Use of SDF may offer an attractive alternative approach to school-based caries prevention.

By Rick Valachovic, DMD, MPH, Clinical Professor and Director of the NYU Dentistry Center for Oral Health Policy and Management

 

Inexpensive, easy to use, effective. The value of silver diamine fluoride (SDF) is becoming harder to dispute thanks to a growing body of research, led in part by my colleagues here at NYU Dentistry.

Since 2014, SDF has been approved as a desensitizing agent for teeth, but pediatric dentists in particular have found other off-label uses for the substance. A hydrophilic liquid that can be painted onto teeth, SDF lends itself to use in children who are too young to cooperate with traditional dental care. With silver to kill bacteria and fluoride to remineralize teeth, SDF can stabilize decay until children are mature enough to sit through a dental procedure.

The catch? SDF leaves a black stain on the teeth that clashes with our image of a healthy smile. The common assumption has been that patients, or their parents, will not accept that discoloration.

“I think there’s a misconception that parents won’t want a black stain on their kids’ teeth,” says Lauren Feldman, DMD, MPH, clinical assistant professor and director of NYU Dentistry’s postdoctoral program in pediatric dentistry. “I do not have that issue, even in my private practice. When you explain to a parent, here are our options, many parents are very happy to avoid general anesthesia, even if it means black staining.”

Traditionally, very young children with severe dental decay have often been treated in hospitals under general anesthesia. That comes with risks, not to mention a hefty price tag. SDF is not a substitute for routine dental procedures, but its ability to arrest the progression of carious lesions makes it an exceptional tool, not just for young patients, but also for dental patients who sometimes wait up to a year for access to a facility offering sedation or general anesthesia. Applying SDF means their cavities won’t get bigger, allowing the dentist to employ more conservative treatment. “You’re able to save teeth rather than just extract teeth, which is extremely beneficial,” Lauren says.

 

The evidence on effectiveness

In 2017, the American Academy of Pediatric Dentistry (AAPD) recommended that SDF be used “for the arrest of cavitated caries lesions in primary teeth as part of a comprehensive caries management program.” The AAPD’s guidance also noted that the recommendation was “conditional” and based on “low-quality evidence.”

Since then, the evidence in support of SDF has mounted, and a recent study provides strong support for its ability to arrest dental caries. Over the past six years, researchers at NYU Dentistry and the University of Michigan School of Dentistry conducted the first randomized controlled trial in the United States of SDF against placebo. With funding from the National Institutes of Health (NIH), the researchers studied SDF’s ability to arrest severe cavitated lesions in very young children. The initial results quantify SDF’s efficacy. Six months after its application, 54% of lesions had not progressed compared to 21% of lesions treated with water, the placebo.

“SDF is very effective in arresting decay in these very young children with severely decayed teeth,” says Amr Moursi, DDS, PhD, professor and chair of the Department of Pediatric Dentistry and principal investigator (PI) for the NYU arm of the study. “On the other hand, it wasn’t 90%,” he adds. “I think the take-home message is: We have to be strategic about how we use it.”

Amr’s team and their colleagues in Michigan, where is overall study PI, will continue to analyze their data to determine how best to use SDF moving forward. They will be asking, Do the results differ at eight months follow up? Do they differ by the children’s ages, or by the size, severity, or position of the lesions in the mouth? These analyses may also help explain why earlier studies suggested the effectiveness of SDF could be as high as 90%. “Many of those studies were actually done on adults,” Amr told me, so perhaps age is a critical variable.

 

Federal interest

The U.S. Food and Drug Administration (FDA), which wants to know if SDF merits a caries-arrest claim for SDF, will be reviewing the Michigan/NYU data as well. If the agency finds the data support the claim, the use of SDF outside of pediatric dental offices could increase significantly.

“A lot of dentists, especially general dentists, don’t feel comfortable using something off label, especially on children,” Amr says. The FDA’s assessment would increase general dentists’ comfort level with using SDF and likely spur more insurance companies to pay for the treatment. It could also encourage more manufacturers to enter the market. According to Amr, only two U.S. companies currently market SDF, but others are expected to follow suit if the FDA approves/supports a caries-arrest claim for the substance. Such developments could spur innovation, and over time, Amr hopes, the development of a non-staining SDF formula.

