Surgical Orthodontic Treatment for Facial Asymmetry with Contradictory Lateral Inclination between the Upper Occlusal Plane and the Inferior Border of the Mandibular Body Caused by Occlusal Collapse in the Molars

Long-term loss and caries of molars cause the collapse of occlusion. Loss of vertical occlusal stop complicates dental and skeletal problems and may make orthodontic treatment difficult. We report a case of facial asymmetry with contradictory lateral inclination between the upper occlusal plane and the inferior border of the mandibular body caused by occlusal collapse in the molars. The treatment outcome including stable occlusion and proper facial appearance was obtained after orthognathic treatment. A female aged 24 years and 3 months visited our hospital because of anterior teeth crowding and open bite. The mandible was deviated to the right in the frontal view. Her profile was straight-type but excessive lower height was noted in the lateral view. As intraoral findings, Class Ⅲ molar relation, −1.0mm of overjet, and −3.0mm of overbite were seen. Missing and crown collapse of the lower left molars caused the reduced occlusal vertical dimension. Skeletal evaluation by cephalometric analysis showed forward and downward projection of the mandible. The mandibular anterior teeth were retroclined. The collapse of the molars caused the facial asymmetry with the maxillary occlusal plane inclined to the lower left and mandibular body inclined to the lower right, as shown in P-A cephalometric analysis. The treatment plan was to perform maxillomandibular surgical orthodontic treatment with extraction of the maxillary right central incisor and first premolar, maxillary left first molar, and mandibular right first molar. In presurgical orthodontic treatment, the occlusal stop was to be obtained by the mesial movement of the molars. The inclined maxillary occlusal plane and the mandibular body were corrected by the bite-raising of the lower left molar section and extrusion of both upper and lower right molars. Orthognathic surgery was performed to improve the anterior-posterior, vertical, and horizontal skeletal discrepancy. In this case, the lateral inclination between the upper occlusal plane and the inferior border of the mandibular body were contradictory due to the loss of occlusal stop in the molars, resulting in the complicated facial asymmetry vertically and horizontally. By planning appropriate treatment, the occlusion and facial appearance were greatly improved.