In Vitro Comparison of Loss of Torque between Gold and Titanium Alloy Abutment Screws in Dental Implants without Any Cyclic Loads

Abstract

Aim: To find and compare the amount of screw loosening in gold and titanium alloy abutment screws without any cyclic load, this study was performed. Materials and methods: A total of 20 implant fixture screw samples with 10 gold abutment screws from Osstem and 10 titanium alloy abutment screws from Genesis. Implant fixtures were placed into the acrylic resin using a surveyor to maintain the same path of insertion. Using a hex driver and calibrated torque wrench, initial torque was given according to the manufacturer’s recommendation. One vertical and other horizontal lines were drawn over the head of the hex driver and resin block. Acrylic block position was standardized using a putty index in a fixed table and using a tripod stand a digital single-lens reflex camera (DSLR) camera was positioned with its horizontal arm facing the floor, as well as perpendicular to the acrylic box. Photographs were taken immediately after the application of the initial torque given as per the manufacturer’s recommendation and 10 minutes after the initial torque. Re-torque of 30 and 35 N cm was given to gold and titanium alloy abutment screws respectively. Photographs were taken again in that same position immediately after re-torquing and 3 hours after re-torquing. The photographs were uploaded into the Fiji-win64 analysis software and the angulations were measured in each photograph. Results: Both the gold and titanium alloy abutment screws exhibited screw loosening after initial torquing. There was a significant difference in the amount of screw loosening between gold and titanium alloy abutment screws after initial torquing and no change in the abutment screw position after three hours of re-torquing. Conclusion: Re-torquing of both gold and titanium alloy abutment screws after 10 minutes of initial torquing should be performed routinely for retaining the preload and minimizing the screw loosening even before loading the implant fixture. Clinical significance: Gold abutment screws may have the ability to retain the preload better than the titanium alloy abutment screws after initial torquing, re-torquing may be necessary after 10 minutes to reduce the settling effect in a routine clinical procedure.