A gummy smile is a smile that shows an excessive amount of gum under the upper lip. It can be caused by several factors, such as small teeth or overgrown gums. In some cases, the cause for this imbalanced look is a hyperactive upper lip, which appears normal when the face is at rest, but tends to rise high above the teeth when one smiles.
If the gummy smile is caused by the upper lip’s tendency to curl up, it can be easily fixed by injecting a botulinum A toxin solution above the upper lip, close to the nostrils. The botulinum A toxin temporarily relaxes the muscle and prevents it from lifting up too high when you smile.