
of
bone
density
was
also
significantly
correlated
with
the
ISQ
of
24
implants
placed
in
human
cadaver
mandibles93.
Higher
ISQ
values
were
obtained
in
the
anterior
(mean
73.5),
compared
to
the
posterior
(mean
66.8)
and,
again,
this
correlated
with
mean
bone
density.


In
a
study
of
50
edentulous
subjects,
Miyamoto
et
al
(2005)
94
found
that
there
was
a
strong
linear
correlation
between
ISQ
values
(Osstell)
and
cortical
bone
thickness,
as
determined
from
pre‐operative
CT
scans.
The
correlation
between
implant
length
and
ISQ
was
weak,
indicating
that
the
effect
of
cortical
bone
thickness
is
greater
than
implant
length.
The
importance
of
preserving
the
cortical
bone
during
implant
site
preparation
was
further
demonstrated
by
Andrés‐Garcia
et
al
(2009)
95,
who
measured
the
primary
stability
(Osstell
Mentor)
of
implants
placed
in
15
cow
ribs
of
intermediate
bone
quality.
A
standard
drilling
protocol
was
used,
with
or
without
eliminating
the
cortical
bone
using
a
countersink.
Higher
ISQ
values
were
obtained
when
the
cortical
bone
was
maintained.


In
a
study
where
implants
were
placed
in
artificial
jawbone
models
with
different
values
of
elastic
modulus96,
Huang
et
al
found
that
the
elastic
modulus
of
trabecular
bone
influences
the
ISQ
(Osstell).
This
study
used
pig
rib
bone
of
two
different
densities,
combined
with
three
placement
techniques:
compaction,
self‐tapping
and
tapping.
ISQ
values
were
always
higher
in
type
1
bone
(thick
cortical
and
dense
cancellous
bone)
than
type
2
bone
(less
cortical
and
loose
cancellous
bone).
The
compaction
method
had
a
slightly,
but
not
statistically
significantly,
higher
mean
ISQ
value
than
self‐tapping.
The
lowest
values
were
obtained
with
tapping.
Finite
element
analysis
was
also
used
to
evaluate
the
effect
of
bone
quality
surrounding
the
implant,
and
demonstrated
higher
ISQ
values
with
greater
bone
density97.
Hsu
et
 
 27
 al
(2011)
98
placed
implants
in
synthetic
material
designed
to
mimic
bone
with
varying
cortical
thicknesses
and
trabecular
strength.
There
was
a
strong
correlation
between
the
cortical
thickness
and
the
ISQ
value,
as
well
as
the
elastic
modulus
of
the
trabecular
bone
and
the
ISQ
value.
The
authors
suggest
that
this
provides
an
argument
for
performing
bone
augmentation
to
increase
the
cortical
thickness.


 2.3.3
Implant
site
Regional
differences
in
stability
are
thought
to
be
due
to
differences
in
bone
density
and
ratios
of
cortical
to
trabecular
bone99.
In
a
study
of
27
implants,
Barewal
et
al
(2003)
9
found
that
mean
RF
values
were
higher
in
the
mandible
at
all
time
points
(0,
1,
2,
3,
4,
5,
6,
8,
and
10
weeks)
and
speculated
that
this
was
likely
due
to
the
higher
density
of
the
mandibular
bone.
In
fact,
no
maxillary
implants
were
placed
in
type
1
bone
and
40%
of
maxillary
implants
were
placed
in
type
4
bone
(compared
with
31%
in
the
mandible).
Balshi
et
al
(2005)
31
also
found
a
significantly
higher
mean
ISQ
for
implants
placed
in
the
mandible
at
all
time
points
(0,
30,
60,
and
90
days).
Becker
et
al
(2005)
100
and
Bogaerde
et
al
(2010)
101
found
a
slight
difference
in
ISQ
values
between
the
maxilla
and
the
mandible.
In
Becker’s
study100,
73
implants
(57
maxillary
and
16
mandibular)
were
placed
in
52
patients.
On
average,
the
primary
stability
was
4
ISQ
units
higher
in
the
mandible
versus
the
maxilla
but
the
difference
was
reduced
by
follow‐up.
No
significant
differences
were
found
for
anterior
compared
to
posterior
sites
at
either
time
point.


Bischof
et
al
(2004)
90
found
a
mean
initial
ISQ
value
of
59.8
for
mandibular
implants,
compared
with
55.0
for
maxillary,
indicating
a
significant
difference
between
the
jaws.
The
final
ISQ
measurements
were
taken
at
12
weeks
and
the
difference
between
mandibular
(63.9)
and
maxillary
(57.9)
implants
was
still
significant.
In
comparing
the
initial
and
12
week
values,
it
can
be
seen
that
the
increase
was
higher
for
the
mandible
(4.1)
than
the
maxilla
(1.9)
and
the
timing
of
the
increase
was
different
between
the
jaws;
for
maxillary
implants,
the
increase
was
moderate
and
became
significant
only
after
12
weeks
whereas
for
mandibular
 
 28
 implants,
the
stability
did
not
increase
much
over
the
first
4
weeks
but
showed
a
significant
increase
over
baseline
by
6
weeks.
Horwitz
et
al
(2007)
102
also
found
significantly
higher
secondary
stability
(12‐month
ISQ
value)
for
mandibular
implants
(70.2
versus
64.1).

The
ISQ
values
were
measured
for
905
Brånemark
implants,
placed
in
267
patients99.
The
mean
ISQ
was
higher
in
the
mandible
(71.4)
than
the
maxilla
(63.0),
which
was
attributed
to
the
lower
quantity
of
stiff
cortical
bone
in
the
maxilla.
Although
higher
ISQ
values
were
expected
in
the
anterior,
the
opposite
was
found,
with
higher
values
in
the
posterior
(68.7
versus
65.2).

However,
since
the
ISQ
was
higher
for
wide‐platform
implants
(73.1),
compared
to
regular‐
or
narrow‐platform
implants
(67.1),
the
difference
between
anterior
and
posterior
implants
was
attributed
to
placement
of
more
wide‐diameter
implants
in
the
posterior.

Miyamoto
et
al
(2005)
94
found
a
mean
ISQ
of
71.7
in
the
mandible
and
63.5
in
the
maxilla.
A
significant
difference
between
the
arches
was
also
found
by
Akca
et
al
(2006)
53,
when
6
Straumann
and
6
Astra
Tech
implants
were
placed
in
a
human
cadaver.
Mean
mandibular
ISQ
was
82.8,
versus
73.5
in
the
maxilla.
The
mean
ISQ
values
for
implants
placed
in
maxillary
incisor,
premolar,
and
molar
sites
were
81,
75,
and
73
for
Straumann
and
81,
69,
and
62
for
Astra
Tech
implants.
The
corresponding
values
for
the
mandible
were
81,
81,
and
83
for
Straumann
and
85,
86,
and
81
for
Astra
Tech
implants.


In
contrast,
Nkenke
et
al
(2003)
72
and
Alsaadi
et
al
(2007)
70
found
no
significant
differences
in
RF
values
between
the
maxilla
and
mandible.
In
one
study70,
the
mean
ISQ
values
(Osstell
Mentor)
at
placement
and
abutment
connection
were
67.8
and
72.0
in
the
maxilla,
and
72.2
and
69.5
in
the
mandible.
Although
many
studies
have
shown
that
the
ISQ
is
higher
in
the
mandible
during
the
early
healing
stages,
this
study
demonstrated
that
the
difference
decreases
during
the
osseointegration
process.
It
was
suggested
that
the
higher
marrow
content
in
the
maxilla
increases
bone
deposition70.
Roze
et
al
(2009)
59
also
found
no
significant
differences
whether
 
 29
 implants
were
placed
in
the
mandible
or
maxilla
but
ISQ
values
were
significantly
higher
for
the
posterior
region
of
both
arches
(mean
ISQ
63,
range
56‐65),
compared
with
the
anterior
(mean
ISQ
55,
range
51‐59).
Karl
et
al
(2008)
57
also
found
higher
values
in
the
posterior.
ISQ
(Osstell
Mentor)
was
determined
for
385
implants
(181
patients)
at
fixture
placement
and
after
a
period
of
healing
(at
least
12
weeks
in
the
maxilla
and
6
weeks
in
the
mandible).
The
highest
scores
were
obtained
in
the
posterior
mandible
(76.0
initially,
and
79.5
after
healing)
and
the
lowest
in
the
anterior
maxilla
(69.4
initially,
and
73.4
after
healing).

 
Other
studies
have
found
higher
ISQ
values
in
the
anterior.
Seong
et
al
(2008)
19
placed
28
implants
placed
in
4
human
cadavers
and
found
that
mandibular
implants
had
significantly
higher
initial
stability
(73.0
in
the
anterior
and
71.0
in
the
posterior)
than
maxillary
(66.5
in
the
anterior
and
53.4
in
the
posterior).
The
difference
between
anterior
and
posterior
values
was
only
significant
for
the
maxilla.
It
was
noted,
however,
that
all
cadavers
were
male,
with
a
mean
age
of
83
and
were
not
representative
of
the
population
as
a
whole.
Turkyilmaz
et
al
(2009)
49
evaluated
the
stability
of
84
implants
placed
in
6
human
cadavers.
Higher
ISQ
values
were
obtained
in
the
anterior,
with
ISQ
values
being
about
10
units
higher
than
those
in
the
posterior.
Use
of
wider
implants
in
the
posterior
was
recommended
to
compensate
for
the
reduction
in
density.



Yamaguchi
et
al
(2008)
103
conducted
a
long‐term
evaluation
of
328
implants
placed
in
the
posterior
mandible
of
113
patients.
RF
measurements
(Osstell)
were
taken
every
year
for
10
years.
The
implant
success
rate
was
100%
over
the
follow‐up
period.
The
mean
ISQ
value
was
75.3
(range
66‐83),
indicating
good
stability.
No
significant
differences
in
the
pattern
of
ISQ
changes
were
detected
among
the
different
bone
qualities
or
quantities,
and
no
significant
differences
were
found
between
the
sides,
sites
(second
premolar,
first
molar,
or
second
molar)
or
genders.
Kahraman
et
al
(2009)
45
also
found
no
significant
difference
in
stability
between
anterior
and
posterior
regions.


 
 30
 2.3.4
Bone
quantity
and
effective
implant
length
Several
studies
have
used
in
vitro,
animal,
or
cadaver
studies
to
evaluate
changes
in
RF
values
associated
with
incremental
peri‐implant
defects.
Meredith
et
al
(1996)
77
placed
Nobelpharma
implants
in
each
tibia
of
a
rabbit,
such
that
they
engaged
only
one
cortex
and
left
threads
exposed
on
one
surface.
One
side
was
treated
with
a
membrane
as
an
attempt
to
enhance
new
bone
formation.
After
16
weeks
of
healing,
RF
measurements
were
taken
and
the
animals
were
sacrificed.
Histology
showed
a
thin
layer
of
mineralized
tissue
where
the
membrane
had
been
placed,
and
this
was
supported
clinically
by
a
lack
of
thread
exposure.
The
side
that
was
not
treated
with
the
membrane
had
threads
exposed
and
a
lower
RF
value,
indicating
that
RFA
was
useful
to
detect
this
difference.


Lachmann
et
al
(2006)
28
placed
Frialit
Synchro
implants
in
blocks
of
bovine
bone
and
created
incremental
marginal
bone
defects
around
each
implant.
The
reduction
in
stability
was
statistically
significant
but
not
linear.
The
particular
model
system
used
was
not
ideal
to
conduct
this
experiment,
however,
since
the
implants
were
not
osseointegrated
and
the
cortical
layer
was
removed
with
the
first
couple
of
millimeters
of
bone
removal.
Similar
results
were
obtained
when
implants
were
polymerized
into
acrylic
blocks
and
material
was
removed
successively
around
the
implants
to
simulate
peri‐implant
bone
loss
of
0‐9mm63.
The
increasing
loss
of
implant
support
was
reflected
in
statistically
significant
changes
in
RF
values,
with
a
threshold
of
about
2mm
for
machined
surface
Brånemark
implants
and
3mm
for
Frialit
2
Synchro
implants.


Detection
of
progressive
peri‐implant
support
loss
was
found
by
Tözüm
et
al44
when
12
Swiss
Plus
tapered,
screw‐type
micro‐textured
implants
were
placed
in
resin
models
with
incremental
defects
of
0‐5mm.
For
3.7mm
diameter
implants,
the
ISQ
dropped
progressively
from
72.6
at
baseline
to
69.8
with
a
1mm
defect
and
57.2
for
a
5mm
defect.
The
corresponding
decrease
for
4.8mm
implants
was
76.5
to
74.5
and
63.4.

 
 31
 
The
effect
of
buccolingual
bone
width
was
assessed
for
forty
implants
placed
in
acrylic
resin
models104.
Statistically
significant
decreases
in
ISQ
were
obtained
when
the
width
was
reduced.
Cautious
interpretation
of
the
results
was
advised
since
in
vivo
osseointegrated
implants
may
respond
differently
than
those
in
artificially
created
defects
in
acrylic44.


Rasmusson
et
al
(2001)
105
also
found
a
correlation
between
BIC
and
RF
values.
Mandibular
premolars
were
extracted
in
six
dogs
and
3
implants
were
placed
bilaterally.
One
side
had
buccal
defects
to
expose
3‐4
implant
threads
and
the
opposite
side
served
as
a
control.
RF
measurements
were
taken
at
the
time
of
implant
placement
and
4
months
later,
prior
to
sacrifice.
The
sides
with
defects
tended
to
have
a
lower
initial
stability
but
the
difference
was
not
statistically
significant.


Sennerby
et
al
(2005)
106
used
RFA,
radiography
and
histology
to
investigate
alterations
in
the
bone
tissue
and
implant
stability
that
occurred
in
response
to
peri‐implantitis.

Mandibular
premolars
were
extracted
in
4
dogs,
followed
by
placement
of
6
implants
in
each
dog.
After
3
months
of
healing,
peri‐implantitis
was
induced
using
cotton
ligatures.

Four
weeks
later,
the
dogs
were
treated
with
antibiotics
and
surgery
then
followed
for
an
additional
25
weeks,
at
which
time
biopsies
were
obtained.
A
linear
relationship
was
found
between
radiographic
findings
and
RF
values
taken
at
9
time
points,
from
ligature
placement
to
final
examination.
During
the
peri‐implantitis
period,
there
was
a
marked
loss
of
marginal
bone,
which
correlated
with
reduced
RF
values.
After
therapy,
there
was
an
increase
in
RF
values,
which
followed
histometric
measurements
indicating
re‐osseointegration.
Since
the
RF
value
is
determined
by
the
bone‐implant
interface
stiffness
and
the
distance
from
the
transducer
to
the
marginal
bone,
it
is
likely
that
most
of
the
change
in
RF
value
was
due
to
marginal
bone
loss
and
an
increase
in
the
effective
implant
length.
It
was
estimated
that
each
millimeter
of
bone
loss
resulted
in
an
RF
value
decrease
of
413
Hz.
The
authors
concluded
that
RFA
was
a
sensitive
technique
 
 32
 that
could
be
used
to
detect
even
small
changes
in
marginal
bone
level.
In
a
study
using
pig
mandibles,
Ohta
et
al
(2010)
84
found
significantly
lower
ISQ
readings
with
each
incremental
increase
in
defect
size;
the
average
ISQ
values
for
defects
measuring
0,
1,
2,
and
3mm
were
77.3,
72.6,
67.3,
and
63.0
respectively.

The
threshold
for
changes
in
RF
values
was
also
investigated
by
Merheb
et
al74.
Implants
(n=32)
were
placed
in
6
human
cadavers
and
randomly
assigned
to
different
types
of
bony
defects:
marginal
bone
loss,
peri‐apical
bone
loss,
and
constant
width
or
length
dehiscences.
Staged
bone
removal
was
done
with
repeated
Osstell
Mentor
measurements.
Significant
differences
were
found
after
2mm
of
marginal
bone
removal,
5mm
of
peri‐apical
bone
removal,
180°
of
bone
removal
around
the
perimeter
of
6‐mm
long
dehiscences,
and
10mm
of
bone
removal
for
3‐mm
wide
dehiscences.
The
authors
concluded
that
the
Osstell
was
not
very
sensitive
in
identifying
peri‐implant
bone
loss,
other
than
in
the
marginal
region,
where
it
was
able
to
detect
marginal
bone
loss
of
2mm
or
greater.


Similar
studies
in
human
cadavers
support
the
sensitivity
of
ISQ
to
detect
changes
in
peri‐implant
bone
level.
For
placement
of
Neoss
implants
at
depths
of
1‐5mm,
Turkyilmaz
et
al
(2009)
49
found
a
marked
decrease
in
ISQ
(about
2.7
ISQ
units
per
mm).
This
sensitivity
to
changing
marginal
bone
levels
is
supported
by
manufacturer
information
that
claims
that
a
change
of
3
ISQ/mm
is
expected
if
implants
are
placed
in
the
same
bone
density.
Tözüm
et
al
(2010)
107
placed
30
MIS
implants
in
fresh
premolar
extraction
sockets
of
dried
human
mandibles.
Circular
vertical
bone
defects
were
created
incrementally
(0‐5mm)
to
mimic
different
sized
areas
of
peri‐implant
bone
loss.
ISQ
measurements,
taken
with
both
Osstell
and
Osstell
Mentor,
decreased
significantly
as
defect
size
was
increased,
meaning
that
both
RFA
devices
were
capable
of
detecting
peri‐implant
bone
loss.


For
implants
placed
in
human
jaws,
Tözüm
et
al
(2008)
107
found
a
consistently
negative
correlation
between
RF
values
(Osstell)
and
marginal
bone
level
changes.
Similarly,
Turkyilmaz
et
al
(2006)
108
found
a
statistically
significant
correlation
 
 33
 between
stability
and
marginal
bone
resorption
from
baseline
to
6
months,
but
not
from
6
to
12
months.
During
the
first
6
months,
the
decrease
in
ISQ
value
was
due
to
a
loss
of
marginal
bone
and
an
increase
in
effective
implant
length.
After
6
months,
bone
formation
appeared
to
balance
out
the
loss
of
stability
due
to
marginal
bone
loss.

Within
the
limitations
of
these
studies,
it
appeared
that
the
Osstell
devices
were
suitable
to
assess
implant
stability
and
decreased
values
were
likely
to
indicate
progressive
peri‐implant
defects.

 
 2.3.5
Healing
time
In
general,
a
high
ISQ
over
time
indicates
maintenance
of
stability,
and
a
reduction
in
ISQ
indicates
a
loss
of
implant
stability.
In
1994,
Meredith
et
al24
used
RF
to
measure
the
integration
between
implants
and
surrounding
bone.
Titanium
implants
were
placed
in
the
tibiae
of
12
rabbits
and
monitored
with
the
device
at
1,
2,
3,
4,
8,
and
12
weeks.
An
initial
decrease
from
baseline
to
1
week
was
noted,
followed
by
a
progressive
mean
increase
of
1.5
kHz
throughout
the
healing
period.
The
initial
decrease
in
stability,
after
implant
placement,
could
have
been
due
to
lateral
compression
of
the
surrounding
bone
which
may
have
caused
microfractures
or
elastic
adaptation,
remodeling
which
reduced
the
stiffness
of
the
implant‐bone
interface,
or
crestal
bone
loss
or
dehiscences
which
increased
the
effective
implant
length109.
According
to
Meredith18,
primary
stability
is
affected
mainly
by
the
BIC
and
compressive
stresses
of
the
bone‐implant
interface.
Some
degree
of
stress
is
beneficial
to
compress
the
bone
surrounding
the
implant
but,
with
excessive
force,
necrosis
and
ischemia
of
bone
can
occur.


Friberg
et
al
(1999)
16
found
the
largest
increase
in
mean
RF
value
over
time
for
implants
with
low
initial
RF
values.
Similarly,
Cornelini
et
al
(2004)
110
concluded
that,
when
good
primary
stability
is
achieved,
there
is
no
further
significant
increase
during
the
period
of
osseointegration.
In
2005,
Sjöström
et
al6
found
that,
while
implants
with
a
low
initial
ISQ
tended
to
increase
in
stability
over
time,
those
with
a
high
initial
stability
showed
decreasing
ISQ
values.
In
a
multi‐center
prospective
 
 34
 clinical
trial
of
52
patients100,
73
implants
were
placed
immediately
following
extraction.
Implants
with
a
higher
initial
ISQ
had
a
slight
decrease
over
time,
whereas
those
with
an
initial
ISQ
<60
increased.
The
reduction
in
ISQ
for
implants
with
an
initially
high
stability
may
relate
to
mechanical
relaxation
and
possibly
bone
resorption
since
it
is
likely
that
these
implants
were
placed
at
high
torque
values.
These
findings
support
the
idea
that
all
implants
eventually
reach
a
similar
level
of
stability,
regardless
of
the
primary
stability.


Balshi
et
al
(2005)
31
investigated
the
stability
of
276
immediately
loaded
Brånemark
implants.
ISQ
values
indicated
a
decrease
in
mean
stability
during
the
first
month,
from
70.4
at
implant
placement
to
66.4
at
30
days.
This
was
followed
by
an
increase
to
68.0
at
60
days
and
68.8
at
90
days.
Statistically
significant
differences
were
noted
from
baseline
to
30
days
and
from
30
to
60
days,
but
not
from
60
to
90
days.
In
general,
results
indicated
that
implants
with
high
initial
stability
do
not
necessarily
return
to
their
initial
values
after
a
decrease
in
the
early
healing
period.
In
contrast,
implants
placed
with
lower
primary
stability
tend
to
return
to,
or
even
exceed,
the
initial
values.
The
same
tendency
was
found
by
Veltri
et
al111,
who
took
RFA
measurements
repeatedly
for
50
Astra
Tech
implants
placed
in
8
edentulous
maxillas.
The
mean
ISQ
(Osstell)
values
at
second
surgery
(6
months),
and
1
and
3
years
were
65
(range
50‐78),
66
(range
53‐76),
and
64
(range
53‐77).
No
statistically
significant
differences
were
noted
between
the
time
points
but
this
was
likely
related
to
measuring
the
ISQ
only
at
second
stage
and
later
and
not
between
placement
and
second
stage,
when
the
greatest
changes
were
expected.
There
was
a
tendency
for
implants
with
a
lower
ISQ
value
at
second
surgery
to
show
an
increase
at
subsequent
follow‐up
appointments,
and
for
those
with
a
higher
initial
ISQ
value
to
show
a
decrease
over
time
but
this
was
not
statistically
significant.


