MANAGEMENT OF THIRD MOLARS: AN IMPORTANT TOPIC WITH UNAPPRECIATED NEW DATA

BY WILLIAM R. PROFFIT

Do orthodontists have any responsibility for advising their patients about management of unerupted third molars? In a world where new information about chronic oral inflammation and systemic health has changed views, they do.
               
Orthodontists trained prior to the 1990s were taught that third molars with no space for eruption should routinely be removed. Ash, the most prominent professor of oral surgery at that time, said it succinctly: “To preserve the periodontal health of the adjacent second molars, third molars should be removed in young adults before root formation is complete.”
               
In the 1990s, efforts to calculate the cost & risk vs. benefit of third molar removal came to the conclusion that for routine third molar removal, the ratio is unfavorable, and that it is better to retain the third molars if possible. The new orthodoxy became “watchful waiting” to see if an unerupted third molar caused a clinical problem before advising its removal. The risk to systemic health of chronic oral inflammation, unfortunately, was not included in those calculations because it was not appreciated at that time.
               
In the 21st century, new bacteriologic data have documented the relationship between chronic oral inflammation and systemic health, especially to heart disease and pre-term birth. The chief of cardiology at the University of Sydney, in the most prestigious lecture at a recent Australian Orthodontic Society meeting, also said it succinctly: “I like to talk to dentists about what I do—because I need your help.”
               
The help, of course, is in preventing and eliminating chronic oral infection, which provides access to the systemic blood flow for oral anaerobic bacteria that play an important role in the development of coronary artery disease. Because the presence of the same organisms increases the risk of pre-term birth, obstetric physicians also now emphasize the importance of periodontal health for their pregnant patients.
               
What does that have to do with third molars? A partially exposed third molar provides a perfect site for colonization by the periodontal pathogens that produce the systemic risk. The 21st century data show, in fact, that periodontal inflammatory disease predicts periodontal pathology in non-3rd molar regions over time, and that asymptomatic patients with visible third molars have an increased risk of early periodontal disease anteriorly. Data from four major studies with a total of 8500 patients documenting the relationship of third molars to periodontal disease were summarized by White et al in Journal of Oral and Maxillofacial Surgery in 2011.





















If your retention patient, looks something like the image above, what do you tell the patient and parents about the third molars? You do have a responsibility to share the current information. The message needs to include the following points:

1. The problem third molars are the partially exposed ones. Even a small exposure allows entry of bacteria and colonization of the systemically-dangerous ones.
2. If a partially exposed third molar is retained, careful follow-up is needed. Two-thirds of asymptomatic subjects like this already have early periodontal disease, and only if the development of pathology is monitored with analysis of tissue fluids is it possible to be sure progression is not occurring. If you wait until symptoms appear, there already will be systemic problems.
3. The development of pericoronitis is an indication for extraction, not for symptomatic treatment.
4.  Recovery from third molar extraction is significantly better and faster in teen-agers.

              
Does that mean all unerupted third molars should be extracted? No, but it does mean the third molars that carry a risk for systemic health should be extracted, and that for this type of extraction, earlier is better.

Perhaps the orthodontist’s role, in addition to advising his or her own patients, also is to help family dentists understand this approach.
 
For further information, see White RP, Proffit WR. Evaluation and management of asymptomatic third molars: lack of symptoms does not equate to lack of pathology. Am J Orthod Dentofac Orthop 140:10-16, 2011.

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