There are five ways in which your teeth can whiten. Some of these types of whitening are permanent, and some are not. This video and the article below show you how each of these types of whitening applies to you, enables you to decide how to whiten your teeth, and helps you avoid gimmicks when choosing your teeth whitening products.

Whiten Teeth by Removing Surface Stains

On the surface of your teeth, stains are called extrinsic stains. These can be black and brown stains from coffee, tea, or soda. Less noticeable, but more commonly, it can be yellow staining of tenacious and tightly bound plaque. If you remove these stains, then your teeth appear more white. The results last as long as it takes the stains to return. The results are also limited, meaning teeth won’t progressively get whiter after something removes the stain.

When you see toothpaste tubes promoted as “teeth whitening,” it is most commonly for their ability to remove surface stains unless they contain hydrogen peroxide. However, most people think it is the ability of these kinds of toothpaste to remove intrinsic stains, which we will get to in just a moment, but they are not. Whitening toothpastes made to remove surface stains aren’t entirely a good thing, and in my opinion, I would avoid these kinds of toothpaste. Why? They can remove tenacious surface stains that others can’t because they are very abrasive. Abrasive toothpastes can destroy your teeth.

There are studies and charts of the most abrasive toothpastes. For example, on a chart that follows this section, you can see that whitening toothpastes tend to be the most abrasive toothpastes.
Many charcoal toothpastes are also very abrasive, which is why some people claim they are so good at whitening.

However, abrasive toothpastes can negatively affect how white your teeth can become. Abrasive kinds of toothpaste contribute to gum recession and thinning of the enamel. Since the underlying levels of your teeth are more yellow, thinning of enamel can lead to more yellow teeth. It doesn’t stop there. The roots of your teeth are not made of enamel and wear much faster too. Once you get gum recession, it will wear away the tooth’s root surface. This issue happens comparatively quickly, so surprisingly, many people develop notches near the tooth's gum line.

Once again, the results are limited to how much yellow staining you have. I would avoid these toothpastes.

Surface Stained Yellow Teeth
Yellow staining of teeth.
Toothpaste Abrasive Chart RDA Score
Toothpaste RDA Chart.

Whitening Teeth by Dehydration

The following way your tooth can whiten is by drying out the tooth. To help understand, I compare this to wet concrete. When concrete is moist, it is darker, and when concrete is dry, it is whiter.

While not as dramatic of a color change, your tooth is whiter when it is dry. When the tooth is wet, it is darker.

It may seem silly for me to cover tooth dehydration because the whitening results reverse within a few minutes. However, this point is essential to understand to avoid teeth whitening gimmicks. Acids will dry out your tooth. So if you put a supposed whitening agent that a blogger or YouTuber told you to put on your tooth, which is acidic like a strawberry or lemon, it will dry out your tooth and make it look whiter. This whiter tooth shade will last for however long it takes your tooth to rehydrate. It usually takes a few minutes to an hour.

It doesn’t stop there. Sometimes the gimmick tooth whitening agent will cause you to stay open for a while, so if saliva isn’t touching your teeth and you are breathing, this will dry out the tooth. Almost any whitening technique will whiten your teeth more than it appears at first because you keep your mouth open, and your saliva stays away from your teeth during the process.

The temporary shift in color is a problem for us dentists too. For example, we will do a crown on a tooth, but if the patient has been open a long time, we may not notice the surrounding teeth are dry and whiter. So if we note the shade for the new tooth while the surrounding teeth are drier and whiter and don’t realize the change, then when we get the crown back, it will be much whiter than the actual color of the surrounding teeth.
When Cement is wet it is darker and whiter when it is dry.
Taking shade of Teeth
Taking a shade of the tooth.

Teeth Whitening by Breaking Double Bonds in Chromogens

That subtitle may be foreign to you, so I will keep it simple. In your teeth, you have molecules that are called chromophores or chromogens. The name isn’t important, but these molecules stain your tooth yellow. If you look up the chemistry of chromophores, they have crucial double bonds. When you oxidize or take away those double bonds, the chromogens emit a lighter color, and thus so does your tooth. Like spilling bleach on your clothes, most bleaching is because of the oxidation of double bonds, and your teeth are no different.