Valderrama
et
al
(2007)
29
took
measurements
with
both
the
electronic
and
magnetic
RFA
devices.
Both
showed
a
similar
pattern
over
time,
with
an
initial
decrease
of
about
3
units
in
the
first
3‐4
weeks,
followed
by
a
gain
of
about
5
 
 35
 (electronic)
to
8
(magnetic)
units
by
12
weeks.
When
the
implants
with
higher
initial
ISQ
were
compared
with
implants
with
a
lower
initial
ISQ,
it
was
found
that
the
group
with
the
higher
initial
stability
showed
more
consistent
readings
with
fewer
fluctuations
between
time
points.
It
was
suggested
that
a
lower
initial
stability
could
indicate
a
higher
proportion
of
trabecular
bone,
which
will
remodel
more
quickly
than
dense
cortical
bone.
All
implants,
however
had
similar
ISQ
readings
by
12
weeks,
regardless
of
their
initial
ISQ.

An
initial
decrease
in
ISQ
after
placement
appears
to
be
a
common
finding.
For
example,
Froberg
et
al
(2006)
112
noted
a
decrease
in
mean
ISQ,
for
both
Turned
Brånemark
and
TiUnite
(Nobel
Biocare)
implants,
from
about
67
at
10
days
to
63
at
3
months.
This
was
followed
by
a
slight
increase
reaching
about
64
by
18
months.
Other
studies,
however,
have
detected
a
steady
increase
in
stability
over
time,
depending
upon
which
time
intervals
ISQ
measurements
were
obtained.
The
Neoss
implant
system
was
evaluated
by
following
218
micro‐rough
implants
up
to
1
year89.
Mean
ISQ
values
(Osstell
Mentor)
obtained
at
baseline,
abutment
connection,
and
1
year
were
73.7,
74.4,
and
76.7,
respectively.
There
was
a
statistically
significant
increase
from
baseline
and
abutment
connection
to
1‐year.
Bornstein
et
al
(2009)
113
presented
a
case
series
of
56
mandibular
Straumann
implants,
loaded
after
3
weeks.
The
mean
ISQ
at
placement
was
74.3
(range
57‐87).
The
ISQ
then
showed
significant
increases
over
baseline
at
all
time
points:
77.7
at
week
3
(range
49‐87);
77.9
at
week
4
(range
51‐86);
81.1
at
week
7
(range
70‐88);
82.2
at
week
12
(range
73‐89);
and
83.8
at
week
26
(range
72‐91).
A
decreasing
trend
was
not
found
in
the
early
healing
and
this
could
be
due
to
RFA
being
done
only
at
baseline
and
3
weeks.
In
a
study
of
32
Straumann
tissue‐level
implants91,
ISQ
values
were
found
to
increase
continuously
over
the
12‐week
period,
rising
from
an
average
of
65.1
at
surgical
placement
to
73.2
at
week
6
to
74.7
at
week
12.
Measurements
taken
at
weeks
6,
7,
and
12
were
significantly
higher
than
at
baseline.


Similar
patterns
of
ISQ
values
over
the
first
12
weeks
of
healing
were
found
by
Huwiler
et
al
(2007)
61
and
Han
et
al
(2010)
114
with
Straumann
implants.
RFA
 
 36
 (Osstell)
measurements
were
taken
for
24
Straumann
SLA
implants
and,
for
4.1mm
diameter
implants,
the
mean
initial
ISQ
was
61.4
(range
55‐74)
61.
The
mean
increased
at
1
week
(63.4)
then
decreased
to
59.6
at
2
weeks
and
reached
a
low
of
59.4
at
4
weeks.
The
value
then
increased
linearly
to
reach
63.8
after
12
weeks.
For
4.8mm
diameter
implants,
mean
initial
ISQ
was
63.3
(range
57‐70).
There
was
an
increase
at
1
week
(64.6),
then
a
decrease
at
2
and
3
weeks
reaching
a
low
of
59.1,
followed
by
an
increase
to
about
62.3
from
4‐6
weeks
and
to
67.9
by
12
weeks.
The
changes
in
ISQ
value
over
time
were
not
significant
for
either
diameter
implant.
Han
et
al
(2010)
114
placed
25
Straumann
implants
in
23
patients.
The
4.1mm
diameter
SLA
implants
had
a
mean
initial
ISQ
(Osstell
Mentor)
of
72.6
(range
64‐78),
which
then
decreased
to
a
low
of
69.9
at
3
weeks
and
70.2
at
4
weeks,
followed
by
a
steady
increase
to
75.2
by
8
weeks
and
76.5
by
12
weeks.
The
SLActive
implants
showed
a
similar
pattern,
with
an
mean
initial
ISQ
of
75.7
(range
65.3‐81.3),
a
low
of
71.4
at
3
weeks
and
an
increase
to
76.2
by
8
weeks
and
78.8
at
the
last
measurement.
Finally,
the
4.8mm
diameter
implants
had
an
initial
mean
ISQ
of
74.4
(range
65.3‐81.3),
which
decreased
to
69.8
at
3
weeks,
then
increased
to
76.9
at
8
week,
with
a
final
value
of
77.8.
Despite
the
consistency
in
the
pattern
of
change
in
ISQ
over
time
for
all
groups,
the
differences
over
time
were
not
statistically
significant
since
the
mean
ISQ
values
fell
within
the
range
of
initial
ISQ
values.
Because
of
the
initial
decrease
in
ISQ
at
3‐4
weeks
and
the
recovery
by
about
8
weeks,
the
authors
recommend
measuring
the
ISQ
at
the
time
of
surgery
as
well
as
at
3
weeks
and
8
weeks
to
monitor
implant
stability
and
tissue
integration.


ISQ
values
were
obtained
for
43
Nobel
Biocare
implants
in
19
patients
at
baseline,
and
at
4,
8,
and
12‐weeks62.
When
all
implants
were
considered,
the
corresponding
mean
ISQ
values
were
75.6,
75.7,
76.3,
and
76.8.
Although
the
mean
value
didn’t
change
significantly,
the
ISQ
in
the
maxilla
increased
significantly
from
4
to
12
weeks
(69.2
to
73.0).
Zix
et
al
(2005)
115
measured
the
RF
values
for
successfully
osseointegrated
ITI
implants
in
the
maxilla.
Implants
were
divided
into
3
stages
of
restoration:
those
which
were
unloaded
(n=41),
loaded
12
months
or
less
(n=31)
or
loaded
longer
than
12
months
(n=48).
All
implants
had
been
left
to
heal
for
at
least
3
 
 37
 months
before
loading.
The
mean
ISQ
for
all
implants
was
52.5
(range
40‐68)
and
there
was
no
significant
difference
between
the
3
groups.
The
mean
ISQ
for
the
unloaded
implants
was
48.8
and
those
for
implants
loaded
less
than
or
greater
than
12
months
were
54.1
and
53.1,
respectively.
These
results
indicate
that
loaded
implants
have
a
slightly
higher
ISQ
value
than
unloaded
implants.
The
value
of
52.5
should
not
be
used
to
represent
osseointegrated
implants,
however,
since
it
includes
measurements
taken
from
implants
in
the
early
stages
of
healing.
Farzad
et
al
(2004)
116
treated
34
patients
with
105
Brånemark
implants,
placed
in
mandibular
premolar
and
molar
sites.
These
implants
were
used
to
support
40
fixed
partial
dentures
(FPD)
and,
after
2‐6
years,
the
prostheses
were
removed
to
measure
the
RF.
Only
one
implant
didn’t
survive
to
follow‐up.
The
mean
ISQ
was
70.1
(range
59‐90),
indicating
good
stability
had
been
achieved
after
2‐6
years.
The
mean
ISQ
was
significantly
higher
when
FPDs
were
supported
by
3
implants
(70.9),
rather
than
2
implants
(67.9).


 2.3.6
Patient
characteristics:
age,
gender,
and
nicotine
Turkyilmaz
et
al
(2006)
50
found
that
bone
density
and
insertion
torque
were
strongly
correlated
with
ISQ
values,
and
were
significantly
higher
in
men
and
in
older
patients.
The
age
difference
was
attributed
to
the
fact
that
older
patients
receive
more
implants
in
the
anterior
mandible
compared
to
younger
patients,
who
tended
to
receive
implants
in
posterior
areas.
The
gender
differences
were
attributed
to
hormonal
differences,
rather
than
implant
site
distribution
or
patient
age.
For
42
self‐tapping
implants
placed
in
13
subjects45,
primary
stability
was
also
found
to
be
significantly
greater
in
patients
older
than
50,
compared
to
those
aged
19‐50
but
there
was
no
significant
difference
in
secondary
stability.
In
a
separate
study
of
30
patients
who
received
mandibular
overdentures,
however,
Turkyilmaz
et
al
(2006)
43
did
not
find
a
statistically
significant
difference
between
genders
and
ages.
The
average
ISQ
at
placement
was
75.0
for
males,
compared
with
73.3
for
females.
When
patients
were
divided
based
on
age,
younger
patients
(average
age
57)
had
a
mean
ISQ
of
74.3,
compared
with
73.5
for
older
patients
(average
age
68).
 
 38
 Although
statistical
significance
was
not
reached,
it
did
appear
that
age
and
gender
have
an
effect
on
insertion
torque
and
ISQ
values,
with
higher
measurements
in
male
and
younger
patients.

In
a
study
of
276
Brånemark
implants,
Balshi
et
al
(2005)
31
found
that
the
initial
ISQ
value
was
lower
for
females
but
there
was
no
significant
difference
after
30
days.
Ostman
et
al
(2006)
99
also
obtained
a
higher
mean
ISQ
for
Brånemark
implants
placed
in
males
(68.5
versus
66.5
for
females),
despite
a
similar
distribution
of
other
parameters
(implant
length,
diameter,
and
surface
treatment).
Only
one
measurement
was
available
for
each
patient,
however,
so
no
comparison
over
time
was
possible.
Zix
et
al
(2005)
115
also
found
that
gender
had
a
significant
effect
for
ITI
implants
placed
in
the
maxilla.
There
was
a
significantly
lower
stability
in
post‐menopausal
women
(48.7)
than
in
men
of
similar
age
(56.3).
Similarly,
Krhen
et
al
(2009)
117
evaluated
the
6‐week
ISQ
values
(Osstell)
for
53
Standard
Plus
Straumann
implants
placed
in
30
patients.
Results
showed
a
significant
difference
in
ISQ
between
males
and
females
(79
vs
72)
but
no
significant
correlations
were
found
for
patient
age.


In
contrast
to
these
studies,
Aksoy
et
al
(2009)
60
found
a
mean
ISQ
of
72.3
for
10
patients
who
received
a
total
of
23
implants.
A
significantly
lower
value
was
found
in
men
(70.2),
compared
to
women
(77.6);
however,
it
was
noted
that
the
sample
size
was
quite
small,
and
that
female
patients
received
more
mandibular
implants
than
male
patients.


Balatsouka
et
al
(2005)
118
used
RF
and
removal
torque
testing
to
analyze
the
impact
of
systemic
nicotine
on
the
osseointegration
of
titanium
implants
placed
in
the
femur
and
tibia
of
16
rabbits.
Animals
received
either
subcutaneous
nicotine
or
saline
(control)
for
2
months
and
32
implants
were
placed
after
4‐6
weeks
of
exposure.
RF
was
measured
at
time
of
placement
and
at
time
of
sacrifice,
2
or
4
weeks
after
implant
placement.
No
significant
differences
were
found
for
either
removal
torque
testing
or
RF
values
between
the
groups.

 
 39
 2.3.7
Implant
dimensions
Several
studies
have
shown
that
implant
length
has
little
influence
on
ISQ
values.
Barewal
et
al
(2003)
9
conducted
a
clinical
trial
in
20
patients,
where
all
implants
were
4.1mm
in
diameter,
10
or
12mm
in
length,
and
placed
in
the
posterior
mandible
or
maxilla.
ISQ
values
obtained
up
to
25
weeks
demonstrated
no
significant
differences
in
RF
between
implant
lengths.
Valderrama
et
al
(2007)
29
also
found
implant
length
to
have
no
bearing
on
stability
values.
It
was
suggested
that
the
effect
of
an
additional
2mm
in
implant
length
(from
8
to
10mm)
is
insignificant
once
marginal
stability
is
established,
particularly
since
the
apical
2mm
of
the
implant
is
typically
surrounded
by
trabecular
bone.

 
Sim
&
Lang
(2010)
91
longitudinally
monitored
the
stability
of
4.1mm
wide
Straumann
Standard
Plus
implants
of
different
lengths
and
placed
in
various
bone
structures.
Thirty‐two
patients
were
included
and
each
received
one
8‐
or
10‐mm
long
implant
in
the
posterior
maxilla
or
mandible.
Implant
length
appeared
to
have
an
effect
on
ISQ
but
the
study
was
underpowered
to
determine
clinical
significance.
The
ISQ
values
obtained
for
10mm
implants
were
higher
than
those
for
the
8mm
implants
but
there
were
large
standard
deviations.
By
2
weeks,
the
groups
had
similar
values
and
this
trend
continued
with
8mm
implants
showing
a
significant
increase
and
10mm
implants
showing
less
significant
changes.
Bone
structure
was
found
to
be
a
more
important
variable
than
implant
length.

 
Bischof
et
al
(2004)
90
also
found
that
neither
implant
diameter,
nor
implant
length
affected
the
primary
(baseline)
or
secondary
(12
week)
stability.
Karl
et
al
(2007)
57
found
a
significant
correlation
between
implant
length
and
ISQ
value
in
the
anterior
mandible
at
insertion,
and
in
the
anterior
and
posterior
mandible
at
follow‐up.
A
significant
correlation
was
also
found
between
implant
diameter
and
ISQ
in
the
anterior
mandible
at
insertion,
and
in
all
regions
except
the
anterior
maxilla
after
healing.


 
 40
 Pattjin
et
al
(2007)
79
obtained
slightly
lower
RF
values
for
longer
implants
in
bone
with
a
high
stiffness.
This
may
be
due
to
the
fact
that,
for
bone
with
such
a
high
stiffness,
an
increase
in
the
length
of
the
implant
does
not
further
increase
the
stability.
The
authors
concluded
that
ISQ
values
should
not
be
interpreted
in
an
absolute
sense
due
to
the
influence
of
the
type
of
anchoring
(trabecular
or
cortical),
the
implant
dimensions,
and
the
bone
stiffness.
Friberg
et
al
(1999)
16
found
a
significant
correlation
between
the
patient
mean
cutting
torque
and
RF,
but
only
for
the
crestal
third
of
the
implant
and
only
for
the
initial
RF
readings.
This
finding
explains
why
short
and
long
implants
have
similar
RF
values.
Ostman
et
al
(2006)
99
found
a
higher
ISQ
for
shorter
implants.
This
was
likely
due
to
a
modified
design
of
the
longer
implants,
with
reduced
diameter
in
the
coronal
area,
which
has
the
greatest
effect
on
implant
stability16.
It
is
also
possible
that
the
reduction
in
ISQ
value
was
due
to
more
prolonged
drilling
times
for
longer
implants.


The
effect
of
implant
diameter
on
ISQ
is
less
clear.
For
ITI
implants
placed
in
the
maxilla,
Zix
et
al
(2005)
115
found
that
diameter
had
a
slight
effect
on
ISQ,
with
standard
(4.1m)
implants
having
a
greater
ISQ
value
than
either
3.3
or
4.8mm
implants.
In
2008,
Zix
et
al73
treated
65
edentulous
patients
with
213
Straumann
implants,
varying
in
length
from
6
to
14mm.
The
average
ISQ
for
all
implants
was
57.7
(range
23‐73).
There
was
no
significant
correlation
with
the
implant
length
but
there
was
with
implant
diameter.


A
single
regular
or
wide
platform
Southern
implant,
or
Neoss
regular
diameter
(4
mm)
implant,
was
placed
in
the
midline
of
36
edentulous
mandibles
for
an
overdenture119.
Primary
stability
was
determined
using
Osstell
Mentor.
The
mean
ISQ
values
were
84.8
for
the
Southern
wide
implants,
82.3
for
the
Neoss
regular
width
implants,
and
75.3
for
the
Southern
regular
width
implants.
The
value
for
the
regular
diameter
Southern
implant
was
significantly
lower
than
that
of
the
other
2
implants
but
no
significant
differences
were
found
between
the
other
implants.
Another
study104
found
that
wider
diameter
implants
showed
a
trend
of
higher
ISQ
values,
for
both
MIS
Seven
and
Tidal
Spiral
implants.
Ohta
et
al
(2010)
84
found
a
 
 41
 trend
of
higher
ISQ
values
for
wider
implants
but
the
differences
did
not
reach
statistical
significance.
Krhen
et
al
(2009)
117
found
a
significant
difference
in
ISQ
values
based
on
implant
diameter
(73
for
3.3mm,
80
for
4.1mm,
and
67
for
4.8mm).
However,
the
lower
ISQ
obtained
for
the
4.8mm
diameter
implants
is
based
on
a
sample
size
of
only
5.


Han
et
al
(2010)
114
conducted
a
longitudinal
assessment
of
Straumann
implants
to
investigate
the
stability
characteristics
of
implants
with
different
surface
treatments
and
diameters.

Twenty‐three
patients
received
twenty‐five
10mm
long
implants
–
12
were
SLA
(sandblasted,
acid
etched)
4.1mm,
8
were
SLActive
(chemically
modified
sandblasted,
acid
etched)
4.1mm
and
5
were
SLA
4.8mm.
ISQ
values
were
taken
with
the
Osstell
mentor
at
baseline,
4
days,
and
1,
2,
3,
4,
6,
7,
and
12
weeks.
The
results
for
both
diameters
of
implants
(4.1
and
4.8mm)
and
both
surface
treatments
(SLA
and
SLActive)
were
not
significantly
different
and
the
authors
concluded
that
implant
diameter
and
surface
treatment
were
not
significant
factors
influencing
ISQ
readings.

Akkocaoglu
et
al
(2005)
67
compared
implants
of
various
designs
and
diameters,
placed
immediately
into
premolar
extraction
sockets
of
cadavers:
4.1/4.8mm
diameter
ITI
TE
as
well
as
4.1mm
and
4.8mm
diameter
screw
synOcta
ITI
implants.
The
TE
implants
were
designed
for
immediate
placement,
with
a
4.8mm
diameter
neck
and
a
4.1mm
diameter
body
to
maximize
surface
area.
The
ISQ
value
of
the
TE
implants
was
significantly
higher
than
the
4.1mm
diameter
implants
but
similar
to
the
4.8mm
implants.
It
was
therefore
concluded
that
it
is
the
diameter
at
the
neck
of
the
implant
that
determines
ISQ.
It
is
possible
that
a
regular
diameter
implant
with
good
bone
contact
at
the
collar
region
may
have
a
higher
ISQ
than
a
wider
implant
without
such
bone
contact.
Radiographic
evaluation
of
BIC
in
this
study
supports
this
concept.


RF
values
were
obtained
0,
3,
12,
and
16
months
after
immediate
loading
of
105
expanded‐platform
Osseotite
(Biomet
3i)
implants120.
These
implants
are
based
on
 
 42
 the
concept
of
platform
switching,
with
the
coronal
aspect
slightly
wider
than
the
straight‐walled
body,
to
result
in
greater
engagement
of
the
bone
crest
and
improve
primary
stability.
The
mean
16‐month
ISQ
(Osstell
Mentor)
values
for
4mm‐
and
5mm‐
diameter
implants
were
both
about
76,
indicating
no
significant
difference
based
on
implant
width.
Similarly,
no
significant
differences
in
ISQ
value
were
found
for
implants
of
length
8.5,
10
or
13mm.


 2.3.8
Implant
geometry
and
surface
characteristics
Sul
et
al
(2002)
121
used
RFA
and
removal
torque
to
evaluate
bone
response
to
implants
with
a
wide
range
of
oxide
properties
(thickness,
pore
configuration,
crystal
structure,
chemical
composition,
and
surface
roughness).
Turned
implants
were
used
as
a
control.
Forty‐eight
implants
were
placed
in
the
tibiae
of
12
rabbits
and
followed
for
6
weeks.
Implants
with
an
oxide
thickness
over
600nm
had
significantly
higher
removal
torque
values
compared
with
thicknesses
less
than
200nm.
There
was
a
trend
of
increasing
RF
values
as
the
thickness
of
the
oxide
layer
increased
but
differences
did
not
reach
statistical
significance.


In
2004,
Sul
et
al122
used
RFA
and
removal
torque
to
evaluate
the
integration
of
a
calcium‐incorporated
oxidized
implant
in
rabbit
femurs.
Ten
rabbits
each
received
one
turned
implant
(control)
and
1
test
implant.
Results
after
6
weeks
indicated
a
statistically
significant
improvement
in
osseointegration
with
the
calcium‐incorporated
implants,
compared
with
controls.
At
6
weeks,
the
mean
RF
for
the
test
implants
was
69.4
(range
67‐72)
and
for
the
control
implants
was
66.1
(range
63‐73).
The
calcium‐incorporated
implants
also
had
a
significantly
higher
removal
torque.
Results
indicate
that
the
calcium
composition
of
the
implant
surface
may
affect
the
implant’s
integration
in
bone.
The
authors
suggest
that
this
may
have
implications
for
immediate
or
early
loading
in
compromised
bone.


Göransson
et
al
(2005)
123
used
RF
and
histomorphometry
to
compare
isotropic
and
anisotropic
implant
surfaces
of
similar
roughness.
Isotropic
implants
do
not
have
 
 43
 any
dominating
direction
of
irregularities
and
are
fabricated
by
blasting
with
titanium
oxide
particles
of
medium
grain.
Anisotropic
turned
implants
were
used
as
controls.
Nine
of
each
type
of
implant
were
placed
in
the
femurs
of
9
rabbits
and
followed
for
12
weeks.
RF
values
indicated
that
implant
stability
had
increased
significantly
with
time.
There
was
no
statistically
significant
difference
in
RF
value
or
in
any
histomorphometric
parameter
between
the
two
groups.
In
a
study
of
40
implants
placed
in
acrylic
resin
models,
Tözüm
et
al
(2009)
104
found
that
MIS
Seven
implants,
with
more
threads
and
a
roughened
surface,
had
higher
ISQ
values
than
Tidal
Spiral
implants
that
had
fewer
threads
and
a
smoother
surface.


