[Correction of mandibular prognathism by intraoral vertical ramus osteotomy and improvement of the technic].

A new procedure, intraoral vertical ramus osteotomy (IVRO) becomes more and more popular in correction of mandibular prognathism recently. Simplified operation, decreased bleeding and mild reaction after operation are the advantages of this procedure. 32 cases of mandibular prognathism corrected by intraoral vertical ramus osteotomy were reported in this paper. Modifications for avoiding fracture and displacement of proximal segment, the main complication and indications of IVRO were discussed.