Abstract: Objective: To establish a three-dimensional finite element model and to investigate the biomechanical characteristics and stress distribution of the cystic lesion in the mandibular central junction part. Methods: A three-dimensional finite element model with cystic lesions in the mandibular central junction part was constructed, based on the spiral CT scan data of a healthy adult female volunteer with normal occlusion relationship, using Mimics, Geomagic Studio, and other software. The relationship between bone resorption in the lesion area and potential risk of pathological fracture under certain constraints and loads was analyzed. Results: The finite element model that can reflect the characteristics of the cyst was established. When the size of the cyst in the mandibular central junction part reached 38.18 mm×9.53 mm×23.49 mm under functional load, the Von Mises value in the stress concentrated area reached 81.205 Mpa, which was close to the yield strength of bone materials, and the critical bone mass in the lingual side, the lip side, and the lower margin of the mandible were 1.33 mm, 0.66 mm, and 1.69 mm, respectively. Conclusion: From the perspective of biomechanics, the strength of jaw significantly reduced due to a wide range of absorption of cortical bone. The remaining bone thickness in the lingual side, lip side, and lower margin of mandible may provide a reference for the development of one-stage decompression combined with two-stage curettage surgical treatment.

Key words: mandible, three dimensional finite element analysis, cystic lesion, biomechanical analysis, pathological fracture