Will Silver Diamine Fluoride Significantly Impact the Standard of Care for Caries Prevention/Treatment in the United States?

Silver diamine fluoride (SDF), a topical medicament consisting of essentially silver, water, fluoride, and ammonia, definitely has a place in the chronic disease management model of dental caries. Clinicians, though, should not view it as a "silver bullet" or one-stop solution for managing dental caries. SDF was approved in the United States as a device to reduce tooth sensitivity and is being used "off label" to arrest caries. The American Academy of Pediatric Dentistry and American Dental Association (ADA) have recently published clinical practice guidelines regarding its use.^1,2 The current evidence supports twice-a-year application of SDF to arrest cavitated caries lesions on any coronal surface of primary or permanent teeth. For non-cavitated lesions the ADA guidelines support interventions such as sealants (occlusal lesions), resin infiltration (interproximal lesions), and 5% sodium fluoride varnish. At present, evidence on the effectiveness of SDF for prevention of caries is limited. Considerable research is still ongoing, and clinicians' understanding of SDF and, subsequently, their acceptance of it appears to be increasing with time.

A minimally invasive treatment option, SDF certainly should be among the strategies in the practitioner's toolbox. When used wisely it can help create an environment conducive to reestablishment of a stable biofilm and thereby lower the risk of development of new caries. However, one should not forget that tried and true approaches to prevention of dental caries, such as optimally fluoridated water, brushing teeth twice daily, and use of fluoride varnish, have long had a major influence on the worldwide reduction in dental caries.

Silver diamine fluoride (SDF) may be the proverbial "brick that breaks the camel's back" for widespread implementation of nonrestorative caries management. Prior to clearance of SDF by the US Food and Drug Administration (FDA) in 2014, topically applied nonrestorative materials were merely preventive. SDF is both a treatment and preventive material. Before the emergence of SDF, the term nonrestorativewas not part of the caries management lexicon. Now, however, the ADA commends SDF as one of "a variety of effective interventions to treat carious lesions nonrestoratively."³

In October 2018, the ADA shook the dental world by publishing two landmark papers, concluding in one, "Clinicians are encouraged to prioritize use of [nonrestorative treatments] based on effectiveness, safety, and feasibility,"² and in the other, "38% silver diamine fluoride solution applied biannually [is] effective for arresting advanced cavitated carious lesions on any coronal surface (moderate to high certainty)."³ This is a significant impact to the standard of care for caries management.

The National Institutes of Health recently expended $10 million to the Universities of Michigan, Iowa, and New York (NYU) to conduct the pivotal trial that will decide whether SDF will be the first FDA-approved drug to treat dental caries. The estimated study completion date of the trial is June 2020.

Already, an abundance of clinical research conducted in the United States and elsewhere shows that SDF stops 81% of active caries lesions⁴ and prevents 61% of new lesions from forming.⁵ Application to all caries lesions takes just a few minutes and requires less skill than applying sealants. These factors bode well for potential major change.

Meanwhile, for clinics operating on a fee-for-service model this approach is not terribly profitable, as SDF and other noninvasive nonrestorative interventions do not pay much. However, these methods don't cost much either. SDF is financially detrimental only to providers who are looking to deliver lucrative operative procedures. Yet, there is money to be made with SDF treatment strategies. Payment models that exploit these opportunities by incentivizing health instead of restorative treatment will eventually upend the dental healthcare system.

Silver diamine fluoride (SDF) has the potential to significantly impact the standard of care for caries prevention and treatment worldwide. Although it comes with one significant esthetic downside, SDF offers some meaningful advantages in treating caries lesions in patients. The science is clear: application of SDF to active caries lesions reduces lesion activity and arrests progression as effectively as and typically better than atraumatic restorative treatment, glass-ionomer cement, or fluoride varnish.^6-10 The application is simple and time/dose dependent. Two applications over a 2-week period followed by biannual reapplication provides excellent outcomes.¹¹

The modes of action have been documented in two studies, demonstrating that SDF develops fluorapatite at the lesion surface, and silver ions precipitate as microwires in dentin tubules.^12,13 The silver ion is known to have strong antimicrobial activity. SDF has been studied for adverse effects, and the only reported concern, as alluded to earlier, is the black discoloration of the lesion. SDF immediately hardens the lesion, but also turns it black. Therein lies the only real clinical issue with SDF.

The material is inexpensive and offers predictable outcomes, albeit at the esthetic cost of the lesions turning black. In my practice this has been an acceptable compromise for many patients. I've used SDF on very young children, saving the parents the cost of hospital dentistry and the risks associated with sedation or anesthesia. In adult patients the use of SDF affords clinicians the chance to arrest lesions and segment treatment phases to help alleviate the financial burden of restorative dentistry. It also provides the opportunity to arrest root surface lesions resulting from gingival recession and medication-induced hyposalivation, which is particularly useful in older adults.

As a practitioner it is a blessing to be able to help memory-care seniors maintain health without extensive dental care. I routinely use SDF in my practice in these applications with great success. SDF has significantly impacted the standard of care for caries prevention and treatment for these patients.

Whether or not this product makes an impact on the profession at large really depends on dentists and hygienists understanding its indications and limitations and adopting its use, and patient acceptance. In my opinion, it is a tool every clinician should have available.

Vineet Dhar, BDS, MDS, PhD
Clinical Professor and Chair, Orthodontics and Pediatric Dentistry, Graduate Program Director, Division of Pediatric Dentistry, University of Maryland School of Dentistry, Baltimore, Maryland

Jeremy A. Horst, DDS, PhD
Postdoctoral Scholar, Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California; Private Practice, San Francisco, California

V. Kim Kutsch, DMD
Mentor, Kois Center, Seattle, Washington; Private Practice, Albany, Oregon