Sagittal split ramus osteotomy has broad indications as a superior surgical procedure for jaw deformity. Recently, u­-HA/PLLA complex plates, composed of stronger bioabsorbable os­teosynthesis material, were developed and clinically applied. We used a titanium plate and u­-HA /PLLA complex plate as osteosynthesis material after sagittal split ramus osteotomy, and biome­chanically analyzed the stress generated at the site of fixation. Models of the jaw were prepared one month after sagittal split ramus mandible osteotomy using a titanium plate and u­-HA/PLLA complex plate as osteosynthesis material based on CT imaging data. Occlusal force and jaw­closing muscle strength were added to the models. Although the equivalent stress level loaded on the osteosynthesis plate was greater in the titanium plate model, the stress distribution was similar.

The stress distribution on the proximal and distal segments and site of fixation was concen­trated at the lower end of the anterior margin of the mandibular ramus in both models, and the stress level was slightly greater in the u­-HA/PLLA complex plate model. However, the difference was very small, and no difference was noted in the amount of displacement of the distal seg­ment due to the change in the osteosynthesis material type. The u­-HA/PLLA complex plate was slightly inferior to the titanium plate in terms of physical strength as a material for osteosynthesis after sagittal split ramus mandible osteotomy. However, it may be clinically useful because re­moval is not necessary, and the stress on segments and the amount of displacement of the dis­tal segment do not differ from those after surgery using a titanium plate. Shika Igaku (J Osaka Odontol Soc) 2018 ;September ;81(2) : 65-­73.

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