Dose and injection site of botulinum toxin type A for gummy smile management: A systematic review and bibliometric analysis.

ABSTRACT

INTRODUCTION: Botulinum toxin type A (BoNT/A) is an effective non-surgical method for treating gummy smile (GS). This systematic review evaluated the efficacy, duration, and safety of different BoNT/A injections. METHODS: Four electronic databases were searched for relevant literature, generating 1106 references. RESULTS: The review included 13 prospective, controlled clinical trials. The mean pre-injection anterior gingival exposure ranged from 3.5 mm to 6.8 mm, reaching maximum effect at 2-4 weeks post-injection. Most studies indicated complete improvement in gingival exposure post-injection, with gingival exposure reduced to ≤3 mm. The dosage of BoNT/A was determined by the severity of gingival exposure, with effects lasting up to 12-24 weeks. Levator labii superioris alaeque nasi (LLSAN), levator labii superioris (LLS), and zygomaticus minor (ZMi) were the main targeted muscles. Next, bibliometric analysis was conducted to provide an overview of the existing publications on managing gummy smiles. CONCLUSIONS: This data demonstrates that BoNT/A can effectively treat various types of GS triggered by muscle hyperactivity. It is a non-intrusive treatment with significant improvement, high safety, minimal side effects, and high patient satisfaction. This study was preregistered in the Prospective Register of Systematic Reviews (CRD42024509183). CLINICAL SIGNIFICANCE: This study systematically reviewed and compared previous results on efficacy, duration, patient satisfaction, and adverse effects of different botulinum toxin type A doses and injection sites, laying a solid foundation for further studies that use BoNT/A in the management of gummy smiles.