PRACTICAL CLASSIFICATION OF CHIN DEFORMITIES

A visually pleasing chin is an important component of facial harmony. This study was undertaken to introduce a practical classification of c hin dysmorphology, which can be used to guide the surgeon toward the a ppropriate surgical approach to chin repair. Analysis of life-size pho tography, based on standard anthropometric measurements, was completed on 2,879 patients from 1981 to 1991. Six hundred eighty-four patients were noted to have normal occlusion with some form of chin deformity. Analysis of this group of patients identified seven categories of chi n dysmorphism: Class I, macrogenia (n = 170, 24.9%); Class II, microge nia (n = 435, 63.6%); Class III, combination of macrogenia in one dire ction and microgenia in the other direction (n = 54, 7.9%); Class IV, asymmetry (n = 4, 0.6%); Class V, soft tissue ptosis (''witch's chin'' ) (n = 13, 1.9%); Class VI, pseudomacrogenia (normal skeletal symphysi s mend with excess soft tissue covering) (n = 5, 0.73%); and Class VII , pseudomicrogenia (long-face deformity producing clockwise rotation o f the normal mandible) (n = 3, 0.4%). Having diagnosed the dysmorphism , logical surgical recommendations for lower face improvement were pos tulated. Only patients with Class II chin deformity can be corrected w ith augmentation. Classes I, III, and IV require an osteotomy of the c hin. Classes V and VI benefit from soft tissue correction. Class VII d eformity can be corrected with a maxillary osteotomy.