Gray teeth usually occur due to several reasons, including certain medications, motion and metal. Such teeth are usually characterized by dark pigmented molecules in the enamel and dentin of the teeth, as stated by ToothIQ. It is always sensible to talk to a dentist to figure out the underlying cause for the discoloration.
There are certain medications, such as Tetracycline, that have been linked to gray teeth. A woman who uses Tetracycline while pregnant risks affecting the dental health of the fetus. This causes a dark gray color that affects the whole tooth of the fetus.
Some metals, such as silver fillings, which are used during dental procedures may also trigger the discoloration, as stated by Oral-B. Talking to a dentist prior to going through certain procedures can help prevent gray teeth.
Any form of trauma to the teeth can also contribute to the discoloration. Injury from a fall or a blow inhibit the development of enamel, especially in children. These incidents may cause the teeth to start turning gray. In adults, a trauma can prevent the flow of blood to the teeth thus leading to gray teeth. Poor dental hygiene can also lead to a grayish color on the teeth, so regular brushing of teeth is advised.