Prediction of primary stability via the force feedback of an autonomous dental implant robot

Statement of problem While the high osteotomy and implant placement accuracy via robotic implant surgery has been verified, whether the force feedback in the osteotomy process can be used to determine appropriate primary implant stability remains unknown. Purpose The purpose of this in vitro study was to explore the relationship between the force feedback and the primary stability of implants placed by using an autonomous dental implant robot. Material and methods Five groups (n=7) of wooden and polyurethane foam blocks were used to execute an implant surgery by using an autonomous implant robot. Tapered bone-level titanium dental implant replicas were placed in the blocks. The Young modulus, the maximal vertical and lateral drilling resistances, the position accuracy, and the insertion torque of implants were recorded. Simple linear regression, principal component analysis, and multiple linear regression were used. The osteotomy strategy for the implant site was adjusted according to the maximal vertical resistance of the pilot drill to achieve appropriate insertion torque. The correlation, Gompertz growth curve fitting of the insertion torque, and Young modulus were determined. The effect of the drilling resistances on the insertion torque was analyzed using 2-way ANOVA, simple linear regression, and the principal component analysis. Results The vertical resistance of the Ø2.2-mm pilot drill, the Ø3.5-mm twist drill, and the Ø4.1-mm profile drill had a strong simple linear correlation with the insertion torque of the implants, and the lateral resistance had a moderate linear correlation with the insertion torque. The contributions of these 6 variables to the implant torque, among which the vertical resistance of the twist drill and the pilot drill ranked first and second, were comparable. Adjustments to the strategy of site preparation according to the vertical resistance of the pilot drill achieved appropriate insertion torque (P<.001). Conclusions The force feedback of the autonomous dental implant robot was significantly correlated with the insertion torque of implants, which may fit an interpretable mathematical model, allowing dental implants to be placed with predictable primary stability.