In
addition
to
the
effect
of
implant
texture,
the
surface
chemistry
is
also
thought
to
contribute
to
implant
stability.
Strnad
et
al
(2008)
38
compared
implants
with
a
turned
versus
a
modified
biosurface
(sandblasted,
acid‐
and
alkali‐treated
surface;
Lasak),
placed
in
the
tibiae
of
3
dogs.
RFA
values
were
taken
at
0,
1,
3,
9,
and
12
weeks
(Osstell).
The
initial
mean
RF
values
were
similar
for
turned
and
modified
implants
(74.5
verus
74.0).
The
modified
group
had
no
statistically
significant
changes
in
ISQ
over
time,
whereas
the
turned
group
showed
a
significant
decrease
at
3
and
9
weeks
with
a
return
to
a
similar
level
as
the
modified
implants
by
12
weeks.
Histological
results
indicated
that
the
alkali‐treated
surface
had
faster
bone
formation,
which
enhanced
the
secondary
stability.
Cannizzaro
et
al
(2007)
124
noted
a
different
bone
response
when
one
Zimmer
Spline
self‐tapping
implant
coated
with
crystalline
hydroxyapatite
(HA)
was
compared
with
other
Swiss
Plus
(Zimmer
Dental)
implants.
The
HA‐coated
implant
had
the
lowest
ISQ
value
at
baseline
(53)
but
the
highest
value
at
12‐months
(78);
however
it
is
important
to
note
that
this
observation
is
based
on
only
one
HA‐coated
implant.


The
stability
of
6
different
types
of
implants
was
compared
by
Al‐Nawas
et
al125:
Brånemark
machined
Mk
III
(minimally
rough);
oxidized
TiUnite
Mk
III
and
Mk
IV,
ZL
Duraplant
Ticer,
and
Straumann
SLA
(moderately
rough);
and
Straumann
TPS
(rough).
A
total
of
196
implants
were
placed
in
16
dogs
and
allowed
to
heal
for
8
weeks
before
being
loaded
for
3
months.
ISQ
values
were
obtained
at
3
months
 
 44
 (Osstell).
The
median
ISQ
value
was
above
60
for
the
Brånemark
and
ZL
Ticer
implants,
but
below
60
for
the
2
Straumann
implants.
Histological
analysis
showed
a
benefit
to
rough
surfaces,
compared
to
minimally
rough
ones,
but
the
RF
values
appeared
to
be
largely
influenced
by
the
different
transducers
used
and
therefore
could
not
be
compared.
Results
for
the
various
moderately
rough
surfaces
demonstrated
only
minor
differences.


Al‐Nawas
et
al
(2007)
126
performed
a
retrospective
study
of
machined
(Mk
II,
Nobel
Biocare)
and
etched
(3i,
Implant
Innovations
Inc)
implants,
that
were
macroscopically
very
similar.
No
significant
differences
were
found
between
the
implants
for
survival,
RF
or
PTV.
The
mean
RF
values
were
64
and
63
for
the
turned
and
the
etched
implants,
respectively.
Fröberg
et
al
(2006)
112
found
no
difference
in
ISQ
between
immediately
loaded
turned
Brånemark
and
TiUnite
implants
placed
in
dense
bone
in
the
anterior
mandible
and
followed
up
to
18
months.
Schincaglia
et
al
(2007)
109
also
found
no
difference
between
turned
and
TiUnite
implants
at
placement.
A
split‐mouth
study
of
10
patients
was
conducted
to
compare
immediate
loading
of
fixed
partial
dentures
supported
by
implants
with
either
machined
or
TiUnite
surfaces.
The
success
rate
for
all
implants
was
95%,
with
no
failures
in
the
group
that
received
TiO
surface
implants.
There
were
no
significant
differences
in
radiographic
bone
level,
peak
insertion
torque
or
ISQ
values
between
the
groups.
The
mean
ISQ
at
baseline
was
73.0
for
machined
implants
and
74.0
for
TiUnite.
The
ISQ
values
decreased
after
insertion,
with
the
machined
implants
reaching
their
lowest
value
at
3
months
and
the
TiUnite
implants
at
6
months.
Stability
was
then
regained
until
final
measurement
at
12
months.
Ostman
et
al7
found
a
slight
difference
between
turned
and
oxidized
Brånemark
implants
at
baseline
(74.6
and
71.8,
respectively)
but
the
difference
decreased
by
6
months
(71.8
and
72.7).
The
slightly
lower
primary
stability
of
the
oxidized
implants
may
have
been
due
to
grinding
of
the
bone
by
the
rough
surface
during
placement,
leading
to
a
looser
fit.


Sennerby
et
al
(2005)
106
placed
6
ITI
implants
(3
SLA
and
3
smooth
surface)
in
each
of
4
dogs.
Ligature‐induced
peri‐implantitis
around
the
implants
resulted
in
a
 
 45
 greater
decrease
in
stability
for
SLA
implants
(1,424
Hz),
than
for
turned
implants
(1,266
Hz).
During
the
healing
phase,
the
increase
in
RF
values
was
also
greater
for
SLA
implants
(483
versus
238).
The
final
RF
values,
however,
were
similar
for
the
two
types
of
implant
–
5,099
Hz
and
5,119
Hz.
Abrahamsson
et
al40
found
a
higher
initial
ISQ
for
SLA
implants,
compared
to
turned,
but
no
significant
difference
at
12
weeks.
Primary
stability
was
achieved
in
all
160
implants
(half
SLA
surface
and
half
turned
surface)
placed
in
the
premolar
region
of
20
dogs.
Histological
findings
and
RF
measurements
were
similar
for
both
groups
initially.
The
BIC
was
nearly
twice
as
high
for
the
SLA
implants
by
one
week,
and
the
difference
between
groups
was
statistically
significant
for
all
time
points
from
1
to
12
weeks.
After
12
weeks,
the
mean
ISQ
was
58.6
for
SLA
implants
and
was
similar
to
that
of
turned
(59.9)


A
randomized‐controlled
clinical
trial
of
modified
and
standard
SLA
surface
implants
(Straumann
Orthosystem),
was
conducted
to
determine
the
effect
of
these
surface
treatments
on
the
stability
of
palatal
implants
placed
for
orthodontic
anchorage127.
Forty
patients
were
treated
and
RF
values
obtained
at
0,
7,
14,
21,
28,
35,
42,
49,
56,
70,
and
84
days.
There
were
no
significant
differences
between
the
standard
and
modified
SLA
implants
at
baseline
(73.8
versus
72.7)
and
both
groups
showed
a
slight
decrease
in
ISQ
over
the
first
2
weeks.
The
modified
SLA
implants
showed
increasing
ISQ
values
after
28
days,
which
reached
values
similar
to
baseline
at
42
days.
For
standard
SLA
implants,
an
increase
in
ISQ
was
seen
at
35
days,
reaching
levels
similar
to
baseline
after
63
days.
At
84
days
(12
weeks),
the
ISQ
was
significantly
higher
for
the
modified
SLA
implants
(77.8
versus
74.5).


Valderama
et
al
(2007)
29
treated
17
patients
with
34
implants
in
the
posterior
jaws.
All
implants
were
Straumann
4.1mm
diameter
and
each
patient
was
randomized
to
receive
one
SLA
and
one
SLActive.
The
effect
of
implant
surface
on
ISQ
values
was
nearly
significant
for
mandibular
implants,
with
the
SLActive
implants
being
consistently
more
stable.
The
authors
commented
that
it
is
possible
that
there
truly
is
no
difference
in
stability
in
the
early
phase
of
healing
but
it
is
also
possible
that
the
RFA
device
is
not
sufficiently
sensitive
to
detect
such
small
differences.
It
is
also
 
 46
 important
to
note
that
the
study
was
not
powered
to
compare
stability
between
the
two
systems.


dos
Santos
et
al
(2009)
56
investigated
the
effect
of
implant
design
and
surface
treatment
on
primary
stability.
High
molecular
weight
polyethylene
cylinders
were
used
in
place
of
bone
to
isolate
the
effects
of
implant
design
from
other
confounding
variables.
Cylindrical
and
conical
implants
with
3
different
surface
finishes
(anodized,
acid‐etched,
or
machined)
were
used.
Surface
treated
implants
were
found
to
have
higher
insertion
torque
and
ISQ
values,
compared
to
machined.

Sul
et
al128
evaluated
different
surface
properties,
by
placing
a
variety
of
implants
in
10
rabbit
tibia
and
following
with
RFA
(Osstell)
for
6
weeks.
Two
oxidized,
cation‐incorporated
experimental
implants
(magnesium‐incorporated
with
or
without
micropatterns),
and
4
commercially
available
implants
(TiUnite,
Osseotite,
SLA,
and
TiOblast)
were
included.
Baseline
ISQ
values
were
not
significantly
different
among
the
various
implants,
other
than
being
significantly
lower
for
the
magnesium‐incorporated
micropatterned
implants.
At
6
weeks,
however,
this
group
of
implants
had
the
highest
ISQ
values,
suggesting
that
bone
had
grown
into
the
micropatterned
threads.
At
6
weeks,
all
implant
types
had
significantly
greater
ISQ
values
than
at
baseline.
The
surface‐chemistry
modified
implants
(both
magnesium‐incorporated
implants,
and
TiUnite)
had
higher
mean
ISQ
values
than
topographically
changed
etched
and/or
blasted
implants
(Osseotite,
SLA,
and
TiOblast).


 2.3.9
Implant
design
An
initial
objective
in
the
development
of
the
RFA
device
was
to
enable
clinical
comparisons
of
different
implant
systems
and
designs18
and
a
number
of
studies
have
used
RFA
for
this
purpose.
However,
Zix
et
al
(2005)
115
noted
that
comparison
of
ISQ
values
between
implant
systems
is
not
reliable.
Brånemark
implants
tend
to
have
a
higher
ISQ
than
the
ITI
implants
and
this
is
likely
due
to
differences
in
design115.
For
example,
differences
in
the
diameter,
materials,
and
tightness
of
components,
can
all
impact
the
stiffness
of
the
system115.
Park
et
al
(2012)
129
 
 47
 studied
81
implants
placed
in
41
patients.
The
implants
placed
either
had
an
external
design
(Branemark,
Nobel
Biocare)
or
an
internal
design
(ITI,
Straumann)
and
the
insertion
ISQ
value
was
significantly
higher
for
the
external‐type
implants.
A
possible
explanation
was
given
as
the
3mm
supracrestal
shoulder
present
on
the
internal
design
implants
used
in
this
study.
This
would
increase
the
effective
length
of
the
ITI
implants,
leading
to
lower
RF
compared
with
placement
of
the
Brånemark
implants
at
the
bone
level9.
Kessler‐Liechti
et
al
(2008)
130
also
recommends
caution
when
comparing
ISQ
values
between
different
implants.
For
example,
an
ISQ
of
64
was
found
to
represent
a
stable
healthy
value
for
Straumann
implants
supporting
mandibular
overdentures,
whereas
Balleri
et
al
(2002)
131
found
a
mean
ISQ
of
73
after
1
year
of
loading
of
Brånemark
mandibular
implants.


Al‐Nawas
et
al
(2006)
48
placed
160
implants
in
16
dogs,
including
3
types
of
Brånemark
(machined
MKIII,
TiUnite
MkIII,
and
MkIV)
and
2
types
of
Straumann
(SLA
and
TPS).
RFA
was
measured
at
implant
placement,
at
8
weeks,
and
after
3
months
of
loading.
There
was
no
significant
difference
in
ISQ
value
between
Brånemark
and
Straumann
implants
at
time
of
placement.
From
fixture
placement
to
loading,
all
implant
systems
displayed
a
significant
decrease
in
median
ISQ
values
but
the
decrease
was
smaller
for
Straumann
implants.
At
study
completion,
high
ISQ
values
were
obtained
for
the
self‐tapping
MkIII
and
MkIV
implants
but
the
non‐self‐tapping
Straumann
implants
had
significantly
lower
ISQ
values
after
3
months
of
loading.
The
authors
believe,
however,
that
the
difference
between
implant
designs
may
have
more
to
do
with
the
type
of
transducer
than
with
the
type
of
implant.


Ersanli
et
al
(2005)
132
evaluated
3
types
of
implants:
Xive
(Dentsply,
n=64),
Camlog
(n=28),
and
ITI
(Straumann,
n=30).
ISQ
values
were
obtained
at
the
time
of
surgery,
3
and
6
weeks
post‐operatively,
and
3
(mandible)
or
6
months
(maxilla)
after
surgery,
at
the
time
of
loading.
In
general,
the
ISQ
values
for
all
implant
types
were
higher
for
the
mandible
and
the
ISQ
readings
at
3
or
6
weeks
were
significantly
lower
than
those
obtained
at
baseline.
For
Xive
implants,
the
decrease
from
placement
to
6
weeks
was
significant
for
both
arches.
For
Camlog
implants,
the
 
 48
 decrease
from
baseline
was
significant
for
both
3
and
6
weeks
and
for
both
jaws.
For
ITI
implants,
the
initial
decrease
was
only
significant
at
the
3‐week
measurement
and
only
for
the
maxilla.
Although
the
absolute
baseline
ISQ
was
lower
for
the
ITI
implants,
the
recovery
period
began
at
3
weeks
and,
by
the
time
of
implant
loading,
the
values
for
all
implant
types
were
approximately
recovered
to
baseline
levels.
The
authors
concluded
that
RFA
is
useful
to
determine
the
healing
phases
and
changes
in
stability
of
implants,
but
that
ISQ
values
must
be
calibrated
for
each
type
of
implant
as
a
standardized
range
for
all
systems
is
unlikely.


Rabel
et
al
(2007)
133
treated
a
group
of
263
patients
with
random
assignment
to
receive
a
total
of
408
non‐self‐tapping
Ankylos
and
194
self‐tapping
Camlog
implants.
RFA
at
baseline
and
3
months
was
available
for
63
patients.
The
mean
ISQ
value
for
all
implants
at
time
of
placement
was
66.5
(67.9
for
Ankylos
and
64.4
for
Camlog).
At
3
months,
the
mean
for
all
implants
was
66.8
(66.5
for
Ankylos
and
67.3
for
Camlog).
Within
each
implant
system,
a
correlation
over
time
was
found.
The
maximum
insertion
torque
was
significantly
higher
for
the
non‐self‐tapping
Ankylos
implants
but
the
RFA
did
not
detect
any
differences
between
the
groups.
The
authors
concluded
that
ISQ
values
should
not
be
compared
between
different
implant
systems
and
that
RFA
should
be
used
to
monitor
stability
over
time,
rather
than
as
a
single
measure
to
quantify
implant
stability.

 
Lang
et
al
(2007)
134
compared
the
outcome
of
standard
cylindrical
screw‐shaped
and
tapered
transmucosal
implants
(Straumann),
placed
in
extraction
sockets.
The
transmucosal
implants
are
root‐shaped
and
designed
to
engage
native
bone
in
the
apical
part
of
the
socket.
This
was
a
multicenter
randomized,
controlled
clinical
trial
with
a
3‐year
follow‐up
period;
however,
this
report
includes
data
only
from
the
first
3
months.
In
total,
208
implants
were
placed
and
patients
were
randomly
assigned
to
receive
either
the
standard
or
the
novel
implant
design.
Most
(84%)
of
the
implants
were
placed
in
the
maxilla.
If
there
was
over
1mm
between
the
implant
and
the
socket
wall,
simultaneous
guided
bone
regeneration
was
performed.
RF
measurements
(Osstell)
were
taken
at
implant
placement
and
after
3
months.
The
 
 49
 mean
initial
ISQ
values
for
the
standard
and
tapered
implants
were
55.8
and
56.7,
respectively,
and
increased
to
59.4
and
61.1
after
3
months.
No
statistically
significant
differences
were
noted
between
the
implants.
The
design
of
the
novel
implant
was
thought
to
reduce
the
need
for
bone
augmentation
and
to
provide
increased
primary
stability
due
to
the
tapered
design
and
decreased
pitch
of
the
threads.
However,
90%
of
the
implants
in
both
groups
required
bone
augmentation
and
there
were
no
significant
difference
in
stability.


Six
Straumann
(4.1
x
10mm,
SLA)
and
6
Astra
Tech
(4.0
x
9mm,
TiO
blast)
implants
were
placed
into
each
arch
of
a
completely
edentulous
human
cadaver53.
The
mean
ISQ
values
for
Straumann
(79.0)
and
Astra
Tech
(77.3)
implants
were
similar
and
no
significant
differences
were
found
between
the
systems.
Similarly,
Kahraman
et
al
(2009)
45
found
no
significant
differences
were
between
Straumann
Standard
Plus
with
sand‐blasted,
large‐grit,
acid‐etched
surface
and
MIS
Seven
implant
with
sand‐blasted
acid‐etched
surface.


Chong
et
al
(2009)
135
placed
10
implants
with
self‐tapping
blades
in
the
apical
third
(Biohorizons)
and
10
without
self‐tapping
blades
(Nobel
Biocare)
in
polyurethane
blocks
with
different
densities
and
at
different
depths.
When
non‐self
tapping
implants
were
fully
inserted
in
medium‐
or
high‐density
blocks,
the
initial
mean
stability
(Osstell
Mentor)
was
significantly
greater
than
that
for
self‐tapping
implants.
When
the
implants
were
not
fully
inserted,
however,
there
were
no
differences
between
the
implant
designs.
The
ISQ
readings
obtained
in
low‐density
blocks
were
unreliable
and
were
excluded
from
analysis.
Insertion
depth
showed
the
strongest
association
with
ISQ
value,
followed
by
block
density.
Only
a
weak
association
was
found
for
implant
design,
indicating
that,
if
bone
quality
and
quantity
is
optimal,
the
implant
design
is
less
important.
The
non‐self
tapping
implant
had
a
greater
surface
area,
due
to
a
higher
number
of
threads,
as
well
as
a
rough
surface
and
an
osteotomy
protocol
requiring
fewer
cutting
burs.
In
contrast,
the
self‐tapping
implant
had
fewer
threads,
a
smooth
surface,
and
a
more
extensive
 
 50
 drilling
sequence.
This
study
did
not
consider
these
factors
when
comparing
the
2
implant
systems.


Fifty‐six
patients
were
randomly
assigned
to
receive
either
Osstem
SSII
or
Standard
Straumann
implants
to
replace
1
or
2
mandibular
molars136.
Implant
stability
was
monitored
at
baseline,
and
after
4
and
10
weeks.
A
significantly
higher
ISQ
(Osstell
Mentor)
was
obtained
for
the
Osstem
SSII,
possibly
due
to
the
differing
thread
designs.
There
were
no
statistically
significant
differences
in
ISQ
at
10
weeks
between
the
implants,
indicating
no
significant
differences
in
secondary
stability.
The
effect
of
thread
design
was
also
demonstrated
by
Roze
et
al
(2009)
59,
who
placed
22
implants
(12
Ankylos
and
10
Straumann)
in
both
arches
of
human
cadavers.
Following
the
first
drill,
the
titanium
cylinders
were
placed
and
an
initial
ISQ
reading
was
taken
–
this
step
was
done
to
compare
smooth
cylinders
with
threaded
implants
and
investigate
the
effect
of
implant
geometry.
The
drilling
protocol
was
then
resumed,
implants
placed,
and
RF
measurements
obtained.
No
difference
was
found
between
Straumann
and
Ankylos
implants
but
there
was
a
significantly
higher
stability
for
both
types
of
threaded
implants
compared
with
the
customized
plain
cylinders.


 2.4
Clinical
Use
of
Resonance
Frequency
Analysis
Measurement
of
ISQ
values
over
the
course
of
implant
therapy
has
several
clinical
uses.
It
may
help
when
determining
the
loading
protocol
(immediate,
early,
or
delayed)
and
in
individualizing
healing
periods137.
Changes
in
stability
can
be
monitored
over
time
and,
with
early
detection,
alleviation
of
occlusal
forces
may
be
able
to
rescue
failing
implants137.
The
ISQ
can
also
be
useful
when
evaluating
new
implants
or
surface
treatments,
and
new
surgical
techniques
or
materials.


 
 51
 2.4.1
Immediately
placed
implants
Lindeboom
et
al
(2006)
138
investigated
the
outcome
when
implants
were
placed
immediately
after
extraction
of
maxillary
anterior
teeth
or
premolars
with
chronic
periapical
infections.
Primary
stability,
defined
as
a
torque
of
at
least
25
Ncm,
was
a
pre‐requisite
for
inclusion.
Implants
were
not
restored
until
at
least
6
months,
at
which
time
ISQ
was
measured.
The
survival
of
immediately
placed
implants
was
92%
and
that
for
the
delayed
placement
was
100%.
The
mean
ISQ
at
6‐months
was
64.5
for
both
groups
of
implants.


Nordin
et
al
(2007)
139
evaluated
the
clinical
and
radiographic
outcome
after
116
Straumann
implants
were
placed
in
19
patients
to
support
rigid,
passive‐fit
permanent
fixed
complete
dentures.
Implants
were
placed
either
in
fresh
extraction
sockets
(66%)
or
in
healed
bone
(34%).
The
prostheses
were
loaded
after
10‐14
days
and
patients
were
followed
for
2‐3
years.
During
the
follow‐up
period,
there
were
no
significant
differences
in
ISQ
(Osstell)
between
implants
placed
in
sockets
(57.1)
and
healed
bone
(57.2).
Only
2
implants
failed,
and
this
was
attributed
to
framework
fracture.


Bogaerde
et
al101
focused
on
implants
placed
in
the
maxilla
or
posterior
mandible
(areas
characterized
by
poor
bone
quality)
and
measured
the
ISQ
of
69
Neoss
implants
which
were
loaded
within
7
days.
Sixteen
of
the
implants
were
placed
in
extraction
sockets
and
7
additionally
received
bone
grafting.
Survival
was
98.5%,
with
one
implant
failing
in
an
extraction
site
in
the
maxilla.
The
mean
ISQs
at
placement,
1,
2,
and
6
months
were
68.1,
66.0,
69.1
and
73.6,
indicating
a
steady
increase
with
osseointegration.
The
ISQ
was
lower
in
extraction
sockets
(65.8
at
placement
and
67.5
after
6
months).


Immediate
implant
placement
and
restoration
was
compared
to
delayed
placement
(8
weeks
after
extraction)
with
immediate
restoration
for
Straumann
tapered
implants
placed
in
the
esthetic
zone
of
16
patients140.
Baseline
ISQ
values
were
 
 52
 significantly
lower
for
the
implants
placed
immediately
(65
versus
74)
but
this
did
not
appear
to
affect
the
treatment
outcome
(final
ISQ
values
72
versus
73).


