Teeth Whitening: How It Works and What to Expect

Medically Reviewed by Zilpah Sheikh, MD on November 15, 2023
8 min read

Teeth whitening is a procedure to lighten the color of your teeth and remove stains. You can have it done at a dentist's office, or do it yourself at home. 

Tooth whitening is most often done using peroxide-based bleaching agents. At-home systems contain from 3% to 20% peroxide (carbamide or hydrogen peroxides). In-office systems contain from 15% to 43% peroxide.

Generally, the stronger the solution and the longer you keep it on your teeth, the whiter your teeth become. But the higher the percentage of peroxide in the whitening solution, the shorter it should stay on your teeth. Keeping it on longer will dehydrate teeth and increase tooth sensitivity.

There are pros and cons to each option, but before you try at-home tooth-bleaching kits, talk to your dentist. Not everyone will see good results. Bleaching will not whiten porcelain crowns or tooth-colored composite bondings.

Whitening vs. bleaching

The terms "whitening" and "bleaching" are sometimes used interchangeably, but they don't always mean the same thing. Teeth whitening can be done with either bleaching or non-bleaching products. Bleaching is the type of whitening that involves using bleach containing peroxide. It cleans both deep and surface stains and can make teeth even whiter than their natural shade.  


You have tooth discoloration when your teeth are stained or darkened. It might affect the whole tooth or look like lines or spots on the tooth's surface. There are two basic types of tooth discoloration: 

  • Intrinsic, or internal, discoloration happens inside the tooth. Things that can cause this type of discoloration include aging, tooth injuries, some health conditions, and certain medications. 

  • Extrinsic, or external, discoloration happens when substances like foods, beverages, or tobacco stain the tooth's surface. Poor oral hygiene can also cause it.  

Teeth whitening done by your dentist can get teeth brighter faster. The bleaching solution is usually much stronger than that in at-home kits. Also, your dentist can use heat, light, or a combination of the two to speed and intensify the whitening process.

The most dramatic results -- teeth generally get three to eight shades brighter -- usually take several 30- to 60-minute in-office visits. Some dentists use techniques that can be done in a single 2-hour appointment (such as the Zoom system). The cost of in-office teeth whitening varies, but can range from $500 to $1,000.


There are many choices for whitening teeth at home. Some common methods include:

  • Tooth whitening strips and gels. Applied directly to the teeth with a brush or a thin strip, these peroxide-based tooth bleaching products usually need to be applied once or twice a day for 10 to 14 days. They can lighten your teeth by a shade or two. Results last four or more months. Products may cost from $10 to $55.
  • Tray-based tooth bleaching systems. With this teeth whitening option, a mouth guard-like tray is filled with a peroxide-based bleaching gel or paste and placed over the teeth for one to several hours a day for up to 4 weeks. You can buy tray-based tooth whitening systems over-the-counter or have one custom-fitted by your dentist. The cost can range from $150 to $600.
  • Tooth whitening toothpastes. Because they're mildly abrasive, every toothpaste helps remove stains from teeth. But whitening toothpastes also contain chemicals or polishing agents that help scrub stains without the aid of a bleaching agent. Tooth-whitening toothpastes are relatively inexpensive and brighten teeth by about one shade. Some contain peroxides, but they aren't left on the teeth long enough to have a strong whitening benefit.
  • Whitening rinses. Rinse your teeth for 60 seconds twice a day with these products, which contain hydrogen peroxide, to make your teeth look slightly whiter. 
  • Whitening chewing gums.You chew these to help prevent stains after you use substances that can stain your teeth, such as tobacco, coffee, and tea.



The first step toward whiter teeth is to practice good oral hygiene at home. Brush your teeth with fluoride toothpaste or toothpaste with baking soda twice a day, floss at least once a day, and drink fluoridated water. 

Some other at-home practices can also help teeth look cleaner and whiter. 

Eat foods that help protect oral health

These include:

  • Dairy products. Foods like milk and unsweetened yogurt contain calcium and phosphates that help protect and rebuild tooth enamel. Cheese boosts the production of saliva, which products your teeth against gum disease and cavities. 
  • Fruits and veggies. High-fiber foods like apples, celery, and broccoli not only help scrub away plaque, but also increase saliva flow. Strawberries contain a substance called malic acid that helps prevent stains on your teeth.

Brush your teeth with baking soda

Baking soda is slightly abrasive, which helps it scrub stains from your teeth. It's an ingredient in many toothpastes. You can also use it by itself. Just put a little on a wet toothpaste and brush gently. Be sure to rinse well. Don't do this more than a couple of times a week. Baking soda's abrasiveness could damage your tooth enamel.

