Thinking about teeth whitening? Here are the most commonly asked questions about the process.
What Causes Discoloration?
While people have different colors of skin and hair, they also have genetic differences in tooth color. Some teeth are more yellow, while others yellow with aging.
Over time, your teeth can go from white to not-so-white for a number of reasons:
Food and Drink
Coffee, tea and red wine are some major staining culprits. What do they have in common? Intense color pigments called chromogens that attach to the white, outer part of your tooth.
Two chemicals found in tobacco create stubborn stains: Tar and nicotine. Tar is naturally dark. Nicotine is colorless until it mixes with oxygen. Then, it turns into a yellowish, surface-staining substance.
Below the hard, white outer shell of your teeth (enamel) is a softer area called dentin. Over time, the outer enamel layer gets thinner with brushing and more of the yellowish dentin shows through.
Because of injury, your tooth may change color because it reacts to trauma by laying down more dentin, which is a darker layer under the enamel.
Tooth darkening can be a side effect of certain medications (antihistamines, antipsychotics and high blood pressure medications). Young children who take antibiotics like tetracycline and doxycycline when their teeth are forming (either in the womb or as a baby) may have discoloration of their adult teeth later in life. Chemotherapy and head and neck radiation can also darken teeth.
Discoloration of the tooth internally can also result from aging, injuries, excessive fluoride, certain illnesses and taking antibiotic tetracycline during early childhood. Although bleaching successfully lightens most discolorations, certain types (like those caused by tetracycline) are more difficult to remove.
How does teeth whitening work?
Teeth whitening is a simple process. Whitening products contain one of two substances: (hydrogen peroxide or carbamide peroxide). These bleaches break stains into smaller pieces, which makes the color less concentrated and your teeth brighter.
Does Whitening Work on All Teeth?
No, That is why it’s important to consult with us before whitening your teeth, as whiteners may not correct all types of discoloration. For example, yellow teeth will probably bleach well, brown teeth may not respond as well and teeth with gray tones may not bleach at all. Whitening will not work on caps, veneers, crowns or fillings. It also won’t be effective if your tooth discoloration is caused by medications or a tooth injury.
In-Office, and At-Home Bleaching
There are two types of bleaching procedures. Sometimes we complete the whole procedure in the dental office (known as “In-Ofice, or“chairside bleaching”) or dispense a system to use at home (called “at-home bleaching”).
Chairside bleaching takes about one hour per visit. It is not uncommon for the teeth to become slightly sensitive following bleaching treatments. To protect the mouth, a gel-like substance is applied to the gums and a rubber “shield” is placed around the necks of the teeth. A chemical solution, the oxidizing agent, is painted onto the teeth. A special light may be used to activate the agent.
Peroxide-containing whiteners actually bleach the tooth enamel. They typically come in a gel that you use in a tray that fits on your teeth. The concentration of the bleaching agent is lower than what we would use in the office.
Single Tooth Bleaching
The following patient complained that her front tooth had turned dark. This sometimes happens when the pulp of a tooth is injured and dies. Typically, the tooth requires root canal therapy. The answer to this patient’s problem was “internal bleaching.” After a few visits the tooth lightened up very nicely. The “after” picture taken immediately after treatment shows the tooth a little lighter than the others. Normally it will “tone down a notch” and blend nicely.