A simple, inexpensive liquid called silver diamine fluoride, or SDF, could spare many of those children. Applied to a cavity with a tiny sponge-tipped applicator in a few seconds per tooth, SDF arrests decay without drilling, shots or sedation.

Dentists have used SDF successfully for decades in many countries and off-label in the United States since 2014, when it was approved as a medical device to treat tooth sensitivity. However, it has lacked the large U.S. population clinical trials on efficacy and safety needed for FDA approval as a drug to treat cavities.