Although removal of wisdom teeth is very common, there are no studies that show a benefit to taking them out when they are not causing pain or other problems, according to a new review of existing research.
Third molars, or so-called wisdom teeth, generally emerge fully or partially between ages 17 and 26 into limited space and they are often wedged against the second molars. This can cause swelling, root damage, decay or gum disease, and in these cases experts agree the wisdom teeth should be removed.
But if there are no symptoms, it is unclear whether the benefits of surgery outweigh the risks, researchers write in the Cochrane Database of Systematic Reviews.
"Given the fact that wisdom teeth are removed on a large scale worldwide, it is surprising that high quality research is lacking," said lead author Hossein Ghaeminia of Radboud University Medical Center in Nijmegen, the Netherlands.
"In the USA for instance, the preventive removal of asymptomatic disease-free wisdom teeth is very common," Ghaeminia told Reuters Health by email. "In the UK, the NICE guidelines advise not to remove asymptomatic disease-free wisdom teeth."
The researchers searched for studies that compared outcomes, such as the likelihood of various dental problems, after disease-free impacted wisdom teeth are either removed or retained.
They found just two studies, including one randomized controlled trial from a dental hospital in the U.K., and one prospective study in the U.S. But neither compared most aspects of health-related quality of life after removal versus retention of asymptomatic wisdom teeth.
The U.S. study, which involved 416 healthy men, found that men who still had their impacted wisdom teeth may have had a higher risk for gum disease around the adjacent molar over the long term compared to men who had their wisdom teeth removed or did not have any to begin with.
The U.K. trial randomized 164 participants to either removal or retention of impacted wisdom teeth and found no evidence of notable differences between the groups in dental health afterwards.
The studies did not measure other outcomes like cost, cyst or tumor formation, bleeding, nerve damage or infection.
The most common risks of surgery are infection, inflammation of the tooth socket and temporary nerve injury causing impaired sensation of the lip and chin, Ghaeminia said.
Surgery is covered by most dental insurance but it generally is not covered by medical insurance, said Martha E. Nunn of Creighton University in Omaha, Neb., who was not part of the new study.
"We will likely conduct another prospective cohort study to examine risks from retained asymptomatic third molars," Nunn told Reuters Health by email. "I personally disagree with surgical removal of third molar tooth buds when an adolescent is young, as I have seen permanent bone damage as a result," she said.
"Some might say that preventive removal should be stopped since there is no high quality evidence to support this practice," but that may lead to more surgeries at an older age when wisdom teeth do become symptomatic, and surgery has more complications for adults than for teens, Ghaeminia said.
"On the other hand, preventive removal of all asymptomatic wisdom teeth is also undesirable: if the tooth would stay asymptomatic and disease free during lifetime, the patient might have been exposed to an unnecessary risk of complications and costs," he said. "In the absence of evidence, orthodontists, dentists and oral surgeons should discuss the pros and cons of wisdom teeth removal in each case individually."