COMPARISON OF SCREW LOOSENING, ROTATION, AND DEFLECTION AMONG 3 IMPLANT DESIGNS

A common problem associated with single tooth implant restorations is abutment screw loosening. Manufacturers of implants have attempted to overcome this problem by incorporating antirotational design character istics into their systems. Micromovement and torque levels required to loosen abutment screws for straight and angled antirotational screw-r etained abutment/implant combinations from three different manufacture rs were examined in this in vitro investigation. A custom-built machin e was used and each sample was subjected to compressive horizontal rec iprocal movements over a 25-degree incline for a simulated 1-month per iod. Data were generated that showed movements of the crown/abutment c omplex during force application. The amount of torque necessary to loo sen the abutment screws before and after testing was also recorded and compared for each system. The results indicated no significant differ ences (p < 0.05) among all the straight and angled abutments for the v ariables studied.