Effect of surgical technique on implant stability using synthetic bone

Objective: The aim of this biomechanical study was to assess the effect of surgical technique and implant surface roughness on primary dental implant stability in synthetic bone.

Material and Methods: For the experiment 120 screw designed implants (Biocomp®) were used with two different surface finishes, i.e.: machined and etched. The implants were inserted in synthetic cancellous/cortical models with a cancellous bone density of 0.48 g/cc (rigid polyurethane foam) and cortical thickness of respectively 0, 1 and 2 mm (Short-fiber-filled-epoxy sheets) using two surgical approaches, i.e. pressfit and undersized. Dental implant stability was measured using insertion and removal torque testing.

Results: Independent of the used surgical technique, both implants types showed an increased mean insertion and removal torque value with increasing cortical thickness. In bone models with a cortical thickness of 0 and 1 mm, both implant types showed statistically higher insertion and removal torque mean values for undersized compared to pressfit preparation (p<0.01). In addition also etched implants showed a statistically higher insertion and removal torque mean values compared to machined implants (p<0.01). In 2 mm cortical models, no effect of implantation technique or implant surface finish was observed by comparing insertion torque mean values.

Conclusion: The installation of etched implants in synthetic bone models using an undersized preparation of the implant bed resulted in enhanced primary dental implant stability. Further, a correlation was found between primary stability and cortical thickness of the synthetic bone. Evidently, synthetic cancellous/cortical bone models are suitable to study the primary stability of dental implants. They have the advantage of producing highly reproducible results compared with biological specimen.