Surgical Orthodontic Correction of a Skeletal Class Ⅲ Case Treated by Dental Decompensation Using Anchor Screws

We report a case of skeletal mandibular protrusion with dwarfed teeth treated by dental decompensation using anchor screws. The patient was a female aged 18 years and 5 months at the first visit with the chief complaint of mandibular protrusion and space between maxillary anterior teeth. She had a concave facial profile with slight midfacial concavity. ∠ANB was −6.0°, ∠SNA was 78.5° and ∠SNB was 84.5°. The intraoral view showed anterior and posterior crossbite. The molar relationship was Angle ClassIII. Lower incisors showed lingual inclination because of dental compensation. In the conventional treatment, labial tipping of the lower incisors was likely to generate interdental spaces in the mandibular arch with mild crowding. Subsequently, in the process of closing spaces, retroclination of the incisors was frequently seen. In the present case, we used orthodontic anchor screws to maintain the lower incisor angle during presurgical orthodontic treatment. After 14 months of preoperative orthodontic treatment, Le Fort I osteotomy and intraoral vertical osteotomy (IVRO)were performed. As a result, the mandibular incisors were inclined labially by 7.0°. The posterior part of the maxilla was moved superiorly by 4.5mm and the mandible was set back by 11.5mm at the menton. The crossbite and concave facial profile were improved by the appropriate amount of mandibular set-back. Additionally, condylar movement and incisal paths(opening and closing, lateral excursive movements)were also improved at 25 months after the initiation of retention.