The effect of screw tightening methods on screw loosening resistance in implant-abutment connection of 2 implant systems

Abstract

The propose of this study was to compare the effect of 3 screw tightening methods on screw loosening resistance. The 2 implant systems (CU dental implant and SimpleLine II were used in the study (N=30).The implant bodies were embedded in the acrylic blocks.The abutment screws were tightened to the manufacturer’s recommended torque using 3 tightening methods as following; method1: tightening the screw 1 time, method2 tightening the screw, wait for 10 minutes, retightening the screw, method3: tightening the screw, wait for 3 minutes,loosening the screw, retightening the screw, wait for 10 minutes, retightening the screw. The fatigue loading was applied.The reverse torque values were measured. Kruskal-Wallis and Conover-Inman were used to compare the reverse torque value in the percentage of initial tightening torque. The method1 showed the significantly lowest screw loosening resistance in 2 implant systems (p<0.05). The method 2 and the method 3 showed no significant difference on screw loosening resistance in 2 implant systems.When comparing between 2 systems. SimpleLine II showed higher screw loosening resistance than those of the CU dental implant significantly (p<0.05).It can be concluded that the highest reverse torque values could be achieved by screw retightening,and the screw loosening before the screw retightening did not increase the reverse torque values to be higher than those achieved from the first screw retightening. SimpleLine II showed the significantly higher screw loosening resistance than CU dental implant.