Correlation between initial BIC and the insertion of torque/depth integral recorded with an instantaneous torque-measuring implant motor: An in vivo study

Background: Quantitative intraoperative evaluation of bone quality at implant placement site and postinsertion implantprimary stability assessment are two key parameters to perform implant-supported rehabilitation properly. A novelmicromotor has been recently introduced allowing to measure bone density at implant placement site and to recordimplant insertion-related parameters, such as the instantaneous, average and peak insertion torque values, and the insertiontorque/depth integral.Purpose: The aim of this study was to investigate in vivo if any correlation existed between initial bone-to-implant contact(BIC) and bone density and integral values recorded with the instrument.Materials and Methods: Twenty-five patients seeking for implant-supported rehabilitation of edentulous areas were consecutivelytreated. Before implant placement, bone density at the insertion site was measured. For each patient, anundersized 3.3 × 8-mm implant was placed, recording the insertion torque/depth integral values. After 15 minutes, theundersized implant was retrieved with a 0.5 mm-thick layer of bone surrounding it. Standard implants were consequentlyplaced. Retrieved implants were analyzed for initial BIC quantification after fixation, dehydration, acrylic resin embedment,sections cutting and grinding, and toluidine-blue and acid fuchsine staining. Correlation between initial BIC values, bonedensity at the insertion site, and the torque/depth integral values was investigated by linear regression analysis.Results: A significant linear correlation was found to exist between initial BIC and (a) bone density at the insertion site(R = 0.96, explained variance R2 = 0.92) and (b) torque/depth integral at placement (R = 0.81, explained varianceR2 = 0.66).Conclusions: The system provided quantitative, reliable data correlating significantly with immediate postinsertion initialBIC, and could therefore represent a valuable tool both for clinical research and for the oral implantologist in his/her dailyclinical practice.