ABSTRACT
BACKGROUND:The stress distribution in the periodontal ligament of bending root can provide reference for the size and manner of force in orthodontic treatment. On this account, it can optimize the design of orthodontic force. OBJECTIVE:To analyze the stress distribution of root and periodontal ligament in the bending roots of the maxil ary first molar under different orthodontic forces. METHODS:The maxil ary first molars with normal roots and bending roots were selected, and then the finite element models of maxil ary first molars and periodontal ligaments were established through CT scan and Workbench 11.0 finite element analysis software. The models were loaded with six different methods to analyze the stress distribution. RESULTS AND CONCLUSION:The stress distribution of bending root was mainly concentrated in the tooth neck, fol owed by the apex. During the overal tooth movement, the stress was smal est on the root, periodontal ligament and alveolar bone. Correction of bending roots needs more accurate positioning and traction.