Effect of a Modified Stepped Osteotomy on the Primary Stability of Dental Implants in Low-Density Bone: A Cadaver Study

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. Differences between insertion torque (IT) and implant stability quotient (ISQ) produced by a conventional osteotomy versus a modified stepped osteotomy were examined. Correlations between IT, density in Hounsfield units (HU), and ISQ were also examined. Materials and Methods: Computed tomographic scans were taken of 16 cadaver heads to determine bone density at maxillary implant recipient sites, which ranged from 173.4 to 312.1 HU. Twenty-two implants were placed in sites with Misch Class D4 bone; control sites received 11 conventional osteotomies and test sites 11 modified stepped osteotomies. Maximum IT was recorded with an implant motor and confirmed with a torque driver, and ISQs were measured. Significant differences were analyzed with a Wilcoxon signed rank test, and correlations were analyzed with the Pearson test. Results: The mean IT in the control group was 15.91 Ncm, and in the test group it was 26.82 Ncm. The modified stepped osteotomy had a significantly greater mean IT than the conventional osteotomy, but no significant difference in ISQ was found between groups. Pearson correlations showed a significant positive correlation between IT in the control and test groups. Significant correlations were found between ISQ and HU in the test group. No other significant correlations between HU, IT, and ISQ were found. Conclusion: Within the limits of this cadaver study, the modified stepped osteotomy resulted in significantly greater implant stability in terms of IT than the conventional osteotomy in soft bone. Significant correlations were found between the IT produced in the modified stepped osteotomy and bone density. No significant correlations were found between IT and ISQ. Keywords: bone density, computed tomography, dental implant, modified surgical technique, primary stability