Objective: to evaluate the effect of two gingival smile treatment techniques using botulinum toxin. Materials and methods: The randomized, double-blind clinical trial (patient and examiner) will be conducted by two trained and calibrated dentists. Ten patients will be randomly assigned to each group, in a total of 20 patients with gingiva smile greater than or equal to 3mm. In group 1, 10 patients will receive 2 units/point of botulinum toxin Botulift® (botulinum toxin type A), in the muscles form the face: Levators labii superioris alaeque nasi muscle and Levators labii superioris muscle, totalizing 4 points. In group 2, 2 units/point was injected in the muscles: levators labii superioris alaeque nasi muscle, totalizing 2 points. The amount of exposed gingiva during smile will be measured using a pachymeter and the muscle activity of the region will be evaluated through electromyography, before and after treatment (2, 8, 12, 21 and 25 weeks). Patient satisfaction and discomfort due to treatment will be evaluated in the same periods through questionnaire. The impact of the treatment in life quality will be evaluated through OHIP-14 questionnaire.

Inclusion Criteria:

1. Patients of both genders exhibiting gingival exposure greater than or equal to 3 mm above the central incisor during smile
2. Patients with good general health and good oral hygiene.

Exclusion Criteria:

1. Patients with Botulinum Toxin allergy or albumin, or who have previously performed botulinum toxin facial treatment previously.
2. Patients with Amyotrophic Lateral Sclerosis, Neuropathy, Myasthenia Gravis or Lambert-Eaton Syndrome, women who are pregnant or planning to become pregnant, are breastfeeding women.
3. Patients who are participating in other research involving other drugs.
4. Patients who use drugs that interfere with neuromuscular transmission