The following are sources of interior stains of the teeth:
1. Antibiotics
Antibiotics such as Tetracycline and Minocycline stain the teeth by interfering with the developing teeth. For this reason, Tetracycline is not given to children.
2. Exposure to excess amounts of Flouride
Excessive exposure to fluoride due to treated water from public facilities, and fluoride-containing toothpastes, as well as fluoride supplements can cause staining by interfering with developing teeth. The teeth take on an uneven whiteness and at worse come through brown.
3. Hereditary
Some people have hereditary dentine conditions that make them prone to intrinsic staining of the teeth. The dentine is responsible for reflecting light that accounts for the colour of the teeth that we actually see.
Hereditary blood conditions (e.g. erythropoietic porphyria) that make the pigment porphyrin, (in the blood) more attracted to calcium may cause interior staining as calcium deposits inside the tooth.
4. Trauma
When a person suffers a heavy blow on the mouth, some of the tissue and blood vessels may decay and cause staining and discoloration of the teeth. This is because the dead cells and blood are deposited into the teeth.