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.

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