Key Takeaway: Silver diamine fluoride (SDF) is a liquid applied directly to cavities in children’s teeth to stop decay from progressing. Health Canada approved 38% SDF in 2017 for the prevention and arrest of dental caries, and the American Academy of Pediatric Dentistry (AAPD) includes it in its evidence-based guidelines for caries management. SDF works by killing cavity-causing bacteria and strengthening weakened tooth structure. The trade-off is cosmetic: treated areas turn dark brown or black. SDF is best suited for shallow cavities, very young children who aren’t ready for conventional dental treatment, or situations where buying time before a filling or crown makes clinical sense. It is not a replacement for fillings or crowns when decay is deep or approaching the nerve. A pediatric dentist decides when SDF is the right tool based on the size, location, and depth of each cavity.
A parent hears “your child has a cavity” and immediately pictures a drill. This is not always the case Depending on the size and location of the cavity, and the child’s age, a drill isn’t always the first step. Sometimes the first step is a tiny brush and a drop of liquid.
What Is Silver Diamine Fluoride?
SDF is a clear liquid made of silver, fluoride, ammonia, and water. The silver kills the bacteria that cause decay. The fluoride hardens the weakened tooth structure underneath. When you combine those two actions, the cavity doesn’t just slow down. In many cases, it stops altogether.
Health Canada approved 38% silver diamine fluoride in February 2017 under the brand name Advantage Arrest. It had already been used for decades in Japan and other countries for exactly this purpose. The Canadian Dental Association (CDA) now lists 38% SDF alongside fluoride varnish as a professional fluoride treatment option, and the AAPD made a conditional recommendation for its use in arresting cavitated caries in primary teeth as part of a broader caries management programme.
The application itself takes about a minute. We dry the tooth, brush SDF onto the cavity with a tiny applicator, let it sit for 60 seconds, and that’s it. No freezing. No needles. No drilling. For a two-year-old who can barely sit still for a cleaning, that difference is enormous.
Why Does It Turn the Tooth Black?
This is the part nobody loves. When SDF reacts with the decayed portion of the tooth, it deposits silver compounds that oxidize and turn dark brown or black. The healthy enamel around the cavity doesn’t change colour. But the spot where the decay was? It goes dark.
That staining is actually the sign that the treatment worked. The dark colour means the silver has penetrated the decay, killed the bacteria, and hardened the area. A dentist looking at a previously treated tooth can tell at a glance whether the SDF has done its job: dark and hard means arrested; soft and light means the decay is still active and needs reapplication or a different approach.
For back teeth, most parents find the colour a non-issue. Nobody sees those molars. Front teeth are a tougher conversation. We always discuss the staining before treatment so parents can weigh the trade-off: a dark spot on a baby tooth that will eventually fall out, versus sedation or general anaesthesia to place a filling on a child who isn’t developmentally ready for that experience.
Which Cavities Does SDF Work Best For?
Not every cavity is a candidate.
Shallow cavities that haven’t reached the nerve respond well. The AAPD’s chairside guide specifies cavitated caries lesions that are not encroaching on the pulp. If x-rays show the decay is close to or has already reached the nerve, SDF alone won’t cut it. That tooth likely needs a filling, crown, or pulp therapy.
Small cavities on baby teeth that your child won’t lose for years are a common use case at our practice. A shallow cavity on a second baby molar in a three-year-old might be better managed with SDF now, then monitored at recall exams and treated with a filling later when the child is more cooperative.
SDF also makes a lot of sense for kids with special healthcare needs, children with severe dental anxiety, or toddlers where the risks of sedation outweigh the benefit of conventional treatment for one small cavity.
On the other hand, a large cavity that’s undermined the tooth structure needs a crown to hold things together. And if a child has a silver allergy (rare, but we always ask), SDF is off the table. It’s one tool in a pediatric dentist’s kit, not the only one.
Does SDF Mean My Child Won’t Need a Filling Later?
Sometimes, yes. For very small cavities on baby teeth, especially teeth that will fall out within a year or two, SDF may be the only treatment needed. The AAPD notes that arrest rates range from 47 to 90 percent with a single application, depending on the cavity’s size and location. Front teeth arrest at higher rates than back teeth. Reapplication every few months improves those numbers.
But for larger cavities, SDF is more of a bridge than a destination. It buys time. It stops the decay from getting worse while you wait for the child to reach an age where they can sit comfortably for a filling or until a space in the surgical schedule opens up for kids who need sedation. The cavity still exists; it’s just been arrested. Your pediatric dentist will let you know whether the plan is “SDF and done” or “SDF now, filling later.”
Is SDF Covered by Insurance in Ontario?
Coverage varies by plan, but SDF is a recognized treatment and most private dental insurance plans in Ontario will cover it. If your family is enrolled in Healthy Smiles Ontario (HSO) or the Canadian Dental Care Plan (CDCP), ask about coverage before the appointment. We can help you check.
SDF is also one of the most affordable treatments in pediatric dentistry. The application takes minutes, requires no anaesthesia, and uses very little material.
What Happens After SDF Is Applied?
We typically want to see the tooth again in two to four weeks. Dark and hard means arrested. We’ll keep monitoring at regular recall visits and reapply SDF every three to six months if needed.
Your child can eat and drink right after. No restrictions. Some kids notice a metallic taste for a few minutes, but it fades fast.
The bigger piece is what’s happening at home. The bacteria that caused the cavity don’t disappear just because we treated the tooth. Brushing twice a day with fluoride toothpaste, cutting back on juice and snacks between meals, and keeping up with dental visits are what prevent new cavities from forming. Our cavity prevention guide goes deeper on that.
If your child has a cavity and you’re wondering whether SDF might be an option, bring it up at your next appointment with a kids’ dentist in Toronto you trust.
Questions about SDF or your child’s cavity? Contact Little Pearls Pediatric Dentistry ⬇️
- Address: 81 Billy Bishop Way, Unit D2, North York, ON, M3K 0C2 | View on Google Maps
- Phone: 416-960-4422
- Email: [email protected]
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