One such approach is applying a clear liquid called silver diamine fluoride to the surface of teeth. Silver diamine fluoride is already FDA approved to treat tooth sensitivity, and recent NYU research shows that the compound’s antimicrobial properties also make it effective at preventing cavities and stopping small cavities from progressing into larger ones. Because it’s inexpensive and easy to administer, it can be given in schools, in rural areas lacking dentists, or to patients who may have difficulty with dental care, including those with disabilities.

But treatment with silver diamine fluoride comes with one notable drawback: When the silver in it interacts with tooth decay, it turns the treated surface black. While this is not a significant issue for molars at the back of the mouth or baby teeth that fall out, it’s not a great option for teeth seen in a smile.