Effect of a Modified Stepped Osteotomy on the Primary Stability of Dental Implants in Type D4 Bone: A Cadaver Study

Effect of a Modified Stepped Osteotomy on the Primary Stability of Dental Implants in Type D4 Bone: A Cadaver Study Chad M. Boustany, D.D.S. Purpose: The aim of this study was to examine the effect of an alternative surgical technique on endosseous dental implant stability parameters in Class D4 Bone. Significant differences between insertion torques (Ncm) produced by a conventional osteotomy verses a modified stepped osteotomy were examined. Significant differences between Implant Stability Quotients (ISQ) produced by a conventional osteotomy verses a modified stepped osteotomy were examined. Correlations between Hounsfield units (HU), Implant Stability Quotient (ISQ), and insertion torque (IT) were examined. Materials and Methods: Sixteen preserved cadaver heads were radiographically examined with a Toshiba Aquilion® 64 Fast Whole Body Computerized Tomography (CT) Scanner. A total of 22 implants were placed in the maxillary bone of nine preserved cadavers which possessed Misch Class D4 bone with adequate volume for this study. The control group consisted of 11 conventional osteotomies. The test group consisted of eleven modified stepped osteotomies. The maximum insertion torque (Ncm) data were recorded with the ZimmerTM Implant Motor and confirmed with the ThommenTM Torque Driver. Implant Stability Quotient (ISQ) was measured with the Osstell MentorTM (Integration Diagnostics AB, Göteborg, Sweden) via resonance frequency analysis. Significant differences insertion torques (IT) and Implant Stability Quotient (ISQ) were analyzed with a Wilcoxon Signed Rank Test. Correlations were analyzed with the Pearson Correlation Test. Results: Maxillary cadaver bone utilized in this study ranged from 173.4 – 312.1 HU. The mean insertion torque in the conventional osteotomy group was 15.91 Ncm. The mean insertion torque in the modified stepped osteotomy group was 26.82 Ncm. A Wilcoxon Signed Rank test also showed the modified stepped osteotomy had a significantly greater mean insertion torque than the conventional osteotomy (S = 33.00 p = 0.0010, ). A Wilcoxon Signed Rank test also showed no significant difference between ISQ in the conventional osteotomy group and the modified stepped osteotomy test group (S = 17.00, p = 0.01475). Pearson correlations showed a significant positive correlation between the insertion torques in the conventional osteotomy test group and the modified stepped osteotomy test group (r = 0.817, p = 0.0021). Significant correlation between between the ISQ in the modified stepped osteotomy and HU also found (r = 0.7099, p = 0.0144). There were no other significant correlations between HU and ISQ. There were no significant correlations between HU and IT. There were no significant correlations between the ISQ in the conventional osteotomy test group and the modified stepped osteotomy group. There were no significant correlations between ISQ and IT in the conventional osteotomies. There were no significant correlations between ISQ and IT in the modified stepped osteotomies . Conclusion: Within the limits of the study, the following conclusion can be drawn: The modified stepped osteotomy resulted in significantly greater implant stability in terms of insertion torque (IT) than the conventional osteotomy in Misch Class D4 bone. Significant correlations were found between the insertion torque (IT) produced in the modified stepped osteotomy and bone density (HU). No other correlations between insertion torque (IT) and bone density (HU) were found. No correlation could be found between insertion torque (IT) and Implant Stability Quotient (ISQ). No correlation could be found between Implant Stability Quotient (ISQ) and bone density (HU).