Wisdom teeth complications - Tooth decay.

- Can a filling be placed? Would extraction make a better choice? | How wisdom tooth cavities may affect neighboring teeth. | Research findings and incidence rates.

Some wisdom teeth need to be extracted due to complications related to tooth decay.

The issue at hand might involve the wisdom tooth itself or else its neighboring tooth, the adjacent 2nd molar.

1) Cavities and wisdom teeth.

Decay can form on any tooth surface where dental plaque is allowed to remain for extended periods of time. (We cover the subject of cavity formation here.)

That means, if the positioning of a wisdom tooth is such that its difficult to clean (which is frequently the case), it will be at increased risk for cavity formation.

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

If a cavity does form, 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.

Of course, these conditions don't always exist.

b) Sometimes pulling the tooth is a better solution.

In some situations, the dentist may feel that extracting the tooth makes a better choice than restoring it.

Repair may not be possible.

In some instances, the decay may be situated in such an awkward location 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.

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" simply means that a new cavity has formed on an aspect of a tooth adjacent to an existing filling.)

If that's the case, dealing with the tooth just once (pulling it) may make better clinical and financial sense.

So, for the reasons above (and possibly many others), once a cavity has formed on a wisdom tooth, it's possible that the best (and often easiest and cheapest) solution is to simply extract it.


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

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

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

Third molars that don't come fully into normal alignment often wind up creating a trap for dental plaque and debris between it and the next tooth forward, the 2nd molar. (See our illustration.)

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

Lose, lose.

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

Second molars are valuable teeth, and when one is needlessly lost it's a tragedy.

3) 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:
  • Shugars (2004) [page references] 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:
  • Chu (2003) 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:
  • Linden (1995) 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:
  • Fischer (2010) 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.


Topic Menu ▶  Wisdom Teeth (third molars).



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?


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.


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.

Add new comment

Excessively long submissions may be edited for brevity and clarity. Comments that don't relate to the content of the page they are posted on especially well will be moved to a more appropriate one, or deleted, after a few days.

Plain text

  • No HTML tags allowed.
  • Lines and paragraphs break automatically.
Please answer the question so we know you're a human.