Is wisdom teeth removal really warranted?

In her 20s, Nancy Fornasiero’s dentist told her that her wisdom teeth should come out. They were impacted, which means they were stuck below the gums because they didn’t have enough room. She was warned that the teeth were more prone to decay and infection than other teeth, and that they should be removed before problems occur. But Fornasiero kept putting off the surgery, which would have required her to take days off for healing. “There was never a good time,” she says.

As the years passed and X-rays showed her teeth weren’t moving and harming other teeth – as dentists said could happen – she decided not to get her teeth removed. “I’m of the philosophy, if it isn’t broken, don’t fix it,” the Oakville, Ontario-based writer explains. Now 50, Fornasiero has listened to four dentists tell her, over the years, to have her wisdom teeth removed. “I let them give their spiel,” she says.

Fornasiero’s dentists have followed a conventional wisdom in dentistry – the thinking goes that it’s better to remove impacted wisdom teeth before they develop infections that spread to the gums or other teeth – and that it’s better to do the surgery at a younger age, when the chance of recovery is higher.

But not everyone in the medical and dental community agrees with the practice of removing healthy wisdom teeth. In addition to the financial cost, the pain and swelling associated with the recovery process often requires people to take a few days away from school or work. As with all surgeries, it involves risks of complications. Those who question the practice have likened it to preventatively removing all appendixes and tonsils simply because they can get infected.

Wisdom teeth surgery can cost anywhere from a few hundred dollars to over $2,000, depending on how many teeth need to be removed and the position of the teeth. Despite the high cost to patients and insurers, however, there are no statistics regarding how often preventative wisdom teeth extractions are performed in Canada. But if US statistics are any indication, it’s possible hundreds of thousands of Canadians have their wisdom teeth taken out each year, before there’s any sign of problems.

Major variation in how often wisdom teeth surgeries performed around the world

Internationally, many major medical organizations have concluded the evidence supports leaving healthy impacted wisdom teeth in the mouth. The Canadian Agency for Drugs and Technologies in Health concluded in 2010 that there is insufficient evidence either for or against the preventative removal of healthy, but impacted wisdom teeth.

Organizations representing dental surgeons tend to err on the side of removal. The American Association of Oral and Maxillofacial Surgeons recommends the removal of impacted wisdom teeth on its website for patients but in a paper directed to medical professionals explains that impacted wisdom teeth that have fully formed roots and are covered by bone may not need to be removed. In the UK, oral surgeons claim that since the roll-out of recommendations not to preventatively remove wisdom teeth in 2000, many patients have experienced pain, decay or infection and had to get their wisdom teeth out anyway as a result.

The Canadian Association of Oral and Maxillofacial Surgeons is more nuanced, explaining that the position of the impacted wisdom tooth should dictate whether they’re removed or not. In an emailed response to questions sent by Healthy Debate, Christopher Robinson, the executive director of the organization and an oral and maxillofacial surgeon, stressed that “each situation is individual as is each patient.”

David Kelner, an associate clinical professor in the School of Dentistry at the University of Alberta, who has been practising dentistry for over 30 years notes “the philosophy on when and whether wisdom teeth are to be removed has changed a number of times through the years.” With the advent of dental implants, he explains, it became less important to retain wisdom teeth as “spare teeth” in case other molars were lost. “This prophylactic removal of wisdom teeth was not evidence based to my knowledge,” he says. “It was just adopted as a philosophy.” Still, he recommends it in some cases for patients, depending on numerous factors, including the positioning of the teeth and age.

The differences in opinion – and funding – mean there are wide differences in wisdom teeth removal rates in the developed world, with a 2015 study finding that western Australia performed wisdom teeth surgeries at a rate 7 times higher than the UK and 1.6 times higher than France.

While oral surgeons and some dentists who do the surgery benefit financially from preventative extraction of wisdom teeth, the sources we spoke to didn’t think the difference in opinion was that simple. “I think that goes to show that the evidence isn’t strong either way,” says David Lam, a surgeon, scientist and professor in oral and Maxillofacial Surgery at the University of Toronto. Because dentists and oral surgeons are the ones who see periodontitis or decay in impacted wisdom teeth firsthand, they tend to err on the side of extraction, he explains. “Some surgeons might push [preventative extraction] a little heavier because they’ve seen the worst case scenarios more – the more difficult, complicated problems,” says Lam.

What’s the evidence behind wisdom teeth extraction?

In 2012, a Cochrane review attempted to evaluate studies that randomly assigned people to either have their wisdom teeth taken out as a preventative measure, or to leave the wisdom teeth. The review turned up one study that looked only at one outcome – teeth crowding – and found that removing wisdom teeth didn’t prevent later crowding of teeth. No other studies were strong enough to be included in the review.

