Angled channel retractor for sagittal split ramus osteotomy

Protecting the adjacent soft tissues using a channel retractor prevents complications, such as excessive bleeding, during sagittal split ramus osteotomy. However, the saucer-shaped blade of the conventional channel retractor fits poorly into the posterior border of the mandibular ramus during medial osteotomy, which is typically performed parallel to the occlusal plane. Therefore, a novel channel retractor was developed with an adjusted blade bending angle, based on cephalometric data. The lateral cephalograms of 339 Japanese patients with jaw deformities were collected. Cephalometric landmarks were identified based on the definitions of the Downs-Northwestern analysis, and the acute angle between the occlusal and ramus planes was calculated. Based on the consistent mean and median occlusal ramus angles obtained, the blade was bent at 70° in the sagittal plane to fabricate the angled channel retractor. The engagement at the posterior border of the mandibular ramus during medial osteotomy enhances its stability. Furthermore, owing to the bending direction, the angled channel retractor used for medial osteotomy on one side can be used as a channel retractor for lateral osteotomy on the other side. The proposed angled channel retractor offers both stability and versatility for osteotomy manoeuvres.