RESUMO
Botulinum toxin type A (BoNT-A) is an easy and fast treatment for gingival smile (GS). The objective of the study was to compare the reduction of gingival exposure using three different doses of abobotulinumtoxinA (ABO) in patients with different severities of anterior GS, and to assess treatment safety and patients' satisfaction. A prospective, single-center, randomized, double-blind study was conducted. Mild GS (2 to < 3 mm) was treated with 2.5 U of abobotulinumtoxinA (ABO) per side, moderate GS (3 to < 4 mm) with 5 U of ABO per side, and severe GS (4 mm or more) with either 2.5 U, or 5 U or 7.5 U of ABO per side. All the 41 enrolled patients completed the study. The mean gingival exposure reduced significantly 4 and 12 weeks after treatment. The average reduction of gingival exposure with 5 U was significantly larger than that obtained with 2.5 U, (3.46 ± 1.39 vs. 2.05 ± 1.29 mm; p = 0.004). All groups of GS severity presented statistically significant reduction in the gingival exposure 4 and 12 weeks after ABO injections. Twelve weeks after treatment, more than 80% of the patients were satisfied or very satisfied. There were no treatment-related adverse events reported by the patients or noticed by the investigators. Gingival smile can be safely and effectively managed with BoNT-A injections and specifically with ABO injections to target the LLSAN muscle. Further and larger studies may determine the exact influence of each factor on BoNT-A treatments of GS.