ORTHODONTIC CONSIDERATION OF FACIAL ASYMMETRY
Yu-Fang Liao, DDS, PhD
Department of Craniofacial Orthodontics
Chang Gung Memorial Hospital, Taoyuan, Taiwan
Graduate Institute of Craniofacial and Oral Science
Chang Gung University, Taoyuan, Taiwan
Facial asymmetry is one of the most challenging dentofacial deformities and is not uncommon in skeletal Class III deformity. Appropriate surgical-orthodontic treatment starts with accurate diagnosis by evaluating all dimensions and determining the nature of the asymmetry because it might be a combination of hard-tissue and soft-tissue components. General skeletal and dental morphologic features of asymmetric skeletal Class III deformity are maxillary hypoplasia and roll asymmetry, mandibular hyperplasia as well as roll and yaw asymmetry, proclined maxillary incisors, retroclined mandibular incisors, and buccal/lingual tilting of maxillary/mandibular posterior teeth on the deviated side. In severe form of this deformity, a functionally and aesthetically acceptable result can only be achieved by combined surgical-orthodontic treatment. Surgical-orthodontic treatment planning should not only base on skeletal assessment of the deformity, but also on post-treatment stability. In our center, the preferred surgical plan has moved over the years from mandibular osteotomies to bimaxillary procedures. At present, asymmetric posterior impaction of the maxilla in association with asymmetric mandibular setback using bilateral mandibular ramus osteotomies and genioplasty is usually the treatment of choice. During treatment planning five factors should be considered: (1) the need for maxillary segmentation, (2) the need for overcorrection, (3) the setup of surgical occlusion, (4) the indication for computer-assisted simulation, and (5) the limit of proximal segment rotation. This presentation will introduce the orthodontic consideration for treating asymmetric skeletal Class III deformity using surgery-first approach. The principles of planning surgical-orthodontic treatment and treatment outcome for asymmetric Class III deformity also will be offered.