Torque Loss in Abutment Screw: Impacts of Type and Angle of Abutments

Despite the generally high success rate of dental implant treatments, some complications may also occur. One of the most common mechanical problems is screw loosening of the abutment. This study aims to assess the impact of abutment type (original vs. non-original) and angle of abutment (angled vs. straight) on torque reduction and screw loosening under cyclic loading conditions. Thirty titanium implants were divided into three groups (n = 10): original straight abutments, non-original straight abutments, and original 15° angled abutments. Each implant, and its respective abutments, were embedded in prepared acrylic blocks and torqued to 25 N.cm. twice, with a 10-minute interval between each torque application. Reverse torque values (RTV) were evaluated before and after 500,000 cycles of cycling loading at 75 Hz with a 100 N load, using an electrical torque meter. Data analysis was conducted using SPSS software (version 21), employing descriptive statistics, ANOVA, and independent t-tests. After cyclic loading, the mean RTV was 18.41 ± 1.86 N.cm in the group of original straight abutments, 13.18 ± 1.75 N.cm in the group of non-original straight abutments, and 14.76 ± 1.04 N.cm in original 15° angled abutments. Statistically significant differences were observed in mean RTV between the two groups of original and non-original abutments as well as between angled and straight abutments (< 0.001). Original straight abutments demonstrated lower torque loss after cyclic loading compared with both non-original and 15° angled abutments. The findings suggest that using original straight abutments may have better outcomes in preventing screw loosening and ensuring proper performance in clinical settings. However, it is essential to thoughtfully evaluate alternative abutment types and angles when necessary.