Common Conditions

Teeth Whitening: What to Know Before You Go

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Teeth whitening is getting cheaper and more accessible, but the more popular it gets, the more money there is to be made—resulting in lots of harmful whitening methods, products and scams that fool or hurt consumers.

by Dr. Burhenne

Teeth Whitening
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Teeth whitening is getting cheaper and more accessible, but the more popular it gets, the more money there is to be made, resulting in lots of harmful whitening methods, products, and scams that fool or hurt consumers. Remember, this is a $15B industry and the marketing often doesn’t emphasize the safety information as well.

If you’re considering teeth whitening, this guide is for you. Make sure you know what you’re doing before jumping in. You only get one set of teeth in life and it’s all too easy to damage them permanently.

By the end of this post, you’ll know:

  • What’s safe and what’s not when it comes to teeth whitening
  • How to spot a whitening scam
  • How to get the best whitening results
  • The safest way to whiten your teeth

Why Teeth Turn Yellow

There are two types of whitening because there are two main ways that teeth turn yellow.

For everyone, teeth yellowing is a normal part of aging. Our hair turns gray and our teeth turn yellow. It’s the inner part of the tooth called dentin—not the outer enamel—that yellows. As teeth repair themselves, the new dentin is darker, and the enamel is getting thinner due to wear, and things like grinding your teeth or acids from foods you eat can thin enamel earlier, making teeth become yellow sooner. The color of dentin reflects through enamel like a prism, making the tooth look yellow.

Besides aging, teeth turn yellow or gray due to:

  • Taking tetracycline before age 10
  • Falling on or hitting a tooth
  • Too much fluoride (also called fluorosis)
  • A rare dental disorder called Amelogenesis Imperfecta (AI) which makes the teeth yellow or brown
  • Genetics, which determine the color of your teeth to begin with
  • Silver fillings

The outer part of the tooth – enamel – can also get stained when you drink tea, coffee, wine, or smoke tobacco. This is called staining and it does not affect the inner color of the teeth.

How teeth Whitening Works


“Intrinsic” refers to whitening the inner part of the tooth, which soaks up hydrogen peroxide gel (also called whitening gel or bleach) and becomes lighter.


When the inner part of the tooth is whitened, the color that’s reflected through the outer enamel of your teeth is lighter, making them look whiter and brighter—reflecting out through the enamel like a prism.

Contrary to what you might have thought, bleach lightens the inner tissue of the tooth, not the hard, outer enamel.


Removing staining on enamel (the outer part of the tooth) is called extrinsic whitening. The stains left behind by smoking, wine, tea, and coffee are usually easily removed with a polish by your hygienist at a teeth cleaning or with polishing and whitening toothpaste, which we’ll discuss in a bit.

Which Kind Is Right for Me?

It depends on whether your teeth are intrinsically yellow or if you’re just dealing with staining.

If you have extrinsic discoloration (i.e. staining from things like coffee and tea) it can be removed by cleaning the teeth with a professional teeth cleaning. Bleach will not work well on extrinsic discoloration.

If you have intrinsic yellowing, no amount of stain-removing toothpaste can lighten the intrinsic color of the tooth. You’ll need to whiten your teeth using a bleaching gel that is held up against the teeth.

What to Know Before You Start

Here’s what to know before you begin:

Start With Healthy Teeth

You can’t remodel the kitchen if there’s dry rot in the floor boards. Whitening your teeth when you have gum disease, exposed roots, cavities, crooked teeth, gum recession, or other untreated issues can cause further pain and problems, plus you’ll have wasted your time and money since the whitening likely won’t take on damaged teeth. An ethical dentist will tell you this and not take your money before fixing problems first.

Be Prepared for Tooth Sensitivity

One common side effect of teeth whitening is sensitivity in the 24 hours after your teeth have been exposed to whitening gel. You can take a pain reliever like ibuprofen if the sensitivity is too much to bear.

It Doesn’t Last Forever

Teeth are always yellowing as part of the aging process. They’re also always becoming stained by the foods and drinks we consume. No matter where or how you whiten your teeth, it won’t last forever. Most results last from 6 months up to 2 years, but it all depends on how easily your teeth stain as well as your diet.

There’s also a rebound effect, where teeth will relapse slightly in shade. You may be whitening your teeth and stop at a certain point once you’re happy with the results, but I would recommend going a bit beyond that thanks to the rebound effect.

