Aug. 15, 2018 -- If your toothpaste is fluoride-free, brushing and flossing alone aren't enough to keep cavities away, according to a recent study.

The fluoride is what helps you avoid cavities, says lead researcher Philippe Hujoel, PhD, a Seattle periodontist and professor of oral health sciences at the University of Washington. "It's not [simply] keeping the teeth cleaner."

For years, dental professionals have debated the importance of the ''clean tooth'' hypothesis versus the ''sound tooth'' hypothesis in preventing cavities.

Those in the first camp say good oral hygiene will remove the sticky film of acid-producing plaque that breaks down the enamel and allows cavity-causing bacteria to invade the teeth.

Others argue that brushing and flossing, no matter how intense, isn't enough to prevent cavities. ''The plaque is inaccessible and you can't get to it," Hujoel says. While oral hygiene may help a bit, it's the fluoride that makes the difference in getting to the plaque and preventing cavities, he says.

Cavities begin in tiny cracks and crevices in the enamel. Exactly how fluoride helps prevent cavities is not certain, according to Hujoel. "There is some evidence it may inhibit the enzymes that break down the tooth," he says. In general, experts believe fluoride helps restore minerals to the enamel, helps strengthen the tooth, and even helps reverse the early cavity process.

Study Details

While fluoride has been recommended for years, Hujoel's team wanted to focus on the intensity of oral hygiene to see if it made a difference in cavity prevention. They searched the published medical literature from 1950 to 2017 and found three randomized clinical trials, including 743 preteens and teens, that were sound enough to include and analyze.  Follow-up ranged from about 2½ to 3 years.

Two were conducted in the U.S. and one in England. None were funded by commercial companies.

Researchers assigned children in the studies to an intense oral hygiene group or to a usual hygiene group of brushing and flossing. In the intense group in all three studies, the children had supervision of their oral hygiene, with plaque removal, at school, but no fluoride toothpaste was used at school. 

In the U.K. study, all used toothpaste with fluoride at home. Some in the U.S. studies used fluoride toothpaste and some did not at home, Hujoel says. While the design was not ideal, the key point was to compare intense hygiene with less intense hygiene, he says. Two studies were done in communities with nonfluoridated water supplies. 

"There was no significant difference in cavities between the groups," Hujoel says. "These intensive oral hygiene interventions, which were successful in removing the biofilm, did not have an impact on the cavities."

ADA Weighs In

The study ''supports what the dental association has said for years, that brushing with fluoride is good," says Matthew Messina, DDS, a dentist in Columbus, OH, who is also a consumer advisor for the American Dental Association and assistant professor of dentistry at The Ohio State University in Columbus.

To earn the ADA Seal of Acceptance, a toothpaste must contain fluoride, he says. The ADA recommends brushing twice a day with a fluoride-containing toothpaste, flossing once a day, eating a healthy diet, and seeing a dentist on a regular basis. "We know that works," he says.

That's lifelong advice, he says, as cavities don't just affect children. "We are seeing an increase in the rate of cavities in the older population," he says. That's partially due to improved dental techniques allowing people to keep their natural teeth longer, he says. Dry mouth, a side effect of numerous medications taken by older adults, can also make teeth more prone to decay, he says.

Toothpaste-Makers' Point of View

Fluoride offers one way to strengthen teeth and does have potential benefits, says Darryl Bosshardt, a spokesman for Redmond, which makes a fluoride-free toothpaste, Earthpaste. But tooth decay is not caused by fluoride deficiency, he says, and fluoride supplementation can't reverse active cavities.

"It can also have some potential negative aspects that some consumers would like to avoid if possible," he says. As one of many examples, he cited a study finding fluoride-containing toothpaste ingestion as a main source of fluoride toxicity, according to the Association of Poison Control, especially in young children.

"We are also quick to point out that a non-fluoride toothpaste may not be the best option for everyone. However, we similarly acknowledge that mandatory fluoride supplementation in all water supplies and in all oral care products may also not be the ideal solution for everyone.'' He encourages people to weigh the pros and cons with their dentist.

While toothpaste with fluoride ''is the best choice for oral health, we also recognize that not all the people that choose our brand want fluoride in their toothpaste, and we offer a fluoride-free alternative," says Rob Robinson, a spokesman for Tom's of Maine. The fluoride-free toothpaste from Tom’s does not carry an anti-cavity claim.

A Different Way

For those who do not want to use fluoride-containing toothpastes, another option is going on a very low-carb diet, generally less than 50 grams a day, Hujoel says. Doing so cuts back drastically on the sugars that can attack the teeth and lead to cavities, he says. That's the path he takes, but he acknowledges that few can follow such a strict diet and so should use fluoride-containing toothpaste as part of their oral hygiene routine.

Show Sources

Gerodontology: “Personal oral hygiene and dental caries: A systematic review of randomised controlled trials.”

Matthew Messina, DDS, consumer advisor, American Dental Association; assistant professor of dentistry, The Ohio State University, Columbus; dentist in Columbus.

Philippe Hujoel, PhD, Seattle periodontist and professor of oral health sciences, University of Washington, Seattle.

Iranian Journal of Basic Medical Sciences: “Potential fluoride toxicity from oral medicaments: A review.”

Rob Robinson, spokesman, Tom's of Maine.

Darryl Bosshardt, spokesman, Redmond Inc.

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