Teeth usually turn gray as a result of trauma or exposure to the antibiotic tetracycline before the age of six, according to Rocky Mountain Endodontics. In the case of trauma, the gray appearance is due to the tooth being dead or the nerve being irritated and in the process of dying. Tooth death often occurs over several years, as the tooth pulp slowly dies after an injury.
A dead tooth can easily be identified using an x-ray, according to Rocky Mountain Endodontics. Tooth discoloration is caused by bacteria feeding on the dying nerve tissue and releasing a substance that causes it to turn gray. Once a tooth is dead and decayed, it must be removed to prevent infection. A root canal is a good solution to prevent complete tooth loss when performed early enough. Once complete, the tooth can be topped with a crown for a natural look and feel.
Being exposed to the antibiotic tetracycline either while in utero or up to the age six can also cause the graying of teeth later in life, according to Rocky Mountain Endodontics. This is a much less common cause of tooth graying, and because of its effects, tetracycline is no longer used in children. In even rarer cases, bleeding inside the tooth can cause graying. When graying occurs, it is recommended to visit a dentist to have a complete evaluation and determine the cause.