Different fixation techniques used in sagittal split ramus osteotomy and comparising the effects of these techniques on the temporomandibular joint by using three-dimensional finite element analysis

Sagittal Split Ramus Osteotomy, is one of the most commonly used orthognathic surgical methods for the correction of mandibular deformities. One of the most preferred techniques to ensure adequate fixation after the application of SSRO surgery is mini plate-screw systems. Many mini-plates have been designed and used to increase the post-operative success of SSRO surgeries. The aim of this study is to determine a safe fixation technique by evaluating the biomechanical factors related to the stabilization of the fixation of SSRO and its effects on the temporomandibular joint. In the current study, an SSRO surgery in which the distal segment was advanced by 10 mm was modeled and analyzed by the SEA method. Bone segments were fixed with 4-hole mini-plate, 6-hole mini-plate and newly designed: 6-hole martin mini-plate, 6-hole fork mini-plate, 4-hole double-Y mini-plate. Models were fixed from the upper skull base and subjected to forces to simulate biting. After the fixation process, the stresses in the bone and the stress values in the TMJ components were evaluated. As a result of the analysis, the lowest stress values were found in martin mini plates compared to other mini plates. Looking at the stresses on the screws, it was seen that the least stress occurred on the screws used in the fixation of martin mini-plates. In addition, it was observed that the martin mini plate transmitted less stress to the bone tissue and was more stable than the routinely used 4-hole and 6-hole mini-plates and other newly designed fork and double Y mini-plates. It was concluded that the martin mini plate, which transmits less stress to the TMJ structures and has the narrowest stress distribution pattern, is the most successful fixation technique among the evaluated techniques.