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Many dental procedures lack scientific backing, data review finds

The “truth about dentistry,” writes Ferris Jabr in the Atlantic, is that “common dental procedures are not always as safe, effective, or durable as we are meant to believe.”

teeth cleaning
Many dental procedures, from twice-yearly teeth cleanings to crowns for root canals, do not have a lot of rigorous scientific backing.
REUTERS/Mark Makela

In a long-form article for the May issue of the Atlantic magazine, science writer Ferris Jabr describes how dentistry is “much less scientific — and more prone to gratuitous procedures” than most of us think.

The “truth about dentistry,” writes Jabr, is that “common dental procedures are not always as safe, effective, or durable as we are meant to believe. As a profession, dentistry has not yet applied the same level of self-scrutiny as medicine, or embraced as sweeping an emphasis on scientific evidence.”

“Consider the maxim that everyone should visit the dentist twice a year for cleanings,” he explains. “We hear it so often, and from such a young age, that we’ve internalized it as truth. But this supposed commandment of oral health has no scientific grounding. Scholars have traced its origins to a few potential sources, including a toothpaste advertisement from the 1930s and an illustrated pamphlet from 1849 that follows the travails of a man with a severe toothache. Today, an increasing number of dentists acknowledge that adults with good oral hygiene need to see a dentist only once every 12 to 16 months.”

“Many standard dental treatments — to say nothing of all the recent innovations and cosmetic extravagances — are likewise not well substantiated by research,” Jabr adds. “Many have never been tested in meticulous clinical trials. And the data that are available are not always reassuring.”

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Disheartening conclusions

Jabr notes that Cochrane, a highly respected nonprofit global organization of independent scientific investigators, has been conducting systematic reviews of oral-health studies since 1999 — with discouraging (for the dentistry profession) results.

“In these reviews,” writes Jabr, “researchers analyze the scientific literature on a particular dental intervention, focusing on the most rigorous and well-designed studies. In some cases, the findings clearly justify a given procedure. For example, dental sealants — liquid plastics painted onto the pits and grooves of teeth like nail polish — reduce tooth decay in children and have no known risks. (Despite this, they are not widely used, possibly because they are too simple and inexpensive to earn dentists much money.) But most of the Cochrane reviews reach one of two disheartening conclusions: Either the available evidence fails to confirm the purported benefits of a given dental intervention, or there is simply not enough research to say anything substantive one way or another.”

“Fluoridation of drinking water seems to help reduce tooth decay in children, but there is insufficient evidence that it does the same for adults,” Jabr adds. “Some data suggest that regular flossing, in addition to brushing, mitigates gum disease, but there is only ‘weak, very unreliable’ evidence that it combats plaque. As for common but invasive dental procedures, an increasing number of dentists question the tradition of prophylactic wisdom-teeth removal; often, the safer choice is to monitor unproblematic teeth for any worrying developments. Little medical evidence justifies the substitution of tooth-colored resins for typical metal amalgams to fill cavities. And what limited data we have don’t clearly indicate whether it’s better to repair a root-canaled tooth with a crown or a filling. When Cochrane researchers tried to determine whether faulty metal fillings should be repaired or replaced, they could not find a single study that met their standards.”

Separate paths

Part of the problem, Jabr points out, is that dentistry and medicine developed separately.

“Most major medical associations around the world have long endorsed evidence-based medicine,” he writes. “The idea is to shift focus away from intuition, anecdote, and received wisdom, and toward the conclusions of rigorous clinical research. Although the phrase evidence-based medicine was coined in 1991, the concept began taking shape in the 1960s, if not earlier (some scholars trace its origins all the way back to the 17th century). In contrast, the dental community did not begin having similar conversations until the mid-1990s. There are dozens of journals and organizations devoted to evidence-based medicine, but only a handful devoted to evidence-based dentistry.”

“Dentistry’s struggle to embrace scientific inquiry has left dentists with considerable latitude to advise unnecessary procedures — whether intentionally or not,” Jabr adds. “The standard euphemism for this proclivity is overtreatment. Favored procedures, many of which are elaborate and steeply priced, include root canals, the application of crowns and veneers, teeth whitening and filing, deep cleaning, gum grafts, fillings for ‘microcavities’ — incipient lesions that do not require immediate treatment — and superfluous restorations and replacements, such as swapping old metal fillings for modern resin ones. Whereas medicine has made progress in reckoning with at least some of its own tendencies toward excessive and misguided treatment, dentistry is lagging behind.”

Ask about options

Jabr’s article is a fascinating read, and its general message — that many dental procedures, from twice-yearly teeth cleanings to crowns for root canals, do not have a lot of rigorous scientific backing — will likely surprise many people.

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The article shouldn’t, though, discourage us from going to the dentist or following our dentist’s suggestions for oral health. But it does underscore the importance of making sure each dental procedure is absolutely necessary — and that all options have been presented to us — before we agree to it.

FMI: You can read the article on the Atlantic magazine’s website.