Abstract: PURPOSE: A three dimensional finite element model is established for analysis of the influence of reaction force on stress and displacement of the temporomandibular joint (TMJ) with anterior traction of the chin. METHODS: A healthy adult male was chosen for the study. Spiral CT data of the original images was collected, 3-D finite element model was established by using Mimics, MSC, Magics, Marc image processing software. 5 N force was applied to the chin, and the direction of force was change. Stress and displacement changes of TMJ and jaw bone were measured and analyzed. RESULTS: Three dimensional finite element model including the maxilla, mandible, TMJ, skull was established, which had 28760 nodes and 110790 units. The maxilla had 20487 nodes and 76982 units, while the mandible had 8273 nodes and 33080 units. When 5N force was loaded on the chin at 37° with the occlusal plane, the equivalent Mises stress value of 20487 maxillary nodes was 0.143N, 0.111N for 8273 mandibular nodes, 0.829N for 14305 condylar head nodes. When the applied load was 5N, the displacement of TMJ from the chin to the condylar position gradually declined, the displacement direction and the applied load direction were consistent. The chin displacement was the biggest, approximately 0.015 mm; while the condylar displacement was minimal, about 0.006 mm. CONCLUSIONS: A three dimensional finite element model of the craniofacial bone was successfully established, with a high degree of similarity and biological entities, which can be used for the study of reaction with anterior traction, and simulation of the distribution of traction force in TMJ.

Key words: Craniofacial bone, Three dimensional finite element, Reaction, Chin, Temporomandibular joint, Displacement