Anyone who notices a grey tooth in their mouth needs to make an appointment at their local dental centre. A grey tooth may require urgent restorative treatment, although it's also possible that no intervention is needed. There are many reasons why a tooth can develop a grey hue, and you simply don't know until a dentist takes a look at the tooth in question.
Perhaps the most serious cause of a grey tooth is pulp necrosis. This involves the death (necrosis) of your tooth's pulp (its nerve). As the pulp becomes inflamed and swells within its chamber, it can leave blood and other residue on the walls of the chamber, which are made of dentin. This discolouration can become permanently ingrained in the dentin, causing a gradual colour change. Pulp necrosis is generally corrected with a root canal treatment, removing the dead nerve. The tooth may need to be covered with a dental crown to restore its colour.
Pulp inflammation doesn't automatically lead to pulp necrosis. If the pulp became infected, inflamed, but then recovered, it may also have left blood and other residue on the walls of the pulp chamber. This will cause your tooth to become grey but may not warrant a root canal. However, only your dentist can make this determination.
Previous Dental Treatment
Earlier dental restorations that may have begun to degrade can contribute to a tooth becoming grey. This is a particular issue with metal restorations, such as silver amalgam fillings. In this case, the restoration will be removed and replaced.
Your dental enamel (the strong, protective outer layer of your teeth) loses some of its thickness as you age, which is perfectly natural. This causes the underlying dentin to become more prominent and can lead to a darkening of your teeth. The teeth may still be perfectly healthy, so this is largely a cosmetic concern.
What Happens Next
The next step depends on what you're hoping to achieve. If the tooth is a rear molar or premolar, and no treatment is technically needed (such as in the case of discolouration caused by ageing or a pulp inflammation from which you've recovered), then you may be content to leave the tooth as it is, since it's not particularly visible. For more prominent teeth, you may wish to have the tooth whitened. It will not respond to at-home treatment. Your dentist can perform internal bleaching (opening the tooth and applying a bleaching strip to lighten it from the inside out). Alternatively, the tooth can be covered with a restoration (a dental crown or dental bonding) in the desired shade.
A grey tooth might be perfectly healthy, or you might be on the verge of a serious dental infection. The important thing is to have the cause identified by your dentist, allowing you to determine the best next step.
Contact a dental centre for more information.