Wisdom Teeth Myths
Wisdom teeth removal is a multibillion-dollar industry that generates significant income for oral and maxillofacial surgeons. It is driven by misinformation and myths that continue to be promulgated by the profession.
See the rebuttal to the five myths below by Dr. Thomas B. Dodson, DMD, MPH.
Myth Number 1—Third Molars Have a High Incidence of Pathology
Not more than 12% of impacted teeth have associated pathology. This incidence is the same as for appendicitis (10%) and cholecystitis (12%), yet prophylactic appendectomies and cholecystectomies are not the standard of care. Why then prophylactic thirdmolar extractions? What about pericoronitis, the pain and infection of the gum tissue surrounding a partially erupted or erupted third molar?
Excluding the normal discomfort of teething as the tooth erupts, the incidence of inflammation and infection of the gum tissue ranges from 6% to 10%. Adding an average of 8% incidence of pericoronitis to the 12% pathology brings the maximum pathology associated with third molars to 20%. However, a single episode of pericoronitis is not a reason to remove a third molar; this should be considered only if the problem fails to respond to conservative treatment or recurs.
Many dentists confuse the incidence of pathology as it shows up in their offices with its prevalence in the population. Advocacy of prophylactic extractions that is based on anecdotal experience (i.e., patients with diseased third molars who make dental appointments) exaggerates the problem and exposes millions of people to the risk of iatrogenic injury. Considering the low prevalence of third-molar pathology in the population, removal of asymptomatic, nonpathologic third molars does not meet the standard of evidence-based practice.
Myth Number 2—Early Removal of Third Molars Is Less Traumatic
The American Association of Oral and Maxillofacial Surgeons states that “about 85% of third molars will eventually need to be removed.” The association recommends extraction of all 4 third molars by young adulthood— preferably in adolescence, before the roots are fully formed—to minimize complications such as postextraction pain and infection.
Early removal of third molars is actually more traumatic and painful than leaving asymptomatic, nonpathologic teeth in. It is estimated that patients suffer an average of 2.27 days of standard discomfort or disability, defined as “the disability normally associated with an uncomplicated surgical extraction of a mandibular third molar: namely, pain, swelling, bruising and malaise.”
Furthermore, dry socket, secondary infection, and paresthesia are less likely to occur in persons aged 35 to 83 years than in those aged 12 to 24 years, who experience more third-molar extractions. The highest risk of complication is in persons aged 25 to 34 years. When a lower third molar is removed, usually the opposing upper third molar is also removed. Assuming an average of 2 extractions per episode, the 10 million third molars extracted annually involve 5 million people and 11.36 million days of standard discomfort or disability.
If only the 20% of wisdom teeth with pathology were extracted, 4 million people would be spared pain, swelling, bruising, malaise, and consequent absence from school or work—an aggregate decrease of 9 million days of discomfort and disability each year. Allowing for some margin of error and for the fact that one third of third molars are reported to cause some symptoms in the past or present, if only 33% were extracted, 3.34 million people would still be spared an average of 2.27 days of discomfort and disability each, or 7.6 million days of discomfort and disability in the aggregate
Myth Number 3—Pressure of Erupting Third Molars Causes Crowding of Anterior Teeth
It is not possible for lower third molars, which develop in the spongy interior cancellous tissue of bone with no firm support, to push 14 other teeth with roots implanted vertically like the pegs of a picket fence so that the incisors in the middle twist and overlap. Yet that is the reason often given for removal of third molars, even though studies have produced contrary evidence. Third molars do not possess sufficient force to move other teeth. They cannot cause crowding and overlapping of the incisors, and any such association is not causation.
Myth Number 4—The Risk of Pathology in Impacted Third Molars Increases With Age
The American Association of Oral and Maxillofacial Surgeons states, without substantiation, “Pathologic conditions [of impacted third molars] are generally more common with an increase in age.” A study of more than 1756 patients who had retained more than 2000mandibular impactions for an average of 27 years found that only 0.81% experienced cystic formation. There is no evidence of a significant increase in third molar pathology with age. Of course, teeth that become repeatedly symptomatic or develop associated pathology should be removed.
Myth Number 5—There is Little Risk of Harm in the Removal of Third Molars
Given the low incidence of pathology, it is specious to contend that less than 3 days of temporary discomfort or disability is a small price to pay to avoid the future risks of root resorption, serious infections, and cysts. Also ignored is the risk of incidental injury such as broken jaws, fractured teeth, damage to the temporomandibular joints, temporary and, especially, permanent paresthesia or dysthesia (numbness and dysfunction of the lower lip and the tongue).
Data on the number of fractured jaws and damaged teeth are lacking. Fractures occur but are uncommon. There is little data on temporary and permanent temporomandibular joint injury after third-molar surgery, although a recent study of patients aged 15 to 20 years reported an incidence of 1.6%, which translates to thousands of such injuries each year. However, mandibular and lingual nerve injury resulting from third-molar surgery has been more widely reported. Because the percentages of incidental (unavoidable) and iatrogenic (avoidable) injury are small, no one has previously performed the simple task of applying these figures to the entire population exposed to surgery.
Reports on the incidence of mandibular (lower jaw) nerve paresthesia vary from a low of 1.3% for temporary and 0.33% for permanent paresthesia to a high of 4.4% for temporary and 1% for permanent paresthesia. Small figures, indeed! But if 3.5 million lower third molars are removed from 3.5 million persons by oral and maxillofacial surgeons, the incidence of permanent paresthesia ranges from a low of more than 11500 to a high of 35000. Two thirds of these patients had no present or previous symptoms to warrant extraction.
If 67% of the surgery is unnecessary, then between 7739 and 23450 people are afflicted with permanent paresthesia unnecessarily each year.
These figures are based on simple extrapolations from studies by independent researchers, many of whom are oral and maxillofacial surgeons and therefore should be credible. Most of the paresthesias derive from third-molar surgery performed by oral and maxillofacial surgeons because they perform most third-molar extractions, including those at a high risk of nerve injury. A recent study reported that 25% of erupted third molars may have deep periodontal pockets that are considered an indicator of periodontal disease.
Many of these are pseudopockets consisting of excess gum tissue that can be treated conservatively or reduced surgically, rather than extracted, as is done for other teeth with this condition. Nonetheless, let us assume that the incidence of third-molar pathology has been underrepresented in the other cited studies and that 50% of third-molar extractions, including those with deep periodontal pockets, are justified.
In that case, among the other 50% there would be 5775 to 17500 individuals with permanent mandibular paresthesia every year. And this does not include lingual (tongue) nerve paresthesia, which may occur as frequently as once in 10000 mandibular extractions, adding another 350 to 500 paresthesia cases a year. At this rate, between 57000 and 175000 persons in the United States have been afflicted with permanent paresthesia over the past 10 years as a consequence of unnecessary prophylactic third molar extractions.
This information is from the American Journal of Public Health and written by retired dentist Jay Friedman.
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Friedman JW. The prophylactic extraction of third molars: a public health hazard. Am J. Public Health 2007;97:1554-1559.