Cephalometric characteristics of Korean Class III surgical patients and their relationship to plans for surgical treatment.

In comparison to gender-matched normal Koreans, Korean patients selected for surgical correction of skeletal Class III problems have, on average, a shorter anterior and posterior cranial base, a shorter maxilla, a longer mandible, increased lower facial height, and a retrusive upper lip. In both males and females, about 40% of a group of Class III patients scheduled for surgery had a maxilla within one standard deviation of the normal position and a prognathic mandible, as compared with a group of normal Korean adults. Almost as many males (37%) in the surgical group had both a retrognathic maxilla and a prognathic mandible, while 18% had a retrognathic maxilla and normal mandible. In females, 25% had only a retrognathic maxilla and 25% had both jaws outside the normal range. The percentage of the Korean patients whose Class III relationship was primarily a result of mandibular prognathism (48%) is more than twice as high as the corresponding number for American Class III surgical patients (19%), somewhat higher than in Chinese patients (39%), and similar to the percentage of Japanese (50%). Maxillary surgery, alone or in conjunction with mandibular setback, is currently used in the treatment of most Class III patients. Both the esthetic consideration of widening the already broad Asian nose and the relative proportions of maxillary versus mandibular abnormalities suggest that mandibular setback alone can be considered for a higher number of Asian than Caucasian Class III patients.