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 put 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 it's 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 partway 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 lose 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 lose 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


 Page references sources: 

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

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

Koerner KR. Manual of Minor Oral Surgery for the General Dentist. Chapter: Surgical Management of Impacted Third Molar Teeth.

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

Shugars DA, et al. Occlusal caries experience in patients with asymptomatic third molars.

All reference sources for topic Wisdom Teeth.


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.


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


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.

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?


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

Tooth #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?


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.

Broken wisdom tooth

So my back right wisdom tooth, the farthest one back was partial erupted. I have a little him flap that I think is from it. This tooth was already broken and falling apart as soon as it broke threw my gums. Now theres only slight fragments under the flap. And a piece that seems like it shifted down my gums closer to my tongue. From what ive said is some sort of surgery my only route here?

* Comment notes.


Well yes, surgery in the sense that you need the tooth extracted. But you don't necessarily have to expect the worst with the procedure. Only your dentist, after an examination that includes x-rays, can determine what level of surgical procedure is needed (simple extraction (routine) vs. surgical extraction).

Probably the biggest thing working against you is how you describe the tooth has decayed extensively and has now started to fall apart. A dentist needs to be able to plant their tools on/against the tooth in some area where it is solid, so force can be applied to remove it. And if the dentist has no such access readily available (the fact that your tooth is only partially erupted works against you here), then yes, they will have to expose the tooth surgically somewhat (reflect gums back, possibly trim bone) so access is achieved.

But it can't be overlooked that some wisdom teeth (often due to their root configuration) can be astoundingly easy to remove. (This would be more likely with an upper 3rd rather than a lower one. You don't mention which yours is.) And therefore, just minimal force needed to remove the tooth (so no surgical exposure possibly needed).

Just go ahead and make the needed consultation appointment with your dentist. Delaying the extraction serves no purpose and will probably tend to add to the degree of difficulty of the procedure. After looking at your tooth, hopefully your dentist will be able to tell you that they expect your procedure to be less of an ordeal than you anticipate.

Wisdom tooth.

I'm 43, I have one wisdom tooth left & it was halfway under the gum & halfway out, kind of slanted. I've had no problems with that tooth until the last couple of years. The tooth has been coming out in pieces so there was just a shell. It has come down to the remainder of the tooth which is barely a rigid area above the gum & nothing but a hole in the middle that catches all kinds of food.

* Comment notes.


What you seem to describe is an impacted, partially erupted wisdom tooth ("halfway under the gum & halfway out, kind of slanted") ... That also has a large carious lesion (cavity) ... ("The tooth has been coming out in pieces so there was just a shell").

There's no real way for a dentist to restore (remove decay, place a filling) in a tooth that's 1/2 under the gum line, especially when it's decayed as extensively as you describe. Your solution lies with having the tooth extracted.

Widsom tooth

My wisdom tooth is fully grown above gums but rotten and hollow and half broken off. It recently tonight started hurting severely and draining a white chunky stubstance. I used a whole tube of maximum strength orajel trying to aleiviate the pain. And now the tooth hole is filled with the white substance. I plan on going to the dentist as soon as possible. What do you think?

* Comment notes.


At this stage, it seems likely that you have an active infection associated with your tooth. Quite possibly rather than originating in the tissues that surround your tooth (pericoronitis), the infection's origin is instead inside the tooth's nerve space (related to the very advanced decay that you describe).

Pus coming from an infection is white in color, however we are less familiar with it being described as "chunky."

The product you mention contains benzocaine, a topical anesthetic. Topicals are typically only effective in numbing up the surface of the gums. If you have an infection (whatever the location), that's probably not going to provide a lot of relief.

Your solution lies with your dentist. One would guess that an extraction is in your future. Your dentist may need to place you on antibiotics before that can be done. You should describe your situation to them when you contact them. If they feel antibiotics are indicated, possibly they can phone your pharmacy so you can get started with them as soon as possible.

