The terms you are using are those that would be used by academics and not so much by practicing cosmetic dentists. But they are a useful way to categorize teeth stains. Of the terms you mentioned, extrinsic and intrinsic would probably be heard more often clinically among practicing dentists than endogenous and exogenous.
Extrinsic stains would be those that exist on the surface of the teeth. Tobacco creates extrinsic stains. Here’s a picture of some teeth with extrinsic stains.
These are child’s teeth, and children, as their teeth are developing, tend to pick up some of these stains as different naturally-occuring bacteria come to populate their mouths. Peridex mouthwash causes this type of stain. The milder stains of this type can be removed by brushing (e.g. whitening toothpastes). The more stubborn ones will need to be removed by a dental cleaning, or by Supersmile toothpaste.
Intrinsic stains would be those that are absorbed into the actual structure of the teeth. They take a long time to develop. Years of drinking coffee or tea, smoking, or even eating highly pigmented fruits such as raspberries, will cause the teeth to darken. These stains tend to be brownish or yellowish. They cannot be removed by any toothpaste, but they can easily be removed by bleaching. Here are before-and-after photographs of teeth that had these accumulated stains which were treated with the Kör deep bleaching system.
Exogenous stains would be those that are caused by outside agents. All of the stains mentioned above would be exogenous. All can be removed by either a surface cleaning of the teeth or by bleaching.
Endogenous stains are those that were acquired during the development of a tooth. Tetracycline stains would be in this category. If the antibiotic tetracycline is taken during the development of permanent teeth (between birth and twelve years old) it binds to the dentin of the tooth and becomes a deeply embedded stain. Fluorosis stains are more superficial but they are also developmental—they are caused by the consumption of too much fluoride while teeth are forming. From the point of view of a cosmetic dentist, you could also call a dark natural pigmentation in the teeth to be an endogenous stain. Some people’s teeth are just naturally dark.
The treatment of these endogenous stains is different. Tetracycline stains respond somewhat to bleaching, but are best treated by porcelain veneers. Fluorosis stains should not be treated by bleaching because they occur in splotches. However, the natural pigmentation of teeth can be treated effectively by bleaching. With persistent bleaching treatments, people can get their teeth whiter than they were when they first erupted into their mouths.
I hope this is helpful. Good luck in your schooling.
– Dr. Hall
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About David A. Hall
Dr. David A. Hall was one of the first 40 accredited cosmetic dentists in the world. He practiced cosmetic dentistry in Iowa, and in 1990 earned his accreditation with the American Academy of Cosmetic Dentistry. He is now president of Infinity Dental Web, a company in Mesa, Arizona that does advanced internet marketing for dentists.