Purpose: Evaluate the screw joint stability of the straight versus angled Multi-Unit (MU) abutment following dynamic cyclic loading and thermo-cycling aging.
Methods: This study compared abutment screws reverse torque values (RTVs) using three different angles (0°, 17°, and 30°) after cyclic loading and thermocycling. The samples comprised 21 full crowns supported by internal hex implant fixtures and multi-unit abutments divided into three groups (A, B & C), representing abutment different angulations. For data analyses, the significance level was set at p> 0.05 (CI 95%).
Results: Paired t-test showed that the mean RTV was significantly lower following aging for each angle (P-value = 0.000). The three angulation groups' abutment screw RTVs differed significantly, with the lowest RTV detected at the 17-degree angulation MU Abutment.
Conclusions: The performance of angled abutments in regards to removal torque values were less than that of straight abutments, yet, have generally been satisfactory. Dynamic cyclic loading and thermocycling had a significant effect on RTV of implant abutments.