 2.4.2
Immediate
and
early
loading
Osseointegration
is
a
dynamic
process
during
initial
establishment,
as
well
as
during
maintenance141.
After
initial
placement
of
implants,
necrosis,
resorption,
and
new
bone
healing
all
occur
around
the
fixture141.
Loading
is
thought
to
have
an
important
role
in
early
osseointegration,
as
the
peri‐implant
tissue
reacts
and
remodels
in
response
to
functional
forces141.
Many
studies
have
investigated
the
potential
of
RFA
to
be
used
in
determining
when
to
load
implants
and
to
indicate
which
implants
may
be
amenable
to
immediate
or
early
loading.


It
was
hypothesized
by
De
Smet
et
al
(2005)
141
that
controlled
early
loading
would
be
beneficial
for
osseointegration
and
stability
values.
Astra
Tech
implants
were
placed
in
the
tibiae
of
10
guinea
pigs
and
loaded
after
7
days.
Unloaded
controls
were
used
for
comparison.
A
controlled,
gradually
increasing,
cyclical
load
was
applied
to
the
test
implants
for
10
minutes
per
day,
5
days
a
week,
for
6
weeks.
RF
was
measured
at
the
time
of
implant
placement
and
weekly
for
6
weeks.
All
implants
displayed
good
osseointegration.
Early‐loaded
implants
showed
a
gradual
increase
in
stability
over
time,
whereas
unloaded
implants
had
a
decrease
in
stability.
At
3
weeks,
the
difference
between
test
and
control
implants
reached
300
Hz,
but
this
was
not
statistically
significant.
By
6
weeks,
however,
both
groups
had
similar
RF
values.
The
authors
concluded
that
controlled
early
loading
is
beneficial
for
implant
stability
in
the
early
healing
stages.


Glauser
et
al142
hypothesized
that
the
surface
texture
of
tapered
Brånemark
TiUnite
implants
would
provide
good
primary
stability
and
improve
healing
for
immediate
loading.
Thirty‐eight
patients
received
102
implants.
If
threads
were
exposed
upon
implant
placement,
the
patients
were
treated
with
guided
bone
regeneration
(GBR).
The
success
rate
after
1‐year
of
loading
was
97.1%.
RF
measurements
were
taken
at
 
 53
 time
of
placement,
as
well
as
at
1,
4,
and
6
weeks
and
3,
6,
and
12
months.
At
placement,
the
mean
ISQ
was
71
and
this
decreased
by
8
units
at
1‐week.
The
ISQ
then
increased
until
1
year,
when
it
was
similar
to
the
initial
value
(70).
A
4‐year
follow‐up
study143
showed
no
additional
failures.
The
RF
measurements
at
2,
3,
and
4
years
remained
stable,
hovering
around
66.
The
5‐year
results,
published
in
2007144,
revealed
a
mean
ISQ
of
66.
The
minimal
decrease
from
1
to
5
years
was
thought
to
reflect
the
minimal
marginal
bone
remodeling
during
this
time
period.



Calandriello
et
al
(2003)
145
also
found
consistently
high
ISQ
values
for
50
Brånemark
single
molar
implants,
placed
using
GBR
as
needed
for
exposed
implant
threads.
All
implants
were
followed
for
6
months
with
100%
survival.
ISQ
values
were
obtained
at
surgery,
and
then
monthly
for
6
months.
The
initial
mean
ISQ
was
76
and
this
dropped
slightly
to
72
at
3
months
then
returned
to
near‐baseline
(75)
by
6
months.
The
7
implants
treated
with
GBR
had
slightly
lower
values
at
baseline
and
3
months
(68
and
66)
compared
to
implants
without
GBR
(77
and
77)
but
both
groups
had
an
ISQ
of
75
by
6
months.
It
was
suggested
that
the
lower
initial
ISQ
values
for
sites
treated
with
GBR
was
due
to
the
exposed
implant
threads
but,
once
the
bone
matured,
the
stability
increased
from
3
to
6
months.


A
number
of
other
studies
have
also
shown
an
initial
decrease
in
RF
values
after
placement
and
immediate
loading,
followed
by
a
steady
increase
to
values
approximating
initial
placement.
In
a
study
of
machined
Brånemark
implants
loaded
either
immediately
or
within
11
days
of
placement,
Glauser
et
al
(2004)
146
found
that
the
mean
initial
ISQ
of
68
dropped
to
60
at
3
months
then
increased
until
it
reached
the
initial
value
by
one
year.
Froberg
et
al
(2006)
112
noted
mean
initial
ISQ
values
around
67‐68
for
turned
Brånemark
or
TiUnite

(Nobel
Biocare)
implants
placed
in
the
anterior
mandible
of
15
patients.
Implants
were
immediately
loaded
and
followed
for
18
months.
A
decrease
to
about
63
was
noted
at
3
months
and
a
final
mean
value
just
over
64
was
found
at
18
months.
In
a
study
of
Zimmer
Screw‐Vent
implants
(Zimmer
Inc.,
USA)
loaded
before
15
days137,
all
implants
had
a
baseline
ISQ
over
50,
however
the
ISQ
decreased
until
30
days
then
increased
to
 
 54
 near‐baseline
levels
by
90
days.
It
was
noted
that
implants
with
a
baseline
ISQ
over
65
maintained
this
value
or
experienced
a
slight
decrease;
however,
implants
with
a
baseline
ISQ
of
50‐60
increased
over
time.
Based
on
these
findings,
it
seems
that
extending
the
healing
period
for
implants
with
an
already
high
ISQ
is
not
beneficial.
These
implants
may
be
suitable
for
immediate
loading.


The
initial
drop
in
ISQ
observed
in
several
studies
has
been
attributed
to
bone
relaxation
following
compression
at
placement,
bone
resorption
associated
with
bone
remodeling,
microfractures
associated
with
loading,
and
crestal
bone
loss
or
dehiscence
which
increases
the
effective
implant
length109,
142,
146.
Portman
and
Glauser
(2006)
147
found
that
the
initial
decrease
in
ISQ
was
more
pronounced
for
implants
placed
in
soft
bone
or
in
areas
with
bone
defects.
It
was
speculated
that
splinting
of
the
implants
reduces
micromotion
and,
therefore,
may
limit
changes
in
stability
during
the
early
healing
phase.

In
contrast,
many
studies
have
shown
a
consistent
increase
in
RF
value
over
time
for
immediately‐loaded
implants
and
this
may
partly
be
due
to
differences
in
design.
Cornelini
et
al
(2004)
110
conducted
a
prospective
clinical
study
of
30
SLA
(ITI)
implants
placed
in
the
posterior
mandible
with
a
minimum
ISQ
of
62
and
restored
immediately
with
single
crowns.
ISQ
increased
from
baseline
(70.6)
to
6
months
(71.7)
to
12
months
(76.7).
In
2003,
Payne
et
al148
used
RFA
to
monitor
stability
of
two
types
of
implants
placed
in
the
anterior
mandible
to
support
overdentures,
which
were
loaded
after
2
weeks.
Patients
were
randomly
assigned
to
receive
ITI
or
Southern
sand‐blasted
acid‐etched
implants
(Southern
Implants
Ltd,
Irene,
South
Africa).
RF
was
measured
at
0,
6,
12,
and
52
weeks.
ISQ
was
higher
for
the
Southern
implants
than
for
ITI
implants
at
every
time
point.
The
mean
initial
and
1‐year
values
for
ITI
implants
were
61.9
and
62.3,
compared
with
79.3
and
73.4
for
Southern
implants.
The
Southern
group
experienced
a
drop
in
ISQ
values
from
surgery
until
6
weeks
but
the
ITI
implants
showed
no
such
decrease.
There
was
no
further
decrease
in
RF
values
from
6
to
52
weeks.
The
differences
between
groups
were
attributed
to
differences
in
implant
design
and
placement
protocol,
as
well
as
 
 55
 the
placement
of
Southern
implants
in
denser
bone.
It
was
suggested
that
the
initially
higher
ISQ
value
and
the
drop
from
baseline
to
6
weeks
for
the
Southern
implants
was
due
to
their
self‐tapping
design.
The
protocol
for
ITI
implants
included
pre‐tapping,
which
likely
resulted
in
less
outward
pressure
and
subsequent
relaxation
of
the
surrounding
bone.
Sites
with
type
3
bone
had
significant
increases
in
ISQ
from
12
to
52
weeks
and
eventually
the
values
were
similar
to
those
with
type
2
bone.


Immediate/early
loading
of
53
tapered
Nobel
Biocare
implants
was
assessed
clinically
and
radiographically
over
the
course
of
1
year149.
Single
tooth
replacements
were
loaded
on
the
same
day
as
implant
placement,
and
bridges
were
loaded
within
16
days.
The
mean
ISQ
values
at
baseline,
3,
6,
and
12
months
were
63.3,
64.3,
65.0,
and
66.8.
The
increase
from
baseline
to
1
year
was
statistically
significant.

 
Several
studies
have
compared
immediate
or
early
loading
with
conventional
loading
or
unloaded
controls,
and
shown
no
statistically
significant
difference
in
ISQ.
These
results
have
been
obtained
with
animal
studies150,
as
well
as
clinical
studies
using
ITI
implants90,
SwissPlus
(Zimmer)
implants151,
and
TiUnite
(Nobel
Biocare)
implants108,
152‐156.

When
deciding
whether
to
immediately
load
an
implant,
many
studies
have
used
a
minimum
of
60
ISQ
units
as
a
key
criterion7,
109,
146,
157‐161.
A
few
studies
have
recommended
slightly
higher
values,
with
Cornelini
et
al
(2006)
162
using
62
ISQ
units,
in
addition
to
a
lack
of
infection
of
adjacent
teeth,
a
bilaterally‐stable
occlusion,
and
placement
of
implants
of
minimum
dimensions,
and
Bornstein
et
al
(2009)
113
using
65
ISQ
units
with
repetitive
measurements
at
3‐week
intervals
until
at
least
65
is
obtained.
Balshi
et
al
(2005)
31
commented
that
the
previously
recommended
minimum
value
of
60
for
immediate
loading
may
need
to
be
altered
depending
on
the
location
of
implant
placement
and
on
the
bone
type.
In
this
report,
 
 56
 successful
osseointegration
was
found
for
97%
of
implants
with
an
initial
primary
stability
of
only
47‐59.

In
contrast,
Shiigai
et
al
(2009)
163
conducted
a
pilot
study
to
assess
the
efficacy
of
using
pre‐selected
sets
of
ISQ
values
to
predict
adequate
stability
for
immediate
or
early
loading
and
recommended
a
minimum
ISQ
of
70
–
a
higher
value
than
other
investigators.
Twenty
patients
had
mandibular
implants
loaded
immediately
(n=10
implants),
at
6
weeks
(early;
n=25),
or
after
12
weeks
(delayed;
n=6).
For
immediate
loading,
the
implants
needed
to
be
at
least
10mm
in
length,
placed
in
moderately‐high
to
high
density
bone,
have
an
insertion
torque
of
at
least
45Ncm
and
an
ISQ
value
of
at
least
70.
For
early
loading,
the
implants
needed
to
be
at
least
10m
in
length,
placed
in
moderately
low
to
high
density
bone,
have
an
insertion
torque
of
at
least
30‐45Ncm
and
an
ISQ
value
of
40‐70.
A
delayed
loading
protocol
was
used
if
these
criteria
were
not
met.
All
of
the
implants
survived
to
12
weeks,
at
which
time
the
immediately‐loaded
ISQ
was
76.6
and
the
early‐loaded
ISQ
was
74.2.
There
was
a
slight
decrease
in
the
ISQ
for
most
of
the
immediately‐loaded
implants
by
week
1,
followed
by
an
increase
by
week
6,
and
stabilization
or
an
increase
at
12
weeks.
In
contrast,
the
ISQ
of
most
early‐loaded
implants
remained
stable
or
increased
for
the
first
3
weeks,
then
68%
increased
at
week
6
and
stabilized
or
continued
to
increase
until
week
12.


 2.4.3
Sinus
augmentation
Lundgren
et
al
(2004)
164
used
RFA
(Osstell),
in
addition
to
clinical
and
CT
exams,
to
evaluate
healing
after
sinus
membrane
elevation
with
simultaneous
implant
placement,
but
without
grafting
material.
Ten
patients
were
treated
with
19
TiUnite
Brånemark
implants
and
the
mean
ISQs
at
placement,
abutment
surgery,
and
after
1
year
of
loading
were
65,
66,
and
64
respectively.
The
high
stability
values,
and
new
bone
formation
visible
on
CT
scans,
support
the
use
of
simultaneous
implants
and
sinus
elevation
procedures,
without
additional
grafts.


 
 57
 Lai
et
al
(2007)
165
used
RFA
to
monitor
the
stability
changes
of
42
ITI
implants
placed
in
conjunction
with
osteotome
sinus
floor
elevation
without
bone
grafting.
The
success
rate
was
95.2%,
with
the
40
successful
implants
having
high
primary
stability.
The
implants
that
failed
had
ISQ
values
(Osstell)
of
69
and
70
at
placement
and
58
and
62
at
2
weeks.
All
implants
had
a
baseline
ISQ
over
66
(mean
69.1).
The
mean
ISQ
then
decreased
to
57.1
by
4
weeks
and
increased
to
64.2
by
6
weeks
and
to
70.1
by
20
weeks.
There
was
no
significant
difference
between
type
3
and
4
bone
at
any
time
point,
other
than
8
weeks,
when
the
mean
ISQ
in
type
3
bone
was
66.3
versus
65.5
in
type
4
bone.
Although
greater
stability
is
generally
anticipated
with
denser
bone,
the
lack
of
difference
found
in
this
study
may
be
due
to
lateral
compression
of
the
bone
by
osteotomes,
which
increases
the
trabecular
density.


RFA
(Osstell)
was
again
used
to
evaluate
the
clinical
outcome
of
simultaneous
implant
placement
(n=62
implants)
and
endoscope‐guided
sinus
elevation
without
graft
material166.
The
overall
success
rate
at
12
weeks
was
94%
and
the
ISQ
values
indicated
good
stability.
The
values
at
surgery
ranged
from
54‐65,
with
a
mean
of
60
and
those
at
4‐
and
12‐weeks
ranged
from
46
to
89,
with
a
mean
of
57.9.


Palma
et
al
(2006)
167
conducted
an
experimental
study
in
non‐human
primates
to
evaluate
the
outcome
of
simultaneous
sinus
elevation
and
implant
placement
with
or
without
autogenous
bone
grafting.
The
maxillary
premolars
and
first
molar
were
extracted
bilaterally
and
sinus
elevation
surgery
was
performed
4
months
later,
at
the
same
time
as
placement
of
two
implants
(one
turned
and
one
oxidized)
on
each
side.
The
left
sinus
received
an
autogenous
tibial
bone
graft
and
the
right
sinus
served
as
an
un‐grafted
control.
In
the
grafted
group,
the
mean
ISQs
at
placement/6
months
were
68.0/67.6
for
turned
implants,
and
68.0/65.0
for
oxidized
implants.
In
the
un‐grafted
group,
the
corresponding
values
were
67.0/64.0
for
turned
implants
and
63.2/65.7
for
oxidized
implants.
No
statistically
significant
histological
or
stability
differences
were
noted
between
the
grafted
and
un‐grafted
sites
but
oxidized
implants
showed
higher
BIC
and
more
bone
within
the
implant
threads.


 
 58
 Degidi
et
al
(2007)
168
compared
63
XiVE
(Dentsply‐Friadent)
implants
placed
in
previously
sinus‐grafted
sites
(after
6
months
of
healing)
with
17
implants
placed
in
healed
bone.
The
graft
material
consisted
of
50%
autogenous
bone
and
50%
deproteinized
bovine
xenograft
material.
In
general,
grafted
sites
had
high
ISQ
values
but
the
difference
between
the
grafted
(62.1)
and
un‐grafted
(61.4)
ISQs
was
not
statistically
significant.
One
possible
explanation
for
this
is
the
relatively
greater
importance
of
the
crestal
third
of
the
implant
site166.


 
 2.4.4
Guided
bone
regeneration
In
a
study
evaluating
the
use
of
non‐absorbable
membranes
for
onlay
bone
grafting
in
rabbits,
Rasmusson
et
al
(1999)
169
used
RFA
to
evaluate
stability
of
implants
placed
in
grafted
areas.
The
animals
were
followed
for
up
to
24
weeks,
with
histological
and
histomorphometrical
evaluation
at
various
time
points.
RFA
showed
that
there
was
no
statistically
significant
difference
in
stability
between
the
groups
at
any
time
point
(0,
8,
16,
and
24
weeks).
The
RF
values
increased
from
approximately
8600
Hz
at
time
of
implant
placement
to
over
11000
Hz
by
8
weeks,
at
which
time
there
was
no
statistically
significant
difference
between
the
groups
with
and
without
the
membrane
despite
a
greater
bone‐implant
contact
at
the
membrane
sites.
It
was
suggested
that
this
could
be
due
to
immaturity
of
the
bone
or
to
comparing
3
sacrificed
animals
with
RF
values
from
a
separate
6
animals.
By
24
weeks,
the
bone
height
was
similar
between
the
groups.

Kramer
et
al
(2005)
78
used
serial
ISQ
values
to
monitor
the
stability
of
implants
placed
in
patients
who
had
previously
been
treated
with
free
fibula
grafts.
Sixteen
patients
received
51
implants
3
months
after
the
bone
grafting
procedure.
ISQ
values
were
obtained
at
implant
placement,
implant
exposure,
and
1
year
and
showed
a
significant
increase
in
ISQ
over
the
12
month
follow‐up
period.
The
authors
concluded
that
implants
placed
in
areas
treated
with
a
fibula
graft
had
reliable
results.
Brechter
et
al170
also
found
an
increase
in
stability
after
12
months
of
loading
of
implants
placed
in
grafted
sites,
including
sinus
elevation
without
graft
 
 59
 material,
sinus
elevation
with
autogenous
bone
harvested
from
the
ramus,
autogenous
onlay
bone
grafting
from
the
iliac
crest,
autogenous
interpositional
bone
grafting,
zygomatic
implants,
and
vertical
distraction
osteogenesis.

Sjöström
et
al
(2005)
6
used
RFA
to
show
that
implants
placed
in
grafted
maxillary
bone
after
6
months
of
healing
achieve
similar
stability
as
those
placed
in
native
bone.
Patients
received
either
autogenous
onlay
grafts
(n=24)
or
interpositional
grafts
with
a
Le
Fort
I
osteotomy
(n=5),
followed
by
6‐8
months
of
healing
and
placement
of
a
total
of
222
Standard
or
Mark
II
Brånemark
implants.
For
comparison,
there
was
a
control
group
of
10
non‐grafted
patients
with
75
Brånemark
implants.
Implants
placed
in
grafted
bone
had
average
ISQ
values
of
61.5
at
implant
placement,
60.2
at
abutment
connection,
and
62.5
after
6
months
of
loading.
The
corresponding
values
for
the
control
implants
were
58.5,
60.9,
and
63.0.
There
were
no
statistically
significant
differences
between
the
groups
but
the
tendency
towards
higher
initial
stability
in
the
grafted
group
was
attributed
to
placement
of
the
implants
in
sites
with
a
smaller
final
preparation
diameter
(2.85mm
versus
3.00mm
for
implants
3.75mm
in
diameter).
RF
values
increased
with
time
in
all
groups
with
a
tendency
towards
higher
stability
for
interpositional
grafts,
likely
due
to
placement
of
implants
in
the
residual
maxilla
versus
in
grafted
bone
with
the
onlay
technique.


Özkan
et
al
(2007)
5
performed
a
clinical
pilot
study
to
compare
the
stability
of
implants
placed
in
posterior
mandibles,
some
of
which
had
received
autogenous
symphyseal
grafts
4
months
prior
to
implant
placement.
Eight
grafted
patients
received
17
implants
and
7
non‐grafted
patients
received
18
implants
(control).
After
1
month
of
healing,
fabrication
of
fixed
partial
dentures
was
initiated.
The
mean
ISQ
values
of
implants
placed
in
grafted
sites
were
63.0,
64.3,
68.4,
and
70.3,
at
baseline,
1
and
4
months
post‐operatively,
and
12
months
post‐loading,
respectively.
The
corresponding
mean
values
for
implants
placed
in
non‐grafted
sites
were
65.3,
64.1,
68.6,
and
70.1.
The
change
in
ISQ
value
from
baseline
to
1‐month
was
insignificant
in
both
groups
but
the
increases
at
other
time
points
were
 
 60
 significant.
There
were
no
statistically
significant
differences
in
ISQ
values
between
the
grafted
and
non‐grafted
groups
at
any
of
the
time
points,
indicating
that
high
implant
stability
can
be
achieved
for
implants
placed
in
grafted
sites.
In
a
separate
study,
16
patients
received
autogenous
bone
grafting,
followed
by
placement
of
42
SLA
(ITI)
implants
in
the
anterior
maxilla,
after
12
weeks
of
healing4.
Comparison
was
made
with
22
patients
with
50
implants
placed
in
non‐grafted
sites.
ISQ
values
taken
at
0,
4,
12,
and
52
weeks
showed
no
significant
differences
between
groups.

 
The
primary
and
secondary
stability
of
implants,
placed
in
either
osseodistraction‐generated
(n=32)
or
native
(n=39)
bone,
was
assessed
using
the
Osstell
Mentor171.
At
the
time
of
placement,
the
mean
ISQ
values
for
osseodistraction
and
native
implants
were
73.0
and
76.8,
respectively.
The
corresponding
values
after
6
weeks
were
77.2
and
79.7.
Although
both
groups
demonstrated
good
stability
at
both
time
points,
the
values
were
higher
for
implants
placed
in
native
bone.


