Effect of Screw Channel Angulation(0-20) on removal torque value of Dental Implant Abutment Screws

Abstract

In patients with an improper position or angle of the implant, function or esthetic may be impaired due to interference with the screw access channel in the screw-retained crown. A new treatment concept is the Angulated Screw Channel(ASC), which changes the angle of the screw channel in the crown while the abutment angle is aligned with the implant. In this study, we evaluate and compare the amount of torque required to remove the screw and its difference with the initial torque of the screw at different angles of the screw channel access. In addition, the tightening protocols were effective in the force required for the screw. Therefore, in this study, we will compare four different protocols for the insertion of torque. Method : In this study, samples were examined in three groups: the DIO abutment with a 0-degree access angle to the screw and a regular screw (D0), the Ti-base angled screw channel abutment with a 0-degree access angle to the screw, and a ball torx screw (A0), and the Ti-base angled screw channel abutment with a 20-degree access angle to the screw and a ball torx screw (A20). Additionally, the samples were divided into four groups based on different tightening protocols, with nine screws used for each tightening protocol. The Dio implant fixture was mounted in the GC methyl methacrylate autopolymerizing resin. Abutments were placed on the fixture, and the implant abutment screw was positioned. The screw was initially tightened with a driver by hand. Subsequently, the samples (screws) were subjected to four different tightening protocols. Before each screw tightening, the Digital Torque Meter was calibrated. To measure the amount of removal torque required to unscrew, the maximum removal torque (RTV) was measured using the Digital Torque Meter. Data were analyzed to compare the removal torque between the three groups using a two-way analysis of variance (ANOVA) and the Tukey HSD post-hoc test (α = 0.05). Results: Regardless of the tightening protocols, there is a statistically significant difference between the D0 and A0 groups (P Value ≤ 0.0001) and between the D0 and A20 groups (P Value ≤ 0.0001). Conclusion: There is no significant statistical difference in torque reduction percentage among various tightening protocols and between the angles of 0 and 20 degrees in the ASC system. Yet, a notable statistical difference exists in torque reduction percentage between the DIO company's abutment and the ASC system for both 0 and 20-degree angles.