Allergic to flossing? It can happen, small study finds

CTV National News: Flossing allergy A Winnipeg researcher says that some people actually have a flossing allergy that affects the gums, but it's very rare. Avis Favaro reports.

Many Canadians like to joke that they are “allergic to flossing,” which is why they never do it.

A report earlier this month seemed to let them off the hook, revealing there wasn’t a lot of evidence to support the practice.

Many dentists immediately scrambled to insist that flossing is as important as ever for preventing gum disease. But a new study finds that in a small group of patients, an allergy to flossing could actually be real.

Winnipeg periodontist Dr. Anastasia Cholakis recently published a study about four of these patients, all of whom found that flossing made their gum problems worse.

Cholakis, who is also a professor at the University of Manitoba, says one of her patients had a stubborn case of periodontal disease that persisted for years. The patient had been a meticulous tooth brusher and flosser, but still had terrible gums that were always red, swollen and bleeding.

“We had been trying to treat her for five to six years with no success. I could see the bone melting away from the teeth,” Cholakis tells CTV News.

A second patient came in who also had gum disease that could not be controlled, no matter how much she brushed and flossed. Then a third patient, and a fourth. Cholakis was at her wit’s end, trying to think what to recommend.

So she took a tiny sample of one of the patient’s gums to examine it under a microscope. She discovered a high number of plasma cells, which often emerge in certain allergic reactions.

Cholakis suspected that the patients had developed a hypersensitivity to something in their oral hygiene routine, wondering if they had grown allergic to flossing.

“Very flippantly, we said, ‘Stop flossing,” she says.

The patients did, and within a few months, the redness and bleeding were gone.

Cholakis suspects there is something in the wax coating or flavouring that triggers an allergic reaction to dental floss in some patients. She has recently published a paper in the Journal of the American Dental Association detailing what she noticed in her four patients.

Study co-author and oral pathologist Dr. John Perry says he and Cholakis were stunned that floss was the problem.

"We have never thought about dental floss…and dental floss changes over time in terms of components manufacturers use,” he said

It’s not clear what ingredient might be behind the reactions. Dental floss manufacturers are not obligated to list their ingredients, so they can change. Cholakis says she and her team were not able to get floss manufacturers to reveal the chemicals they use in their floss coatings.

CTV News contacted a number of floss manufacturers but didn’t hear back

Dr. Larry Levin, the president-elect of the Canadian Dental Association, says an allergy to dental floss is likely rare, but he still thinks manufacturers should start listing the ingredients in dental floss.

“I would want my patients to know specifically what it is they are using and as a practitioner, I would like to know what it is I am recommending,” he said.

In a statement to CTV News, a Health Canada spokesperson said that dental floss is listed as a Class I medical device, “representing the lowest risk out of 4 classes.”

Floss manufacturers must follow labelling rules, but those requirements “do not state that the composition of a medical device must appear on the device labelling,” the statement said.

“Consumers who have questions or concerns about the ingredients in dental floss can contact the manufacturer for more information.”

With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip