[Finite-element investigation on center of resistance of maxillary anterior teeth]

A three-dimensional finite element model of premaxillary bone and anterior teeth was established with ANSYS 13.0. The anterior teeth were fixed with strong stainless labial archwire and lingual frame. In the horizontal loading experiments, a horizontal retraction force of 1.5 N was applied bilaterally to the segment through hooks at the same height between 7 and 21 mm from the incisal edge of central incisor; in vertical loading experiments, a vertical intrusion force of 1.5 N was applied at the midline of lingual frame with distance between 4 and 16 mm from the incisal edge of central incisor. After loading, solution was done and displacement and maximum principle stress were calculated. After horizontal loading, lingual displacement and stress in periodontal membrane (PDM) was most homogeneous when the traction force was 14 mm from the edge of central incisor; after vertical loading, intrusive displacement and stress in PDM were most homogeneous when the traction force was 12 mm from the incisal edge of central incisor. The results of this study suggested that the location of center of resistance (CRe) of six maxillary anterior teeth is about 14 mm gingivally and 12 mm lingually to incisal edge of central incisor. The location can provide evidence for theoretical and clinical study in orthodontics.