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Internal Tooth Bleaching: Things To Know

Updated: Feb 6

Internal tooth bleaching is a professional teeth whitening procedure that is done in-office to whiten a discolored dead tooth from the inside out. It is considered non-vital tooth bleaching since it can only be done on teeth that are no longer alive.


It is often used as a last resort for when traditional tooth bleaching has failed to meet the expectations of the patient. However, despite how effective it can be there are risks involved which you should be aware of before you start it.


Table of contents:


What is internal teeth whitening?

As its name implies, internal bleaching is teeth whitening but from inside of the tooth. Instead of placing the whitening agent on the exterior of the tooth, it is placed inside of the tooth's pulp chamber.


Traditional teeth whitening which you're probably thinking of is extracoronal bleaching. The bleaching agent is placed on the outside surfaces of the enamel and is allowed to bleach the tooth from the outside in.


What we described above is the difference between vital vs non-vital tooth bleaching.


The bleaching agent

There are different bleaching agents which can be used for internal tooth whitening.

  • Hydrogen peroxide. Often in a very high concentration such as 30% or more.

  • Carbamide peroxide. A shelf stable version of hydrogen peroxide.

  • Sodium perborate. A safer whitening agent than hydrogen peroxide, at least for internal whitening purposes. Typically not used for external bleaching.


Internal vs External teeth whitening

Attributes

External Bleaching

Internal Bleaching

Tooth vitality

Vital or Non-vital

Non-vital

Bleaching agent

Hydrogen peroxide or carbamide peroxide

Hydrogen peroxide, carbamide peroxide, sodium perborate

OTC products

Yes

No

Sensitivity

Yes

None

Root resorption

No

Yes


When it's needed

Internal bleaching is only used on severely discolored dead teeth that do not respond to traditional whitening techniques. Even if a tooth is non-vital but if it is only mildly discolored, the traditional methods should still work. It is only the ones with substantial discoloration that needs professional help.


The reason we keep emphasizing dead teeth is because it is actually a requirement for the procedure. Since the whitening gel gets placed inside of the pulp chamber, the tooth cannot be alive or you'll be in severe pain.


Only dead teeth which have had their nerves removed via a root canal are eligible for this procedure. Imagine if you had bleach on a live nerve. That wouldn't be pleasant would it?


Why do non-vital teeth discolor?

When a tooth dies, the blood within it will start to decompose which is the source of the discoloration. Therefore, the color change is due to the lack of blood flowing within the crown. The situation is very similar to how dead bodies which are devoid of blood look very greyish.


discolored dead front tooth
discolored dead front tooth

The color of dead teeth:

  • Grey

  • Black

  • Dark yellow


How does it work?

Both external and internal whitening will work on a dead tooth, it's just that whitening it from the inside tends to be more effective. The reason is because the discoloration begins from the inside and moves outwards. Therefore if you start the process from the inside, it will bleach it at its source.


The way internal tooth whitening works is nearly identical to the external one, the only difference is where you place the gel. This procedure places it inside the pulp chamber as opposed to on the outside on the enamel.


The bleaching agent is still a form of peroxide, which is the same in both types of procedures. In case you forgot how whitening works, we'll give you a refresher below.


How peroxide whitens teeth

When hydrogen peroxide decomposes, it forms very potent free radicals that can diffuse through the tooth.


hydrogen peroxide decomposition to radicals - reaction equations



Hydrogen peroxide oxidation of double bonds
Credit: Clifton Carey

When tooth stains lose their double bonds, they absorb less light and reflect more of it. That makes them appear whiter. The vice versa is also true in that stains with more double bonds will absorb more light and reflect less of it. That makes them appear darker.


How carbamide peroxide and sodium perborate compare

As you may have astutely noticed, we only talked about how hydrogen peroxide (HP) whitens but we also mentioned carbamide peroxide (CP) and sodium perborate. Both of them still produce hydrogen peroxide.


Carbamide peroxide will break down into HP. Since it requires extra steps to reach there, it is considered more shelf stable. That is why it is often found in OTC products.


Chemical-decomposition-of-CP-in-hydrogen-peroxide
Credit: Aina N. Gadanha, Charline R. Rossini, João P. S. Fernandes & Márcio Ferrarini

Sodium perborate also decomposes into HP. Here is the mechanism below:


Sodium perborate decomposition formula

Essentially, all of these various bleaching products will turn into hydrogen peroxide which further breaks down into a powerful oxidizing free radical. The true workhorse are the free radicals, hydroxyl (HO) and perhydroxyl (HO2).


