Science

The scientific puzzle of wisdom teeth – Québec Science

Primum non nocere, first do no harm. This is the commitment that must be made in medicine. Why operate if there is no problem? »Asks Cyril Vidal, dental surgeon in Paris and president of the FakeMed collective, which promotes health care based on scientific evidence. We can guess, he is critical of his profession. “Without saying that all dentists do, many prophylactic wisdom tooth extractions are done for nothing and many victims of side effects could very well have kept their teeth and avoided this trouble. “

Geneviève Chiasson, director of the oral and maxillofacial surgery program at McGill University, is more nuanced. “If I could see the future, my life as a dentist would be so much easier,” she says. This is what I always tell my patients when it comes to wisdom teeth. We have no way of knowing how a healthy tooth will behave at the moment in a few years. Often, the decision is based on the dentist’s “comfort level” in the face of the dilemma: leaving healthy teeth in place, knowing that they could become problematic, or removing them by surgery despite possible complications afterwards. ”

Cabotine teeth

This is because the third molars are preceded by their reputation as spoilers. Thought to come out around their twenties, they sometimes emerge in the wrong place, sometimes in fanciful axes or just don’t erupt, when it’s not just halfway, quite often due to a lack of space on the floor. jaw. We speak of an impacted, semi-impacted or submucosal tooth when it comes out of the bone without being able to pierce the gum.

Situations that can cause different problems: from simple discomfort to systemic infection that causes heart problems, including cysts, abscesses, bone loss or an infection called pericoronitis, which occurs when a tooth only comes out. half is still topped with a little gum on which bacteria settle and cause painful inflammation.

What happens when you let an impacted tooth live its life? This is where we lack statistics. And all-out extractions have no reason to exist, according to Jay Friedman, now retired American dentist and author of an inflammatory book on the subject and articles in scholarly journals. He maintains an almost hateful relationship with the dentists of his country, criticizing them sharply, daring to suggest that several acts are carried out mainly for financial interest.

In the United States, for 10 million annual wisdom tooth extractions, tens of thousands of patients would remain with permanent sequelae, he wrote in 2007 in the influential American Journal of Public Health. In his eyes, this is nothing less than a silent epidemic, a public health problem.

In particular, he fights the “myth” according to which wisdom teeth have a high rate of pathology by referring to a 1988 study which showed that, when “potentially problematic” third molars are left in place, they cause problems (cyst, loss of bone tissue, damage to the neighboring molar) in only 12% of cases. A rate comparable to appendicitis (10%) or inflammation of the gallbladder (12%). However, he argues, we do not systematically remove everyone’s appendix and gallbladder …

If we add the rates of pericoronitis (typical condition of semi-impacted teeth), the proportion of problem cases rises to 20%. However, a single episode of pericoronitis is not, according to Jay Friedman, always a reason to extract a third molar and this should only be considered when more traditional treatments fail, such as antibiotics or the removal of excess tissue around the tooth. tooth.

Of course, this dentist has his detractors, at home and here. But he is right on one point: the decision to resort to the surgical arsenal and to seek the teeth included in the bone also carries its share of risks. Among the possible “side effects”: fracture of the jaw, deterioration of a neighboring healthy tooth, injury to the jaw joint, damage to the mandibular nerve … This exclusively sensitive nerve threads its way into the lower jaw, between the legs. molar roots, and surgery can damage it, causing loss of sensation (paresthesia) in the chin, lower lip and half of the tongue, sometimes temporary, sometimes permanent.

Here too, statistics on the rates of such collateral damage are quite scarce. For injuries to the jaw joint, the only study available, conducted in 2006 on American patients aged 15 to 20, speaks of a rate of 1.6%. And for paresthesias, according to independent studies, they occur temporarily in 1.3 to 4.4% of cases and permanently in 0.33 to 1% of patients.

But how do these risks compare to those of inaction? Impossible to say, as the proportion of healthy wisdom teeth that become problematic is unknown.

The proverb When in doubt, forbear could it be the credo of dentists? Could we not simply monitor suspicious teeth with regular x-rays and intervene only when necessary? Why are they removed almost immediately in adolescence? “Because it is easier to remove wisdom teeth sooner rather than later,” answers Geneviève Chiasson. Teeth develop their crown first, they have little or no roots at the start of their formation, which makes it easier to extract. And the alveolar bone in which the teeth are located is more easily operable in adolescence. Remission after surgery is also easier when you are young. “

On the contrary, a 1985 study of complications after the extraction of an impacted third molar showed that patients aged 35 to 83 are less likely to suffer from secondary infection and mandibular nerve injury than the segment of 12-24 year olds, who nevertheless undergo more extractions. But the highest risk of complications occurs in those aged 25 to 34. Conversely, a 2007 study concluded that older people had more postoperative complications and took longer to recover. Studies therefore, when they exist, contradict each other … A fine example of science in progress, where no consensus seems to have been found.

Despite the lack of solid data, the United Kingdom opted in 2000 for cautious recommendations to its dentists: if the teeth are healthy and not problematic, they should not be extracted. Thus, seven times less wisdom teeth are removed there than in other countries, including Australia. Twenty years later, the results of this relative “laissez-faire” are not so clear. “The extraction rate has definitely decreased,” wrote British dentist Naeem Adam in 2018. “But it went up a few years later because they had to be removed later, when the problems arose. The age of mining has simply been pushed back. “

“One of the most common problems,” he explains in an interview, “is cavities that develop on the back of the second molars. When the third grows horizontally forward and its chewing surface rests on the second, in 42% of cases, an impossible to clean food trap is created and decay sets in. These cavities form very slowly and are detected when they have become too large. It is often necessary to remove both molars and do orthodontics! “

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