The NYTimes has an incredible story on a simple, paint-on liquid that stops tooth decay and prevents further cavities:

Nobody looks forward to having a cavity drilled and filled by a dentist. Now there’s an alternative: an antimicrobial liquid that can be brushed on cavities to stop tooth decay — painlessly. The liquid is called silver diamine fluoride, or S.D.F. It’s been used for decades in Japan, but it’s been available in the United States, under the brand name Advantage Arrest, for just about a year. The Food and Drug Administration cleared silver diamine fluoride for use as a tooth desensitizer for adults 21 and older. But studies show it can halt the progression of cavities and prevent them, and dentists are increasingly using it off-label for those purposes.

Ari Armstrong has the right reaction:

So the Japanese have been using this drill-free treatment for “decades,” yet we in the United States have had to wait until last year to get it. And the only reason we can get it now to treat cavities is that it happens to be allowed as on “off-label” use for what the FDA officially approved it for.

The NYTimes continues:

Silver diamine fluoride is already used in hundreds of dental offices. Medicaid patients in Oregon are receiving the treatment, and at least 18 dental schools have started teaching the next generation of pediatric dentists how to use it. …The main downside is aesthetic: Silver diamine fluoride blackens the brownish decay on a tooth. That may not matter on a back molar or a baby tooth that will fall out, but some patients are likely to be deterred by the prospect of a dark spot on a visible tooth. …[But] “S.D.F. reduces the incidence of new caries and progression of current caries by about 80 percent,” said Dr. Niederman, who is updating an evidence review of silver diamine fluoride published in 2009. Fillings, by contrast, do not cure an oral infection.

But as Armstrong writes the craziest part of the story is this:

American dentists first started using similar silver-based treatments in the early 1900s. The FDA is literally over a century behind the times.

It seems that the future of dental treatment has been here all along but a combination of dentists wanting to be surgeons, lost knowledge, and FDA cost and delay prevented it from being distributed. Incredible.