Wisdom teeth complications - Tooth decay.

- Can a filling be placed in a wisdom tooth? Would extraction make a better choice? | How cavities on third molars may affect neighboring teeth. | How often does this problem occur? - Incidence rates.

Some wisdom teeth need to be extracted due to complications related to tooth decay. The issue at hand might involve just the wisdom tooth itself, or even possibly it and its neighboring tooth, the adjacent 2nd molar.

This page explains what it is about some third molars that puts them, and possibly their neighboring tooth too, at higher risk for cavity formation. And when extraction or repair (filling placement) might make the better (more predictable, longer-lasting, less costly) choice.


1) Cavity formation on wisdom teeth.

Decay may form on any tooth surface where dental plaque is allowed to remain for extended periods of time.

(If you're interested, we cover how cavities develop here.)

What are the special concerns with wisdom teeth?

If the positioning of a third molar is such that its difficult, or possibly even impossible, to clean, it will be at increased risk for cavity formation.

This situation routinely exists with thirds that are misaligned (erupted but crooked), and those that are only partially erupted (only poke part way through the gums).

Add in the fact that by being in the very rear of the mouth they're difficult to access with a brush and floss, tooth decay formation on wisdom teeth is not uncommon (see statistics section below).

You might be surprised to learn ...

As a type of worst case scenario, it's possible for a wisdom tooth to be entirely impossible to clean.

Diagram showing the empty space around a wisdom tooth where decay causing bacteria can accumulate.

Plaque can accumulate in the space underneath the gum line.

This type of situation would be one where the developmental space that exists around the crown of a partially impacted tooth (a tooth that to some degree has penetrated through the gums) has been colonized by bacteria.

Since this space is both minute and entirely underneath the gum line, it can't be accessed. And as such, the dental plaque that the bacteria form will remain undisturbed, and therefore has the potential to cause a cavity on the tooth.

It's not all that often that this scenario creates problems. But it is a possibility. And different from what's shown in our graphic above, the connection between the developmental sac and the person's mouth through which the bacteria invade may be so minute that it is not obvious and never suspected.

Section references - Koerner

2) Treating cavities that have formed on wisdom teeth.

Just as you would expect, the possibility or practicality of repairing a decayed wisdom tooth simply depends on the scenario and conditions that exist. Here are some examples.

a) Some cavities in third molars can be repaired by placing a dental filling.

If a cavity has formed, it's possible that the wisdom tooth can be repaired by way of placing a filling, just like with any other tooth. This would be especially true in those cases where:

  • The amount of decay is relatively small.
  • The cavity is found on a part of the tooth that's readily accessible.

Unfortunately, these conditions don't always exist. And if not, then placing a filling may not be an option at all.

Why would you want to consider this approach?

Wisdom teeth are just that, a type of tooth. There's nothing different or lacking about them. And there's no reason why a properly positioned one can't function as a valuable member of a person's dentition (set of teeth). Since you're only born with 32 (at most), why loose any tooth that could be saved?

Why wouldn't you want to consider this approach?

If the repaired tooth can't be kept plaque-free, or you're not willing to regularly put in the effort to keep it that way, saving the tooth by placing a filling may not provide a lasting solution. (Discussed below.)

b) Sometimes pulling the tooth simply offers the better solution.

In some situations, a dentist may feel that extracting a wisdom tooth makes a better choice than restoring it. Here are some of the reasons why they might hold this opinion.

1) Repair may not be possible.

In some instances, the decay may be situated in such an awkward location on the tooth that the dentist finds their access to it is extremely limited, if not impossible.

It's easy enough to imagine that if the area has been difficult to clean with a toothbrush and floss that it would be equally inaccessible when the dentist's instruments are used. If so, the tooth should be extracted.

2) The long-term outlook for the tooth may be poor.

Even in cases where a filling could be successfully placed, if the wisdom tooth still cannot be adequately maintained and its surface kept plaque free, it will run the risk of developing recurrent decay.

(The term "recurrent decay" means that a new cavity has formed on an aspect of a tooth adjacent to an existing filling.)

If this scenario exists, dealing with the tooth just once (pulling it now) may make the more prudent choice.

  • Teeth that experience further decay may be more difficult to extract.
  • Those with advanced decay may cause episodes of pain and swelling.
  • Extraction offers the financial economy of knowing that you'll only have to pay for a procedure for the tooth once.

3) A wisdom tooth may put neighboring teeth at risk for cavities.

If the space between a wisdom tooth and its neighbor can't be kept clean, a cavity may form.

Impacted wisdom teeth can help cause tooth decay on neighboring teeth.

Advanced decay can cause nerve tissue death, with extraction or root canal then being required.

