Trimline Length As A Variable In Aligner-Based Distalization A Finite Element Analysis Study

AIM: This study aimed to evaluate the impact of aligner trimline length on the movement of the upper second molar during the distalization process. MATHERIALS AND METHOD: Two finite element models were developed utilizing different aligner trimline lengths. One model featured a trimline at the gingiva (Mode A1), while the other had a trimline positioned 2 mm above it (Model A2). Both models were applied to a 3D full-toothed maxillary model, excluding the upper third molars. During the simulation, a distal displacement of 0.25 mm was applied to the upper first and second molars. The results regarding von Mises stress associated with the upper second molar and its periodontal ligament, as well as the tooth displacement data, were analyzed. RESULTS: The stresses in the apical region of the periodontal ligament (PDL) increased with longer trimlines. The crown displayed stress areas mainly on the mesial side in both models. In Model A2, stresses began to extend distally, and the stresses on the roots also increased. Both groups exhibited rotation in the distal direction, and Model A2 showed a greater distal crown displacement. CONCLUSION: Increasing the trimline length is a more effective approach for managing the movement of upper second molar teeth during distalization.