Effect of Sagittal Dentoskeletal Discrepancies on the Vermilion Height and Lip Area

A frontal evaluation of the lips could provide important information during a routine clinical evaluation of facial aesthetics. There is a lack of ample evidence in the literature regarding variations in the vermilion height and lip area in various sagittal discrepancies when assessing facial aesthetics. The aim of this cross-sectional study was to evaluate and compare the vermilion height and lip area in dentoskeletal Class I, Class II, and Class III malocclusions.

Subjects included female patients divided into four groups (Angle's Class I bimaxillary proclination [Class I BMP], Class II Division I [Class II Div 1], Class III and Class I normal [Class I N]) with 36 samples each. Standardized frontal facial photographs were taken at rest and during a posed smile. Thirty-five landmarks on the upper and lower lips were identified for measurements of the vermilion height and lip area. A one-way analysis of variance was used to identify overall differences, and the post-hoc Bonferroni test was applied for multiple comparisons.

Class III showed a significantly smaller upper-lip area and significantly higher ratios of the upper-to-lower lip vermilion height/area. The ratios displayed an increasing trend from the midline to the corners of the mouth. Class I BMP and Class II Div 1 had significantly larger upper and lower-lip areas.

Morphology of the lips is significantly correlated with underlying anteroposterior dentoskeletal discrepancies. During a clinical examination, a critical frontal evaluation of the lips is important as it is apparently indicative of the underlying sagittal discrepancy, especially in skeletal Class III malocclusions.