Assessment of Prolonged Effect of Repeated Botulinum Toxin-A Injection for Gummy Smile Correction

Abstract

Objective: The present study was conducted to evaluate the prolonged effect of repeated Botulinum toxin-A injection for correction of gummy smile.Materials & methods: Sixteen subjects with a mean age of 23.5 years, showing excessive gingival display mainly due to hypermobile upper lip or mild vertical maxillary excess participated in this study. Standardized 2D frontal and profile both resting and maximum smile photographs were taken before and 14 days after each botulinum toxin -A injection and four months later. The study participants were randomly allocated into two groups where the first group received two injections that are four months apart while the second group received three injections that are four months apart as well.Results: Both groups showed reduction in incisal-gingival display, upper lip mobility and upper lip length reduction fourteen days after injection, The first group relapsed almost back to baseline four months after the second injection, however the second group maintained a larger increment of the achieved corrections four months after the third injection.Conclusion: From the results obtained from this study, it could be concluded that repeated injections of Botulinum toxin helped maintain a larger increment of the corrections achieved.