 2.4.5
Predictive
value
of
RFA
Implants
can
fail
for
a
variety
of
reasons,
mostly
related
to
the
design
of
the
particular
implant,
surgical
placement
technique,
adverse
host
response
or
excessive
loading
forces13,
18.
Glauser
et
al
(2004)
146
evaluated
immediate
or
early
loading
of
implants
in
23
patients
and
found
a
failure
rate
of
11.1%,
with
implants
lost
in
6
patients.
RFA
was
able
to
detect
failing
implants
earlier
than
clinical
assessment,
since
the
ISQ
decreased
continuously
until
failure.
Low
RF
values
at
1
and
2
months
were
indicative
of
implants
at
risk
of
failure.
Since
this
was
a
blinded
study,
it
was
not
possible
to
use
the
ISQ
values
to
dictate
reduction
of
loading
forces
in
failing
implants.
In
a
separate
study
of
122
implants
in
31
patients132,
the
ISQ
values
of
2
implants
that
did
not
integrate
showed
a
gradual
decrease
and
a
final
reading
around
40
ISQ.
The
drop
in
ISQ
was
evident
prior
to
detection
of
clinical
mobility.
Nkenke
et
al
(2005)
47
also
found
that
the
pattern
of
implant
failures
was
reflected
in
decreasing
RF
values.
In
this
study,
there
was
a
high
rate
of
failure
(46
out
of
108
implants)
for
XiVE
implants
placed
in
minipigs.

Vanden
Bogaerde
et
al172
 
 61
 observed
a
decrease
in
ISQ
from
67
at
baseline
to
53
at
6
weeks,
when
there
were
signs
of
failure.

Payne
et
al
(2004)
173
observed
that
the
ISQ
of
failed
implants
was
lower
than
that
of
surviving
implants
and
ranged
from
36‐50.
A
lower
ISQ
for
failing
or
failed
implants
has
also
been
found
in
several
other
studies.
Thor
et
al
(2005)
174
found
a
large
decrease
in
ISQ
for
one
failing
Astra
Tech
implant
(from
64
at
implant
placement
to
40
at
abutment
connection).
Degidi
et
al
(2006)
159
obtained
a
mean
ISQ
value
of
43
for
3
failing
implants,
compared
to
about
60
for
surviving
implants.
Horwitz
et
al
(2007)
102
observed
failure
of
12
implants,
out
of
a
total
of
74
that
were
placed
in
19
patients.
Most
(10)
of
the
failures
were
in
the
maxilla
and
the
mean
ISQ
for
implants
that
failed
was
57.5.
Turkyilmaz
et
al
(2008)
92
also
found
that
the
mean
ISQ
for
successful
implants
was
significantly
higher
than
for
failed
implants
(67.1
versus
46.5).


Balleri
et
al
(2002)
131
presented
a
pilot
study
using
Osstell
for
45
implants
in
14
partially
edentulous
patients
after
1
year
of
loading.
At
one
year,
ISQ
values
ranged
from
57‐82
(mean
69)
and
all
implants
were
clinically
stable.
It
was
therefore
concluded
that
an
ISQ
value
falling
in
this
range
represents
good
implant
stability
and
osseointegration
for
partially
edentulous
patients.


Sjöström
et
al
(2005)
6
found
lower
RF
values
for
implants,
which
were
rotationally
mobile
at
placement.
Overall
implant
survival
was
92%
at
the
1‐year
follow‐up.
Failed
implants
tended
to
have
lower
RF
values,
compared
to
successful
implants.
The
mean
initial
ISQ
for
implants
that
failed
was
54.6
and
that
for
mobile
implants
was
52.8.
The
mean
initial
ISQ
values
for
successful
implants
was
62.0
and
that
for
stable
implants
was
62.3.
In
2007,
a
3‐year
follow‐up175
was
reported,
with
implant
survival
of
90%.
The
mean
ISQ
value
after
3
years
was
61.8,
which
is
similar
to
that
at
baseline
(61.9).
Successful
implants
had
a
mean
initial
ISQ
value
of
62.6,
whereas
implants
that
failed
had
a
mean
initial
ISQ
of
only
54.9,
representing
a
statistically
significant
difference.
The
authors
suggested
that
the
initial
ISQ
may
be
useful
in
 
 62
 predicting
future
failure
of
implants,
particularly
if
several
measurements
are
available.
The
value
of
a
single
ISQ
measurement
in
predicting
failure,
however,
is
limited.

Al‐Nawas
et
al48
observed
the
loss
of
11
implants
(6
during
healing
and
5
during
loading),
from
a
total
of
160
placed
in
dogs.
ISQ
values
at
time
of
fixture
placement
were
significantly
higher
for
successful
implants.
When
an
initial
stability
threshold
of
65.5
was
used,
a
sensitivity
(the
ability
to
correctly
identify
mobility)
of
83%
and
specificity
(the
ability
to
correctly
identify
stability)
of
61%,
for
prediction
of
future
implant
loss,
was
obtained.
If
the
ISQ
at
the
time
of
loading
was
used
instead
of
the
initial
value,
no
statistically
significant
difference
was
found
between
successful
and
unsuccessful
implants.
Nedir
et
al33
also
investigated
a
threshold
ISQ
value,
which
could
predict
osseointegration.
Once
a
threshold
ISQ
to
indicate
stability
was
proposed,
it
was
used
to
calculate
the
sensitivity,
the
specificity,
the
positive
predictive
value
(PPV,
the
likelihood
that
an
ISQ
below
the
threshold
corresponds
to
a
mobile
implant),
and
the
negative
predictive
value
(NPV,
the
likelihood
that
an
ISQ
value
above
the
threshold
corresponds
to
a
stable
implant).
At
the
time
of
implant
placement,
ISQ
values
of
106
implants
ranged
from
42‐72.
Two
implants
experienced
mobility
and
were
removed;
the
ISQ
values
of
these
implants
were
43
and
46.
Since
no
implants
with
a
higher
initial
ISQ
were
mobile,
a
threshold
of
47
was
selected
to
represent
a
stable
implant.
Using
this
cut‐off
value,
the
sensitivity
was
1,
specificity
0.973,
PPV
0.087,
and
NPV
1.
A
PPV
of
0.087
means
that
only
8.7%
of
the
implants,
indicated
to
be
mobile
based
on
an
ISQ
of
<47,
were
actually
mobile.
Nedir
et
al
concluded
that
the
ISQ
values
were
not
reliable
to
accurately
identify
implant
mobility.
The
ISQ,
however,
was
found
to
be
very
reliable
in
identifying
stable
implants.
The
sensitivity
of
1
meant
that
all
stable
implants
were
correctly
identified.
It
has
been
suggested
that
the
inability
of
RFA
to
consistently
identify
mobile
implants
is
due
to
the
extremely
low
stiffness
of
mobile
implants,
which
prevents
the
device
from
detecting
the
first
resonance
frequency8.
Instead,
the
second
value
may
be
registered
which
provides
a
falsely
elevated
RF
value8.

 
 
 63
 Nedir
et
al
33
found
delayed‐loaded
implants
with
an
initial
ISQ
over
49
were
osseointegrated
at
one
year.
The
value
for
immediately
loaded
implants
was
higher,
at
54.
Clinically,
this
translates
to
an
expectation
of
osseointegration
above
these
ISQ
values.
It
is
logical
that
the
value
for
immediate
loading
is
higher,
since
these
implants
are
subject
to
higher
stresses
early
in
the
healing
process.
The
clinical
implications
of
the
findings
are
that
an
initial
ISQ
of
≥49
in
a
delayed
loading
protocol
is
likely
to
predict
osseointegration
at
1
year.
If
the
implant
is
to
be
immediately
loaded,
an
initial
ISQ
of
≥54
predicts
osseointegration.
Values
less
than
these
thresholds
do
not
necessarily
mean
that
the
implant
will
fail
but
do
indicate
a
higher
risk
situation
which
may
benefit
from
rigorous
follow‐up
and
a
reduction
in
loading
forces.
Scarano
et
al
(2007)
35
measured
the
ISQ
(Osstell)
of
37
implants
that
were
removed
due
to
failure.
The
mean
ISQ
for
these
failed
implants
was
37,
and
data
suggested
that
any
ISQ
value
less
than
40
is
associated
with
irretrievability.

Using
the
mean
ISQ
of
surviving
osseointegrated
implants,
guidelines
were
provided
with
a
range
of
expected
implant
stability
values
for
immediately
loaded
implants31.
A
safety
margin
of
1
standard
deviation
was
included.
For
implants
placed
in
the
anterior
mandible,
ISQ
values
were
as
high
as
86±2
for
males
with
type
1
bone
and
as
low
as
74±6
for
females
with
type
3
bone.
In
the
posterior
mandible,
the
values
ranged
from
73±6
for
females
with
type
2
bone
to
85±2
for
males
with
type
1
bone.
For
implants
placed
in
the
anterior
maxilla,
expected
ISQ
values
were
as
high
as
75±6
for
males
with
type
2
bone
and
as
low
as
64±7
for
females
with
type
4
bone.
In
the
posterior
maxilla,
the
values
ranged
from
64±7
for
females
with
type
3
or
4
bone
to
72±6
for
males
with
type
2
bone.
It
is
clear
that
higher
values
were
found
for
males
and
for
denser
bone
types.
The
authors
caution
that
these
values
will
not
apply
to
all
implants
in
all
clinical
situations.
They
do
not
mean
that
implants
placed
at
lower
values
will
not
survive
if
immediately
loaded
and
do
not
guarantee
that
implants
placed
at
or
above
these
values
will
be
successful.


 
 64
 A
threshold
of
65
was
suggested
by
Ramakrishna
and
Nayar
(2007)
137
as
the
ISQ
above
which
few
failures
should
be
expected.
Setting
a
value
below
which
failure
is
more
likely
is
difficult.
ISQ
values
tend
to
be
between
50
and
60
for
maxillary
(softer)
bone
and
between
60
and
80
in
mandibular
(denser)
bone.
A
value
of
45
was
suggested
as
a
threshold
below
which
measures
to
increase
stability
should
be
considered.
A
temporary
increase
in
primary
stability
value
can
be
obtained
by
using
thinner
drills
and
wider
or
tapered
implants.
This
increases
the
lateral
compression
of
the
bone,
resulting
in
an
increased
ISQ
value
at
the
time
of
implant
placement.
However,
this
may
be
followed
by
a
decreased
ISQ
value
as
the
bone
remodels.
This
modified
surgical
protocol
may
be
beneficial
in
softer
bone.
In
order
to
improve
secondary
stability,
extending
the
healing
period
to
9
or
12
months
was
recommended.
If
a
decreased
ISQ
value
is
obtained,
a
radiograph
is
necessary
to
determine
whether
the
change
is
due
to
marginal
bone
loss
or
demineralization
of
the
bone
surrounding
the
implant.



Karl
et
al
(2008)
57
measured
ISQ
values
(Osstell
Mentor)
of
385
ITI
implants
at
placement
and
after
a
healing
period
of
6
(mandible)
to
12
(maxilla)
weeks.
At
fixture
placement,
ISQ
values
ranged
from
39
to
86
and
after
healing
from
35
to
89
–
this
large
variation
indicates
that
it
is
difficult
to
identify
a
standard,
which
would
define
a
successful
implant.
Further,
the
difference
between
the
arches,
and
for
anterior
versus
posterior,
means
that
comparisons
should
only
be
made
within
the
same
region.


Valderrama
et
al
(2007)
29
found
an
association
between
implant
rotation
and
decreased
ISQ.
For
8
implants
that
rotated,
the
ISQ
decreased
by
an
average
of
11
for
magnetic
RFA
and
6
for
electronic
RFA,
followed
by
an
increase
over
the
next
2‐3
weeks.
Marginal
bone
loss
was
noted
around
one
implant
and
the
magnetic
RFA
detected
this
change
as
a
decrease
in
the
ISQ.
It
was
suggested
that
lower
initial
ISQ
values
indicate
implants
that
are
more
susceptible
to
failure
and
may
benefit
from
a
prolonged
period
of
healing.
The
authors
discuss
the
possibility
that
repeated
 
 65
 application
of
the
transducer
and
multiple
RF
readings
may
have
contributed
to
the
rotational
movement
found
in
these
implants.


In
a
longitudinal
study91
of
32
patients
who
received
Straumann
Standard
Plus
SLA
implants,
all
ISQ
readings
taken
at
the
time
of
surgery
indicated
adequate
stability.
All
implants
osseointegrated
and
showed
clinical
stability
at
weeks
1,
2,
3,
4,
5,
6,
8,
and
12.
The
authors
describe
any
ISQ
reading
above
55
as
indicating
clinically
relevant
stability
but
discuss
the
lack
of
a
defined
ISQ
value,
above
which
stability
of
the
implant
is
reliable.
Han
et
al
(2010)
114
placed
25
Straumann
implants
in
23
patients.
All
implants
were
considered
clinically
successful.
At
the
time
of
implant
placement,
ISQ
values
ranged
from
64‐81
and
over
all
follow‐up
periods,
the
ISQ
ranged
from
55‐84.
As
such,
it
was
suggested
that
ISQ
values
falling
in
the
range
55‐84
likely
represent
homeostasis
and
stability
of
implants
during
the
healing
phase.
Huwiler
et
al61
found
the
normative
range
for
ISQ
values
of
Straumann
SLA
implants
to
be
57‐70.


Implant
stability
was
determined
by
the
Osstell
Mentor
for
542
SLA
(Straumann)
implants,
at
implant
placement
and
at
restoration
(2‐4
months)
176.
The
implants
were
divided
based
on
an
ISQ
value
above
or
below
60.
There
was
no
significant
association
between
the
baseline
ISQ
and
implant
survival
but
there
was
a
significant
association
between
the
ISQ
at
restoration
and
implant
survival.
There
were
no
failures
when
the
secondary
stability
measurement
was
>60
but,
for
the
21
implants
with
an
ISQ
≤60,
there
were
4
failures
(19%).
This
study
showed
that
primary
stability
might
not
be
a
prerequisite
for
long‐term
implant
survival.
Veltri
et
al111
found
that
osseointegrated
Astra
Tech
TiO2
implants
placed
in
the
maxilla
have
ISQ
values
in
the
range
of
53‐76
after
1
year
of
loading
and
an
ISQ
value
>50
at
second‐stage
surgery
likely
indicates
implants
that
will
maintain
their
stability
for
at
least
a
3‐year
period.

 
Huwiler
et
al
(2007)
61
found
no
predictive
value
of
ISQ
for
losing
stability
(failing).
One
Straumann
SLA
implant
lost
stability
at
3
weeks
and
had
a
drop
in
ISQ
value
 
 66
 from
68
at
2
weeks
to
45
at
3
weeks
but
this
decrease
did
not
occur
until
after
the
failure
was
detected
clinically.
Östman
et
al
(2008)
7
also
found
that
implant
failure
was
not
correlated
with
primary
stability
and
the
initial
ISQ
values
for
the
4
implants
that
failed
were
71,
66,
65,
and
82.
Similarly,
Sennerby
et
al
(2010)
89
found
initial
ISQs
of
3
failed
implants
to
be
72,
77,
and
63.
These
implants,
however,
did
show
a
decrease
in
ISQ
from
initial
placement
to
abutment
connection.
Koka177
reviewed
the
performance
of
RFA
and
challenged
its
use
as
a
prognostic
or
diagnostic
tool
in
clinical
practice.
Koka
emphasizes
that
there
is
no
information
demonstrating
that
RFA
is
superior
to
subjective
information
obtained
at
the
time
of
implant
placement
by
an
experienced
surgeon.

In
considering
the
literature,
Sennerby
and
Meredith8
state
that
ISQ
values
of
65‐75
and
55‐65
are
likely
to
represent
adequate
stability
for
Brånemark
and
Straumann
implants,
respectively.
Values
below
55
for
Brånemark
or
45
for
Straumann
should
be
considered
as
a
warning
of
reduced
or
inadequate
implant
stability.
If
these
low
values
are
detected
at
placement,
extension
of
the
healing
period
is
recommended.
For
lower
values
obtained
after
loading,
a
period
of
unloaded
healing
is
advised
to
regain
stability,
in
addition
to
radiographic
examination
to
evaluate
the
marginal
bone
level.


 
 67
 3.
OBJECTIVES
A
retrospective
chart
review
was
performed
to
assess
the
stability
of
implants
in
a
variety
of
clinical
situations,
including
placement
at
sites
with
a
history
of
bone
augmentation
using
bone
allograft.


The
following
hypotheses
were
tested:

 1. Implants
placed
in
sites
grafted
with
bone
allograft
or
other
bone
materials
will
have
similar
stability
to
those
of
implants
placed
in
native,
healed
bone.
2. Implant
stability
will
vary
based
on
the
implant
dimensions
(length,
width,
and
surface
area).
3. Implants
with
bone
loss
or
bony
dehiscences
will
have
lower
stability
values
than
implants
surrounded
entirely
by
bone.
 
 
 68
 4.
MATERIALS
AND
METHODS

A
chart
review
was
performed
of
286
implants
placed
in
149
patients
from
July
2009
to
September
2011,
at
two
centres
in
Vancouver,
British
Columbia.
Human
ethics
approval
was
obtained
from
the
Clinical
Research
Ethics
Board,
University
of
British
Columbia
Office
of
Research
Services.
Implants
were
placed
in
partially
dentate
and
edentulous
patients,
in
maxillary
and
mandibular
arches,
using
either
immediate
or
conventional
placement.
Implants
were
placed
in
both
native
bone,
as
well
as
sites
previously
or
simultaneously
augmented
with
guided
bone
regeneration
or
sinus
augmentation.


The
Osstell
ISQ
device
(Gothenburg,
Sweden)
was
used
to
measure
implant
stability
(RFA),
by
emitting
magnetic
pulses
that
cause
a
SmartPeg
attached
to
the
implant
to
resonate
according
to
the
stability
of
the
implant.
RFA
measurements
were
taken
in
triplicate
from
the
buccal,
lingual,
mesial
and
distal
and
recorded
in
Implant
Stability
Quotient
(ISQ)
units
ranging
from
1‐100,
with
higher
values
indicating
higher
implant
stability.
All
included
implants
had
measurements
taken
after
a
period
of
initial
healing
and
prior
to
functional
loading.
Measurements
were
also
obtained
at
the
time
of
implant
placement
if
the
patient
was
treated
at
the
University
of
British
Columbia
and
had
a
minimum
insertion
torque
value
of
15Ncm.
This
torque
value
was
selected
because
attachment
of
the
SmartPeg
to
finger
tightness
was
found
to
lead
to
rotation
of
the
implant
at
lower
torque
values.


 Inclusion
criteria:
1. Patients
who
had
at
least
one
implant
placed
either
in
a
private
periodontal
practice
or
in
the
UBC
graduate
periodontics
clinic.
2. Availability
of
ISQ
values
taken
after
a
period
of
initial
healing.
Analyses
included
implants
which
subsequently
were
removed
due
to
failure.


 
 69
 
Patient
demographic
information
and
clinical
data
concerning
implant
placement
and
bone
augmentation
procedures
were
collected
and
entered
into
a
computer
database
(Microsoft
Excel
2008;
Microsoft
Corporation,
Redmond,
WA).
Implants
were
considered
to
have
failed
if
they
were
lost
or
removed
due
to
mobility,
unresolved
infection
or
clinical
symptoms,
or
if
they
had
advanced,
untreatable
bone
loss.
Failure
of
the
implant
did
not
preclude
inclusion
for
statistical
analysis.
ISQ
measurements
were
obtained
prior
to
implant
removal.

Variables
identified
as
likely
to
affect
implant
stability
and
ISQ
value
included
patient‐related
factors
(age,
gender,
smoking
status,
and
diabetes),
RFA‐related
factors
(direction
of
measurement,
repeatability
of
measurements),
anatomic
site‐related
factors
(arch,
site,
previous
or
simultaneous
bone
augmentation,
and
presence
of
a
dehiscence
at
implant
placement),
implant
design
properties
(implant
type,
length,
width,
and
surface
area),
implant
placement‐related
factors
(insertion
torque,
bone
density,
and
number
of
implants),
timing
of
placement
(immediate
versus
delayed),
and
the
level
of
training
of
the
surgeon.


Smoking
status
and
diabetic
control
were
determined
based
on
information
obtained
from
the
medical
history
questionnaire.
Immediate
implant
placement
referred
to
placement
of
the
implant
immediately
following
and
at
the
same
appointment
as
extraction
of
the
tooth.
Bone
density
was
classified
as
soft,
medium,
and
dense,
and
was
determined
at
the
time
of
implant
placement
at
the
discretion
of
the
surgeon.
Patients
were
provided
with
a
variety
of
provisional
restorations
after
implant
placement
and
until
loading
of
the
implants.


Statistical
analysis
was
performed
using
the
PASW
statistics
program
(PASW,
Chicago,
IL,
version
18.0)
and
included
ANOVA
with
post‐hoc
Bonferroni
adjustment,
T
test,
and
Spearman’s
and
Pearson’s
correlation
tests.
Most
data
was
analyzed
at
the
implant‐level.
Patient‐level
data
included
the
impact
of
age,
gender,
diabetes,
smoking,
and
number
of
implants
placed
in
the
patient,
on
the
ISQ
value.

 
 70
 Box
plots
were
selected
to
show
results,
in
order
to
display
the
distribution
of
data.
In
this
representation,
the
central
rectangle
displays
a
span
of
the
first
quartile
to
the
third
quartile
–
this
is
referred
to
as
the
interquartile
range
(IQR)
and
includes
75%
of
the
data.
Within
the
rectangle,
the
band
indicates
the
median.
The
lines
extending
above
and
below
the
rectangle
indicate
the
range
of
data,
except
if
there
are
data
points
that
lie
significantly
outside
the
other
results
‐
these
are
referred
to
as
outliers
and
are
displayed
as
individual
data
points.
Outliers
are
defined
as
results
lying
either
above
or
below
the
rectangle
by
more
than
3
IQR.


For
the
majority
of
the
analyses,
ISQ
measurements
from
the
buccal,
lingual,
mesial,
and
distal
were
combined
to
provide
one
mean
value
per
implant.
Variables
that
were
analyzed
using
only
the
buccal‐lingual
ISQ
measurements
included
lateral
ridge
augmentation
and
the
presence
of
a
buccal
dehiscence
at
implant
placement.
The
majority
of
the
records
were
lacking
ISQ
measurements
at
implant
placement,
therefore
it
was
decided
to
perform
statistical
analysis
primarily
on
the
follow‐up
ISQ
measurements
taken
at
second
stage.
In
most
cases,
the
implant
stability
was
not
followed
or
reported
after
functional
loading.
The
p‐value
of
0.05
was
considered
to
be
statistically
significant.

