Classification and craniofacial features of gummy smile in adolescents.

Classification of gummy smile was tried first according to gingival exposure site during posed smile, then several items were measured on cephalometric radiograph to analyze the morphologic features in both sexes and further divided into subgroups. Two hundred twenty-eight adolescents with gingival display of more than 2 mm during smile were clustered according to gingival exposure site. Measurements of 18 pertinent items with great clinical concern or controversy in previous study in each groups were compared with corresponding references. Four distinctive types of gummy smile could be distinguished, and they exposed a continuous band, posterior parts, and one side or anterior part of upper gingiva, respectively. The type exposing a continuous band of upper gingiva took up the majority (200 cases, 88%) of all subjects and were chosen for further cephalometric analysis. Among the characteristic features of gummy smile, adolescents have skeletal class II relationship, vertical growth pattern, retrusive mandible, excessive anterior maxillary height, labially inclined upper incisors and upper lip, great overjet and overbite, and relatively short lip compared with anterior maxillary height. Skeletal class III relationship and horizontal growth pattern were absolutely absent. As a result, treatment planning should be adjusted according to the exposure site and craniofacial feature of each individual patient to obtain the best result.