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.