One Size Does Not Fit All

Custom trays help ensure to keep the bleach where it’s intended, and not on your gums, where bleaching gel causes free radical reactions and damages them. Since everyone’s smile is different and we all shouldn’t be using the same size tray to whiten our teeth.

Keep teeth Whitening Gel Away From Soft Tissue

Another common side effect of teeth whitening is soft tissue irritation. This usually happens when the whitening solution gets on the gums. Lastly, you might ingest a bit of the gel in take-home whitening kits, which can cause nausea or vomiting.

Results Vary

The results you get depend on what your teeth were like when you started. Some people think whitening erases all the damage they’ve done to their teeth over their lifetimes. The opposite is true — the better you’ve cared for your teeth, the greater the results. If you have kept up on your dental appointments, brushed and flossed regularly, and avoided damage and discoloration, the whiter your teeth will appear after treatment.

You Can Overdo It

Too much whitening gel too fast will permanently damage teeth. Over-whitening can make make them look translucent or discolored, which can’t be fixed without replacing the tooth completely (not an option to take lightly).

teeth Whitening Is Safe When Done as Recommended

Whitening is for the most part safe—if done correctly. What most people don’t realize before jumping in is this: because you’re dealing with live tissue (unlike hair or nails) teeth whitening can cause damage, pain, and sensitivity.

Which teeth Whitening Method Is Right For You?

There are a million ways to whiten teeth—at the mall, at the dentist, and even at home. Here’s a breakdown of the options.

Whitening Toothpaste

The name “whitening toothpaste” is a bit misleading. Toothpaste only lightens your teeth superficially by being more abrasive than regular toothpaste, so it can remove staining on your teeth, but not the internal color of your teeth.

Pros: Great for removing staining. Don’t use more than once a week to protect your teeth. Look for an ingredient called citroxain—I use Rembrandt Intense Staining Toothpaste with citroxain.

Risks: Whitening toothpaste also can cause sensitivity, be too abrasive on the teeth, and lead to gum recession. Use it no more than once a week, brush gently with proper technique and check in with your dentist to make sure you’re not doing damage.

Professional Whitening at the Dentist’s Office

You’ll come into the office for a few sessions for about an hour each time. A high concentration of peroxide is applied to the teeth and a light is used, which supposedly accelerates the chemical reaction and the whitening.

Pros: If you need whitening fast for an upcoming event, this can be a good option. Theoretically, since the dentist is present, you reduce your risk of doing damage to your teeth.

Risks: I’m not a fan of these light systems and won’t use them in my practice. At best, they’re safe but won’t get nearly the results from wearing custom trays or white strips. At worst, accelerating the chemical reaction damages the tooth, which can lead to premature aging and yellowing and maybe require future dental work after the tooth dies prematurely. Think of chocolate chip cookies — they’re best baked at 325 degrees for ten minutes. If you try to shorten the time to just five minutes at a higher temperature, you’ll probably burn them.

Custom-Made Whitening Trays 

For the best results, I recommend trays, which are custom-made by your dentist after taking impressions of your teeth. After squirting the hydrogen peroxide gel into the trays, you pop them in your mouth. The trays keep the whitening gel in place, surrounding the 3D surfaces of the teeth and keeping the gel away from the gums where it can do harm.

Pros: You’ll get the best results in the most cost-effective way. Once you have these trays, you can whiten your teeth for the rest of your life (assuming your teeth don’t move). You add a peroxide gel to the trays and can wear them for a few hours or overnight. The gel keeps in the fridge and you can pop in your trays anytime you need to!

Risks: If you use a gel that’s too strong and you leave your trays in for too long, you risk penetration of the hydrogen peroxide too deep into the tooth, which can result in damage of the pulp (the next layer inside the tooth, inside dentin). Children especially are at risk of this because they have larger areas of pulp relative to the size of their growing teeth. Damage of the tissue can cause the death of the tooth, tooth pain, or sensitivity.

Whitening Strips

The active ingredient in whitening strips is carbamide peroxide which is an effective teeth whitener.

Whitening strips are small pieces of a flexible plastic called polyethylene. Each flexible strip is coated with a whitening gel that contains hydrogen peroxide or carbamide peroxide.

You take each strip and mold it around your teeth — one strip for the top and one strip for the bottom. The peroxide gel in the strips is now held up against the teeth, so it can seep into the teeth to lighten them.

