RESUMEN
OBJECTIVES: To objectively classify shapes of the human lip vermilion in the lateral view, and to examine whether any morphologic characteristics of dentoskeletal patterns are specific to each classified lip profile pattern. MATERIALS AND METHODS: Pretreatment, lateral facial photographs of 234 Japanese women were selected. Investigators with expert knowledge of the anatomic traits of the lip vermilion in the lateral view extracted from images of the face a 13-dimensional feature vector that represented lip vermilion profile shapes. The vector quantization technique was applied to the feature vectors to mathematically optimize the number of lip vermilion profile patterns. Dentoskeletal patterns that corresponded to each classified lip shape were compared statistically. RESULTS: Seven patterns were found, and differences between patterns were notably maximized by the flatness of the anterior portion of the lip vermilion for the upper and lower lip, the position of the most protruded point of the lip vermilion, lip fissure inclination, and differences between the horizontal positions of the upper and lower lip vermilions. The dentoskeletal forms showed significant differences between classified lip vermilion profile patterns (P < .01). CONCLUSIONS: (1) Vector quantization revealed that classifying lip vermilion profiles into seven representative patterns was optimal for maximizing differences in the configuration of the lip vermilion. (2) Lip vermilion profile shapes were found to be associated with horizontal lengths of the anterior cranial base, horizontal/vertical positions, inclination and length of the mandible, and horizontal positions and labio-lingual inclinations of the upper and lower incisors.
