Effects of different doses of abobotulinumtoxinA for the treatment of anterior gingival smile

Non-Surgical Management of the Gingival Smile with Botulinum Toxin A-A Systematic Review and Meta-Analysis

Currently, concern about facial attractiveness is increasing, and this fact has led to orthodontics in adult patients being an increasingly demanded treatment, and with it, multi-disciplinary work. When it is caused by a vertical excess of the maxilla, the ideal solution is orthognathic surgery. However, in borderline cases and when the cause is hyperactivity of the upper lip levator muscle complex, alternative conservative solutions can be considered, such as the application of botulinum toxin A (BTX-A). Botulinum toxin is a protein produced by a bacterium and causes a reduction in the force of muscle contraction. The multi-factorial nature of the smile requires an individualized diagnosis in each patient, since there are multiple ways to treat the gummy smile (orthognathic surgery, gingivoplasty, orthodontic intrusion). In recent years, interest has grown in the simplest techniques that allow the patient to quickly return to their usual routine, such as lip replacement. However, this procedure shows recurrences in the first 6-8 post-operative weeks. The main objective of this systematic review and meta-analysis is to analyze the effectiveness of BTX-A in the treatment of gummy smile in the short term, to study its stability, and to evaluate potential complications. A thorough search of the PubMed, Scopus, Embase, Web of Science, and Cochrane databases and a grey literature search were conducted. The inclusion criteria were studies with a sample size greater than or equal to 10 patients with gingival exposure greater than 2 mm in smile, treated with BTX-A infiltration. Those patients whose exclusive etiology of their gummy smile was related to altered passive eruption, gingival thickening, or overeruption of upper incisors were excluded. In the qualitative analysis, the mean pre-treatment gingival exposure ranged between 3.5 and 7.2 mm, reaching a reduction of up to 6 mm after infiltration with botulinum toxin at 12 weeks. Although multiple muscles are involved in the facial expression, the muscles par excellence selected for blockade with BTX-A were levator labii superioris, levator labii superioris ala nasalis, and zygomaticus minor, infiltrating from 1.25 to 7.5 units per side. In the quantitative analysis, the difference in mean reduction between both groups was -2.51 mm at two weeks and -2.24 mm at three months. The benefit of BTX-A in terms of improvement of gummy smile is demonstrated, as a significant reduction in gummy smile is estimated by BTX-A therapy two weeks after its application. Its results gradually decrease over time, however, they stay satisfactory without returning to their initial values after 12 weeks.

Effects of Dose and Injection Site on Gingival Smile Treatment with Botulinum Toxin Type A: A Prospective Study

BACKGROUND

Botulinum toxin type A is an easy and efficacious treatment for gingival smile. However, the optimal dose and injection site are controversial. The authors compared the reduction in gingival exposure using two methods with different doses and injection sites.

METHODS

In this prospective self-controlled study, healthy participants with gingival smile (anterior gingival exposure of >3 mm) underwent two treatment methods. First, participants received a single-point injection of 2 U of botulinum toxin type A per side (simplified method). After 8 months, the individualized method was performed with 2 to 5 U of botulinum toxin type A (total, 4 to 10 U), which was injected at one or two sites according to pretreatment severity. Data were collected at baseline and at 4, 12, and 32 weeks of follow-up.

RESULTS

Fifty-five participants were enrolled. Anterior gingival exposure and bilateral posterior gingival exposure were significantly reduced 4 and 12 weeks after botulinum toxin type A injection ( P ≤ 0.05) with both methods. These parameters returned to baseline by 32 weeks ( P > 0.05). Posttreatment anterior gingival exposure at 4 weeks and 12 weeks with the individualized method was significantly lower compared with the simplified method (both P ≤ 0.05). Patient satisfaction with the individualized method was preferred compared with the simplified method ( P ≤ 0.05). Few adverse events were observed with both methods without statistical significance.

CONCLUSION

It is necessary to increase the injection dose and tailor the injection site according to the pretreatment severity of anterior gingival smile.

Effect and longevity of botulinum toxin in the treatment of gummy smile: a meta-analysis and meta-regression

OBJECTIVE

The aim of this systematic review is to synthesize the evidence on the effectiveness and longevity of the botulinum toxin in the treatment of individuals with excessive gingival exposure.

METHODS

The search was adapted to six electronic databases and gray literature. The risk of bias was assessed using the Cochrane Risk of Bias Assessment Tool for Non-Randomized and Randomized Studies of Interventions. Meta-analyses and meta-regression were performed using random effects models.

RESULTS

A total of 5247 articles were collected during the final search in the database, resulting in 17 articles included. There was a mean decrease of 3.42 mm [95% CI = -4.50 to -2.34; I² = 97%] in the level of gingival exposure 2 weeks after the application of botulinum toxin. The application time explained 29.58% of the observed variance (p < 0.001), with a tendency for the effect size to decrease from the second week of application onwards, with values returning close to baseline levels in 24 weeks.

CONCLUSION

Botulinum toxin is an alternative technique considered effective for reducing gummy smile, especially for gummy smiles up to 4 mm, with a longevity of at least 12 weeks, returning close to initial values within 24 weeks after application.

CLINICAL RELEVANCE

The knowledge about the longevity and effectiveness of botulinum toxin in the treatment of gummy smile allows for a more adequate clinical planning for these cases, as well as for clinical decisions, as for prognostic factors.

The effect of botulinum toxin A in patients with excessive gingival display with and without zinc supplementation: randomized clinical trial

OBJECTIVE

The objective is to determine the effect of oral zinc supplement intake on the clinical efficacy and sustained effect of BTXA injection, in patients with excessive gingival display (EGD).

MATERIALS AND METHODS

Twenty-five participants with excessive gingival display (EGD) were included in this parallel-group RCT, treated with BTXA with and without Zinc supplementation prior to treatment. Participants were assessed for excessive gingival display reduction and results of stability at 2, 6, 12, 18, and 24 weeks. Patient satisfaction questionnaires were filled at 2, 12, and 24 weeks.

RESULTS

The results of this study revealed that after 6, 12, 18, as well as 24 weeks; The control group (BTXA) showed statistically significantly higher median gingival display than the intervention (Zinc supplement with BTXA). In the intervention group, the median gingival display after 24 weeks showed statistically significantly lower median value compared to the baseline measurement CONCLUSIONS: The use of zinc supplementation prior to BTXA injection prolonged its effect and maintained long-term decreased amount of gingival display, and it did not return to baseline measurements. Patients reported high satisfaction levels and self-confidence.

CLINICAL RELEVANCE

Botulinum Toxin A (BTXA) is used to correct gummy smile; however, its main drawback is its short-lasting effect. Oral zinc supplement intake prior to BTXA injection could maintain the effect of BTXA and enhance its clinical efficacy.