Oxidizing and breaking up double bonds of intrinsic chromogens is the teeth whitening method that people find the most valuable and effective in whitening their teeth, especially for the typical “yellow teeth” scenario.

What is the Difference Between Carbamide and Hydrogen Peroxide?

Two main types of bleach whiten teeth: hydrogen peroxide and carbamide peroxide. All the effective gels, strips, and over-the-counter whitening products will generally contain one of these two compounds. Whether you do over-the-counter products, take-home trays from the dentist, mall whitening booths, or dental office one-time bleaching, they all use varying concentrations of these two active ingredients. The higher the concentration, the faster it will whiten your teeth. Even at lower concentrations, if either product is left on your tooth long enough, it will eventually whiten. It then becomes a matter of how long you want to take to whiten your teeth. Dental office whitening will whiten your teeth the fastest, in about 2 hours, as it uses the highest allowable concentration of hydrogen peroxide. However, the stronger the concentration of peroxides, the more likely it will cause temporary teeth sensitivity. When in-office whitening started, it was excruciating for some people with sensitive teeth. Today, if the office is informed, they will first apply a desensitizer, heavily minimizing the sensitivity.

If you have really sensitive teeth using a slower and low concentration approach may be beneficial, and brushing with anti-sensitivity toothpaste will also decrease the likelihood of sensitivity. Low concentration will also likely be less expensive, as most of the over-the-counter products are less concentrated and less costly.

Carbamide peroxide will break down to form hydrogen peroxide then become active to whiten your teeth. So essentially, they are both hydrogen peroxide in the end. However, a few differences should help you decide which is right for you.

Hydrogen peroxide works faster and wears off more quickly. Therefore, you can only use it for 20 to 30 minutes before it becomes ineffective, no matter its concentration. Carbamide peroxide, contrarily, will stay effective for hours. If you leave carbamide peroxide in a tray on your teeth while you sleep, which is not recommended, it will whiten your teeth all night.

I prefer carbamide peroxide when I whiten as it gets my teeth whiter, faster than other over-the-counter products. I whiten with the highest carbamide peroxide concentration I can find on Amazon, which is 44%. Here is an affiliate link to 44% carbamide peroxide. It’s much less expensive than all the other less efficient options too. It’s not a name-brand product, so it shows up in an ordinary syringe. If ever it starts to make my teeth sensitive and I still want them whiter, I just wait a week until the sensitivity is gone. Then I start whitening again and make sure that I brush with my favorite anti-sensitivity toothpaste.

Hydrogen peroxide concentrations are about three times stronger than carbamide peroxide concentrations. For example, 10% Hydrogen peroxide is about the same potency as 30% carbamide peroxide. Another example is that 40% hydrogen peroxide is only permitted for use in a dental office, but 44% carbamide peroxide is safe for at-home whitening. See the chart following this section.

Will Teeth Get Yellow Again After Whitening?

After intrinsically whitening, months and years down the road, the teeth will become more yellow again because those double bonds in the chromogens reappear. So touching up your whitening from time to time will keep your teeth white.

Can You Whiten Your Teeth Too Much?

There is the possibility of whitening your teeth too much, which can be counterproductive. You should be aware of how much bleaching is too much. My most significant warning, and downside to intrinsically whitening teeth with peroxides, is overbleaching. Once your enamel has gotten to a certain point of whiteness, it starts to become more transparent or see-through when you bleach with peroxides instead of getting whiter. At this point, you can no longer whiten your teeth with peroxides. In fact, overbleached teeth will start to become darker. This darkening happens because the shadows from the back of the mouth begin to show through. Also, the teeth become more yellow because the underlying layer, called dentin, is more yellow and emits through the now transparent enamel.

