By Emma Yasinski
Silver Diamine Fluoride (SDF), a topical treatment used to prevent dental caries from decaying teeth - popular for decades in Japan and other countries - may soon replace drilling and filling cavities as a standard of care in the United States.
SDF is currently approved only as a medical device for treating dental sensitivity, but it's much more commonly used off-label - treating dental caries in both children and adults. Moreover, approval of SDF to treat caries appears on its way, thanks to a breakthrough drug designation and promising results from a randomized, placebo-controlled trial published in the January 2018 Journal of Dentistry.
One dentist has played an especially large role in making both of those things happen: Dr. Peter Milgrom, DDS, Professor of Oral Health Sciences and Pediatric Dentistry in the School of Dentistry at the University of Washington.
Dr. Milgrom is "the kind of guy you want on your side," says Steven Pardue, a co-owner at Elevate Oral Care, in a face-to-face interview with Incisor. Elevate Oral Care is currently the only company that sells silver diamine fluoride in the United States.
Many dental offices receive a flat payment per patient from a managed care company, regardless of what procedure they use to treat caries. A colleague of Dr. Milgrom's asked him how to keep costs down and still provide the best care to all those patients governed by a managed-care budget. That's when Dr. Milgrom thought of a treatment he'd seen overseas - silver diamine fluoride.
Dentists and dental hygienists outside of the United States have been using SDF, a clear liquid that gets painted on the surface of a dental lesion that solidifies and stops caries from progressing, for decades, but when Dr. Milgrom first wanted to bring it to the United States, he was told there'd be no market for it.
Discoloration Remains an Issue
Regulators told Dr. Milgrom that dentists are accustomed to drilling and filling cavities, and that patients wouldn't agree to the treatment because the silver oxidizes and leaves black spots on their teeth. Discoloration remains an issue, but researchers are actively looking at ways to mitigate or eliminate the staining, Pardue says.
"Because of my academic connections, I was able to get access to [SDF] and begin to use it with my patients." Dr. Milgrom told Incisor, "From there, it was clear to me that this was a valuable tool [and] that I should try to figure out how to get it into the market."
It took seven years, as opposed to the usual 90 days, but SDF finally got medical device clearance from the FDA in 2014. It can still only be marketed to treat hypersensitivity, but American dentists have been using it off-label to treat caries since 2015.
Determined to get the drug approved for treating caries, Dr. Milgrom fought for, and won, a breakthrough drug designation status to expedite the process.
Working in Dr. Milgrom's favor is the fact that many patients, especially children, require sedation in order to allow their dentists to drill and remediate cavities. Although the drilling itself isn't life-threatening, there have been alarming cases of pediatric patients who've died in incidents related to improper sedation used by some practitioners.
No sedation is necessary for the SDF application.
SDF advocates also contend that silver diamine fluoride is more effective than traditional treatments. Caries are caused by cariogenic bacteria, and traditional restorations are only beneficial if these bacteria are under control. Otherwise, eventually, the patient will be back with more caries. SDF is thought to work by managing the bacterial infection, and thus preventing both further decay and future caries.
Awaiting FDA Approval
The current study is one of the last steps toward full FDA approval. A part of the Stopping Cavities Study, it was a double-blind, placebo-controlled trial. The researchers recruited 64 children aged three to five from Head Start preschools in Oregon who had dental caries that reached the tooth's dentin. Twenty-nine of the children were treated with SDF, while the other 35 were treated with a placebo. More than half of the children who received the SDF treatment showed complete arrest of their caries at their follow up appointments two-three weeks later, compared to only one child in the placebo group. There was no significant difference in adverse events between the two groups.
Additionally, the team tested swabs from the children's mouths for the RNA of different microbes before and after treatment. Since the silver ions in SDF are thought to exert antimicrobial effects that prevent further tooth decay, the team expected to see a decrease in the RNA of oral bacteria associated with dental caries. The researchers were surprised to see that despite previous ex vivo studies showing these antimicrobial effects, there was no significant difference in the children before and after treatment.
Nonetheless, the evidence that SDF seemed to stop caries in their tracks in this and nearly ten other clinical studies, is more than enough for the group to keep moving forward.
Back in October, Margarita Fontana, DDS, Ph.D., Professor of Cariology, Restorative Sciences and Endodontics at the University of Michigan School of Dentistry, received $9.8 million from the NIH to conduct a phase III clinical trial, the final step for approval. The trial is scheduled to start this summer.
In the meantime, about 10% of U.S. dental offices already offer SDF. Some dentists hesitate to go off-label, still concerned that their patients won't accept a treatment that will leave black spots on their teeth. Other dentists remained convinced that the best way to treat dental caries is through "drilling and filling."
But insurance companies are beginning to cover SDF treatment, and Dr. Milgrom argues, "Somebody who's not using this is out-of-date. That's the bottom line, and this is now standard of care."
[Also in this issue, see Severe periodontal disease increasing along with the associated risk of several cancers]
Contributing writer Emma Yasinski received her Master of Science (MS) in science and medical journalism from Boston University. Her articles have also appeared at TheAtlantic.com, Kaiser Health News, NPR Shots, and Genetic Engineering and Biotechnology News.