Tooth filling for wisdom teeth

Im 39 years and went to see a dentist due to having severe pain on both lower sides of my wisdom teeth. She checked and found cavity and that both 2 wisdom teeth were rotten. It was my first Dentist visit since I was born I think, however she numbed the right hand side lower gums, drilled the rot out and put white fillings. Sshe never prescribed anything or booked me off, so I assumed that I would be good to go back to work after my one hour lunch. But since then I'm experiencing a throbing or poking feeling and teeth sensitivity on the side that the procedure was performed. So I went back to ask if there is some meds she can give me, she re-checked me and couldn't find anything wrong. She was so upset and scolded me saying she doesn't believe that I'm in pain but I honesty am feeling pain both when my mouth is closed or open. What could be wrong

Mrs. M

As guesses, and situations your dentist could explain further for you ...

1) Related to the presence of decay and/or the placement of a filling, a tooth's nerve tissue sometimes displays signs of having been traumatized. The throbbing you mention might be a sign of that.

The tooth's condition (inflammation of the nerve tissue) is generally classified as "reversible" or "irreversible."

With the former case, the tooth will settle down. To help, a dentist will sometimes recommend the use of an OTC anti-inflammatory pain reliever, which aids with controlling pain and settling the irritated nerve tissue down more quickly.

"Irreversible" cases are those where the nerve doesn't recover because it has been traumatized too much. (The "severe" pain you had initially might be a sign of that condition.) Irreversible cases lead to the need for root canal therapy or tooth extraction.

While a dentist can't know which way a case will resolve, they will have an opinion based on what they observed when working with the tooth (like how extensive the decay was, what your symptoms were and currently are).

If this is what's going, it would seem your dentist expects that your situation is the "reversible" kind and the tooth should settle down. You might quiz them about the use of an anti-inflammatory analgesic to aid this process. And of course, if the tooth doesn't improve, you need to let them know too.

2) The placement of "white" (dental composite) fillings is sometimes associated with post-operative tooth sensitivity. We don't really have a page that explains that situation, but just Googling those terms should provide you with sources of information so you can judge if instead that seems to be what's going on with your tooth.

Good luck.

Hole in wisdom tooth

In the last month, I happened to pick broken chips of my lower left wisdom tooth out of my moth on two different occasions. The tooth is fully erupted with a thin flap of skin, though it had always had cracks and fissures since it's eruption (which was protracted and painful). Since the past month I get constant pain, (even on drinking room temperature water) and lodgement of food particles. Do you advise a filling or an extraction?


Only an evaluation by your dentist can determine what makes the right choice for your tooth. Beyond quizzing you and direct examination, they will also probably need to take an x-ray to fully diagnose your case.

Short of having almost any of that information, it seems you are describing a tooth that has very advanced tooth decay:

1) It's at a point where its structurally unsound enough that portions have started to fragment off (here's our page about broken teeth). So much of the tooth is now missing that it accumulates/retains debris.

Generally, that doesn't sound like a tooth that's in need of just a "routine" filling (a procedure where there's minimal concern about the outcome for the tooth's nerve or the longevity of the restoration). (Here's a discussion about rebuilding seriously compromised teeth with a filling vs. crown.)

2) The fact that the tooth has pain suggests that the decay has advanced close enough to the tooth's nerve tissue to irritate it. If the nerve tissue is at a point where it has been significantly traumatized, the tooth would require root canal treatment before rebuilding it would be possible.

You state "constant" pain but it's hard to interpret what you mean. The worst case would be the situation where the pain often/typically occurs on its own. If instead it only occurs in response to a stimulus (like the water you mention), then that possibly poses a more favorable outlook for how affected the nerve tissue is. Once again, only your dentist can determine this (here's more information about endodontic pain characteristics).

4) You also mention an associated flap of skin that covers the tooth, which very likely could be the reason why you can't clean it properly and the decay has started. If so, that would need to be trimmed away (if that can provide a long-term solution), otherwise you would be at risk of the same set of events occurring again.

In the case where a wisdom tooth is seriously compromised, its needed repair will be extensive, and after repair it will still remain at risk for a recurrence of problems, then yes, and especially on the recommendation of your dentist, the more practical solution may be to extract the tooth.

* Comments marked with an asterisk, along with their associated replies, have either been edited for brevity/clarity, or have been moved to a page that's better aligned with their subject matter, or both. If relocated, the comment and its replies retain their original datestamps, which may affect the chronology of the page's comments section.

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