Two cases of skeletal open bite treated by sagittal splitting osteotomy of the mandibular ramus--a comparison between successful treatment and subsequent relapse.

Sagittal split-ramus osteotomy was performed on two patients with severe open bite due to Class I malocclusion. The original open bite was -9 mm in case 1 and -6 mm in case 2. After presurgical orthodontic treatment, these values were changed to -7 mm and -8 mm, respectively. The surgical procedure for treating these patients required mobilization of the mandible to close the open bite. The operation was successful in one case, but partial relapse occurred in the other during retention. The factors leading to the relapse were considered by comparison between the two cases.