EVIDENCE MEANS THINGS:

What about everything else? It turns out there's a whole journal dedicated to the idea that we could use more rigor in dental recommendations. Evidence-Based Dentistry either publishes systematic reviews or summarizes reviews from other organizations, like the Cochrane Collaboration.

The good news is that brushing appears to work. But it's important to know that it's brushing with fluoride toothpaste that matters, not the brushing alone. Doing that doesn't just prevent gingivitis and plaque formation; it also prevents cavities, which is the outcome that we care most about.

My dentist has always recommended a powered toothbrush. The evidence seems to agree that, as many randomized controlled trials confirm, powered toothbrushes reduce both plaque and gingivitis more than regular toothbrushes. An older Cochrane review concluded that the rotating powered toothbrushes were superior than the side to side powered brushes. I use the latter, and this disappointed me. But the difference between the two types, while statistically significant, was really small.

There appear to be no good randomized controlled trials on brushing frequency. The other studies that do exist, while flawed, seem to support twice-a-day brushing.

Surely the twice-a-year teeth cleanings matter? In 2005, Evidence-Based Dentistry highlighted a systematic review on the effects of routine scaling and polishing (you call it teeth cleaning). Researchers found eight randomized controlled trials that were on point, but they were all judged as having a high risk of bias. The results were all over the map. Their conclusions were that the evidence isn't of sufficient quality to reach any conclusions as to the benefits or harms of scaling and polishing. [...]

What about preventive dental visits themselves? In 2013, Bisakha Sen, Nir Menachemi and colleagues used data from the Alabama Children's Health Insurance Program to follow more than 36,000 children to see how preventive dental visits affected dental care and spending over time. They found that preventive visits were associated with fewer visits for restorative dental care in the future, implying that there was an improvement in oral health. But they found that, for the most part, more than one annual preventive visit in children was not cost-effective.

Further work found that it may have been the use of sealants, and not preventive visits in general, that had this protective effect. Since sealants could be applied without an actual visit to the dentist, that brings into question whether a more cost-effective means of getting sealant on children's teeth might be possible -- using a lower-cost dental hygienist, perhaps. Fluoride varnish appears to work well, too.

No review of dental health would be complete without at least acknowledging water fluoridation. Much of the evidence is old because it's getting hard to do studies. It would be somewhat unethical to withhold fluoridation at this point from some people, because the evidence in favor of the practice is so compelling.

In fact, fluoride is so important that the U.S. Preventive Services Task Force recommends that in areas where the water supply is deficient, providers prescribe oral fluoride supplementation to children. They recommend the use of fluoride varnish as well.

To recap, there's good evidence that brushing twice a day with fluoride toothpaste is a good idea, especially with a powered toothbrush. For children, there's good evidence that the use of fluoride varnish or sealants can be a powerful tool to prevent cavities. The rest? It's debatable.

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