Smiling incorporates a variety of facial muscles, in particular the Levator Labii Superioris and the Orbicularis Oris. When these muscles are over active, it is possible that they will pull the upper lip to an elevation that exposes the gums when smiling, which is called “Excessive Gingival Display”. This is not always an aesthetically pleasing effect, as the teeth may then seem disproportionate, or the gums too prominent.