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

BACKGROUND

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.

METHODS

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.

RESULTS

Participants included 66 NHB and 65 NHW adults. Ergotrid height (greater among NHW; p = 0.019) averaged 14.0 mm. 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 5.9 mm, 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.

CONCLUSIONS

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.

Lip repositioning surgery for gummy smile: 6-month clinical and radiographic lip dimensional changes

OBJECTIVES

The present case series aimed to examine lip repositioning surgery (LRS) outcomes related to changes in external and internal upper lip (UL) dimensions, utilizing both conventional clinical and novel radiographic approaches.

MATERIALS AND METHODS

Patients (n = 13) diagnosed with hypermobile UL (>8-mm mobility during smile) and excessive gingival display (≥4-mm) were included and assessed at baseline and 6 months postoperatively. Clinical parameters at rest included total lip and internal lip length (vestibular depth). At maximum smile included total lip, philtrum (ergotrid), and vermilion lengths. Cephalometric parameters included anterior maxillary height; lip length; nasolabial angle; anteroposterior lip thickness; internal lip length (vestibular depth); and vestibular fornix position (using novel approach employing radiopaque marker). Linear mixed-effect models, Pearson's correlation, and linear regression were used for statistical analyses.

RESULTS

LRS did not affect total UL length at rest (p = 0.418). It resulted in significant internal UL length decrease (-3.8 ± 2.1 mm, p < 0.001) and significant increases of vermilion length (1.9 ± 1.0 mm, p < 0.001) and anteroposterior lip thickness (0.7 ± 0.7 mm, p = 0.002). The clinical and radiographic measurements of total UL length at rest (r ≥ 0.734) and of internal UL length (r ≥ 0.737), and the two radiographic assessments of vestibular depth (r = 0.842), were strongly correlated.

CONCLUSIONS

LRS resulted in significant decrease of vestibular depth/internal UL length and in significant increases of UL vertical vermilion length and UL anteroposterior thickness, without affecting total UL length at rest.

CLINICAL RELEVANCE

The documented lip dimensional outcomes should help practitioners when treatment-planning LRS and counseling patients seeking treatment for hypermobile UL.