Why do i have a big white patch on one of my front teeth?

Several options: 1. It could be flourosis from too much flouride accumulating in that area of the tooth while it was developting. 2. It could be from decalcification, a breakdown of the enamel from acids, or excessive plaque. Location is a key factor. If it is at the gumline on your back teeth, watch the carbonated beverages, or acid indigestion. If it is the front teeth it is probably floruosis or poor hygiene.

Fluorosis : Many things can influence the formation of a tooth. A baby tooth with a cavity can cause damage to the permanent tooth underneath. Braces can cause decalcifiaction under the bracket or band. Trauma to the area during development. Or too much or not enough flouride can cause mottling in the enamel layer. The white patch may be an area where the enamel layer is thicker. Let the dentist look.