 
 Illustration
1.
Box
plot
representations
 Median (50th percentile) IQR 25th percentile 75th percentile Range of data, with the exception of any outliers Outlier 
 71
 5.
RESULTS
 5.1
Population
and
Implant
Distribution
The
patient
population
included
149
patients,
comprised
of
43.6%
males
and
56.4%
females,
aged
54
±
15
years.
A
total
of
286
implants
were
placed
at
two
centres
in
Vancouver,
British
Columbia:
a
private
periodontal
practice
(n=231)
and
a
university
Periodontics
clinic
(n=55).
The
following
types
of
implants
were
placed:
Nobel
Replace
Tapered
Groovy
(n=85),
Nobel
Replace
Straight
Groovy
(n=12),
Nobel
Replace
Select
Straight
(n=3),
Nobel
Replace
Select
Tapered
(n=9),
Nobel
Active
(n=70),
Nobel
Conical
Connection
(n=1),
Straumann
BL
SLA
(n=31),
Straumann
BL
SLActive
(n=11),
Straumann
Roxolid
(n=5),
Straumann
SP
SLA
(n=10),
Straumann
SP
SLActive
(n=8),
and
Astra
Straight
(n=41).


 

 Figure
1.
Distribution
of
implants

 
 72
 A
total
of
3
implants
failed
to
osseointegrate
and
were
removed,
resulting
in
an
overall
survival
rate
of
98.9%.
Additionally,
of
the
55
implants
placed
at
the
University
of
British
Columbia
Periodontics
clinic,
3
(5.5%)
were
treated
for
peri‐implant
bone
loss
and
were
re‐submerged
for
additional
healing.
No
data
was
available
for
implants
treated
for
peri‐implant
bone
loss
at
the
private
periodontal
clinic.


 5.2
Osstell‐Related
Factors
 5.2.1
Orientation
of
transducer

Measurements
were
taken
in
triplicate
from
each
of
the
buccal,
lingual,
mesial,
and
distal
of
each
implant
and
the
highest
value
for
each
implant
was
recorded.
The
mean
ISQ
was
77.36±6.59
from
the
buccal
(range
52‐90),
78.00±6.53
from
the
lingual
(range
52‐93),
79.02±
5.84
from
the
mesial
(range
48‐89),
and
79.01±
5.80
from
the
distal
(range
52‐89).
Measurements
taken
from
the
buccal
and
lingual
were
not
significantly
different
(p=0.84).
Similarly,
measurements
taken
from
the
mesial,
distal,
and
lingual
did
not
differ
significantly
(p=>0.30).
A
statistically
significant
(p=0.004)
difference,
however,
was
found
for
measurements
taken
from
the
buccal,
compared
with
both
the
mesial
and
distal
orientations.
A
significant
difference
(p=<0.001)
was
also
found
when
the
buccal
and
lingual
directions
were
combined
and
compared
with
a
combination
of
mesial
and
distal
measurements.
However,
the
mean
difference
was
clinically
quite
small
(1.33
±
2.96).


 
 73
 
 
 Figure
2.
ISQ
values
for
measurements
taken
from
the
buccal,
lingual,
mesial,
and
distal

 
 Figure
3.
ISQ
values
for
measurements
taken
from
the
buccal/lingual
and
mesial/distal

 
 74
 5.2.2
Repeatability
of
measurements
Triplicate
measurements
were
taken
for
24
implants
at
surgical
placement
and
48
implants
at
second
surgery.
All
repeated
measurements
were
highly
correlated,
with
a
range
of
0.753
to
0.978.

Specifically,
for
buccal
measurements
taken
at
implant
placement
and
exposure,
the
correlation
ranges
were
0.887‐0957
and
0.753‐0.946,
respectively.
For
lingual
measurements,
the
ranges
were
0.956‐0.978
and
0.783‐0.954.
For
mesial
measurements,
the
ranges
were
0.922‐0.972
and
0.936‐0.974.
For
distal
measurements,
the
ranges
were
0.908‐0.974
and
0.916‐0.956.


 5.3
Patient‐Related
Factors
 5.3.1
Patient
age
The
study
population
was
divided
into
3
age
groups:
those
younger
than
45
years
(n=36),
those
aged
45‐64
(n=78),
and
those
aged
65
years
or
older
(n=34).
The
mean
ISQ
for
the
youngest
age
group
was
77.30±6.68,
compared
with
79.37±4.95
for
the
middle
age
group,
and
78.73±4.06
for
the
oldest
age
group.
Although
the
youngest
patients
tended
to
have
lower
stability
values,
no
statistical
significance
was
found
when
comparing
these
age
groups.
The
mean
difference
between
the
youngest
age
group
and
the
middle
age
group
was
2.07
ISQ
units
(p=0.156).
The
mean
difference
between
the
youngest
and
oldest
age
groups
was
1.43
ISQ
units
(p=0.764),
and
that
between
the
middle
and
oldest
age
groups
was
0.637
(p=1.00).

 
 
 Figure
4.
Distribution
of
age
groups
 
 75
 5.3.2
Patient
gender
Of
the
149
patients,
84
were
women
(56.4%)
and
65
were
men
(43.6%)
and
these
groups
received
149
(52.1%)
and
137
(47.9%)
implants,
respectively.
For
gender
comparison,
the
data
was
evaluated
at
the
patient
level,
rather
than
the
implant
level.
The
mean
ISQ
for
females
was
78.44
±
5.33
and
that
for
males
was
79.03
±
5.21.
The
difference
in
ISQ
between
implants
placed
in
women
and
men
was
not
statistically
significant,
with
a
mean
difference
of
0.59
units
(p=0.502).


 
 Figures
5
Distribution
of
patients
according
to
gender

 
 Figure
6.
Distribution
of
implants
according
to
gender

 
 76
 5.3.3
Diabetic
status

There
were
no
cases
of
Type
1
diabetes
mellitus
but
9
patients
(6.0%)
were
being
treated
for
Type
2
diabetes
mellitus.
The
mean
ISQ
for
diabetic
patients
(n=9)
was
80.26
±
4.65,
and
that
for
non‐diabetic
patients
(n=140)
was
78.60
±
5.31.
The
difference
between
the
groups
did
not
reach
statistical
significance
(p=0.33).


 
 Figure
7.
ISQ
depending
on
diabetic
status
of
patient
(patient‐level
analysis)

 5.3.4
Smoking
status
Smokers
constituted
6.0%
(n=9)
and
former
smokers
20.1%
(n=30)
of
the
population.
Pack
years
of
smoking
ranged
from
1
to
60.

Half
of
the
smokers
and
ex‐smokers
had
a
cumulative
pack
year
history
between
10
and
20
years,
while
18.8%
had
a
history
of
5
or
fewer
years,
and
31.2%
had
a
history
of
30
or
more
years.

The
mean
ISQ
in
never‐smokers
was
79.04
±
5.22,
compared
with
77.99
±
5.16
in
former‐smokers,
and
76.87
±
6.24
in
current
smokers.
No
statistically
significant
difference
was
found
between
current
or
former
smokers
and
non‐smokers;
however,
a
greater
proportion
of
those
individuals
with
stability
values
consistently
 
 77
 lower
than
average
were
heavier
smokers
or
had
a
history
of
heavy
smoking.
The
mean
difference
between
smokers
and
never‐smokers
was
2.17
(p=0.707),
that
between
smokers
and
former‐smokers
was
1.12
(p=1.000),
and
that
between
never‐smokers
and
former‐smokers
was
1.05
(p=1.000).


 
 Figure
8.
ISQ
depending
on
smoking
status
of
patient
(patient‐level
analysis)

 5.4
Implant
Design‐Related
Factors

 5.4.1
Implant
system
Although
there
was
some
variation
in
stability
values
between
implant
systems,
no
consistent
trends
were
noted.
Nobel
Replace
Conical
Connection
implants
were
not
included,
as
the
number
placed
(n=1)
was
too
low
to
perform
statistical
analysis.

 
 78
 

 
 Number
placed
(%
of
 total)
 Mean
ISQ
value

 Nobel
Replace
Tapered
Groovy
 85
(29.7)
 79.87±6.09
 Nobel
Replace
Straight
Groovy
 12
(4.2)
 81.04±5.20
 Nobel
Replace
Select
Straight
 3
(1.1)
 81.42±4.16
 Nobel
Replace
Select
Tapered
 9
(3.2)
 78.01±4.52
 Nobel
Active
 70
(24.5)
 75.42±4.59
 Straumann
BL
SLA
 31
(10.8)
 77.06±5.99
 Straumann
BL
SLActive
 11
(3.8)
 79.52±6.49
 Straumann
Roxolid
 5
(1.7)
 75.60±4.93
 Straumann
SP
SLA
 10
(3.5)
 79.12±4.13
 Straumann
SP
SLActive
 8
(2.8)
 79.66±5.33
 Astra
Straight
 41
(14.3)
 79.73±6.53

 Table
1.
Distribution
and
mean
ISQ
for
types
of
implants
placed


 
 
 Figure
9.
Distribution
of
implants
according
to
implant
system

 
 79
 
 
 Figure
10.
ISQ
values
for
each
implant
type
placed

A
total
of
180
Nobel
Biocare
implants
were
placed,
with
a
mean
ISQ
of
78.16±5.77.
The
mean
ISQ
values
of
Straumann
(n=65)
and
Astra
(n=41)
implants
were
78.00±5.68
and
79.73±6.53,
respectively.
No
statistically
significant
differences
were
found
between
any
of
the
groups.

 
 80
 

Figure
11.
Mean
ISQ
values
for
Nobel
Biocare,
Straumann,
and
Astra
Tech
implants

The
mean
ISQ
of
Straumann
tissue‐level
implants
(n=18)
was
79.36±4.56
and
that
for
Straumann
bone
level
implants
(n=42)
was
77.71±6.14.
The
difference
between
the
groups
was
not
statistically
significant.


 
 Figure
12.
Mean
ISQ
values
for
Straumann
SP
and
Straumann
BL
implants

 
 81
 5.4.2
Implant
dimensions
‐
length
Implants
were
divided
into
3
length
groups:
≤9mm
(short),
10‐12mm
(regular
length),
and
≥13mm
(long).
Of
the
286
implants,
43
(15.0%)
were
short,
150
(52.5%)
were
regular
length,
and
93
(32.5%)
were
long.
Shorter
implants
were
found
to
have
significantly
higher
ISQ
values
than
both
regular
length
implants

(p=0.01),
and
long
implants
(p=<0.001).
No
significant
difference
was
found
between
regular
length
implants
and
long
implants
(p=
0.11).

 
 Figure
13.
Distribution
of
implants
according
to
implant
length

 
 Figure
14.
ISQ
of
implants
based
on
length
 
 82
 When
implant
length
was
considered
in
the
maxilla
in
isolation,
no
statistically
significant
differences
were
detected.
The
mean
difference
between
short
and
regular
length
implants
was
2.54
±
1.95
ISQ
units
(p=0.59)
and
that
between
short
and
long
implants
was
2.63
±
1.95
ISQ
units
(p=0.68).
The
difference
between
regular
length
and
long
implants
was
negligible
(0.18
±
0.96
ISQ
units,
p=1.0).


 
 Figure
15.
ISQ
of
maxillary
implants
based
on
length

In
contrast,
statistically
significant
differences
were
found
between
mandibular
implants
of
different
lengths.
The
mean
difference
between
short
and
regular
length
implants
was
3.27
±
1.10
ISQ
units
(p=0.01).
The
difference
between
short
and
long
implants
was
even
greater
at
7.86
±
1.52
ISQ
units
(p=<0.001),
as
was
the
difference
between
regular
length
and
long
implants
(mean
difference
4.59
±
1.35
ISQ
units,
p=<0.001).


 
 83
 
 Figure
16.
ISQ
of
mandibular
implants
based
on
length

Short
implants
(<10mm
in
length)
were
isolated
and
analyzed
by
comparing
those
in
the
anterior
and
posterior,
as
well
as
those
in
the
maxilla
and
mandible.
There
were
10
short
implants
placed
in
the
maxilla
and
33
placed
in
the
mandible.
The
mean
ISQ
in
the
maxilla
was
79.60
±
4.78
and
that
in
the
mandible
was
82.69
±
2.91.
The
mean
mandibular
ISQ
value
was
3.09
units
higher
than
the
maxilla
and
this
was
statistically
significant
(p=0.016).
 
 84
 
 Figure
17.
ISQ
of
short
implants
(<10mm)
placed
in
the
maxilla
and
mandible

There
were
7
short
implants
placed
in
the
incisor
and
canine
sites
(defined
as
anterior)
and
36
placed
in
the
premolar
and
molar
sites
(defined
as
posterior).
The
respective
means
for
these
groups
were
82.75
±
2.70
and
81.81
±
3.78.
The
mean
difference
between
the
groups
was
0.93
ISQ
units
and
was
not
significant
(p=0.54).


 
 Figure
18.
Mean
ISQ
of
short
implants
placed
in
anterior
or
posterior
sites
 
 85
 5.4.3
Implant
dimensions
‐
diameter
Implant
body
diameter
was
divided
into
3
groups
based
on
average
dimensions
of
the
various
implant
systems
studied;
these
included
<4.0mm
for
narrow
(56
implants,
19.6%),
4‐4.3mm
for
regular
width
(148
implants,
51.7%),
and
>4.3mm
for
wide
(82
implants,
28.7%).
A
statistically
significant
difference
was
found
between
narrow
and
regular
width
implants
and
between
narrow
and
wide
implants
(p=<0.001),
but
no
significant
difference
was
found
between
regular
width
and
wide
implants
(p=0.67).
The
mean
stability
of
narrow
implants
was
6.76

±
0.81
ISQ
units
lower
than
regular
width
implants
and
7.6
±
0.90
ISQ
units
lower
than
wide
implants.
The
mean
ISQ
of
wide
implants
was
slightly
greater
than
regular
width
implants
(0.87
±
0.71
units).


When
only
maxillary
implants
were
considered,
there
was
a
statistically
significant
difference
between
narrow
implants
and
regular
or
wide
implants
(p=<0.001),
but
not
between
regular
and
wide
implants
(p=1.00).
The
mean
difference
in
ISQ
between
narrow
and
regular
width
implants
was
5.68
±
1.04,
while
that
between
narrow
and
wide
implants
was
5.55
±
1.21,
and
that
between
regular
and
wide
implants
was
0.13
±
1.04.
Similar
findings
were
obtained
when
only
mandibular
implants
were
considered.
A
statistically
significantly
(p=
<0.001)
lower
mean
ISQ
was
obtained
for
narrow
implants
compared
with
both
regular
width
(mean
difference
8.37
±
1.28),
and
wide
(mean
difference
9.96
±
1.36)
implants.
The
difference
was
not
significant
between
regular
width
and
wide
implants
(1.59
±
0.94
units,
p=0.28).


 
 86
 
 
 Figure
19.
ISQ
according
to
implant
diameter

 
 
 Figure
20:
Distribution
of
implants
according
to
diameter

 
 87
 
 Figure
21:

Maxillary
ISQ
values
according
to
implant
diameter

 
 Figure
22:

Mandibular
ISQ
according
to
implant
diameter
 
 
 88
 Data
were
available
for
179
Nobel
Biocare
implants.
The
mean
ISQ
for
Nobel
Active
implants
(n=70)
was
75.42±4.59
and
that
for
other
Nobel
Biocare
implants
(n=109)
was
79.89±5.82.
The
mean
difference
between
these
types
of
implants
was
4.47
and
this
was
highly
statistically
significant
(p=0.000).


 
 Figure
23.
Mean
ISQ
for
Nobel
Active
implants,
compared
with
all
other
Nobel
Biocare
implants
 
 5.4.4
Implant
dimensions
‐
surface
area
Surface
areas
were
available
for
the
Nobel
implants
and
ranged
from
133
to
295mm2.
A
positive
correlation
was
found
between
surface
area
and
ISQ
but
the
value
was
very
low
(Pearson
correlation
coefficient
0.172,
P‐0.027).
The
scatter
plot
shows
that
there
are
no
consistent
patterns.


 
 89
 
 Figure
24:
ISQ
according
to
implant
surface
area
(Nobel
Biocare
implants
only)

 5.5
Implant
Placement‐Related
Factors

 5.5.1
Insertion
torque
value
Implants
were
classified
into
five
groups,
based
on
the
insertion
torque
value
(Ncm)
obtained
at
surgery,
when
available.
The
groupings
were:
0‐10
(n=5),
11‐20
(n=45),
21‐30
(n=68),
31‐40
(n=104),
and
>40
Ncm
(n=51).
Insertion
torque
values
were
not
available
for
39
implants
(12.5%).
No
statistically
significant
difference
was
found
in
ISQ
between
groups
at
second
surgery
(p=
>0.20
for
all
comparisons).
Additionally,
both
ISQ
taken
at
the
time
of
implant
placement
and
insertion
torque
were
available
for
58
implants
but
the
relationship
between
the
two
was
completely
insignificant
(p=1.00).


 
 90
 
 Figure
25:
Second
stage
ISQ
of
implants
based
on
insertion
torque
(Ncm)
 
 5.5.2
Bone
density
A
tactile
assessment
of
bone
density
was
available
for
151
implants.
A
statistically
significant
difference
in
ISQ
was
found
for
implants
placed
in
soft
(n=22),
medium
(n=99)
and
dense
(n=30)
bone.
The
mean
ISQ
for
implants
placed
in
dense
bone
was
77.60±6.18
and
that
of
implants
placed
in
medium
bone
was
77.82±5.52.
In
comparison,
the
mean
ISQ
for
implants
placed
in
soft
bone
was
only
73.75±7.87,
which
was
statistically
significantly
lower
than
the
value
for
implants
placed
in
bone
of
medium
density
(p=0.014).
The
differences
between
soft
and
dense
bone
(p=0.074)
and
between
medium
and
dense
bone
(p=1.00)
did
not
reach
statistical
significance.
ISQ
measured
at
implant
placement
and
bone
density
were
available
for
36
implants
and
the
relationship
between
the
two
was
not
statistically
significant
(p=1.00).


 
 91
 
 Figure
26.
ISQ
of
implants
based
on
bone
density

 5.5.3
Number
of
implants
Patients
in
this
study
population
received
between
1
and
14
implants,
with
53.7%
receiving
only
1
implant,
25.5%
receiving
2
implants,
and
11.4%
receiving
3
implants.
Most
patients
had
4
or
fewer
implants
but
5.4%
had
4
or
more
implants.

A
slightly
lower
ISQ
value
was
observed
in
patients
who
had
more
implants.
The
mean
ISQ
obtained
for
the
135
patients
receiving
between
1
and
3
implants
was
78.97
±
5.24,
compared
with
76.12
±
4.94
for
the
14
patients
receiving
between
4
and
14
implants.
The
difference
between
the
two
groups
bordered
on
statistical
significance
(p=0.054).

 
 92
 
 5.6
Anatomic
Site‐Related
Factors

 5.6.1
Arch
Implants
were
placed
in
all
regions
of
both
jaws,
with
54%
in
the
maxilla
and
46%
in
the
mandible.
The
mean
ISQ
for
implants
placed
in
the
mandible
was
79.57
±
5.76
and
that
for
implants
placed
in
the
maxilla
was
77.22
±
5.79.
A
significantly
higher
mean
ISQ
was
obtained
for
implants
placed
in
the
mandible,
compared
with
implants
placed
in
the
maxilla
(p=<0.001)
 
 
 Figure
27.
ISQ
according
to
arch
(maxilla
or
mandible)
 
 5.6.2
Location
in
arch
Implant
sites
included
74
incisors,
24
canines,
81
premolars,
and
107
molars.

ISQ
values
for
incisors
were
lower
than
the
values
for
canines
but
the
difference
was
not
statistically
significant
(p=0.487).
Incisors
did,
however,
have
a
significantly
lower
mean
ISQ
than
premolars
(p=0.01)
and
molars
(p=<0.001).


 
 93
 
 
 Figure
28.
ISQ
according
to
implant
site
 
Data
were
also
analyzed
based
on
site
within
each
arch.
In
the
maxilla,
there
was
no
statistically
significant
difference
in
ISQ
value
based
on
the
site
(p=0.079).
In
the
mandible,
however,
a
significant
difference
was
seen
between
incisors
and
premolars
(p=<0.001,
mean
difference
6.51
ISQ
units),
between
incisors
and
molars
(p=<0.001,
mean
difference
8.81
ISQ
units),
and
between
canines
and
molars
(p=0.005,
mean
difference
5.18
ISQ
units).


 
 94
 
 Figure
29.
ISQ
according
to
implant
site
in
the
mandible
only

 
 Figure
30.
ISQ
according
to
implant
site
in
the
maxilla
only

 
 95
 Further
comparison
of
arch
site
was
done
comparing
maxilla
and
mandible.
There
were
57
maxillary
incisor
implants
(mean
ISQ
75.95
±
5.11)
and
17
mandibular
incisor
implants
(mean
ISQ
73.11
±
7.53).
The
difference
between
arches
was
not
statistically
significant
(p=0.16,
mean
difference
2.84
ISQ
units).
There
were
11
maxillary
canine
implants
(mean
79.14
±
3.85)
and
13
mandibular
canine
implants
(mean
76.73
±
6.46).
The
difference
between
arches
was
not
significant
for
canines
either
(p=0.27,
mean
difference
2.41
ISQ
units).
There
were
42
maxillary
premolar
implants
(mean
77.21
±
6.10)
and
39
mandibular
premolar
implants
(mean
79.62
±
4.48).
The
difference
between
maxilla
and
mandible
was
statistically
significant
but
clinically
small
(p=0.045,
mean
difference
2.41
ISQ
units).
There
were
45
maxillary
molar
implants
(mean
78.67
±
6.35)
and
62
mandibular
molar
implants
(mean
81.91
±
4.05).
The
molars
accounted
for
the
largest
difference
between
the
maxilla
and
mandible,
with
a
significant
(p=0.004)
mean
difference
of
3.24
ISQ
units.

 
 Figure
31.
ISQ
value
for
incisor
implants
placed
in
the
maxilla
and
mandible

 
 96
 
 Figure
32.
ISQ
value
for
canine
implants
placed
in
the
maxilla
and
mandible

 
 Figure
33.
ISQ
value
for
premolar
implants
placed
in
the
maxilla
and
mandible

 
 97
 
 Figure
34.
ISQ
value
for
molar
implants
placed
in
the
maxilla
and
mandible
 
 5.7
Bone
Grafting‐Related
Factors
 
A
total
of
110
implants
were
placed
at
sites
that
were
not
treated
with
any
type
of
bone
grafting,
with
a
mean
ISQ
of
78.81±6.46.
The
mean
ISQ
for
the
176
implants
placed
after
any
type
of
grafting
(LRA,
socket
preservation,
or
sinus
lift)
was
78.06±5.47.
The
difference
between
these
groups
did
not
reach
statistical
significance.
 