White strips work but often give uneven results. Since strips are 2-D, they do a poor job of getting into the curves in between teeth, which can make your teeth look whiter on their flat surfaces, but yellower at the edges. If you have crooked teeth, even results will be hard if not impossible to get.

Pros: They’re readily available at drugstores and on Amazon, are easy to use, and get results within a few days or weeks. A lot of people would consider it a “pro” that you don’t have to see your dentist to get them, but if you haven’t been to the dentist in a while and you have a cavity and the whitening materials get within that cavity, it can cause excruciating pain.

Risks: Whitening strips can be dangerous because they are not custom-fit, so the whitening chemicals come into contact with the gums and other tissues in the mouth. When whitening strips touch other live tissue, you have free radical reactions—those are the reactions the speed up the aging process. With trays you make yourself or with whitening strips, you’re holding oxidant against living tissue which causes a reaction that is unsafe and is creating free radicals in the mouth.

teeth Whitening Methods to Avoid

ZOOM/Light/Halogen/LED/Laser Whitening

Studies have shown the lights do not work to lighten teeth, whether laser, LED, or halogen. At worst these machines can kill teeth by devitalizing the nerve.

Staff running these tooth-whitening kiosks often have no healthcare training and no license, yet are dispensing chemicals that could permanently affect your teeth and gums. They get around the law by having consumers themselves place the whitening tray into their mouths, thereby never entering the mouth and, under the law, not performing a dental procedure. The technicians do not have the appropriate training nor can they follow-up if there are issues after the procedure, such as sensitivity or damage to the gums.

Whitening Mouthwash

A mouthwash might contain the right whitening ingredient, but it’s not going to whiten your teeth. Bleach needs to be held up against the tooth for several minutes or more to seep into the inner part of the tooth and produce a color change if done daily for a few weeks.

Plus, every time you rinse, you’re exposing the sensitive inner tissues of your mouth and gums to bleach, harming them.

DIY Strawberry or Lemon Paste

You’ll get results, yes, but at a cost. These DIY pastes “work” because the fruit’s acid wears away the top layer of enamel, revealing whiter enamel underneath.

When enamel is worn away by acid, teeth begin to look worn, old, and discolored. Just like sun tanning means you’ll get wrinkles faster, the acids in these DIY pastes speed up the aging process of your teeth.

This is why I don’t recommend these acidic pastes under any circumstances. For surface-whitening (extrinsic whitening), use a whitening toothpaste instead.

Do Your Homework

Teeth whitening is an easy way to make money because of the high demand. Compared to a filling or surgery, it doesn’t require a lot of work by the dentist. Everyone wants to know where they can get it quickest and cheapest because they’ve got a blind date next week or a high school reunion to go to. The big corporations are in on it and the dentists are in on it – everyone’s fighting for a piece of the action.

Methods like these are often used for the sake of convenience and time. When people see teeth whitening offered at the shopping mall, that’s way more convenient than making an appointment at the dentist. Whenever you need whiter teeth immediately – for an upcoming date or big event – and don’t have any time to wait, you’re much more likely to be taken advantage of. Take your time and do it right. It’s worth it.

When You May Not Want to Whiten

If you fall into one of these groups, I recommend you talk with your dentist about your unique case, as whitening might not be right for you:

  • Your teeth are already very sensitive
  • You have GERD or acid erosion on your teeth
  • You have gum recession
  • Your gums are sensitive
  • You have sensitivity to hydrogen peroxide
  • You have cavities
  • You have white spot decalcifications (early cavity) which will become whiter and more noticeable after whitening
  • You are pregnant or breastfeeding
  • You’re under age 18
  • You have visible plastic fillings or crowns



Does dental insurance cover teeth whitening?

A: No. Whitening is a cosmetic procedure that’s not medically necessary, so it’s very often not covered.

How safe is teeth whitening?

A: There is a significant amount of clinical data that shows whitening gel is safe, particularly bleaching gels with a neutral pH and 10 percent carbamide peroxide.

Here are some safety considerations to be aware of:

There is some speculation as to the carcinogenic effects associated with the free-radical release of hydrogen peroxide. None of the studies on this are conclusive—but the absence of evidence doesn’t necessarily mean the absence of harm.

Some studies have reported alterations of the enamel surface, which include demineralization or etching, shallow depressions, and slight erosion. These findings were with the use of high concentrations.