Third molars that don't come fully into normal alignment are often responsible for creating a configuration that results in the formation of a trap for dental plaque and debris between it and the next tooth forward, the 2nd molar. (See our animation.)

If the accumulation that builds up in this space can't be cleaned out thoroughly (which is frequently the case), not only will the wisdom tooth be placed at much greater risk for developing a cavity but so will the 2nd molar.

A lose-lose outcome.

The worst case scenario for this type of situation is one where decay has formed on both teeth to such a great extent, or in such an inaccessible location, that neither can be repaired and as a result both must be extracted.

Another dire outcome would be one where it may still be possible to salvage the 2nd molar but only after performing root canal treatment and placing a dental crown.

Generally speaking, it's one thing for a person to loose a wisdom tooth (a tooth that a large percentage of people function without). But when a second molar (typically considered a much more valuable tooth) is needlessly lost or severely damaged, it's a tragedy.

4) How often do problems with tooth decay occur?

What does research show?

Here are the findings of some studies that have evaluated wisdom teeth and the incidence of cavity-related problems.

Study #1:

Title: Occlusal caries experience in patients with asymptomatic third molars. (Shugars DA, et al.)

  • This study evaluated the decay rate of asymptomatic, erupted wisdom teeth. (In this case, Erupted = Teeth that have been able to come into place normally, or at least fairly close to it.) All participants had one or more wisdom teeth.

    The study determined that for subjects 25 years and older, 39% of them had at least 1 wisdom tooth that had a history of decay (either active or repaired).

    Lower wisdom teeth were more likely to be affected than upper ones (24% vs. 18%).

 

Study #2:

Title: Prevalence of impacted teeth and associated pathologies--a radiographic study of the Hong Kong Chinese population. (Chu F, et al.)

  • This large study evaluated over 3800 impacted wisdom teeth. The findings of this report were that 2 to 3% of the lower ones, and roughly 7.3% of their adjacent second molars, had cavities.

    - Since fully impacted wisdom teeth (which have limited potential to decay) were included in this study, one would have to assume that the decay rate for partially erupted lower impacted wisdom teeth would be greater than the numbers stated above.

Tooth decay between a wisdom tooth and 2nd molar.

The space between this wisdom tooth and neighbor can't be cleaned.

Study #3:

Title: Diseases and lesions associated with third molars. Review of 1001 cases. (Linden W, et al.)

  • Linden evaluated a group of patients ages 13 to 75 years who collectively had over 2800 wisdom teeth removed. In regard to these extracted teeth, 7% had cavities, as did 42% of their adjacent 2nd molars. (Our picture shows an extensively decayed 2nd molar.)

    - The numbers above quite possibly were skewed by the fact that the study group was composed of patients whose wisdom teeth were removed for a reason, including the diagnosis that decay was present. In normal populations, the rate might be expected to be lower.

Study #4:

Title: Third molar caries experience in middle-aged and older Americans: a prevalence study. (Fisher E, et al.)

  • Fischer determined that, for a population of 52 to 74 year-olds, the incidence of tooth decay on third molars strongly correlated with the decay rate the person experienced with their other teeth.

    - This suggests that, in regard to making a determination about how significant the risk of third molar tooth decay complications might be for you, you should first consider what your cavity rate has been in general.

Section references - Shugars, Chu, Linden, Fisher

 
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Comments

Cavity in wisdom teeth. Pull them?

My dentist says fillings on wisdom teeth don't work and that I need two pulled. What do you think? Is that true?

Mellie

It's not really for us to second guess what your dentist thinks makes the best treatment plan for you. After all, they have actually examined your teeth and we have not.

Without question the blanket statement "fillings on wisdom teeth don't work" isn't accurate. But we think you've misinterpreted what's been said.

Widsom teeth aren't any different than any other kind of tooth. So yes, absolutely, fillings can be placed in them.

What may make fixing a cavity/placing a filling in one a poor choice often has to do with the wisdom tooth's positioning in the mouth.

If the dentist doesn't have adequate access to the part of the tooth that has developed the cavity, fixing it can be difficult to do correctly, and sometimes not possible at all.

Another consideration associated with the tooth's positioning is how well you brush and floss it. If you can't keep it plaque free, then the dentist may feel that the risk of a new cavity forming on the tooth (after a first filling has been placed) is high. If so, possibly the less troublesome solution is simply to extract the tooth.

In your case, you state that two of your four wisdom teeth have cavities. That implies that you do have difficulty in keeping them clean. So as with the second scenario, possibly the simpler, less costly, less troublesome, etc... solution is to simply have yours taken out.

Read through this page above, we explain these points in greater detail.

