Implant Abutment Screw Loosening: Biomechanical Analysis of Bruxism-Induced Mesiodistal Loads With FEA and Their Effect on Shear Stress.

Abutment screw loosening in dental implant systems is one of the most common causes of long-term clinical failure. This study investigated the biomechanical effects of bruxism-induced mesiodistal loads on shear stress and screw loosening tendency at the implant-abutment connection using finite element analysis. In this study, a titanium alloy (Ti6Al4V) implant-abutment-screw system was three-dimensionally modeled, and mesiodistal loads (23.4, 128, and 234 N), representing mesiodistal forces, were applied. The friction coefficient between the contact surfaces was defined, and the screw preload and load transfer mechanism were analyzed. The results showed that shear stress in the connection area increased significantly with increasing mesiodistal loads, and that loads applied in a mesiodistal direction caused microrotation in the screw connection, increasing the risk of loosening. These findings emphasize the need to optimize load, screw preload, and connection geometry in implant design for individuals with bruxism and provide a scientific basis for material and design improvements to prevent screw loosening clinically.