Upper lip characteristics and associated excessive gingival display etiologies in adults: Race and sex differences.

Abstract

This cross-sectional study aimed to examine upper lip (UL) and smile characteristics and soft tissue excessive gingival display (EGD) etiologies (hypermobile upper lip [HUL], altered passive eruption [APE], and short upper lip [SUL]) in a nondental adult population and to analyze interracial (Black and White) and intersex differences. Community participants, non-Hispanic Blacks (NHB) and non-Hispanic Whites (NHW), were recruited and examined for UL vertical dimensions at rest and maximum smile and for HUL, APE, and SUL. Associations between gingival display (GD) or EGD and UL anatomical characteristics, HUL, APE, and SUL were analyzed. Participants included 66 NHB and 65 NHW adults. Ergotrid height (greater among NHW; p=0.019) averaged 14.0mm. Upper lip vermilion length (ULVL), total UL length, internal lip length, total UL length during smile, and UL mobility averaged 8.6, 22.5, 23.1, 16.6, and 5.9mm, respectively (all significantly greater in NHB; p≤0.012). SUL prevalence was 4.6%, found only among NHW. Lip length change from rest to smile (LLC) averaged 26.2% (significantly greater in females; p=0.003). HUL prevalence was 10.7% (NHB 13.1%, NHW 3.5%; p=0.024). NHB had significantly greater GD (p≤0.017). EGD and APE prevalence (6.9% for both) showed significant interracial and intersex differences (p≤0.014). Multivariate logistic regression analyses indicated that LLC and HUL were the most consistently significant EGD determinants. UL anatomical and functional characteristics and soft tissue-related EGD etiologies exhibit significant interracial and intersex differences, with UL mobility/hypermobility being the most consistently significant determinant of GD.