 

SDF for prevention

A separate research team at NYU released findings this year on the use of SDF for a different purpose: caries prevention. The “CariedAway” study, published in JAMA Network Open, compared the effectiveness of two cavity-prevention techniques—a “simple” treatment using SDF and fluoride varnish, and a “complex” treatment using traditional glass ionomer sealants and fluoride varnish. The study population was children 5 to 12 years old in New York City and New Hampshire schools where at least 80% of students received free or reduced-cost lunch. Study funding was provided by the NIH and the Patient-Centered Outcomes Research Institute (PCORI).

The results suggest that SDF, which is much easier to apply than traditional glass ionomer sealants, may be just as good as glass ionomer in preventing and arresting dental caries. Based on a population-level review of the data, the researchers found a single dose of either topical treatment had prevented roughly 80% of cavities in healthy teeth and arrested 50% of existing cavities when children were examined two years later, an interval resulting from the COVID-19 pandemic. “As school-based dental sealant programs are limited by burdening costs and lack of available, trained clinicians, use of SDF may offer an attractive alternative approach to school-based caries prevention,” the researchers concluded.

One notable aspect of the CariedAway study was the use of non-dental professionals to apply SDF. “One of the questions we asked is, ‘Is a nurse as effective as a hygienist in delivering fluoride varnish and silver diamine fluoride?’” says Rick Niederman, DMD, a professor in the Department of Epidemiology and Health Promotion who conducted the study with our departmental colleagues, Ryan Richard Ruff, PhD, and Tamarinda Barry-Godín, DDS, MPH. Their answer: Yes. A recent interview with Dr. Barry-Godin filmed at one of the New York City school sites affirms their stance.   

Rick’s interest in SDF springs from the persistent growth in childhood caries rates—from 5% at age 5 to 25% at age 20—despite a steady increase in dental spending over the last 30 years. He sees the application of SDF as a powerful preventive tool, not just because of its medicinal properties, but because it is inexpensive and easy to apply outside traditional dental settings. Borrowing a metaphor from the COVID-19 pandemic, he asks, “If physicians and nurses could administer SDF independently, could we flatten that curve? I think using non-dental professionals in this way is absolutely doable,” he told me, “but you have two barriers: practice acts and finances.”

The financial barrier appears to be surmountable. Reimbursement rates for SDF application are far lower than for traditional fillings, but a dentist can apply many SDF treatments in the time it takes to restore a single tooth. Because Lauren uses SDF as a stabilizing medium, she says the treatment is usually in addition to rather than in place of traditional care, which her patients receive at a later time. Rick knows of one pediatric dentist who no longer treats his patients in the operating room, but instead employs six to eight dental hygienists to apply SDF while he focuses on diagnosis. “On a scale like that, he is making a good living,” Rick says.

Lauren agrees increasing the number of people trained to provide SDF could be very beneficial to vulnerable populations. She would like to see greater efforts to engage general dentists in this work. In her professional encounters, she’s been surprised to learn how few dentists use SDF in their practices. 

Some oral health advocates would like to see non-dental professionals apply SDF in other healthcare and community settings as well. That possibility troubles some dentists. They fear SDF could be applied ineffectively or in situations where it is contraindicated, e.g., when a nerve is exposed or a tooth is infected.

Amr shares these concerns. “There are some pediatricians who are really enthusiastic about using SDF outside the dental office because its application is very easy. They argue it’s an access to care issue,” he says. “I get it, but the argument that it’s better than nothing is not true. You can actually cause harm. Trying to diagnose a cavity is not as easy as some may think, and if you can’t make a definitive diagnosis, then you really need to be careful about applying some treatment.”

Rick has heard these concerns before, but counters that his experience does not bear them out. His study team found nurses were fully capable of recognizing when SDF should and should not be applied, and the team reported no adverse events.

Amr, who is past president of AAPD, and his departmental colleague Divya Khera, DDS, are working with the AAPD and the American Academy of Pediatrics to develop SDF application guidelines that address the concerns of pediatric dentists while allowing other professionals to use SDF outside the dental office, as Rick would like to see. “We have done modeling that indicates that, were the whole country to do prevention using SDF and provide it to every child in the United States, it would cost about half of what Medicaid currently spends for children’s oral health,” Rick says.

My colleagues here at NYU make persuasive arguments for harnessing SDF’s potential to improve both individuals’ and the public’s oral health. I look forward to seeing what the FDA concludes after reviewing the latest research on caries arrest and whether the AAPD or American Dental Association guidelines, which do not currently recommend SDF for prevention, evolve in response to the CariedAway study findings. Wherever the evidence takes us, these developments underscore the value of research and the role of policy in advancing oral health. It’s exciting to see these contributions to the growing body of evidence get the attention they deserve.