Lip vermilion profile patterns and corresponding dentoskeletal forms in female adults

Abstract

Objectives: To objectively classify shapes of the human lip vermilion in the lateral view, and toexamine whether any morphologic characteristics of dentoskeletal patterns are specific to eachclassified lip profile pattern.Materials and Methods: Pretreatment, lateral facial photographs of 234 Japanese women wereselected. Investigators with expert knowledge of the anatomic traits of the lip vermilion in thelateral view extracted from images of the face a 13-dimensional feature vector that representedlip vermilion profile shapes. The vector quantization technique was applied to the feature vectorsto mathematically optimize the number of lip vermilion profile patterns. Dentoskeletal patterns thatcorresponded to each classified lip shape were compared statistically.Results: Seven patterns were found, and differences between patterns were notably maximizedby the flatness of the anterior portion of the lip vermilion for the upper and lower lip, the positionof the most protruded point of the lip vermilion, lip fissure inclination, and differences between thehorizontal positions of the upper and lower lip vermilions. The dentoskeletal forms showed significantdifferences between classified lip vermilion profile patterns (P - .01).Conclusions: (1) Vector quantization revealed that classifying lip vermilion profiles into sevenrepresentative 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 theanterior cranial base, horizontal/vertical positions, inclination and length of the mandible, andhorizontal positions and labio-lingual inclinations of the upper and lower incisors. (Angle Orthod.2009;79:849-858. © 2009 by The EH Angle Education and Research Foundation, Inc.