You may feel as though you followed your dentist's instructions to the letter with your dental crowns, taking the best possible care of these porcelain additions to your teeth. The porcelain crown that was fitted to a tooth may still fit and function perfectly—indicating that the tooth structure beneath the crown has remained strong. But your dental crown no longer looks as healthy as it used to. Could it be beginning to decay?
Porcelain and Decay
Just because a porcelain dental crown is beginning to discolor, it's not in danger of decaying. There's a very simple reason for this, and it's that porcelain can't decay. It's not organic matter like dental enamel (the mineralized substance that forms a tooth's outer layer), and so it's not susceptible to corrosion caused by cariogenic (cavity-causing) oral bacteria (which is what happens to dental enamel). The porcelain surface of the crown isn't developing a cavity, because it can't. Any changes to the appearance of the crown are limited to its appearance.
The discoloration of a dental crown can be compared to the discoloration of natural teeth. Porcelain, like dental enamel, is porous. Residual amounts of color pigments can be absorbed by natural and porcelain teeth alike. These pigments are found in foods and drinks, with some being notorious for their staining abilities. It's not an immediate development—far from it, in fact. As the years go by, the cumulative effect of diet (despite a high standard of oral hygiene) will lead to some wear and tear on natural teeth and porcelain dental restorations, with discoloration (a yellowing) being quite common in varying degrees.
The trouble with this gradual development is that while porcelain mimics the look of a natural tooth, it doesn't mimic the chemical structure of enamel. Teeth whitening kits are designed to be effective on natural dental enamel and will have minimal effect on porcelain, or even no effect whatsoever. Whitening your discolored porcelain crown might appear to be a logical solution to your problem but will end in frustration.
Scale and Polish
See your dentist about your discolored crowns. They can perform a scale and polish—the same procedure carried out on dental enamel during a routine professional teeth cleaning. This process will break up surface discoloration on your porcelain crowns and will restore their appearance to some degree. The specific degree of restoration will vary from person to person. Lightly discolored crowns may look close to new again, whereas heavily discolored crowns may only improve slightly. There's a limit to how white an old porcelain restoration can be made to look, and in some cases, new dental crowns may be the only solution.
Don't despair about your discolored dental crowns, but don't buy a teeth whitening kit either. See your dentist to learn more about maintaining your dental crowns.