This transparency will happen to most people if they whiten their teeth too much. A few lucky people can whiten their teeth until they are as white as marshmallows with no transparency issues. However, most of us are not like that. There are two indicators to tell if you have bleached too much. First, you will notice your teeth aren’t getting any whiter. Lack of whitening isn’t a great indicator because it may be hard to distinguish. The second way to tell is if you look closely at a front tooth and you can trace the border of the underlying dentin layer, then it is likely too much. If you look at the example picture to the side of this subsection, I can determine where the dentin border is. This person has already bleached too much and won’t get any benefits of bleaching more.

Is There a Natural Teeth Whitening Method?

Before moving on to other types of bleaching, I always hear people talking about “natural teeth whitening methods” as they don’t want to use peroxide because it isn’t “natural.” So what do they do? They put banana peels or ground up strawberries or lemons on their teeth. These methods are supposedly more natural, but they sound like an excellent way to get cavities. Another “natural” method includes scrubbing teeth with activated charcoal. None of these are healthy for your teeth, nor are they natural.

You could make a case that using hydrogen peroxide is more natural as almost every cell in your body produces hydrogen peroxide. Of course, cells don’t produce near as much as you are putting in your mouth to whiten your teeth, but peroxide is at least closer to a natural solution than the other suggested methods are.

Unless you consider hydrogen peroxide natural, there is no safe, natural teeth-whitening method that is long-lasting. So let’s just stop pretending that teeth whitening is natural because what is natural is having slightly yellow teeth.
Example of a chromogen
Before & After of Dental Office Whitening
Hydrogen Peroxide vs Carbamide Peroxide Chart and Times
Carbamide Peroxide vs. Hydrogen Peroxide Concentration and Wear Time

Teeth Whitening by Internal Bleaching

Every once in a while, a tooth will stain from the inside. Internal darkening occurs typically because the tooth died by some sort of trauma that happened previously. When the tooth dies, its pulp chamber fills with bacteria and turns purple, red, or black, which stains the tooth from the inside.

If this happens to you, there are two ways to fix it. First, you can have a dental restoration like a crown done. The second thing you can do is perform a root canal on the tooth and then bleach the tooth from the inside, called internal bleaching. You can count on one hand the number of times I have done this as a dentist in 15 years. Unfortunately, the results aren’t very predictable, and while it may get whiter, the tooth still looks different from the other teeth anyway. Also, even if internal bleaching whitens the tooth how you would like, it usually darkens again after a few months.
Internal bleaching before & after 

Whitening Teeth by Veneers, Crowns, & Fillings

There are a lot of tooth defects, like white spots or tetracycline staining, that just won’t whiten well. So sometimes, you need a tooth restoration procedure done as a last alternative.

The following are scenarios or conditions for which the teeth will not whiten predictably, or at all: Teeth with white spots that won’t go away, staining that happened during tooth development, teeth that already have unsightly fillings, teeth that won’t whiten with other manners, transparency in teeth from over-whitening, staining from metal fillings, and internal stains. Also, some people may want to just change the overall look of the teeth for whatever reason. Then crowns, veneers, and bondings are the way to go. Don’t worry; many famous people and Hollywood stars have them.

These options can look beautiful if done in the correct situation with a skilled dentist. These restorative options are the only way to whiten your teeth for some people. The most significant benefit is that these options whiten your teeth for good.

The downside of dental restorations for teeth whitening is that they are costly, and also you have to file down teeth that might otherwise be healthy. Therefore, each person should weigh out the risks and benefits of dental restorations to whiten teeth.

An important note about whitening with fillings, cosmetic crowns, and veneers is that you need to whiten any natural tooth, not getting a restoration first. This is because once a tooth has a final dental restoration, that tooth will not whiten to future bleaching. So if you do whiten your natural teeth after a crown, veneer, or bonding, they will no longer match the dental prosthesis.

These are the significant ways in which you can whiten your teeth. Now you just need to choose the right one for you.

Before and after of cosmetic crowns as a way of whitening teeth. Work done by Richard R. Buck DDS

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