Evaluation of different models of intrusive force application and temporary anchorage device (TAD) placement in total arch intrusion using clear aligners; a finite element analysis

INTRODUCTION: Present study aims to evaluate different models of total arch intrusion using clear aligners in a finite element setup, which might be helpful in gummy smile patients who seek this treatment modality. METHODS: Four patterns of intrusive forces were applied on each side of the upper arch aligner model: (1) Distal to the lateral incisors (facial − 80 g) and distal to the first molar (palatal − 150 g). (2) Distal to the lateral incisors (facial − 80 g) and distal to the first molars (facial − 80 g and palatal − 80 g). (3) Distal to the canines (facial − 80 g) and distal to the first molars (facial − 150 g). (4) Distal to the lateral incisors (facial − 80 g) and mesial to the first molars (facial − 150 g). Vertical and horizontal movements of the teeth were measured. RESULTS: Extrusion movements were solely detected at buccal cusps of the first and second molars in the first model. Palatal movements of posterior teeth were detected in this model. Model II showed a homogeneous intrusion in anterior and posterior teeth and the amount of palatal movements of posterior teeth was reduced compared to model I. In contrast to Model IV, Model III had more intrusion in the posterior compared to anterior teeth. Facial movements of posterior teeth were detected in the third and fourth models. Incisor teeth showed facial movements among all of the models except for the lateral incisor in the third model. CONCLUSIONS: Each model of force application, causes different outcomes and side effects which is beneficial in certain clinical situations.