Silver diamine fluoride (SDF) is a liquid applied to teeth to stop cavities from getting worse. It contains roughly 25% silver, 5% fluoride, and 8% ammonia dissolved in water, and it works by killing bacteria on the tooth surface while strengthening the remaining tooth structure. The FDA classifies it as a Class II medical device, cleared for treating tooth sensitivity, though dentists widely use it off-label to arrest active decay in both children and adults.
How SDF Stops Cavities
SDF works through two complementary actions. The silver component is antimicrobial: it disrupts the bacteria responsible for tooth decay, effectively sterilizing the cavity. Meanwhile, the fluoride reacts with calcium in saliva to form calcium fluoride almost immediately on the tooth surface. Over the next 24 hours or so, that calcium fluoride gradually converts into a harder, more acid-resistant mineral that integrates into the tooth structure. This process essentially plugs and reinforces the damaged area, making it far more resistant to further breakdown.
The ammonia in the solution keeps the silver and fluoride stable and in liquid form so they can penetrate into the decayed tooth structure rather than sitting on the surface. Together, these ingredients don’t just slow decay. They can stop it entirely.
How Well It Works
The American Academy of Pediatric Dentistry estimates that about 68% of cavitated lesions in baby teeth are arrested within two years of SDF application, with treatments applied once or twice a year. In studies with larger sample sizes and longer follow-up, the arrest rate climbed to roughly 72%, compared to 50% in control groups. That’s a meaningful difference, especially considering how simple the treatment is.
Most of the strong clinical data comes from studies on primary (baby) teeth. Evidence for permanent teeth, including root cavities in older adults, is growing but less robust. Still, the FDA designated one SDF product as a “breakthrough therapy” for arresting cavities in both children and adults back in 2016, a designation reserved for treatments that address an unmet medical need.
What the Application Looks Like
The procedure is fast and painless. No drilling, no numbing shots. A dentist or other dental professional isolates the tooth, dries it, and brushes a small amount of the liquid directly onto the cavity with a tiny applicator. One drop of SDF can treat up to five cavities depending on their size, and a maximum of eight drops is used per visit. The entire process for a single tooth takes under a minute.
Reapplication is typically recommended every six to twelve months to maintain the protective effect. The tooth is checked at each visit, and if the cavity has hardened and darkened (a sign the treatment is working), additional SDF is applied to keep it arrested.
The Staining Trade-Off
The biggest drawback of SDF is cosmetic. When silver reacts with the decayed portion of a tooth, it turns that area permanently black. Healthy enamel surrounding the cavity is not significantly affected, but the dark spot on the decay is obvious and irreversible without a filling or crown placed over it. On back teeth or baby teeth that will eventually fall out, this is often an acceptable trade-off. On visible front teeth in adults, it’s a harder sell.
SDF can also temporarily stain skin and gums on contact, though those stains fade within a few days to weeks. Dental professionals wear gloves during application because the solution stains anything it touches, including countertops and clothing.
Who Benefits Most
SDF is especially valuable for patients who can’t easily tolerate traditional dental work. Young children who aren’t cooperative enough for drilling and fillings are a primary group. So are older adults with root decay, people with disabilities that make long dental appointments difficult, and patients in settings where access to a full dental operatory is limited, such as nursing homes, schools, or rural clinics.
It’s also used as a temporary measure to buy time. A child with multiple cavities might receive SDF to halt the decay while a more comprehensive treatment plan is arranged, or while waiting for baby teeth to naturally shed. For patients with high anxiety about dental procedures, it can serve as a low-stress first step.
People with a known allergy to silver should not receive SDF. It’s also avoided on teeth with exposed pulp (the nerve inside the tooth) or on areas with open sores in the mouth.
Cost and Coverage
SDF is one of the least expensive treatments in dentistry. It has its own billing code (D1354), and in states like California, Medicaid pays $12 per tooth for the application. Private insurance coverage varies, but even out of pocket, the cost per tooth is typically far less than a filling. For families managing multiple cavities in young children, the savings can be substantial, both in dollars and in avoided sedation or operating room visits.
SDF Is Not a Filling
It’s worth understanding what SDF doesn’t do. It stops decay, but it doesn’t rebuild the tooth’s shape or restore its full function. A cavity treated with SDF remains a cavity in terms of its physical form. For small cavities or those in less structurally important areas, that’s perfectly fine. For larger cavities where the tooth needs structural support to handle chewing forces, a filling or crown is still the better long-term solution. Many dentists use SDF as a complement to traditional restorative work rather than a replacement for it.