Correcting a class III malocclusion with pre surgical orthodontics and oblique ramus osteotomy. Case Report

Resumen

Class III malocclusion is a growth alteration of the maxilla and mandible. According to some studies it can be present in 4% (of us citizens) to 50% in Japanese and Korean populations. Its main feature is the anteroposterior growth of the mandible, accompanied by its dental organs, giving a clear Angle’s class III occlusion with a negative overjet. This anomaly shows an evident cosmetic defect due to fact that a prominent jaw gives a sunk and blurred appearance of the facial middle third, giving anadust expression to the face, sometimes accompanied by depression. This article reports the results of an orthognathic surgery (oblique ramus osteotomy) on a 21-year-old female patient that presented a class III malocclusion caused by an increase in mandibular growth, who came to the Orthodontics Specialty Clinic at UNAM FES Iztacala and presented a concave profi le, skeletal class III, skeletal maxillary biprotrusion, prognathism, Angle’s class III malocclusion and anterior and posterior crossbite. The purposes of the reduction of prognathism by a ramus oblique osteotomy (subsigmoid) with an extra oral approach were: to improve her profi le and skeletal and dental alignment; to obtain an adequate overbite; to maintain the dental midline; to achieve left and right molar class I; and obtain left and right canine class I. After nearly two years of treatment, the results were very satisfying, as can be seen in this report.

Key words: Class III malocclusion, oblique ramus osteotomy.