What to Do about the Fourth Molar: Similar Management Strategies as the Third Molar aka Wisdom Tooth?

So wisdom teeth are also known as third molars but did you know that there are also fourth molars in a small subset of patients?

A recent study was performed by the United States at an Air Base in Japan which is currently in press to appear in the Journal of Oral and Maxillofacial Surgery titeld Prevalence and Management of Fourth Molars: A Retrospective Study and Literature Review by Khurram M. Shahzad and Lawrence E. Roth, 2011.

In the study conducted 409 patients were referred for a third molar (wisdom teeth) consultation. Two of 227 white patients (0.9%) had a fourth molar and 6 of 94 black patients (6.4%) had a fourth molar. One of the other 84 patients (1.2%) also had a fourth molar.

Of these patients with a fourth molar 5 out of 9 (55%) had only 1 fourth molar and 4 out of 9 (45%) had 2 fourth molars. In 7 of the 9 (78%) of the patients the fourth molars were in the maxilla (upper) and in 2 of the 9 patients (22%) the fourth molars were in the mandible (lower). No patients had fourth molars in both the maxilla and mandible.

All of the mandibular (lower)  fourth molars were found to be smaller than the mandible (lower) wisdom teeth but similar in their shape. While the maxillary (upper) fourth molars were smaller than the maxillary (upper) wisdom teeth but appeared with a peg shape which did not represent the shape of the wisdom teeth.

The prevalence in this study of fourth molars was 2.2% and this is similar to the prevalence found from a few other studies were it was between 1% and 2%.

The authors recommend:

“The presence of fourth molars as well as the risks and benefits of extraction versus observation should be discussed with the patients and an individualized treatment plan should be fabricated.”

The authors comment that fhe fourth molars have a possibility of being displaced in the infratemporal fossa or the maxillary sinus during surgery and note that this is more likely to occur if the bone distal to the fourth molars is thin. (Note these are known complications of wisdom teeth removal as discussed on the complications page http://www.teethremoval.com/complications.html)

The authors of course recommend that each patient should have a panoramic x-ray and/or computerized tomography performed.

The authors also say it is even possible to remove a third molar (wisdom tooth) and leave the fourth molar in place which may allow the fourth molar to migrate down and after some time (a few years) a safer extraction can be performed.

Of course the risks of leaving a fourth molar are similar as leaving a third molar (wisdom tooth) for observation http://www.teethremoval.com/risks_of_keeping_wisdom_teeth.html

Below I have added the 2 panoramic radiographs that are in the journal article and I have added some labels for the fourth molars.

Looking at these x-rays removing a fourth molar appears to be even more risky than removing a third molar (wisdom tooth), so hopefully you are fortunate enough to not have a fourth molar.

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13 Responses to What to Do about the Fourth Molar: Similar Management Strategies as the Third Molar aka Wisdom Tooth?

  1. edward December 15, 2012 at 9:19 am #

    i have had my wisdom teeth removed in 1991 and am getting 4th molars in my lower areas L,R. now.the R is migrating forword and the L is pushing roots out to make room. should i alow time for them to finish?

  2. Sophie December 18, 2012 at 2:23 pm #

    Hi there,

    I’ve just had fourth molars found which show similarly to the last image in the above post (upper-behind wisdom teeth). I’m finding it quite difficult to find information about this, what the options are and if the symptoms I have tie into this. I’m in the UK and wondered whether you might know anyone that could advise me or be able to point me in the right direction of some more information?

    Thank you!

  3. wisdom December 19, 2012 at 8:37 pm #

    Hi edward and Sophie,

    Unfortunately, I too have not seen much literature or information on 4th molars.

    So I can’t really point you in the right direction or make any comments.

    All I would say is try to do your due diligence to find a well educated and respected oral surgeon and/or dentist for some advice and pay them handsomely for their efforts.

  4. Future Dentist June 10, 2013 at 3:12 pm #

    so i had my first bicuspid at the top on each side removed. It didn’t hurt at all but someone tell me please, why is getting your wisdom teeth out much more painful than getting any other tooth pulled?

  5. Future Dentist June 10, 2013 at 3:13 pm #

    BTW I am only thirteen so don’t think I’m stupid please thank you 😉

  6. Future Dentist June 10, 2013 at 3:19 pm #

    Another question, sorry I must know. My third molar (wisdom teeth are starting to come in. I’m guessing they’re very close to fully grown on the bottom left and the others have started. Is it bad if they’re growing so early and will i get a fourth molar because of this?

  7. wisdom June 12, 2013 at 5:08 pm #

    Only a very small percentage of people get a four molar as discussed in the post above, so you likely won’t get one. However, see a dentist and have an x-ray done and get evaluated.

  8. vero August 23, 2014 at 10:02 am #

    At the age of 32 while going through orthodontic treatment it was discovered that I not only have all of my wisdom teeth in place that have grown in and not need extractions but I also have three fourth molars that raise question to what will happen after I have begun to shift and move teeth? I have two in the lower and one in the upper.

  9. wisdom August 23, 2014 at 10:12 am #

    @vero, that is quite a lot of third molars and fourth molars to have. You should get evaluated further by an oral and maxillofacial surgeon and have imaging performed as needed. As suggested in the article it is possible to have wisdom teeth extracted to help make room for fourth molars later on, but you say you don’t need any of the wisdom teeth extracted….

  10. KsCasey October 24, 2016 at 3:51 pm #

    I had my upper wisdom teeth removed and being hit under the chin causing me to bite down and break them. The dentist suggested I have them out before they became impacted. I was in my 20’s at that time. When I was 57, a new tooth began coming in on the upper left side where the wisdom tooth had been. It has taken it three years to come part ways in. It is causing a crown I have back there to become loose and there is now a gap between my gum and the top of the crown. I cannot chew on that side. It does not feel like a viable tooth, but unless it is going to cause problems I do not intend to have it removed. Doing so would cause me to lose the fourth molar and the tooth with the crown on it. It has really opened up the gum back there and I have to work extra hard to make sure that no food particles get lodged back there.

    Years ago, I developed and ulcer on my gum right where this tooth is coming in. The dentist told me it was somehow connected with my sinuses. The ulcer has since healed itself, but was there for quite a while and it was obvious there was some infection in there. I gargled peroxide and I believe that helped to clear up the ulcer.

  11. Anya January 19, 2017 at 11:36 am #

    I got a 4th molar on my both L & R upper maxilla. On my R my 3rd molar was completely erupted. However, my L is more difficult since my 3rd molar was an impacted tooth and hits my 2nd molar and my fourth molar was just sitting in there.

  12. Dave June 5, 2017 at 9:10 pm #

    I got my third molars(wisdom teeth) on both rows at the age 17, and just recently my fourth molars(2nd wisdom teeth) are popping up; I have an abnormally large jaw with room for another set teeth, Should I have them extracted? Or should I extract my first wisdom teeth to make more for the second?

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