Wisdom teeth filling

Wisdom teeth have more roots than regular molars, so harder to numb, plus my wisdom was broken, Dr built it up and filled it 4 mos ago, but it's really sensitive, eat even really use it much & I've developed infection twice and had to get antibiotics. Going back to have it pulled now, cause it's constantly a nuisance and I'm tired of taking Tylenol almost every day. I suggest just having them pulled from the get go.

Marcy

We'll agree that due to their location that wisdom teeth can be difficult to clean, leaving them vulnerable, as in your case, to decay and infection. And we agree that in terms of function (like eating), most people do just fine without having their 3rd molars.

We'll take issue on the points that wisdom teeth have more roots than regular molars (they may but don't usually). And the actual number of roots any one has should seldom have any bearing on the difficulty with which it can be numbed.

Best of luck with your extraction. It sounds like a good plan for you.

Fillings in wisdom teeth

Hi I am 25 and the lucky owner of four almost perfectly erupted wisdom teeth. But also the owner of fillings in all four wisdom teeth. Short after the eruption I had cavities, which my dentist chose to drill and fill - I was not questioned. But he said that it was difficult to dry the teeth and therefore he needed to prepare silver fillings and not composites like (the too many fillings) I have in my other teeth. The silver fillings are about 2/3 of the upper chewing surface but are so far back in my mouth that they are not visible – unless if I open wide, so that is OK with me. Dentist says that the fillings should be very long lasting if I brush thoroughly

We think you have a great dentist.

Just like your dentist's treatment suggests, well positioned wisdom teeth can be valuable teeth to have and there is no reason to extract them.

What we really like is that for the repair they saw the advantage of placing amalgam fillings (not as technique sensitive to place). And yes, your silver fillings should last as long or longer than your composite ones. Not every dentist still places amalgam (the primary filling material for back teeth in decades past, that has now fallen out of fashion primarily because it is not white in color).

Your words about your general decay rate (historic/current) is a concern. Keep in mind that filled teeth can get cavities if you don't clean them properly. This would especially be a continued concern with hard to reach wisdom teeth.

You should read our pages that cover tooth decay, just so you have a better idea of why it forms and how to prevent it. It will save you a lot of grief over your lifetime.

Thanks for your comments on fillings in my wisdom teeth

Hi, thanks a lot for your comments. Nice to hear that my dentist took a good decision when he filled my wisdom teeth with amalgam fillings.
Yes, I wrote that I have (too many) fillings which might indicate a concerning decay rate. The story behind is, that during my teenage years I was eating lots of sugar, sweets and candies and drinking soda, while I was not brushing my teeth frequently and thoroughly. So, within two or three years I got 12 cavities drilled and filled with composites, so happy it is not visible I had all these cavities!! That was about 10 years ago, and since then, I have only had the mentioned cavities in my four wisdom teeth, bringing me at totally 16 fillings (which I think is far too many for a 25-year-old).
Thanks for the links to tooth decay pages – I certainly learned that my fillings are not lasting forever and need to be redone at some point in time, probably due to “recurrent” decay, which you also mention in your comments. That was an eye-opener to me and placed some major concerns in my head, especially because I have so many fillings - obviously I can’t ignore the recurrent decay risk. I still have a “sweet tooth” to satisfy, but nowadays I am taking very good care of my teeth. Therefore, I hope my high decay rate is historic and under control and that my recurrent decay risk is limited. I trust my dentist is checking all my fillings at my regular dental checkups, so that any recurrent decay is detected and fixed early so that my fillings (amalgams and composites) will be lasting for many years ahead.

help

what would cause a wisdom tooth to decay right INSIDE the gum?

KG

There are two issues to know:

1) Tooth decay can form on any tooth surface where dental plaque is allowed to build up and persist.

2) The gum line (the place on a tooth where the gums tissue attaches) is the same on all teeth. So even though a wisdom tooth may look like it is buried in gum tissue, where its gum tissue actually attaches to it is further below the gum's surface. This means there can be a lot of empty space that exists between a tooth and its surrounding gum tissue.

(The illustration above on this page shows an extreme of that situation. The space that surrounds the buried wisdom tooth is shown in a tan color.)

If that space fills in with dental plaque, and since you can't effectively brush a tooth buried in gum tissue, a cavity may form.

Unerupted lower bottom impacted (Mesial impaction)

I have an unerupted impacted tooth (#32), it cannot be seen at all. I am 52, recently just had an infection in the area, never felt anything wrong before. The doctor think I should have both #32 and #31 extracted, and maybe an implant for #31. Is it really necessary to extract both teeth? My #31 is perfectly fine, but from x-ray, #32 is kind of leaning against it a bit. I no longer have the pain after taking some Advil, and the swelling is gone with antibiotics. With my age and history of no pain really, do I need to have both #32 and #31 taken out? Thanks!

