Causes of a Gummy Smile
There are several possible causes of gummy smile, including:
- An excessive display of gum tissue in your upper jaw can result from the abnormal eruption of the teeth. Teeth covered by excessive gum tissue appear short, even though they may actually be the proper length.

- The muscle that controls the movement of your upper lip could be hyperactive, causing your upper lip to rise up higher than normal. When this occurs, more of your gum tissue is exposed when you smile.

- The manner in which your upper jaw bone grew and developed could cause the appearance of a gummy smile. For instance, if there was an excessive bulging protrusion of the upper jaw within the gum tissue, you would experience an obvious gummy appearance when you smile.

CLINICAL CASE
This procedure was performed by Dr Vo Van Nhan
Patient: a 50 year old men patient. He complains of excessive gum tissue was exposed when he smiles and want to replace new ceramic crown of the front teeth on the upper and lower teeth.

the old crowns will be replaced excessive gum tissue was expoesd when he smilesThe old crowns will be removed and during the treatment procedure, the excess gum tissue – and possibly bone - will be removed in order to expose more of the tooth's surface. 
As a result, gummy smile sufferers see more of their teeth when they smile and less of their gums.