Often, a specific product’s documentation on safety and effectiveness is limited and consists of research sponsored by the respective manufacturer of that product, which I don’t find to be reliable as there’s a conflict of interest.

Teeth whiteners are not classified as drugs, therefore the FDA does not regulate them.

That said, I myself use a bleaching gel with a neutral pH and 10 percent carbamide peroxide since it appears to be the safest according to studies. My whole family has whitened their teeth using this system. I’ve tried to mitigate the risks by using custom-made trays, which keep bleaching gel off of the gums and oral tissues. I think teeth whitening is safe if you take it slow, work with a dentist you trust, and research the bleaching gel you use beforehand.


How can I whiten my teeth naturally?

A: The best method to naturally keep teeth whitened is using prevention.

Drink plenty of water throughout the day and especially with meals, which reduces staining. Order a large cup of water with your coffee. Swish with water after meals. Protect your teeth with a mouthguard, because teeth that get hit yellow faster.

Teeth can also be “whitened” at your hygienist appointment with a polish, which removes staining and can make teeth a shade or two lighter.

In some cultures, it is common to suck on lemons. Sometimes a new patient will come in who has sucked on lemons their whole life before coming to my office and their teeth are completely worn away from the acid.

When you purchase custom-made trays, you own a whitening system that will allow you to permanently change the color of your teeth for the rest of your life.

Teeth whitening is never permanent because it works by penetrating the porous tooth and oxidizing the organic tissue between the enamel rods. Dentin yellows as we age and refracts out through the enamel rods, so even if you’re happy with your results now, they will change in a few years. With custom-made trays from your dentist, all you have to do is put the gel on and pop the trays back in for a few days to lighten back up to the shade you want.

It’s the safest method because with custom made trays, the gel will be held up to your teeth only – and not your gums. Oh, and by the way, if you already have Invisalign aligners, you’re in luck – Invisalign inadvertently make the best whitening trays due to the unique way they manufacture their aligners. Dentists and dental labs vacuum form their trays, which is not as accurate as manufacturing them via lasers from a digital model.


Why and how do teeth yellow and darken?

A: A few reasons.

1. Biology: Adult teeth are naturally grayer and yellower than baby teeth. So many people whiten their teeth these days and see sparkling white teeth in magazines that we forget that teeth are not naturally that white.

2. Staining: Your teeth might also appear yellow because of staining from years of drinking wine, tea, coffee, etc. By rinsing with water while eating and right after staining foods and drinks, you can do a lot to protect the color of your teeth.

3. Aging: This type of yellowing is much deeper than the superficial staining caused by drinking coffee or wine. As we age, the organic tissue deep inside the tooth yellows. In this case, it’s not the tooth itself that’s yellow, but what’s deep inside the tooth and then refracts out and gives the tooth a yellow color.

If your teeth appear yellow when you look in the mirror, it’s likely a combination of all three of these factors – totally natural and nothing to worry about.


Is whitening ever medically necessary?

A: No, never. There is no health reason for needing to whiten your teeth. Most of the yellowing of the teeth is due to aging. This condition is perfectly normal. Whitening is a personal preference.


Acid: Softens the surface of tooth enamel thanks to its low pH, causing teeth to become worn, sensitive, and prone to cavities. Acidic foods and drinks include fruit, soda, orange juice, and wine. Reducing the acids in your diet with alkaline foods like veggies as well as swishing with water after acids can help protect your teeth.

Abrasion: Scraping or wearing away tooth enamel. Imagine sandpaper on your teeth.

Carbamide peroxide gel: A type of whitening gel. It penetrates the tooth at a slower rate and can aid in patient comfort and compliance by reducing sensitivity. Contains hydrogen peroxide.

Hydrogen peroxide gel: Another type of whitening gel. Hydrogen peroxide is what actually whitens your teeth. Carbamide peroxide first breaks down into hydrogen peroxide before having whitening power.

Gum recession: Gum recession is when gums pull down, away from the tooth, after healing from inflammation. Receding gums aren’t pretty and they lead to tooth sensitivity because the root of the tooth starts to become exposed as the gum pulls down. Gum recession is 100% irreversible. It’s permanent and no surgery can fix it.

Mark Burhenne DDS

What are your experiences with teeth whitening? Are there any tips you’d like to share? Join the discussion below in the comments!

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Dr. Mark Burhenne DDS

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