Relationship between the CT Value and Cortical Bone Thickness at Implant Recipient Sites and Primary Implant Stability with Comparison of Different Implant Types.

BACKGROUND: Studies have shown that bone quality at the implant recipient site can influence primary stability. PURPOSE: The aims of this study were to explore the quantitative estimation of the primary stability of implants preoperatively using CT values and to examine the effect of different implant designs with recommended socket preparation on primary stability. MATERIALS AND METHODS: Forty-four fresh porcine femoral heads were prepared. The bone surrounding implant sockets was preoperatively evaluated by helical CT. Forty-four implants (φ 4.3 × 10 mm), 22 straight and 22 tapered, were placed according to the manufacturer's instructions. The insertion torque value (ITV), implant stability quotient (ISQ), and removal torque value (RTV) were recorded as indicators of primary implant stability. RESULTS: Significant correlations and linear relationships were found between the CT value and ITV, ISQ, and RTV for both straight and tapered implants (Spearman's correlation coefficient, p < .001; linear regression analysis, p < .01). Tapered implants had a significantly higher ITV than straight implants (analysis of covariance, p < .01). CONCLUSIONS: Obtained results suggest that the primary stability of implants could be quantitatively estimated using the CT value preoperatively, indicating the CT value of bone surrounding an implant can contribute considerably to implant planning and design choice in clinical situations.

Primary Stability of a Hybrid Implant Compared with Tapered and Cylindrical Implants in an Ex Vivo Model.

BACKGROUND: Hybrid implants are thought to offer good stability and bone-implant contact. PURPOSE: This study sought to evaluate the primary stability of a hybrid implant compared with tapered and cylindrical implants in an ex vivo model and compare undersized drilling with standard drilling in attaining primary stability. MATERIALS AND METHODS: Hybrid (Straumann® Bone Level; BL), tapered (Straumann® Tapered Effect; TE), and cylindrical (Straumann® Standard Plus; SP) implants were inserted into 15 mm-thick porcine iliac crest blocks using standard (corticocancellous or cancellous bone) or undersized (cancellous bone only) drilling (n = 7). Stability was evaluated using maximum insertion torque (MIT), implant stability quotient (ISQ), and push-out tests. RESULTS: The mean MIT for BL and TE was significantly higher than that for SP (p < 0.05). With standard drilling in corticocancellous bone, the mean ISQ for TE was significantly higher than that for SP (p < .05). The mean MIT, ISQ, and push-out test scores for BL, TE, and SP with standard drilling in corticocancellous bone were significantly higher than those with undersized or standard drilling in cancellous bone (p < .05). CONCLUSIONS: In this ex vivo model, the hybrid implant demonstrated promising primary stability compared with the cylindrical implant. The improved stability of the hybrid implant was especially evident in cancellous bone. The influence of the cortical layer should be recognized when selecting implants for primary stability.