Does activated charcoal work to whiten teeth?

Activated charcoal is another abrasive material that some people use to try to whiten their teeth.You can buy toothpastes and tooth polishes that contain it. But there's no strong evidence that it's effective or even safe. In fact, the American Dental Association warns that using abrasives on your teeth can wear down the enamel and they could end up looking more yellow. 

What about oil pulling?

In this traditional Indian remedy, you swish a spoonful of sesame or coconut oil around your mouth for 15-20 minutes per day. Proponents say it can whiten teeth as well as improve your overall dental health. But there's little scientific evidence that it works.

There are all sorts of teeth whitening options. Which is best for you depends on your circumstances, needs, and budget. Talk to your dentist about which teeth whitening methods or products work well and are safe for your teeth and oral health. 

In-office whitening is highly effective, safe, and long-lasting. But it's more expensive than over-the-counter options, and often isn't covered by dental insurance. Ask your dentist for a cost estimate before committing to teeth whitening. 

Other factors that may determine the best teeth whitening method for you include:

  • Your dental health. You'll need treatment for issues like gum disease or cavities before you whiten your teeth. 
  • The natural color of your teeth and how white you want then to be. Whitening can only lighten your teeth so far. Veneers or crowns might be the only way for you to get truly white teeth.   
  • What previous dental treatments you've had. Whitening won't work on bonding, tooth-colored fillings, crowns, or implants and could even damage them.
  • Potential risks and side effects. Whitening can lead to temporary sensitivity in your teeth and gums. We need more research, but studies have shown some whitening products might change the surface of your teeth or even damage them. 
  • How quickly you want results. One professional treatment might do the trick. You may need to use at-home products every day for a week or more to get similar results.


Whether you use an at-home tooth-whitening system or have your teeth bleached by a dentist, you can help maintain the results by regularly brushing and flossing and keeping up with dental appointments

 Also, avoid acidic foods and beverages, those that are rich in tannins (substances found in plants that have an astringent quality), and deeply colored ones that could stain your teeth. These include:

  • Black teas and coffee
  • White and red wine
  • Sports drinks
  • Carbonated beverages (dark and light-colored sodas)
  • Intensely colored foods like blueberries
  • Sauces (soy, tomato, curries)


Tooth bleaching can make teeth temporarily sensitive -- or be uncomfortable for people who already have sensitive teeth. When used incorrectly, home kits can also lead to burned -- even temporarily bleached -- gums.

Tooth-whitening works best for people with yellow teeth and is less effective for people with brown teeth. If your teeth are gray or purple, tooth bleaching probably won't work at all.

To be sure tooth-whitening is worth your time and money, talk to your dentist before you use an over-the-counter tooth whitening kit.

When done correctly, teeth whitening is generally safe. But it can come with risks, depending on what you use to whiten your teeth and how often and how long you use it.  The risks of overly aggressive teeth whitening include:

  • Gum irritation
  • Increased tooth sensitivity
  • Softening of the tooth enamel
  • Roughening of the teeth's surface
  • Damage to or discoloration of dental restorations like crowns

We need more research on this, but some early studies indicate there could be additional risks, such as:

  • Erosion (wearing away) of the teeth
  • Loss of minerals from the teeth 
  • Damage to the pulp inside your teeth

To minimize the risks:

  • Follow your dentist’s recommendations for whitening your teeth.

  • Carefully follow the manufacturer's instructions for using whitening products.

  • Use only teeth whitening products whose labels say they're approved by the American Dental Association.

  • Tell your dentist if you notice undesirable changes in your teeth or health after teeth whitening.

Can teeth whitening damage teeth? 

Teeth whitening can damage your teeth if the procedure or product is too harsh.  This is due to dehydration of the teeth and the loss of essential minerals like calcium.  

Teeth whitening lightens your teeth and removes stains using ingredients such as hydrogen peroxide. There are many safe and effective ways to whiten your teeth, including professional treatment at your dentist's office and over-the-counter products you use at home. Whichever method you choose, it's important to seek your dentist's advice and follow the directions carefully.

Can badly yellowed teeth become white again

You can get badly yellowed teeth due to aging, certain foods and beverages, and poor oral hygiene. These yellowed teeth can become white again through dental care like teeth whitening, dental bonding, and crown procedures. Your dentist can help you choose what’s best for you. 

What’s the most effective way to whiten teeth? 

For long-lasting results, experts recommend a whitening treatment in your dentist's office, followed by monthly over-the-counter treatments for maintenance. But this may not be right for everyone.