Relation between insertion torque and bone–implant contact percentage: an artificial bone study

Abstract

The purpose of this study was to determine the correlation between the peak insertion torque value (ITV) of a dental implant and the bone-implant contact percentage (BIC%). Dental implants were inserted into specimens comprising a 2-mm-thick artificial cortical shell representing cortical bone and artificial foam bone representing cancellous bone with four densities (groups 1 to 4--0.32, 0.20, 0.16, and 0.12 g/cm(3)). Each specimen with an inserted implant was subjected to micro-computed tomography (micro-CT) scanning, from which the 3D BIC% values were calculated. Pearson's correlation coefficients (r) between the ITV and BIC% were calculated. The ITVs in groups 1 to 4 were 56.2 ± 4.6 (mean±standard deviation), 45.6 ± 0.9, 43.3 ± 4.3, and 38.5 ± 3.4 N cm, respectively, and the corresponding BIC% values were 41.5 ± 0.5%, 39.0 ± 1.0%, 30.8 ± 1.1%, and 26.2 ± 1.6%. Pearson's correlation coefficient between the ITV and BIC% was r = 0.797 (P < 0.0001). The initial implant stability, quantified as the ITV, was strongly positively correlated with the 3D BIC% obtained from micro-CT images. The ITV of a dental implant can be used to predict the initial BIC%; this information may provide the clinician with important information on the optimal loading time.