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The effect of micromachined surfaces on osteogenesis in vitro

University of British Columbia

Since the use of osseointegrated implants became common in both dentistry and orthopaedics, researchers have been investigating the problem of improving stabilization of the implant. It is widely accepted that the solution lies in improving the biomaterial interface. Implants with various surface designs and chemical compositions have been investigated at the experimental and clinical levels. Micromachining, a technique widely used i n microelectronics, has the capability to produce surface topographies with precise dimensions and high reproducibility. This allows the testing of the effect of implant surface topography on osseointegration in controlled experiments. These experiments aimed to test the ability of micromachined surfaces to promote bone formation in vitro. A recently developed osteogenic culture was optimized and characterized, in which rat calvarial cells were cultured in the presence of ascorbic acid and organic phosphate in the medium. This method provided a reliable model of reproducible mineralized tissue formation. Histochemical methods, TEM, S EM and EDX techniques demonstrated that the mineralized tissue formed after two weeks culturing had an elevated alkalinephosphatase activity, was rich in collagen, and had a structure, similar to the original calvarial bone. The ability of micromachined surfaces to facilitate osteogenesis was studied when these osteogenic cultures were grown on grooved, pitted, and smooth micromachined surfaces. The developed mineralized tissue was stained utilizing von Kossa's technique and its amount quantified with an UltroScan X L Laser Densitometer. The area, shape and orientation of the mineralized bone colonies were measured with a Videoplan Image Analysis System (Zeiss). There was a statistically significant difference of bone formation between the micromachined and smooth surfaces. Bone-like tissue formed to the greatest extent on pitted surfaces, and to a lesser extent on grooves, but few bone nodules were found on the smooth control surfaces. The colonies on the grooved surfaces were elongated and followed the direction of the grooves, while those on the smooth and pitted surfaces were rounder and randomly oriented. The results indicate that bone-like tissue formation is influenced by the substratum surface topography and micromachining may be useful i n determining the ideal surface topography for promoting bone formation on titanium surfaces.

Thesis/Dissertation

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2009-01-17

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http://hdl.handle.net/2429/3743

Dental Science

University of British Columbia

UBCV

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