 
 98
 
 Figure
35.
Mean
ISQ
of
implants
placed
in
native
bone,
compared
to
those
placed
at
sites
treated
with
guided
bone
regeneration

 5.7.1
Lateral
ridge
augmentation
Of
the
assessed
implants,
98
were
placed
at
sites
with
lateral
ridge
augmentation
(LRA)
and
188
at
sites
without
LRA
(mean
ISQ
values
77.55
±
5.64
and
78.76
±
5.96,
respectively).
Overall,
the
ISQ
values
of
implants
which
were
placed
at
grafted
or
non‐grafted
sites
did
not
differ
significantly
(p=0.094).
There
was
also
no
statistically
significant
difference
(p=0.22)
in
buccal
ISQ
between
implants
placed
at
sites
treated
with
LRA
(76.72
±
6.01)
and
those
placed
at
sites
with
native
bone
(77.69
±
6.86).

 
 
 99
 
 Figure
36.
ISQ
based
on
whether
or
not
the
site
was
treated
with
lateral
ridge
augmentation

 
 Figure
37.
Buccal
ISQ
based
on
whether
or
not
the
site
was
treated
with
lateral
ridge
augmentation

 
 100
 Materials
used
for
lateral
ridge
augmentation
included
autograft
(n=12),
allograft
(n=64),
and
xenograft
(n=22).
The
ISQ
did
not
differ
statistically
significantly
among
most
groups
of
implants
placed
in
sites
grafted
with
different
LRA
materials
(no
LRA
78.7±6.0;
autograft
80.0±3.5;
and
allograft
78.0±5.8);
however,
the
mean
ISQ
value
for
implants
placed
at
sites
treated
with
xenograft

(75.2±5.2)
was
consistently
lower
than
for
other
groups
and
significantly
lower
than
for
implants
placed
in
sites
with
no
LRA
(p=0.042).
When
only
the
buccal
ISQ
value
was
considered
for
the
various
bone
graft
types,
there
were
no
statistically
significant
differences
(p=>0.05
for
all
variables).
Data
regarding
LRA
and
the
ISQ
at
time
of
implant
placement
were
available
for
55
implants,
all
of
which
were
placed
in
the
university
setting.
The
mean
ISQ
for
implants
placed
in
non‐grafted
bone
(n=32)
was
77.25±6.90.
For
grafted
sites,
the
mean
placement
ISQ
was
78.40±2.65
for
autograft,
70.29±7.35
for
allograft,
and
76.32±4.65
for
xenograft.
The
duration
of
healing
from
LRA
to
implant
placement
also
did
not
appear
to
affect
either
the
overall
or
the
buccal
ISQ
value
(p=>0.16
for
all
variables).


 
 Figure
38.
ISQ
based
on
type
of
lateral
ridge
augmentation
material
used
 
 
 101
 
 Figure
39.
ISQ
based
on
timing
of
lateral
ridge
augmentation

 
 
 102
 
 Figure
40.
Buccal
ISQ
based
on
timing
of
lateral
ridge
augmentation

 
 5.7.2
Socket
preservation
No
significant
difference
(p=0.835)
was
found
in
ISQ
between
implants
placed
in
sites
treated
with
socket
preservation
(n=53,
mean
78.21
±
5.21)
and
those
not
treated
with
socket
preservation
(n=232,
mean
78.38
±
6.03).
Socket
preservation
was
performed
at
40
sites
using
allograft
and
13
sites
using
xenograft
and
there
were
no
significant
differences
in
ISQ
between
these
groups
(p=>0.20
for
all
variables).
Additionally,
there
was
no
significant
effect
whether
the
socket
preservation
was
performed
at
the
time
of
implant
placement
(for
example,
to
fill
in
the
gap
between
the
implant
surface
and
the
alveolus
during
immediate
implant
placement),
or
if
it
was
performed
1‐5,
6‐9,
or
>9
months
prior
to
implant
placement
(p=>0.05
for
all
variables).



 
 103
 
 Figure
41.
ISQ
based
on
whether
or
not
socket
preservation
was
performed
 
 
 Figure
42.
ISQ
based
on
socket
preservation
material
used
 
 
 104
 
 Figure
43.
ISQ
based
on
timing
of
socket
preservation

 
 5.7.3
Sinus
lift
A
total
of
59
implants
were
placed
at
sites
treated
with
sinus
lifts.
There
was
no
significant
difference
in
ISQ,
whether
or
not
the
site
had
received
sinus
grafting
(p=0.62).
There
were
also
similar
results
at
sites
treated
with
sinus
lifts,
regardless
of
the
material
used
(no
sinus
lift
78.3±6.1;
allograft
79.6±4.8;
and
xenograft
78.1±5.1).
No
statistical
significance
was
reached
(p=>0.1
for
all
comparisons).
Implants
placed
simultaneously
with
sinus
lifting
(n=27)
had
similar
ISQ
values,
compared
with
those
placed
both
1‐9
(n=14)
and
>9
months
later
(n=18)
(p=0.67).


 
 105
 
 Figure
44.
ISQ
based
on
whether
or
not
sinus
lift
was
performed

 
 Figure
45.
ISQ
based
on
sinus
graft
material

 
 106
 
 Figure
46.
ISQ
based
on
sinus
graft
timing

 5.7.4
Presence
of
dehiscence
at
implant
placement
If
a
dehiscence
was
present
at
the
time
of
implant
placement,
it
was
measured
and
classified
as
either
0.5‐2mm
(n=23)
or
>2mm
(n=9).
There
was
no
significant
difference
in
overall
ISQ
value
whether
a
dehiscence
was
present
or
between
groups
(p=1.00).
Similarly,
there
was
no
significant
difference
when
only
the
buccal
ISQ
was
considered
(p=1.00).
Analysis
of
ISQ
at
the
time
of
implant
placement
was
not
possible
due
to
the
small
sample
size.

 
 107
 
 Figure
47.
Overall
ISQ
based
on
presence
and
size
of
buccal
dehiscence

 
 Figure
48.
Buccal
ISQ
based
on
presence
and
size
of
buccal
dehiscence

 
 108
 5.8
Factors
Related
to
Timing
of
Implant
Placement
 5.8.1
Healing
time

A
significant
correlation
(p=0.004)
was
found
between
number
of
months
of
healing
after
implant
placement
and
the
ISQ,
however
the
scatter
plot
demonstrated
that
there
were
no
consistent
trends

 

Figure
49.
Scatter
plot
demonstrating
no
consistent
pattern
between
the
overall
ISQ
value
and
the
months
of
implant
healing
prior
to
measurement
of
the
ISQ.

 5.8.2
Immediate
placement
Immediately
placed
(n=40)
and
conventionally
placed
(n=246)
implants
were
compared
using
the
T
test.
A
significant
difference
was
found
(p=0.008),
with
immediately
placed
implants
having
a
lower
mean
ISQ
(75.98
±
5.91)
than
conventionally
placed
implants
(78.73
±
5.79).
The
mean
difference
between
the
groups
was
2.75
ISQ
units.
Insufficient
data
was
available
on
ISQ
values
taken
at
the
time
of
implant
placement.



 
 109
 
 Figure
50.
ISQ
based
on
placement
timing
 
 5.8.3
Staging
protocol
No
statistically
significant
difference
was
found
between
implants
which
were
placed
with
a
one‐stage
or
a
two‐stage
(submerged)
protocol.

A
total
of
112
implants
were
placed
in
a
one‐stage
manner,
with
a
mean
ISQ
of
78.72
±
5.92,
compared
with
174
two‐stage
implants
with
a
mean
ISQ
of
78.11
±
5.86.

ISQ
measurements
at
the
time
of
implant
placement
were
available
for
55
implants,
10
of
which
were
placed
with
a
one‐stage
protocol.
The
mean
ISQ
for
this
group
was
78.66±3.61,
compared
with
75.98±6.88
for
implants
placed
with
a
two‐stage
protocol.
The
difference
between
the
groups
did
not
reach
statistical
significance
(P=0.093).
 
 110
 
 Figure
51.
ISQ
based
on
placement
protocol

 5.9
Level
of
Training
of
the
Surgeon
Of
the
286
implants,
231
were
placed
by
experienced
periodontists
in
private
practice
and
55
by
graduate
periodontics
residents
at
the
University
of
British
Columbia
(U.B.C.).
This
data
was
analyzed
at
the
patient‐level;
127
of
the
patients
were
treated
by
a
periodontist
and
22
were
treated
at
U.B.C.
The
mean
ISQ
for
implants
placed
by
periodontists
was
79.03
±
5.22
and
that
for
implants
placed
at
U.B.C.
was
76.83
±
5.30.
The
mean
difference
was
2.20
ISQ
units
and
did
not
reach
statistical
significance
(p=0.083).


 5.10
Linear
Multiple
Regression
Coefficients

When
controlled
for
gender,
smoking
(pack
years,
as
a
continuous
variable),
diabetes
(presence/absence),
number
of
implants,
and
surgeon
(periodontist/resident),
age
remained
a
significant
predictor
of
ISQ
value
(p=0.003).

The
remaining
factors
did
not
show
statistical
significance
in
this
model:
gender
(p=0.499),
smoking
(p=0.078),
diabetes
(p=0.673),
number
of
implants
(0.062),
and
surgeon
(p=0.078).

 
 111
 6.
DISCUSSION

Measurement
of
implant
stability
is
integral
in
evaluating
the
success
of
implants
and
deciding
when
to
functionally
load
implants.
Resonance
frequency
analysis,
as
used
in
this
study,
has
the
potential
to
provide
an
early
indication
of
stability
and
allows
repeated
measurements
over
time
to
monitor
changes.
ISQ
values
were
not
consistently
taken
at
implant
placement,
since
most
studies
have
shown
that
the
initial
ISQ
has
little
bearing
on
the
value
obtained
after
a
period
of
healing.

It
has
been
well‐documented
that
initially
high
levels
may
decrease
and
initially
low
levels
may
increase
in
the
early
healing
period,
leading
to
similar
ISQ
values
over
time,
regardless
of
the
initial
reading6,
16,
24,
29,
31,
100.
The
initial
decrease
in
ISQ
has
been
attributed
to
lateral
compression
during
implant
placement,
leading
to
remodeling
of
the
bone‐implant
interface
post‐insertion
109,
114.
Others,
however,
have
found
a
steady
increase
in
ISQ
after
placement89,
91,
113,
although
this
may
be
due
to
infrequent
monitoring
of
ISQ
in
the
early
healing
stages
when
the
greatest
change
is
expected.
Cornelini
et
al
(2004)
110
found
that
there
was
little
change
in
ISQ
if
good
primary
stability
was
obtained.
In
the
clinical
setting
in
which
the
present
study
was
conducted,
the
ISQ
value
was
used
to
ensure
sufficient
stability
had
been
reached
to
load
the
implant
and
to
provide
a
baseline
value
for
further
follow‐up.
For
these
purposes,
an
additional
measurement
taken
at
the
time
of
surgery
would
provide
very
little
value,
as
it
would
not
help
in
detecting
early
failure.

 6.1
Osstell‐Related
Factors
 6.1.1
Direction
of
measurement
The
ISQ
can
be
measured
either
perpendicular
or
parallel
to
the
alveolar
crest.
The
current
study
found
that
the
buccal
ISQ
was
not
significantly
different
from
the
lingual
or
palatal
ISQ,
but
that
it
was
significantly
lower
than
measurements
taken
from
the
mesial
and
distal.
Several
other
studies
have
found
lower
ISQ
values
in
a
 
 112
 buccal‐lingual
orientation,
compared
with
a
mesial‐distal
orientation
and
this
has
been
attributed
to
thinner
bone
on
the
buccal
and
lingual,
compared
to
the
interproximal
areas78,
79,
178.
It
has
been
suggested
that
the
difference
between
a
parallel
and
perpendicular
orientation
to
the
alveolar
crest
may
be
up
to
10
ISQ
units82.
It
has
also
been
shown
that
buccal
and
lingual
values
are
not
significantly
different
from
each
other,
nor
are
the
mesial
and
distal
values178.
The
manufacturer
of
Osstell
recommends
taking
measurements
in
both
directions,
to
ensure
that
any
discrepancies
are
identified.

 6.1.2
Repeatability
of
measurements
Good
reproducibility
of
ISQ
measurements
has
been
demonstrated
by
several
authors,
with
many
indicating
a
difference
in
the
range
of
1‐2%9,
33,
34,
63.
Very
good
reproducibility
was
also
reflected
in
the
results
from
the
present
study.


 6.2
Patient‐Related
Factors
 6.2.1
Age
and
gender
A
trend
for
lower
mean
ISQ
was
found
for
implants
placed
in
younger
patients,
however
the
difference
among
genders
and
age
groups
was
not
statistically
significant.
Results
reported
in
the
literature
have
been
conflicting.
A
study
by
Turkyilmaz
et
al
(2006)
50
found
significantly
higher
ISQ
values
in
men
and
in
older
patients;
however,
it
was
hypothesized
that
this
was
due
to
a
greater
proportion
of
implants
placed
in
dense
bone
in
the
anterior
mandible
in
older
patients,
as
well
as
hormonal
differences
between
the
genders.
Other
authors
have
found
higher
values
in
males99,
117
but
the
difference
has
been
observed
to
dissipate
with
time31.
Zix
et
al
(2005)
115
found
a
significantly
lower
ISQ
value
in
post‐menopausal
women,
compared
with
men
in
the
same
age
group.
Another
study
found
a
significantly
lower
ISQ
value
in
men60;
however,
in
this
study
females
received
more
implants
in
denser
bone
in
the
mandible
and
the
sample
size
was
quite
small.
Another
study
failed
to
find
any
difference
between
genders43.

 
 113
 
 6.2.2
Diabetic
status
This
report
did
not
show
a
statistically
significant
association
between
Type
2
diabetes
and
ISQ
value;
however,
it
is
important
to
note
that
all
diabetic
patients
were
required
to
demonstrate
acceptable
diabetic
control
prior
to
receiving
implant
surgery.
At
the
time
of
implant
placement,
all
diabetic
patients
were
considered
to
be
well‐controlled.
The
level
of
diabetic
control
(glycosylated
hemoglobin,
HbA1c),
however,
was
often
self‐reported
by
the
patients.
Even
with
poor
control
(defined
as
HbA1c
between
7.5
and
11.4%),
Khandelwal
et
al
(2011)
179
demonstrated
implant
success
of
98%
based
on
48
Straumann
implants
placed
in
the
mandible
at
least
4
months
after
extraction.

Further,
the
implants
had
high
baseline
ISQ
values
(means
ranging
from
70.1
to
75.4),
which
increased
significantly
until
16
weeks
(means
ranging
from
78.8
to
79.3).


 6.2.3
Smoking
status
The
current
study
failed
to
find
a
statistically
significant
difference
in
mean
ISQ
for
smokers,
ex‐smokers,
and
non‐smokers.
Only
6%
and
22%
of
the
population,
however,
were
smokers
and
former‐smokers,
respectively,
and
smoking
status
was
self‐reported.
There
was
a
wide
range
of
cumulative
exposure
to
tobacco
smoking,
with
pack‐years
ranging
from
1
to
60,
but
this
did
not
significantly
impact
the
ISQ
values.
Balatsouka
et
al
(2005)
118
also
failed
to
show
a
significant
effect
of
smoking
on
RF
values
in
a
study
on
rabbits.
While
the
differences
were
not
statistically
significant
in
the
current
study,
it
was
interesting
to
observe
the
frequency
with
which
smokers
experienced
complications
and
had
ISQ
values
below
the
expected
ranges.


 
 114
 6.3
Implant
Design‐Related
Factors

 6.3.1
Implant
type
Despite
some
trends,
the
current
study
failed
to
find
any
statistically
significant
difference
between
implant
types.
An
important
consideration,
however,
is
that
63.0%
of
the
implants
were
Nobel
Biocare
and
only
22.7%
and
14.3%
were
Straumann
and
Astra
Tech,
respectively.
Another
study
comparing
Straumann
and
Astra
Tech
implants
found
similar
values
for
both
types
(mean
ISQ
79.0
and
77.3,
respectively)
53.
In
contrast,
a
comparison
of
6
implant
types
including
both
Brånemark
and
Straumann125
found
that
the
mean
ISQ
was
above
60
for
Brånemark
implants
and
below
60
for
Straumann
implants.
The
reliability
of
comparing
ISQ
values
of
these
two
implant
systems
has
been
questioned
and
the
difference
attributed
to
variations
in
design
and
stiffness
of
components115,
as
well
as
the
typical
placement
of
the
Straumann
implants
in
these
studies
in
a
supracrestal
position,
compared
with
placement
of
the
Brånemark
implants
at
the
bone
level9,
130.


 6.3.2
Implant
dimensions
A
statistically
significantly
higher
ISQ
value
was
obtained
for
short
implants
(≤9mm),
compared
with
regular
length
(10‐12mm)
and
long
(≥13mm)
implants;
however,
when
the
maxilla
was
evaluated
in
isolation
there
was
no
statistical
significance.
The
greatest
difference
between
implants
of
various
lengths
was
seen
for
implants
placed
in
the
mandible,
with
short
implants
having
significantly
higher
ISQ
values
than
both
regular
and
long
implants.
A
significant
difference
was
also
found
between
regular
and
long
implants,
with
longer
implants
having
a
mean
ISQ
4.6
units
lower
than
regular
length
implants.


The
mean
ISQ
for
short
implants
(<10mm)
placed
in
the
maxilla
was
79.6,
whereas
that
in
the
mandible
was
82.7
and
this
difference
reached
statistical
significance.
The
ISQ
for
short
implants
placed
in
the
incisor
or
canine
region
was
similar
to
that
of
implants
placed
in
the
premolar
or
molar
region,
with
the
mean
difference
less
 
 115
 than
1
ISQ
unit.
There
was
an
uneven
distribution
of
short
implants,
however,
with
76.7%
placed
in
the
mandible
and
only
16.3%
placed
in
the
incisor
or
canine
sites.
The
increased
use
of
short
implants
in
the
posterior
mandible
was
related
to
limited
vertical
height
superior
to
the
inferior
alveolar
nerve
canal
and,
in
this
area,
the
use
of
wider
implants
may
have
compensated
for
any
effect
on
ISQ
that
the
reduced
height
may
have
had.
This
is
reflected
in
the
fact
that,
of
all
43
short
implants,
only
one
was
narrow
and
this
was
placed
in
a
maxillary
incisor
site.


Most
studies
have
shown
that
implant
length
either
has
little
effect
on
ISQ
or
that
shorter
implants
have
higher
values
than
longer
implants.
Pattjin
et
al
(2007)
79
found
slightly
lower
ISQ
values
for
longer
implants
placed
in
dense
bone.

Similarly,
Ostman
et
al
(2006)
99
obtained
higher
values
for
shorter
implants
and
attributed
this
to
design
features
of
the
implant
with
a
reduced
diameter
in
the
coronal
area
for
longer
implants,
as
well
as
increased
drilling
needed
to
place
longer
implants.
Other
studies
have
found
that
implant
length
has
very
little
effect
on
ISQ
values9,
29,
73,
90,
117.
Valderrama
et
al
(2007)
29
noted
that
additional
length
has
less
effect
once
sufficient
stability
is
obtained
in
the
marginal
area
and
related
this
to
the
fact
that
added
implant
length
tends
to
be
located
in
trabecular
bone,
rather
than
the
dense
cortical
bone
found
in
the
crestal
region.


In
the
current
study,
implant
diameter
was
divided
into
three
groups
and
a
significantly
lower
ISQ
was
obtained
for
narrow
implants
(<4mm),
compared
with
both
of
the
wider
groups.
Narrow
implants
were
found
to
have
a
mean
ISQ
5.7
units
lower
than
regular
diameter
implants
and
5.5
units
lower
than
wide
implants
in
the
maxilla,
and
8.4
and
10.0
units
lower
in
the
mandible,
respectively.
In
both
arches,
the
difference
between
regular
and
wide
diameter
implants
did
not
reach
statistical
significance.

While
some
studies
have
found
that
implant
diameter
has
little
bearing
on
ISQ
values90,
114,
others
have
reported
a
significant
correlation
between
implant
diameter
and
ISQ57,
73,
117.
Further,
some
studies
have
reported
only
a
trend
for
 
 116
 lower
values
with
narrow
implants84,
104
and
Akkocaoglu
et
al
(2005)
67
concluded
that
ISQ
value
is
determined
not
by
the
overall
implant
diameter,
but
rather
by
the
diameter
at
the
neck
of
the
implant.
With
this
in
mind,
a
comparison
was
done
between
all
narrow‐diameter
Nobel
Replace
implants
(n=6)
and
Nobel
Active
implants
(n=70),
both
of
which
have
the
same
platform
diameter.
The
mean
ISQ
values
of
the
two
groups
did
not
differ
significantly
but
the
number
of
narrow
Nobel
Replace
implants
was
very
low.


Implant
dimensions
were
further
analyzed
according
to
surface
area
for
Nobel
Biocare
implants.
A
positive
correlation
was
found
between
total
surface
area
and
ISQ
but
the
value
was
very
low.
This
finding
is
not
particularly
surprising,
given
the
higher
ISQ
for
shorter
implants,
which
could
dilute
the
differences
found
between
narrow
and
wider
implants.
Further,
as
discussed
previously,
several
studies
have
discussed
the
importance
of
the
crestal
bone‐implant
contact
in
determining
ISQ
value.


 6.4
Implant
Placement‐Related
Factors
 6.4.1
Insertion
torque
value
No
statistically
significant
association
was
found
between
insertion
torque
and
ISQ
taken
at
second
stage.
In
support
of
this
finding,
several
authors
have
reported
a
significant
association
between
insertion
or
cutting
torque
and
initial
ISQ43,
45
but
often
this
difference
is
no
longer
significant
after
a
period
of
initial
healing16.
Becker
et
al
(2006)
46
found
that,
for
every
1‐unit
increase
in
torque,
the
ISQ
increased
by
0.3
units
at
the
time
of
implant
placement,
but
decreased
by
0.2
units
after
3
months.
This
was
attributed
to
pressure
necrosis
caused
by
placement
of
the
implant
at
a
higher
torque
and
similar
results
were
obtained
by
Nkenke
et
al47.
In
contrast,
others
have
reported
no
significant
correlation
between
insertion
or
cutting
torque
and
ISQ
value10,
54,
55
and
Karl
et
al
(2008)
57
argued
that
insertion
 
 117
 torque
provided
little
clinical
benefit,
given
that
it
can
be
used
only
at
the
time
of
implant
placement
and
has
little
association
with
stability
after
a
period
of
healing.
 
