Stress distrubition of posteriorly inclined condyles after surgically induced counter-clockwise rotation of the mandible

In our study, posterior angular condyle stress was evaluated after conterclockwise rotation and advancement of mandible with Sagittal Ramus Osteotomy (SSRO) technique, which is widely used in orthognathic surgery. In this study, Finite Element Analysis (SEA) method, which is supported by literature, has been used. The aim of the study was determine the maximum stress areas in the condyle and the stability and relapse problems after 5 different amounts mandibular advancement. In our study computed tomography image of a patient with an anterior open bite has been computerized and mandible model was created by using Finite Element Analysis method. By operating bilateral sagittal split ramus osteotomy on the mandible model, 2 different advancements (5 and 10 mm) and counter-clockwise movement operations, also models which the lower limit of the proximal segment was correctedand left passively in place during fixation of bone segments, were developed. The pressure, tension and Von Mises stresses on the posterior angular mandibular condyle were evaluated by the SEA method. Stress intensity of mandibular condyle varies according to the amount of advancement of the mandible. As the amount of advancement increases, the amount of stress increases in the posterior and lateral sides of the condyle. The mandible may show angular changes and deplase depending on the amount of condyle advancement and fixation. The posterior angulation of the condyle in the rigid fixation stage affects the amount and intensity of the stress. The posterior angulation of the condyle increases the intensity of stress. In cases with mandibular progression and counter-clockwise rotation, the amount of stress on the condyle increases as the amount of mandibular advancement increases. When the mandibular condyle is not retained its original position and in angular posterior during fixation, the amount of stress increases. When the condylar is exposed to overload, its feeding from the synovial fluid begins to decrease and resorption develops. Excessive advancements are not suitable for TMJ tissues.