A gummy smile is a term used to describe a smile in which there is an excessive amount of gum showing between the upper lip and the upper row of teeth. A smile looks perfect when the upper lip sits just above the top row of teeth, revealing barely any gum tissue. A gummy smile, however, reveals an excessive amount of gum tissue and creates a noticeably disproportionate gum-to-tooth ratio. About 15 percent of all Americans are affected by gummy smiles.