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Objectives: The aim of this study was to evaluate the effect of two different designs, tapered vs cylindrical, on the primary stability of implants placed with an immediate loading protocol in edentulous mandibles to support fixed prostheses within occlusal contacts during the first 48 h., Material and Methods: Tapered and cylindrical implants were placed in a split-mouth study using the same implant protocol in ten patients with edentulous jaws. A total of 20 tapered implants (test group) and 20 cylindrical implants (control group) were placed. All implants were loaded immediately with provisional fixed prostheses during the healing period before the final restoration. The implants were evaluated at the implant placement by analyzing the insertion torque values (ITVs) and the resonance frequency analysis (RFA) and after the healing period of three months, the success of those implants and the marginal bone loss were evaluated., Results: Two cylindrical implants were mobile within the same patient and no tapered implants failed, resulting in implant survival rates of 90% and 100%, respectively after three months. The ITVs were statistically significantly different (P = 0.0210) for the tapered implants than for the cylindrical implants. However, no statistically significant differences in RFA values were found (P = 0.6063) when comparing the implant designs and the primary stability measured with implant stability quotient (ISQ) values. The control group resulted in a mean bone loss after three months of 0.91 mm while the test group resulted 0.42 mm., Conclusion: The tapered implant achieved greater primary stability values measured with ITVs and less marginal bone loss than the cylindrical implants., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: The purpose was to assess thermal changes and drill wear in bovine bone tissue with the use of twisted stainless steel and zirconia-based drills, during implant site preparation., Methods: A total of 100 implant site preparations were performed on bovine ribs using a surgical unit linked to a testing device, in order to standardize/simulate implant drilling procedures. Bone temperature variations and drilling force were recorded when drilling at a depth of 8 and 10 mm. A constant irrigation of 50 ml/min. (21±1°C) and drilling speed of 800 r.p.m. were used. Scanning electron microscopy analysis was preformed prior and after drilling., Results: Mean temperature increase with both drills at 8 mm was 0.9°C and at 10 mm was 2°C (P<0.0001). Statistical significant higher bone temperatures were obtained with stainless steel drill (1.6°C), when comparing with the ceramic drill (1.3°C) (P<0.05). Temperature increase was correlated with higher number of perforations (P<0.05) and drilling load applied. There was no significant association between drilling force applied and temperature increase by either drill or at either depth. No severe signs of wear of either drill were detected after 50 uses., Conclusions: Drill material and design, number of uses, depth and drilling load applied appear to influence bone temperature variations during implant site preparation. Drilling depth was a predominant factor in bone temperature increase. Both drills can be used up to 50 times without producing harmful temperatures to bone tissue or severe signs of wear and deformation., (© 2011 The Authors. Journal compilation © 2011 John Wiley & Sons A/S.)