Practical classification of chin deformities

Abstract

A visually pleasing chin is an important component of facial harmony. This study was undertaken to introduce a practical classification of chin dysmorphology, which can be used to guide the surgeon toward the appropriate surgical approach to chin repair. Analysis of life-size photography, 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 chin dysmorphism: Class I, macrogenia (n = 170, 24.9%); Class II, microgenia (n = 435, 63.6%); Class III, combination of macrogenia in one direction 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 symphysis menti with excess soft tissue covering) (n = 5, 0.73%); and Class VII, pseudomicrogenia (long-face deformity producing clockwise rotation of the normal mandible) (n = 3, 0.4%). Having diagnosed the dysmorphism, logical surgical recommendations for lower face improvement were postulated. Only patients with Class II chin deformity can be corrected with augmentation. Classes I, III, and IV require an osteotomy of the chin. Classes V and VI benefit from soft tissue correction. Class VII deformity can be corrected with a maxillary osteotomy.