Objective classification of nose-lip-chin profiles and their relation to dentoskeletal traits.

OBJECTIVES: To objectively classify the nose-lip-chin profiles of adult women and identify any associations between the nose-lip-chin profile patterns and dentoskeletal patterns. SETTING AND SAMPLE POPULATION: Lateral facial photographs and lateral cephalograms were obtained for 229 Japanese women who were being assessed for orthodontic treatment. METHODS: A feature vector that was effective in distinguishing differences in nose-lip-chin profiles was extracted for each photograph. To categorize the records into an optimum number of subclasses according to nose-lip-chin profile configurations, a vector quantization method was applied to the feature vectors of all samples. Dentoskeletal patterns that corresponded to the nose-lip-chin profile subclasses were compared. RESULTS: Eight profile patterns were identified, and the differences among patterns were notably maximized by the nasolabial angle, configuration and vertical length of the subnasal region, vertical thickness of the lip vermilion borders, sagittal position of the upper- and lower-lip vermilion borders and their relation to each other, labiomental angle, depth of the labiomental sulcus, degree of prominence of the chin, and degree of protrusion of the mandible. The dentoskeletal patterns showed significant differences between the classified profile patterns (p < 0.01). CONCLUSIONS: A method to objectively classify the nose-lip-chin profiles of adult women was established, and the nose-lip-chin profile patterns were found to be associated with the dentoskeletal patterns.