Brushing and flossing are everyday ways to keep your teeth bright, white and healthy. Still, if you might feel like your smile is lacking some sparkle or is more yellow than it used to be, you’re not alone. When the American Academy of Cosmetic Dentistry asked people what they’d most like to improve about their smile, the most common response was whiter teeth. The American Association of Orthodontists also found that nearly 90% of patients requested tooth whitening.

Thinking about teeth whitening? Get the facts first. Here are five of the most commonly asked questions about the process.

Why Did My Teeth Change Color?

Over time, your teeth can go from white to not-so-bright 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 (enamel).

Tobacco Use
Two chemicals found in tobacco create stubborn stains: Tar and nicotine. Tar is naturally dark. Nicotine is colorless until it’s mixed with oxygen. Then, it turns into a yellowish, surface-staining substance.

Age
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.

Trauma
If you’ve been hit in the mouth, your tooth may change color because it reacts to an injury by laying down more dentin, which is a darker layer under the enamel.

Medications
Tooth darkening can be a side effect of certain antihistamines, antipsychotics and high blood pressure medications. Young children who are exposed to 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.

How Does Teeth Whitening Work?

Teeth whitening is a simple process. Whitening products contain one of two tooth bleaches (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, which is why it’s important to talk to your dentist before deciding to whiten 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.

What Are My Whitening Options?

Talk to your dentist before starting. If you are a candidate, there are three ways to put the shine back in your smile:

Whitening Toothpastes
All toothpastes help remove surface stain through the action of mild abrasives that scrub the teeth. Look for the ADA Seal for safe whitening toothpastes that have special chemical or polishing agents to provide additional stain removal effectiveness. Unlike bleaches, these types of ADA Accepted products do not change the color of teeth because they can only remove stains on the surface.
In-Office Bleaching
This procedure is called chairside bleaching and usually requires only one office visit. The dentist will apply either a protective gel to your gums or a rubber shield to protect your gums. Bleach is then applied to the teeth. A special light or laser might be used to enhance the action of the whitening agent.

At-Home Bleaching
Peroxide-containing whiteners actually bleach the tooth enamel. They typically come in a gel and are placed in a tray that fits on your teeth. You may also use a whitening strip that sticks to your teeth. The concentration of the bleaching agent is lower than what your dentist would use in the office.
Read the ADA’s Statement on the Safety and Effectiveness of Tooth Whitening Products.

Are There Any Side Effects from Teeth Whitening?

Some people who use teeth whiteners may experience tooth sensitivity. That happens when the peroxide in the whitener gets through the enamel to the soft layer of dentin and irritates the nerve of your tooth. In most cases the sensitivity is temporary. You can delay treatment, then try again.

Overuse of whiteners can also damage the tooth enamel or gums, so be sure to follow directions and talk to your dentist.