The causes are many. The most common are natural aging and the prolonged consumption of staining agents such as tobacco, coffee, tea, red wine, dark-colored soda, and staining foods like mustard, tomato sauce, or blueberries. A good rule to go by is that if it will stain a white handkerchief or white t-shirt, then it may similarly stain your teeth. Other people may have a different type of staining that occurs when the permanent adult teeth are forming, typically at age prenatal through 12. When children of this age group are exposed to excessive fluoride, tetracycline or other antibiotics, certain embedded and permanent stains or discolored tooth formations may occur. These types of “tooth-formation” stains do not respond well to any form of teeth bleaching. These individuals should consult their dentist for other options, such as bonding, veneers, or crowns.