Primary Apical Stability of Tapered Implants Through Reduction of Final Drilling Dimensions in Different Bone Density Models: A Biomechanical Study.

PURPOSE: A biomechanical study of the primary apical stability obtained in tapered implants through the reduction of final drilling dimensions in different bone density models. MATERIAL AND METHODS: An in vitro study of maximum insertion torque and primary stability based on the resonance frequency analysis (RFA) of 24 conical implants measuring 13 mm in length and 3.75 and 4.20 mm in diameter, randomly inserted in 10-mm sockets prepared in 4 polyurethane blocks with a density of 15, 20, 30, and 40 pounds per cu ft, respectively, reducing the diameter of the final drill at constant speed (400 rpm) to obtain exclusive 4 mm anchoring of the apical third of each implant. RESULTS: The decrease in drilling diameter resulted in an increase in the insertion torque and implant stability quotient (ISQ) values in all implants, although without reaching statistical significance. In turn, a significant direct correlation was found between increasing bone analog block density and the insertion torque and ISQ values. CONCLUSIONS: Under the conditions of this study, the primary apical stability obtained may be more dependent on bone density than on reduction of the final drilling diameter.