SH

a) The fact that you've experienced one infection associated with the wisdom tooth, suggests that future infections are at least possible. And the solution for one that's impacted and completely buried by gum tissue typically would be extraction.

b) You mention that your dentist feels that if lost, #31 should be replaced. That implies that that tooth has importance (stabilizing the position of opposing teeth and possibly adjacent ones too, maintaining adequate chewing function for you, etc...). And as such, not a tooth to remove without good reason.

c) The way you phrase your comment implies that #31 is a tooth that has zero issues, and must be extracted solely to be able to remove #32.

---

1) From a technical standpoint, possibly there is something about the positioning of the impacted wisdom tooth that makes it's extraction exceedingly difficult and by creating extra space (extracting #31), the nature of the extraction then becomes much easier.

This wouldn't usually be the sort of treatment plan that a dentist would want to suggest. Instead, they would typically refer the extraction to a person who had a higher level of skill (an oral surgeon). One who could accomplish the extraction of #32 on its own.

If it's already an oral surgeon who is making this recommendation to you, then one would have to assume that there is a need for this approach. Possibly the amount of jawbone removal necessary for the extraction would be excessive otherwise. We don't know, but a explanation should be simple enough to give.

2) Probably more likely is that some current issue associated with #32, or a problem resulting from its removal, will affect/has affected #31 .

Gum disease issues (current or future) or root resorption, or decay like this page discusses, would be possibilities.

The general idea would be that the 2nd molar either has (asymptomatic) problems now, or would be expected to be left in a situation where problems would develop (gum disease, inadequate bone support) following the extraction of the wisdom tooth, thus making extraction of both and the replacement of #31 a reasonable solution.

Once again, whatever the situation, your dentist should be able to explain simply enough. Right now it seems you need more information.

Thank you so much for your

Thank you so much for your response. I will talk to my dentist and ask about the condition of #31. I am in two minds now because having an implant is expensive and it is not without complication in the long term. This is the first time I remember having an infection in the area, and is now fine, feel pretty normal. 13 years ago, I had some pain in #16 and #17 area (both are fully grown wisdom teeth and still have them), the then dentist (a different dentist) recommended removing both #16 and #17, I did not and was too busy and forgot about that, after a while, the pain disappeared (no antibiotics or anything), I've never had any problems since. I almost forgot about that not until I pulled out an old record, so with that past experience, I am not sure if I can ride it out this time too, I understand it is different this time with #32 being an impacted wisdom tooth, I just don't know what is the best way to do. Thanks again for your help.

Bottom right side wisdom tooth

My bottom right wisdom tooth is fully through my gum and has a cavity. I’m having pain especially when it touches the top tooth. I’m having it removed but am worried. Will it be easily extracted since it’s fully out of the gum? Or will the cavity cause a problem?

AS

Extracting a wisdom tooth that is fully erupted can be as routine as extracting any other molar.

The concern with advanced decay is that it might have compromised the structural integrity of the tooth. A common scenario would be one where the crown portion (the part of the tooth above the gum line) fractures or comes off during the extraction process.

1) The x-ray of your tooth that your dentist took would give them an idea of the extent of the decay. If it was especially extensive, it seems that they might have made some comment.

2) Just because a tooth breaks during its extraction process doesn't mean that it will then be difficult to remove. Having a tooth break is common, fairly routine and doesn't necessarily add to the degree of difficulty of the procedure. It may, but it absolutely doesn't always. With a two-rooted molar with divergent roots, the crown coming off could conceivably make the extraction easier (because that event would facilitate removing each root independently).

Non-impacted wisdom tooth removal

T3oth #32 is not impacted and looks like a normal molar in X-ray in terms of positioning but it has a very large internal cavity. It didn't bother my until I stopped using Sensodyne toothpaste. Then pain alternated between wisdom tooth and second from last molar in upper jaw where I had a crown put on about 5 months ago. Pain decreased and stopped once I started using Sensodyne and Listerine mouth wash about 2 weeks ago. Dentist said I should have it removed but he doesn't do that. Do I need to have it removed if it is not impacted and not causing pain but has large internal cavity?

HSM

If the wisdom tooth has a cavity in it (especially a very advanced one) and that situation cannot be corrected (by placing some type of restoration, possibly root canal treatment would be needed too), then the only alternative is to have the tooth extracted.

As the cavity increases in size over time, you place yourself at increasing risk for experiencing an acute episode (infection, pain, swelling). And the advancing cavity will only further weaken the tooth, and therefore possibly making it's removal more difficult.

It's not possible for the products you mention to provide a solution for active decay.

That's not to say there is no question that your discomfort isn't caused by the upper tooth. That's for your dentist to determine. But no good will come from your leaving #32 unattended.


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