Orthodontic Maxillary Molar Movement-Induced Zygomatic Pillar Remodeling and its Consequences on Occlusal Characteristics and Stress Distribution

Abstract

Objective: To evaluate zygomatic pillar changes during orthodontic treatment with premolar extraction, then analyze the effects of maxillary first molar movement on zygomatic pillar remodeling, and examine occlusal characteristics and stress distribution after reconstruction. Methods: 25 premolar extraction patients were included. Zygomatic pillar measurement range was defined, and cross-sectional areas, surface landmark coordinates, and alveolar and cortical bone thickness and density changes were assessed using Mimics based on the CBCT taken before(T0)and after treatment(T1). Multiple linear regression was employed to explain correlations between zygomatic pillar changes and maxillary first molar 3D movement and rotation. Correlations between pillar remodeling and occlusal characteristics, as analyzed by Tteester, were calculated. Pre- and post-reconstruction 3D finite element models (FEA) were constructed and loaded with average occlusal force of two period , respectively. Results: Zygomatic pillar cross-sectional area, landmark coordinates, bone thickness and alveolar bone density decreased. The mesial and lingual movement of the maxillary molars was strongly correlated with these changes, accounting for >40% variations. Occusal stress concentrated on weak areas after remodeling. Conclusions: Orthodontic treatment with premolar extraction led to zygomatic pillar remodeling, making it more fragile and reducing the occusal force of the maxillary first molar and the entire dentition with stress concentrating on weak areas. Clinical Relevance: No other study has focused on the effects of orthodontics on pillar structures.This research indicates that mesial movement of the maxillary first molar weakened zygomatic pillar, reduced occlusal function, and providing insights for insrting anchorage screws and facial aesthetics.