Stress Distribution After Different Apical Resection Techniques Under Different Vertical Facial Pattern-Related Loading Conditions: A Finite Element Analysis.

AIM: This study evaluated stress distributions in mandibular molars following different apical resection techniques under maximum occlusal forces representing short, average, and long facial patterns. MATERIALS AND METHODS: The model was generated from anonymized Visible Human Project data. Four experimental models with 4-mm mesial and distal root lesions were simulated: targeted endodontic microsurgery (TEMS) with 1.5-mm and 4.4-mm trephine burs, endodontic microsurgery (EMS), and the bone window technique (BW). Control models included healthy teeth and root canal treated teeth with or without lesions. Maximum occlusal forces representing short, average, and long facial patterns (680 N, 593 N, and 454 N) were applied vertically and obliquely to the buccal cusps and central fossa. RESULTS: Biomechanical stress was highest in short-face patterns under oblique loading. Among the experimental groups, the bone window model generally showed the highest stress values, whereas trephine models demonstrated loading direction-dependent stress patterns. Stress concentrations were mainly localized in the cervical bone and graft-bone interface. CONCLUSIONS: Within the limitations of this finite element study, apical surgical technique, loading direction, and facial pattern-related occlusal force magnitude influenced stress distribution after apical surgery.