The procedure

The most common internal tooth bleaching procedure is called the walking bleach technique.


Essentially, your dentist will drill a hole through the back of your front tooth and place the bleach inside. They will seal it up and let you go on with your life and return in a few days to check on the process. True to its name, you're whitening your teeth as you're walking about your daily life.


What to expect during the walking bleach technique:

  1. Photos. Take clinical photos and a tooth shade to be used as starting reference.

  2. Rubber dam. Isolate the teeth with a rubber dam to protect adjacent dentition.

  3. Access opening. Drill a hole through where the root canal was first done.

  4. Clean. Remove residual pulp tissue and also root canal filling material to 3mm below the cervical margin.

  5. Seal and protect. Place a 2-3 mm layer of glass ionomer, cavit G, IRM, or zinc phosphate cement on the pulpal floor. This is to protect the root from the bleaching gel.

  6. Mix bleach. Mix sodium perborate with water until a wet sand consistency.

  7. Apply. Place the bleach mixture inside of the tooth using an instrument.

  8. Close. Seal off the open cavity with cavit G that is at least 2-3 mm thick.

  9. Follow up. Have the patient return in about 3-10 days for evaluation. Remove the old whitening material and replace with a fresh one.

  10. Repeat. If desired results have not been achieved, repeat Steps 1-9 up to 4 times.


Other internal techniques

Aside from the walking bleach, there is also the inside-outside method and the in-office technique.

  • Inside-outside. Your dentist will make you take home whitening trays. Then they will drill a hole through the back of your front tooth. You will whiten your teeth normally with the take home trays. The only difference is that since there is a hole through the back, the bleaching gel can whiten the inside as well.

  • In-office. This is very similar to your typical in-office whitening except your dentist will drill a hole through the back of the tooth. This way you can whiten from the exterior and interior at the same time.


Before and after

For before and after clinical photos, please check out this study which includes a case report. They document the entire treatment from start to finish. That means there are photos as to what the dead teeth look like before and after the internal whitening treatment.


If you want to see additional images you can also visit ultradent's opalesence endo product page which is one of the commonly used internal whitening products. They do provide photos for each step of the treatment as well as what the final result looks like look.


Side effects

The major risk of internally bleaching a dead tooth is potential external root resorption. What that means is that your body will start to resorb the tooth and disintegrate it starting from the root. If it resorbs enough of it, the tooth will become loose and fall out.


According to the American Dental Association, root resorption may happen from using 30% hydrogen peroxide for interior bleaching. It does however provide very good immediate color change but the success drops below 50% in the long term. Use of such a high concentration of peroxide has demonstrated this adverse effect, both experimentally and clinically.


Therefore, the ADA recommends that you only use sodium perborate mixed with water since that minimizes the chances of it occurring. The sodium perborate appears to be a safer solution. Studies have shown that it also gives a very similar and equivalent bleaching effect.


Alternatives

If chemically whitening your teeth internally does not work, you only have two options left. You can either put a crown or a veneer on the tooth, both of which require masking the color with porcelain.


Alternative treatments:

  • Crown. Prior to fitting a crown on, the tooth does need to be shaved down or prepared for it. This involves drilling around the entire tooth 360 degrees in order to get it to fit.

  • Veneer. A more conservative approach than a crown because it only requires shaving down the front half of your tooth. Essentially only 180 degrees of the tooth needs to be prepared.


Unfortunately, these are the only options left if chemical treatment doesn't work. There are no other ways to whiten your teeth.


Costs

The average cost of internal bleaching without insurance is $301.52 and that is per tooth. That means if you have more than one tooth, you'd have to multiply that by however many teeth needs it.


However, you should be aware that most teeth require more than one treatment. Some patients may attempt this procedure up to 4x before they get the desired result.


Cost with insurance

Unfortunately all cosmetic procedures are not covered by dental insurance and that includes internal whitening. Basically, both types of whitening, external and internal are non-covered procedures.


Nonetheless, if you wanted to double check with your insurance plan, you can ask them if they cover dental procedure code D9974. That is the billing code used for this procedure.


Outlook

When internal tooth whitening is done safely, the risks can be minimized. The great news is that the color change can last a very long time. If you manage to bleach it back to its original shade, it may take years or even a decade before it re-darkens again.


The color change for dead teeth is naturally a very slow and gradual process. The first time it took for you to nice that it was darker than the adjacent teeth probably took a decade. If the the tooth relapses or redarkens, it would most likely take a similar amount of time.

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About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

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Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

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