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Intrinsic Stains

What are Intrinsic Stains?

Gray teeth with tetracycline intrinsic stain can be covered by porcelain veneers.

Figure 1: This patient had a history of tetracycline treatment (an antibiotic) while the teeth were forming. The teeth incorporated the tetracycline molecule (which binds to calcium), making them gray. Bleaching the teeth has been attempted in such patients, with some success reported in the literature from long-term (up to nine months) application of the bleach. However, the safety of such long-term bleaching has not been established.


Stains on teeth are generally of two varieties, extrinsic stains and intrinsic stains. They are generally considered to be of cosmetic significance only; however, a single dark tooth may indicate that the tooth is dead (necrotic), particularly if it has a history of trauma and/or infection. It should be evaluated by a dentist, who may perform vital testing to determine if it requires root canal (endodontic) treatment. Vital testing involves the application of heat, cold, and mild electrical stimulation to the teeth to see whether, and how, they respond.

Intrinsic stains occur much deeper in the tooth than extrinsic stains. Sometimes they occur when the tooth is forming, by incorporating dark pigmented molecules into the crystal structure of the tooth. Common causes include treatment with tetracycline antibiotics while the tooth is forming (Figure 1); and excess fluoride consumption during enamel formation, which can produce brownish staining or mottling.

Intrinsic stains can also occur when a tooth is injured. In such cases, excess blood flows to the tooth (hyperemia) to deliver healing and immune cells. Reddish-brown iron pigments saturate the dentin and cause the tooth to darken.

How does the dentist diagnose Intrinsic Stains?

Note: ToothIQ.com contains general information. Only a dentist can properly diagnose your specific condition.

Intrinsic stains are easy to diagnose from a visual examination of the teeth. The cause of the intrinsic stain will also need to be determined, so that appropriate treatment can be prescribed.

How are Intrinsic Stains treated?

Intrinsic stain of dentin from hyperemia after dental injury that left the tooth dead (necrotic).

Figure 2: This patient lost a tooth and injured the adjacent tooth (see arrow) in an accident, causing it to darken. The darkened tooth was diagnosed as dead (necrotic).

It is usually not possible to neutralize intrinsic stains, and common treatments include veneers and bonding. Sometimes prolonged tooth bleaching can reduce the severity of intrinsic staining, but the safety and efficacy of prolonged bleaching are not well established.

When a tooth is forcefully injured, the body sends healing and immune cells into the tooth by way of the blood stream. The increased blood pressure in the tooth saturates the porous dentin with reddish-brown iron pigment, causing the tooth to darken. It may also cause severe discomfort. Figure 2 shows an example of such a tooth. Root canal treatment was performed on the tooth to relieve inflammation from the injury.

Internal bleach performed in tooth reversed stain and restored lighter shade.

Figure 3: After the darkened tooth had a root canal (endodontic) treatment, a cotton pellet saturated with bleach solution was placed into the tooth for one week. The bleach neutralized the iron pigment, returning the tooth to its previous shade.

In the case of endodontically treated teeth, bleach can be placed inside the tooth and left for approximately one week. It is then removed, and a filling is placed. The iron-saturated dentin will generally lighten to its normal shade in this procedure, which is referred to as internal bleaching (walking bleach).

There are several options for placing veneers on teeth. Photographs can help to document the progress.

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Author: Thomas J. Greany, D.D.S. / Editor: Ken Lambrecht

This page was last updated on March 6, 2018.

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