Without randomized clinical trials – the gold standard of evidence – organizations that make recommendations around wisdom teeth removal must necessarily turn to other studies, which, though instructive, are open to bias and vary widely.

Some of these studies look at what happens to impacted wisdom teeth that are left in. For example, one study involved 1,756 people with an average age of 47 who had never had their impacted wisdom teeth out. It found 12% of the participants had experienced a complication that wouldn’t have happened had they had surgery. Another study found that those who had a partially visible wisdom tooth had double the risk of having pockets of 5mm or more beside the adjacent tooth – a sign of gingivitis or even periodontitis. Cysts and tumours (usually benign) can also develop in wisdom teeth that aren’t removed – a risk most studies estimate between 1% and 2%.

Research has also looked at the number of people who develop complications after surgery. One study reported that nearly 10% of people who underwent the surgery, either for preventative or treatment reasons, had a complication. More than 90% of these complications were minor, such as inflammation, dry socket or delayed healing, but six of the 583 participants had injury to the inferior alveolar nerve, which can cause impaired speech and chewing. The symptoms can take months to resolve and lasted more than a year in one case.

Studies also show that the chance of serious complications is lower if wisdom teeth extraction surgery occurs before 25 years of age. In a large study of around 10,000 people the risk for nerve damage was lowest among those below 25, at 0.5%, compared to 2.11% for those 25-34 and 1.35% for those 35 and older. Interestingly, when it comes to the overall complication rate, the 35-83 age group had the lowest risk of post-extraction complications, compared to younger age groups. Other studies show, however, that healing is faster when wisdom teeth extraction surgery occurs at a younger age.

How should you decide on wisdom teeth removal?

Given the mixed evidence around wisdom teeth removal, how should people decide if impacted teeth should be extracted?

Lam recommends finding a dentist who takes into account individual risk factors and preferences, rather than encouraging extraction simply because a tooth is impacted – and he thinks the overwhelming majority of dentists fall into the former camp. “I would like to think that all of my colleagues out there would give the true risks to the patients and let them decide as opposed to just saying you need them out,” he says.

In Lam’s view, most impacted wisdom teeth that are completely covered by bone and gum tissue – and are expected to stay that way – don’t need to be taken out. With “partially impacted” teeth, however, he usually recommends surgery. “If the tooth is peaking through the gum tissue any bit or the dentist can probe it, that means there can be a pathway for bacteria to get in there.”  Lam recognizes that, even with the wisdom teeth he recommends for extraction, “you can have people who will never have a problem, but it’s a little bit of a gamble.”

Victor Kutcher, president of the Ontario Dental Association, also recommends the removal of wisdom teeth that aren’t fully covered by bone. “I’ve been practicing for 34 years and I feel very comfortable making that recommendation to my patients based on what I’ve seen happen [when patients don’t take out partially emerged wisdom teeth],” he says.

Still, all the dentists we spoke to stress a patient’s own preferences – whether they prefer a watch and wait approach or a nip it in the bud approach – should factor into the conversation. “It’s a co-decision making thing when it comes to dealing with anything in the health care system,” says Kutcher. Robinson explains that, along with the dental surgeon’s expertise, “the individual patient’s needs, autonomy and rights to self-determination must remain paramount.”

Kutcher recommends that patients ask their dentists questions like “Is [removal] necessary? What happens if I don’t do it? What are the risks if I do it?” He points out that the angle of the impacted tooth, and how close it is to the nerve or to other teeth also factor into surgery recommendations.

For those who prefer the monitoring approach, wisdom teeth are left in unless they develop cavities that can’t be fixed, cellulitis, or repeated or severe episodes of pericoronitis.

More research needed

Though Lam and Kutcher make the distinction between fully and partially impacted wisdom, studies often lump the risks and benefits of removing impacted wisdom teeth in general.

Julia Boughner, a professor of anatomy and cell biology at the University of Saskatchewan, thinks more specific research is necessary to more precisely determine when preventative extraction of impacted teeth is a good idea, and when it’s not. She is currently supervising research that is using 3-D X-rays of patient’s wisdom teeth to determine which factors, such as angles of wisdom teeth growth, predict the likelihood of future disease in wisdom teeth.

She argues that the Canadian government needs to invest in larger and longer term research to examine the risks and benefits of preventative wisdom teeth removal in the Canadian population, pointing out that our country’s ethnic diversity, diets, dental hygiene patterns and other factors mean that studies from other jurisdictions might not best address the needs of our population. “I really wish the government of Canada would include data on third molars in the next Oral Health Survey,” she says.

Another experiment Boughner would like to see funded is whether a widespread public health campaign that encourages better brushing and flossing at the back of the mouth would cut down on wisdom teeth issues. “We know that wisdom teeth are more likely to develop cavities and infections over time,” she says. “But how much of that has to do with us not being fastidious brushers when it comes to wisdom teeth, which are the hardest to reach and clean?”