Hard and soft tissue correlations in facial profiles: a canonical correlation study

BACKGROUND: The purpose of this study was to analyze the relationship between facial hard and soft tissues in normal Saudi individuals by studying the canonical correlation between specific hard tissue landmarks and their corresponding soft tissue landmarks. METHODS: A retrospective, cross-sectional study was designed, with a sample size of 60 Saudi adults (30 males and 30 females) who had a class I skeletal and dental relationship and normal occlusion. Lateral cephalometric radiographs of the study sample were investigated using a series of 29 linear and angular measurements of hard and soft tissue features. The measurements were calculated electronically using Dolphin(®) software, and the data were analyzed using canonical correlation. RESULTS: Eighty-four percent of the variation in the soft tissue was explained by the variation in hard tissue. CONCLUSION: The position of the upper and lower incisors and inclination of the lower incisors influence upper lip length and lower lip position. The inclination of the upper incisors is associated with lower lip length.