UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Traditional and digital assessment of a protective matrix to minimize iatrogenic damage of adjacent teeth during crown preparation by dental students Ballo, Ahmed


Crown preparation is a challenging procedure for dental students, especially in the posterior region. It has been reported that the incidence of iatrogenic damage to adjacent teeth is very high during conventional crown preparation. Objectives: To determine the effect of using a protective matrix for preventing iatrogenic damage to adjacent teeth during crown preparation on typodont teeth by undergraduate dental students. Methods: 60 undergraduate students, in their second-year, volunteered for this study as part of their formal learning to prepare the mandibular first molar for a full-metal crown restoration on a manikin-mounted typodont. The study was divided into three parts: Part I- students were randomly assigned into two groups to either undertake tooth preparation according to a traditional crown preparation protocol, or tooth preparation using a protective matrix, followed by Part II- a crossover of the groups in the subsequent session. Part III - subsequent to the initial sessions, the students undertook a usual timed crown preparation exercise, during which using the matrix was optional. Damage to the adjacent teeth was evaluated subjectively by calibrated faculty members both using a standard traditional approach and virtual-assisted using a digital system. Depth and volumetric measures of the damage were also objectively evaluated using a digital system. Results: During the practice sessions, the traditional subjective assessment found that adjacent tooth iatrogenic damage was significantly (p=.027) less frequent when the protective matrix was used, 76.9%, compared to when it was not used, 92.5%. A similar statistically significant (p=.009) pattern was found with the subjective virtual-assisted digital assessment, which showed a frequency of 82.4% when using the matrix compared to 98% when it was not used. The objective digital assessment tended to show a higher overall frequency of damage than that found with the subjective faculty-member assessments. During the two combined initial sessions the mean depth scores were 0.281±0.14mm without a protective matrix and 0.216±0.13mm with a protective matrix, which was significantly deeper iatrogenic depth damage (p = .041) without the matrix. Conclusions: The use of a protective matrix during typodont crown preparation by dental students reduced the frequency of iatrogenic damage to adjacent teeth.

Item Citations and Data


Attribution-NonCommercial-NoDerivatives 4.0 International