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.