Evaluation of primary and secondary stability of titanium implants using different surgical techniques

Objective To investigate the influence of different surgical techniques on the primary and secondary implant stability using trabecular bone of goats as an implantation model. Material and methods In the iliac crest of eight goats, 48 cylindrical-screw-type implants with a diameter of 4.2mm (Dyna((R)); Bergen op Zoom, the Netherlands) were installed, using three different surgical techniques: (i) 5% undersized, using a final drill diameter of 4mm; (ii) 15% undersized, using a final drill diameter of 3.6mm; and (iii) 25% undersized, using a final drill diameter of 3.2mm. Peak insertion torque values were measured by a Digital((R)) (MARK-10 Corporation, New York, NY, USA) torque gauge instrument during placement. At 3weeks after implantation, removal torque was measured. Histomorphometrically, the peri-implant bone volume was measured in three zones; the inner zone (0-500 mu m), the middle zone (500-1000 mu m) and the outer zone (1000-1500 mu m). Results Evaluation of the obtained data demonstrated no statistically significant difference between different surgical techniques regarding removal torque values. With respect to the percentage peri-implant bone volume (%BV), also no significant difference could be observed between all three applied surgical techniques for both the inner, middle and outer zone. However, irrespective of the surgical technique, it was noticed that the %BV was significantly higher for the inner zone as compared to middle and outer zone (P<0.05) around the implant. Conclusion At 3weeks after implant installation, independent of the used undersized surgical technique, the %BV in the inner zone (0-500 mu m) peri-implant area was improved due to both condensation of the surrounding bone as also the translocation of host bone particles along the implant surface. Surprisingly, no mechanical beneficial effect of the 25% undersized surgical technique could be observed as compared to the 5% or 15% undersized surgical technique to improve primary or secondary implant stability.