 6.4.2
Bone
density
Although
initial
ISQ
has
been
shown
to
be
lower
in
soft
bone,
the
ISQ
taken
after
healing
appears
to
be
similar
regardless
of
bone
density9,
31,
87,
89‐91.
Barewal
et
al
(2003)
9
observed
the
lowest
ISQ
in
all
bone
types
at
3
weeks,
with
a
large
drop
in
ISQ
from
baseline
to
3
weeks
in
softer
type
4
bone,
followed
by
a
large
increase
until
10
weeks.
At
5
weeks,
there
was
no
significant
difference
in
ISQ
based
on
different
bone
densities.
Bischof
et
al
(2004)
90
found
that
the
values
equalized
among
different
densities
by
12
weeks.
In
contrast
to
these
reports,
the
current
study
found
a
significantly
lower
mean
ISQ
for
implants
placed
in
soft
bone,
compared
with
medium
or
dense
bone,
even
after
several
months
of
healing.
It
is
important
to
consider,
however,
that
the
measurement
of
bone
density
was
based
on
tactile
sensation
and
was
at
the
surgeon’s
discretion.
It
may
be
argued
that
it
is
inappropriate
to
compare
these
subjective
measurements,
taken
by
several
different
surgeons
in
different
clinical
environments.
As
such,
subsequent
analysis
was
done
of
only
the
implants
placed
in
private
practice
by
an
experienced
periodontist,
for
which
stability
values
were
available
(n=96).
Results
of
this
analysis
showed
borderline
significance
(p=0.06),
with
the
highest
values
in
bone
of
medium
density
and
the
lowest
values
in
soft
bone.
However,
the
distribution
between
groups
was
uneven,
with
15
implants
placed
in
dense
bone,
64
in
medium
bone,
and
17
in
soft
bone.
Further,
the
standard
deviation
of
implants
placed
in
soft
bone
was
very
high
and
nearly
reached
8
ISQ
units.


 6.4.3
Number
of
implants
A
lower
mean
ISQ
was
obtained
in
patients
who
received
more
implants
and
this
bordered
on
statistical
significance
(p=0.054).
It
may
be
important
to
consider
why
these
patients
lost
multiple
teeth
and
whether
the
predisposition
to
multiple
tooth
loss
could
also
predispose
to
a
lower
implant
stability.

 
 118
 
 6.5
Anatomic
Site‐Related
Factors

 6.5.1
Arch
and
location
in
arch
A
statistically
significantly
higher
mean
ISQ
was
obtained
for
mandibular
implants
compared
with
maxillary
implants
but
the
difference
was
clinically
small.
Implants
placed
in
the
incisor
position
were
found
to
have
a
significantly
lower
ISQ
than
those
at
the
premolar
or
molar
sites
but
no
significant
difference
was
found
between
implants
at
any
other
positions.
When
the
arches
were
analyzed
independently,
the
difference
between
anterior
and
posterior
sites
was
found
to
pertain
only
to
mandibular
implants.
In
the
mandible,
implants
in
the
canine
position
had
significantly
lower
ISQ
values
than
those
at
molar
sites
and
those
at
incisor
sites
had
significantly
lower
ISQ
values
than
those
at
premolar
and
molar
sites.
The
only
significant
difference
between
the
arches
was
found
at
molars,
which
had
statistically
significantly
higher
ISQ
values
in
the
mandible.


Barewal
et
al
(2003)
9
followed
implants
up
to
10
weeks
and
found
higher
values
in
the
mandible
at
all
time
points.
In
this
patient
population,
no
maxillary
implants
were
placed
in
dense
type
1
bone
and
a
greater
proportion
of
maxillary
implants
were
placed
in
soft
type
4
bone,
which
likely
accounts
for
the
difference
between
the
arches.
Balshi
et
al
(2005)
31
had
similar
findings
up
to
90
days.
Other
authors
have
also
observed
higher
values
in
the
mandible53,
94,
99
but
not
all
studies
support
these
findings
and
some
reports
show
no
significant
difference
between
the
arches59,
70,
72.


Although
some
studies
have
shown
that
the
difference
between
the
arches
diminishes
over
time100,
101,
a
common
finding
was
a
continued
higher
ISQ
for
mandibular
implants.
Bischof
et
al
(2004)
90
demonstrated
that
the
difference
was
still
significant
at
12
weeks,
and
that
the
increase
in
maxillary
ISQ
was
slower,
becoming
significant
only
after
12
weeks,
compared
to
6
weeks
for
mandibular
implants.
At
12
months,
Horwitz
et
al
(2007)
102
still
found
a
significantly
higher
ISQ
for
mandibular
implants.

 
 119
 
Ostman
et
al
(2006)
99
found
higher
values
in
the
posterior
and
reasoned
that
this
was
due
to
the
use
of
wide‐platform
implants
in
the
posterior,
compared
with
regular‐
or
narrow‐platform
implants
in
the
anterior.
Other
authors
have
also
supported
this
finding57,
59
and
Karl
et
al
(2008)
noted
that
the
highest
values
were
in
the
posterior
mandible
and
the
lowest
values
in
the
anterior
maxilla.
Becker
et
al
(2005)
100,
however,
did
not
find
a
significant
difference
between
implants
placed
in
the
anterior
or
posterior,
nor
did
Kahraman
et
al
(2009)
45
and
2
cadaver
studies
even
found
a
higher
mean
ISQ
at
anterior
sites19,
49.


 6.6
Bone
Grafting‐Related
Factors
 6.6.1
Guided
bone
regeneration

Most
studies
on
GBR
have
been
done
using
autogenous
bone.
Kramer
et
al
(2005)
78
reported
good
success
of
implants
after
a
fibula
graft,
with
progressively
increasing
ISQ
values
over
12
months.
Brechter
et
al170
found
a
similar
pattern
of
stability
over
12
months,
for
implants
after
sinus
elevation
without
graft
material
or
with
a
ramus
graft,
and
for
autogenous
(iliac
crest)
onlay
or
interpositional
bone
grafting.
Sjöström
et
al
(2005)
6
compared
the
ISQ
of
implants
placed
in
native
bone
or
after
autogenous
onlay
or
interpositional
grafts
and
found
similar
values
in
all
groups.
Similar
values
at
grafted
and
native
sites
were
also
shown
by
Özkan
et
al
(2007)
5,
with
autogenous
symphyseal
grafts,
and
by
Tong
et
al
(2008)
4
with
autogenous
grafts
in
the
anterior
maxilla.


The
present
study
sought
to
determine
if
the
ISQ
value
would
also
be
similar
between
implants
placed
in
native
bone
and
those
placed
in
bone
augmented
with
bone
allograft.
Overall,
no
significant
difference
was
found,
whether
or
not
a
lateral
ridge
augmentation
was
performed,
and
this
finding
was
confirmed
for
both
an
overall
mean
ISQ
value,
as
well
as
for
ISQ
taken
only
from
the
buccal.
Since
there
was
only
one
case
treated
with
alloplast,
this
case
was
excluded,
leaving
12
implant
 
 120
 sites
treated
with
autogenous
bone,
64
treated
with
allograft,
and
22
treated
with
xenograft.
No
significant
difference
in
ISQ
was
found
for
autograft
or
allograft,
however
sites
treated
with
xenograft
had
significantly
lower
ISQ
values.
Similarly,
no
significant
difference
in
ISQ
was
found
for
sites
treated
with
socket
preservation,
compared
with
native
bone,
regardless
of
the
material
used
and
the
duration
of
healing
prior
to
implant
placement.


 6.6.2
Sinus
lift
A
total
of
59
implants
in
this
population
were
placed
at
sites
that
received
sinus
lifting
and
no
significant
difference
in
ISQ
was
found,
whether
or
not
sites
had
been
treated.
The
majority
of
the
sinus
lifts
were
performed
using
allograft
or
xenograft
and
no
significant
difference
was
found
with
the
different
materials.
Only
one
case
had
been
treated
with
autogenous
bone
and
this
treatment
was
not
performed
at
either
of
the
centres
included
in
this
study.
The
case
was
transferred
to
the
clinic,
having
been
previously
treated
with
an
autogenous
sinus
lift.
Since
full
records
were
not
available,
this
case
was
not
considered
for
further
analysis.
Degidi
et
al
(2007)
168
also
compared
implants
placed
in
previously
sinus‐grafted
sites
(50%
autograft,
50%
xenograft)
with
those
placed
in
healed
bone
and
found
no
significant
differences.
The
similarity
of
ISQ
values,
whether
or
not
sinus
augmentation
has
been
performed,
likely
relates
to
the
relative
importance
of
the
crestal
portion
of
the
bone‐implant
contact,
compared
with
any
added
length
that
may
be
obtained
from
performing
a
sinus
augmentation.


 6.6.3
Presence
of
buccal
dehiscence
at
implant
placement
With
the
Osstell
ISQ
device,
magnetic
pulses
cause
vibrations
in
two
perpendicular
directions,
therefore
a
low
ISQ
in
one
direction
should
indicate
if
bone
is
missing
on
only
one
side
of
the
implant8.
In
this
study,
the
presence
and
length
of
a
buccal
dehiscence
was
noted
at
the
time
of
implant
placement.
No
statistically
significant
difference
in
ISQ
was
found
after
initial
healing,
regardless
of
the
length
of
the
dehiscence
(0‐5‐2mm
or
>2mm).
There
were
also
no
significant
findings
when
only
 
 121
 the
buccal
ISQ
was
considered.
The
lack
of
significance
could
be
due
to
the
relatively
small
size
of
the
dehiscence
defects.
Merheb
et
al74
found
that
significant
differences
were
detected
only
above
6‐mm
in
length.
These
authors
noted
that
the
Osstell
was
most
sensitive
at
detecting
marginal
bone
loss
(threshold
2mm)
but
not
very
sensitive
with
other
patterns
of
peri‐implant
bone
loss,
including
dehiscence‐type
defects.
Further,
larger
dehiscence
defects
were
typically
treated
with
bone
grafting
at
the
time
of
implant
placement
and
it’s
possible
that
this
affected
the
ISQ
at
second
surgery.


 6.7
Factors
Related
to
Implant
Timing
 6.7.1
Immediate
placement
Immediately
placed
implants
were
found
to
have
a
significantly
lower
ISQ
value
compared
with
implants
placed
in
healed
bone.
This
is
likely
due
to
the
coronal
gap,
which
is
typically
present
between
immediate
implants
and
the
surrounding
socket.
Since
ISQ
values
are
highly
dependent
upon
coronal
stability
and
bone‐implant
contact
in
the
coronal
region,
this
may
have
led
to
lower
ISQ
values
for
immediate
implants.
In
the
present
study,
however,
lower
values
were
observed
to
persist
after
several
months
of
healing.
Bogaerde
et
al101,
found
a
lower
ISQ
value
for
implants
placed
immediately
(65.8
at
placement
and
67.5
at
6
months),
compared
with
those
placed
in
healed
bone
(68.1
at
placement
and
73.6
at
6
months).


In
contrast,
Lindeboom
et
al
(2006)
138
obtained
the
same
ISQ
at
6
months
after
implant
insertion
(64.5),
whether
implants
were
placed
immediately
after
extraction
or
delayed
by
3
months.
Nordin
et
al
(2007)
139
also
obtained
the
same
ISQ
for
immediate
implants
and
those
placed
in
healed
sites.
Palattella
et
al
(2008)
140
observed
lower
surgical
ISQ
values
for
Straumann
implants,
but
the
final
ISQ
values
were
similar.


 
 122
 6.8
Experience
of
Surgeon
A
trend
was
noted
for
higher
ISQ
values
for
implants
placed
by
an
experienced
periodontist,
compared
with
periodontics
residents;
however
the
difference
did
not
reach
statistical
significance.
While
a
similar
protocol
for
ISQ
measurement
was
used
at
both
centres,
a
different
Osstell
ISQ
device
was
used
at
each
location.


 6.9
Prediction
of
Failure
The
mean
ISQ
for
the
three
implants
that
failed
and
were
removed
were
70,
74,
and
51
at
the
time
of
second
surgery.
The
value
of
51
was
the
lowest
recorded
ISQ
of
the
entire
data
set
and
clearly
indicated
a
failing
implant.
The
values
of
70
and
74,
however,
were
closer
to
the
overall
mean
of
all
implants
(78)
and
were
not
as
clearly
associated
with
failure.

One
patient
had
four
implants
placed
(sites
12,
32,
42,
45)
and
experienced
peri‐implant
bone
loss
at
two
of
his
implants
within
18
months
of
placement
(sites
42
and
45).
For
the
implant
placed
at
site
42,
the
initial
mean
ISQ
measurements
were
70.3,
72.7,
73.0,
72.0
from
the
buccal,
lingual,
mesial,
and
distal,
respectively.
The
corresponding
values
taken
9
months
later
were
59.0,
56.7,
57.0,
and
57.0.
The
implant
was
exposed
surgically
(Illustration
1),
revealing
circumferential
bone
loss,
most
advanced
on
the
buccal.
The
patient
also
had
an
implant
placed
at
site
32
at
the
same
appointment
and
both
were
Straumann
BL
SLA
3.3mm
x
12mm,
placed
at
bone
level
with
an
insertion
torque
of
about
25Ncm
in
dense
bone.
Surgery
was
unremarkable
with
no
complications.
No
bone
augmentation
needed
prior
to
or
in
conjunction
with
implant
placement
and
a
two‐stage
protocol
was
used.
The
implant
placed
at
site
32
had
initial
mean
ISQ
values
of
66.0,
67.0,
68.3,
and
68.3
(buccal,
lingual,
mesial,
distal).
At
9
months,
the
corresponding
values
were
64.3,
66.3,
68.7,
and
64.7.
This
implant
did
not
present
with
the
same
degree
of
bone
loss
but
did
show
about
1mm
of
crestal
bone
loss.
This
particular
patient
reported
a
history
of
50
pack
years
of
smoking.
He
was
able
to
refrain
from
smoking
for
several
weeks
prior
to
implant
placement
but
resumed
smoking
at
a
reduced
volume
two
weeks
 
 123
 after
implant
placement.
Following
this,
he
continued
to
smoke
at
a
much
higher
volume,
reaching
up
to
1
pack
per
day
at
the
time
of
osseointegration
check.
The
other
implant
with
advanced
bone
loss
in
this
patient
was
placed
at
site
45
(Straumann
BL
SLA
4.1mm
x
12mm),
flush
with
the
bone
crest
in
medium
density
bone
with
an
insertion
torque
of
20Ncm.
Again,
this
surgery
was
unremarkable
and
a
two‐stage
protocol
was
used
(Illustration
2).
The
mean
initial
ISQ
values
were
68.3,
67.0,
66.3,
and
66.7.
Seven
months
later,
the
corresponding
ISQ
values
were
68.0,
69.7,
68.7,
and
68.7.
This
implant
showed
significant
circumferential
bone
loss,
despite
the
relatively
stable
(or
increasing)
ISQ
values.
In
this
particular
situation,
the
ISQ
value
did
not
provide
an
early
indication
of
failure.


 
 Illustration
2:
Implants
at
sites
32
and
42,
with
advanced
bone
loss
at
42

 
 Illustration
3:
Circumferential
bone
loss
at
site
45

 
 124
 Another
patient
experienced
mobility
of
an
implant
placed
at
site
17
(Nobel
Replace
Straight
Groovy
5.0mm
x
12mm)
and
the
implant
was
removed.
No
bone
loss
was
detected
on
the
facial
or
palatal,
however
the
site
was
filled
with
granulation
tissue.
The
implant
was
placed
using
a
one‐stage
protocol
in
bone
of
medium
density
with
an
insertion
torque
of
20Ncm.
This
site
had
been
treated
with
a
sinus
augmentation
9
months
prior
to
implant
placement
using
xenograft.
Surgical
ISQ
values
were
not
available
but
seven
months
after
implant
placement,
the
ISQ
ranged
form
68‐70
from
all
directions.
This
patient
also
reported
a
heavy
smoking
history
of
40
pack
years
but
was
not
a
current
smoker
at
the
time
of
surgery.
Another
mobile
implant
was
noted
at
site
27
in
a
non‐smoker.
This
was
a
Nobel
Replace
Tapered
Groovy
5.0
x
15.0mm
implant
placed
using
a
one‐stage
protocol
in
soft
bone
with
an
insertion
torque
of
15Ncm.
The
ISQ
values
taken
at
5
months
ranged
from
48‐52.
No
initial
ISQ
values
were
available
for
comparison.


Implant
loss
was
also
experienced
by
another
former‐smoker
(10
pack
year
history),
at
site
12.
The
same
patient
had
an
implant
placed
at
site
15,
which
showed
radiographic
bone
loss
to
the
third
thread.
Both
implants
were
Nobel
Replace
Tapered
Groovy
4.3mm
x
10mm
and
were
placed
with
insertion
torques
of
25
and
45Ncm,
respectively.
Neither
received
any
bone
augmentation
and
both
were
allowed
to
heal
for
11
months
prior
to
obtaining
ISQ
values.
The
ISQ
values
at
the
failed
12
implant
were
62
and
63
from
the
buccal
and
lingual,
and
71
from
the
mesial
and
distal.
The
ISQ
values
at
the
15
were
62
from
the
buccal
and
lingual
and
78
from
the
mesial
and
distal.


A
low
or
reduced
ISQ
has
been
reported
for
failing
or
failed
implants
in
several
studies6,
47,
92,
102,
132,
146,
159,
172‐175
and
some
reported
reduced
ISQ
values
prior
to
clinical
detection
of
mobility132,
146,
indicating
prediction
of
implant
failure.
In
the
present
study,
with
measurements
taken
only
once
or
twice
for
each
implant,
monitoring
decreasing
ISQ
values
was
not
possible.


 
 125
 6.10
Limitations
of
Study
This
retrospective
study
had
a
large
sample
size
in
general,
however
some
comparisons
were
not
possible
due
to
the
low
number
of
subjects
for
certain
conditions.
The
study
was
conducted
at
two
different
centres
and
by
a
number
of
different
practitioners,
with
different
levels
of
experience.
Different
Osstell
units
were
used
at
each
centre,
however
they
were
the
same
model
and
were
used
with
the
same
protocol
and
each
was
calibrated
prior
to
each
use.
No
standardization
or
calibration
was
possible
between
practitioners
and
patients
were
treated
on
an
individual
basis,
at
the
discretion
of
the
surgeon.
The
healing
time
prior
to
osseointegration
check
varied
widely
and
was
also
at
the
surgeon’s
discretion.
Measurement
of
bone
density
was
subjective
and
no
standardization
was
possible
between
practitioners.
However,
a
simplified
classification
was
used,
with
distinction
made
only
between
soft,
medium
and
dense
bone.
Initial
placement
data
was
not
available
for
all
patients
and,
logistically,
ISQ
could
not
be
measured
if
the
implants
did
not
meet
a
minimum
insertion
torque.
This
was
to
avoid
potentially
rotating
the
implant
in
the
osteotomy
while
attaching
the
SmartPeg.
Information
was
not
collected
regarding
the
extent
of
bone
grafting
that
was
necessary.
It
is
possible
that
patients
receiving
a
very
large
volume
of
graft
material
would
have
lower
stability
values;
however
they
were
pooled
with
sites
having
only
minimal
grafting
and
this
could
have
diluted
the
results.
Finally,
ISQ
values
were
not
followed
beyond
the
time
of
osseointegration
check
and
after
loading
of
the
implants.


Completion
of
statistical
analysis
was
done
at
the
implant‐level
for
most
implant‐related
variables,
however
an
attempt
was
made
to
evaluate
systemic
factors
at
the
patient‐level,
to
reduce
the
effect
of
patients
with
multiple
implants.
By
performing
the
analysis
at
the
implant‐level,
the
sample
size
was
increased
but
the
data
could
have
been
more
heavily
weighted
towards
patients
receiving
multiple
implants.
Similarly,
averaging
the
ISQ
values
for
many
patients
may
have
diluted
extreme
results;
however,
box
plots
were
used
to
highlight
the
range
of
results
and
to
indicate
the
number
of
outliers.
 
 126
 7.
CONCLUSION
Based
on
the
results
from
this
study,
the
following
conclusions
can
be
drawn:
 • The
Osstell
ISQ
device
provides
good
repeatability
but
measurements
may
need
to
be
taken
in
both
buccal‐lingual
and
mesial‐distal
directions,
since
the
difference
was
found
to
be
statistically
significant.

 • ISQ
values
are
significantly
affected
by
implant
dimensions,
with
higher
values
for
short
implants,
compared
with
long
implants,
and
higher
values
for
regular‐
or
wide‐diameter
implants,
compared
with
narrow
implants.

 • ISQ
values
are
significantly
affected
by
implant
site,
with
higher
values
in
the
mandible
than
the
maxilla
and
lower
values
for
incisor
sites.
This
likely
relates
to
the
selection
of
certain
sized
implants
for
different
regions
of
the
jaws.

 • ISQ
values
were
not
significantly
affected
by
a
history
of
lateral
ridge
augmentation,
socket
preservation
or
sinus
lifting
using
bone
allograft,
regardless
of
the
time
that
had
passed
between
grafting
and
implant
placement.
 • Patient‐related
factors
did
not
seem
to
affect
the
ISQ
value.
This
included
age,
gender,
diabetes,
and
smoking.

 
Although
the
Osstell
ISQ
device
is
useful
to
determine
implant
stability,
there
remain
some
challenges
with
widespread
use.
The
ISQ
value
appears
to
be
most
valuable
in
following
one
particular
implant
over
time
to
detect
failures,
as
well
as
to
determine
when
to
functionally
load
the
implant.
A
wide
range
of
ISQ
values
has
been
reported
for
successful
implants
of
various
designs
so
it
is
difficult
to
draw
conclusions
regarding
a
particular
implant
based
on
a
single
measurement.

 
 
 
 127
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 146
 APPENDIX
1


 
 Table
2.
Surface
area
specifications
of
Nobel
Active
implants

 
 Table
3.
Surface
area
specifications
of
Nobel
Replace
Straight
Groovy
implants


 
 147
 
 Table
4.
Surface
area
specifications
of
Nobel
Replace
Tapered
Groovy
implants



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