The Precision of Mechanical Torque Wrenches Used for Implants in Dental Offices

Purpose: This study aimed to investigate the precision of mechanical torque wrenches used for implants in dental offices. Materials and Methods: Mechanical torque wrenches (n = 138) with two functional designs and made by three manufacturers were tested by three groups of investigators. Potential influences on accuracy were tested. Relative deviations from targeted torque values and the precision of recorded torque values were analyzed. Results: Most abutment screws were tightened too tightly rather than too weakly. Differences were apparent in the influence of the functional design of torque wrenches on their precision. No significant correlation between absolute frequency of use and relative deviation or precision was detected. Investigators with different levels of experience exhibited significantly different deviations from targeted torque values. Conclusions: Average deviation from intended torque values, and levels of imprecision, are evidently not major problems in implant prosthetics; however, high torque values are a cause for concern.