OnabotulinumtoxinA for the treatment of a "gummy smile"

Background: Excessive gingival display, or a "gummy smile," is defined as 2 mm or more of gingival exposure upon smiling. Such excessive gingival exposure can be aesthetically unappealing to patients. One factor that contributes to a gummy smile is hyperfunctional lip elevator muscles.

Objectives: The authors evaluate onabotulinumtoxinA as a safe and minimally invasive treatment for a gummy smile.

Methods: In this prospective study, 14 patients (13 women, 1 man) underwent pretreatment photographs and measurements, followed by bilateral injection of onabotulinumtoxinA into their lip elevator muscles. All patients selected for the study had more than 2mm of gingival show and were classified as having a "cuspid smile," where action of all elevator muscles raised the upper lip- like a window shade-to expose the upper teeth and gingival scaffold; these patients were thought to have a better chance for a more superior result. Repeat measurements and photographs were collected at 2 weeks and 3 months. Patient-reported outcomes were collected at 2 weeks, and data were compared to determine the correlative relationship.

Results: An average of 5 units (range, 4-6 U) of onabotulinumtoxinA were injected into 3 sites bilaterally. The average preinjection gingival show over the central incisors and canines were 4.89 mm and 4.25 mm, respectively. Postinjection gingival show decreased to an average of 0.75 mm (85% improvement) and 0.74 mm (83% improvement) over the central incisors and canines, respectively. Average follow-up time was 12.6 days. One patient felt the resulting smile was unattractive and opted not to undergo repeat injections, while all other study participants experienced no negative effects and wished to undergo repeat treatment.

Conclusions: As treatment for a "gummy smile," onabotulinumtoxinA provides an effective, minimally invasive, and safe therapy. This treatment option can lead to significant improvement in smile aesthetics with high patient satisfaction.

Level of evidence: 3.