[Distribution features of surface stress on the bilateral condyles of the unilateral mandible model for 3 kinds of surgeries of temporomandibular joint ankylosis].

OBJECTIVE: To determine the distribution features of surface stress on the bilateral condyles of the normal mandible and the unilateral mandible model for 3 kinds of surgeries of temporomandibular joint ankylosis under normal occlusal strength. METHODS: The normal mandible 3-dimensional finite element model and the 3-dimensional finite element mandible model for 3 kinds of surgeries of unilateral temporomandibular joint ankylosis were built. The jaw triangle area and the condyle transverse ridge was fixed and bound at mid-point. And 100 N of load was applied to the first molars of the bilateral mandible to obtain a von Mises stress diagram of the condylar surface and the unit von Mises stress of the condylar surface. Statistical analysis was carried out. RESULTS: The transmission of von Mises stress at the operated side of fractured articular arthroplasty of the condylar was interrupted. The von Mises stress at the operated side of the condylar in the group of point-surface contact joint reconstruction was bigger than that of the normal group (P<0.05) whereas there was no significant difference between the group of surface-surface contact joint reconstruction group and the normal group (P>0.05). The von Mises stress of the condylar at the non-operated side in the group of fractured articular arthroplasty was bigger than that of the normal group (P<0.05), whereas there was no significant difference between the group of point-surface contact or surface-surface contact group and the normal group (P>0.05). CONCLUSION: The surface-surface articular reconstruction is beneficial to the recovery of the masticatory function without increasing the burden for contralateral temporomandibular joint and is helpful to the joint. Thus this surgical method is recommended.