Abstract
Botulinum toxin type A is effective in reducing excessive gingival display caused by hyperfunctional upper lip elevator muscles; however, this effect is transient. This study aimed to determine the duration of the effectiveness of botulinum toxin type A on a gummy smile. A systematic search was conducted using Medline (PubMed), Scopus, and Web of Science electronic databases, from 1970 to March 2017 with no language restriction; the search included studies evaluating adult patients with excessive gingival display who were treated with botulinum toxin and were followed-up for at least 3 months. OpenGrey and Clinical Trial Registry were also consulted. Quality assessment was applied to determine the level of evidence and bias, and a meta-analysis was performed. Of 2181 full texts, 71 were obtained, with 3 prospective studies meeting the selection criteria. The gingival display was significantly reduced to baseline with 2, 4, and 8 weeks of treatment. The gingival display considerably reduced at the baseline-2-week comparison (-4.44 mm using raw data and-4.05 mm using the standard difference) and increased throughout the weeks of follow-up. There is scant evidence to determine the duration of the effectiveness of toxin type A on a gummy smile. The effect tends to be stable until at least 8 weeks of follow-up, and the gingival exposure may not return to baseline within 12 weeks of follow-up. Well-designed randomized clinical trials with a minimum of 6 months of follow-up are necessary to strengthen the evidence.
Highlights
Submitted: September 15, 2017 Accepted for publication: January 29, 2018 Last revision: March 08, 2018A pleasant smile is important for socialization, because one conveys a sense of joy through facial expressions
This review report is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.[27]
The eligibility criteria were designed to answer the research question in the PICO format as follows: In patients with excessive gingival display or gummy smile (P) who received botulinum toxin type A (BTX-A) (I), how long do the effects last (O) compared with the baseline (C)? The inclusion criteria were prospective clinical studies that included: individuals with excessive gingival display as the main complaint; minimum 3 mm of excessive gingival display reported in the anterior buccal region during the initial phase of treatment; a sample size of minimum 10 patients in the study group; the BTX-A dose specified; a description of the results obtained in millimeters or percentages; and a follow-up of at least three months after treatment reported
Summary
Submitted: September 15, 2017 Accepted for publication: January 29, 2018 Last revision: March 08, 2018. Diagnosis is essential to select the best possible therapy for each patient.[2,3,4] Various procedures, such as gingivoplasty, orthodontic teeth intrusion, orthognathic surgery, and bone resection are available for reducing a gummy. It is a potent biological toxin and constitutes as a therapeutic resource with increasing clinical applications.[12]. It is a natural protein produced by the anaerobic bacterium Clostridium botulinum, which inhibits the release of acetylcholine, a neurotransmitter responsible for the activation of muscle contraction and gland secretion. For the correction of gummy smile with BTX-A, it is necessary to examine the type of smile and the main muscles involved for accurate treatment application. Our aim was to perform a systematic review of the literature to determine the duration of the effects of BTX-A in the correction of gummy smile
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