For a toddler with a cavity, or anyone who finds the drill too much, there is a way to stop decay that involves no needle and no drilling: a few drops of silver diamine fluoride (SDF) painted onto the soft, decayed area. A 2016 systematic review of children's trials found that about 81% of baby-tooth cavities treated with 38% SDF stopped progressing. The catch is cosmetic. The decayed part of the tooth turns dark, usually black.
At Lumi Dental, a dentist or oral health therapist can talk through whether SDF suits your child, alongside other preventive and minimally invasive options.
It stops decay rather than removing it
SDF combines silver, which kills the bacteria driving the decay, with fluoride, which helps harden what is left of the tooth surface. Brushed onto a cavity, it can turn an active, spreading lesion into a hard, stable one.
It does not rebuild tooth that has already been lost, and the decayed tissue stays in place. What it does is stop a cavity from getting bigger, which can buy time for a young child to grow into more involved treatment, or avoid that treatment altogether for a baby tooth that will be lost in a few years.
Applying it is quick. The tooth is kept dry with cotton rolls, a tiny brush paints the liquid onto the decayed area, and it is left to soak in for a short time. There is no injection and nothing to drill. It works well alongside other gentle measures such as fluoride varnish and fissure sealants.
What the research shows
The review by Gao and colleagues, published in JDR Clinical and Translational Research in 2016, pooled eight trials that used 38% SDF on baby teeth. Overall, 81% of active cavities became arrested, with a 95% confidence range of 68% to 89%. Apart from black staining of the arrested decay, the review found no significant complications reported in children.
A single application is not a permanent fix. Teeth treated with SDF are reviewed over time, and reapplication is often recommended at follow-up visits. Your dentist or OHT will suggest a schedule based on how many teeth are affected and how active the decay is.
The dark stain is the main trade-off
When SDF works, the decayed part of the tooth darkens. The treated spot is usually easy to see. On a baby molar at the back of the mouth, many families find this an easy trade for avoiding a difficult procedure, especially as the tooth will fall out naturally. On a front tooth, or for an older child or adult who would be self-conscious, the staining may tip the decision the other way.
Some silver fluoride products add a second step with potassium iodide, which is intended to lessen the discolouration. The evidence that this prevents darkening in the longer term is limited. A small 2025 Australian randomised trial in JDR Clinical and Translational Research by See and colleagues, in 12 adults with special needs, found that treated lesions had darkened significantly by three months with both of the silver fluoride products tested, including one with a potassium iodide step. It is best to expect some dark staining and talk it through before treatment.
| Question | SDF alone | SMART (SDF then a glass ionomer filling) | Conventional filling |
|---|---|---|---|
| Drilling | No | Usually none | Yes |
| Injection | No | Usually none | Often |
| Decayed tissue removed | No, it is arrested | No, it is arrested and sealed over | Yes |
| Tooth shape rebuilt | No | Yes | Yes |
| Look of the treated area | Dark | Partly covered by tooth-coloured filling | Tooth-coloured or metal |
SMART adds a filling on top
SDF on its own leaves a hole in the tooth, which can trap food and be harder to clean. The SMART technique (silver modified atraumatic restorative technique) adds a second stage: once the decay has been treated with SDF, a tooth-coloured glass ionomer filling is placed over it. This seals the cavity, restores the shape of the tooth for chewing and cleaning, and hides some of the staining. It is usually done without drilling or local anaesthetic. Our article on SMART fillings explains the technique step by step.
Who it suits
SDF is especially useful for very young children with early cavities who cannot yet manage a filling, children with several cavities where treating them all at once would be overwhelming, and people with additional needs or high anxiety for whom conventional treatment is hard. It can also hold a tooth stable until fuller treatment is possible.
Adults can have it too, for example on decay along exposed root surfaces, although the staining is often more of a concern for adults.
It is a way of managing decay, not a substitute for daily care. Our guides on early childhood tooth decay and how much fluoride toothpaste children need cover prevention at home.
Seeing an oral health therapist at Lumi
Oral health therapists are registered dental practitioners trained in prevention and in treating children and adults with minimally invasive techniques. At Lumi, our oral health therapists Sabrina Tran and Jennifer Nguyen see children, adults and families and focus on prevention and gum health. If SDF is suitable, treatment may be spread over more than one appointment, with SDF applied first and a filling placed at a follow-up visit where needed. When booking, mention that you would like to discuss SDF.
Questions parents ask about SDF
Does it hurt?
It is not usually painful. It is painted on, with no drilling or injection, and most children manage it well.
Why does the tooth turn black?
The silver reacts with the decayed tooth tissue and darkens it. It is mainly the decayed area that darkens. A SMART filling can cover part of the treated area.
Is it covered for children?
Eligible children aged 0 to 17 may be able to receive treatment bulk billed under the Child Dental Benefits Schedule, which has a benefit cap of $1,158 over two calendar years in 2026. Our CDBS guide explains who is eligible and what is covered.
Booking SDF or SMART treatment
Silver diamine fluoride offers a usually painless way to stop many cavities from progressing, with the trade-off of a dark stain that can be partly covered by a SMART filling. To book, contact our team and ask about SDF for your child. Current offers are on the current deals page.
This article is general information and not a substitute for personalised advice. A clinical examination is needed to confirm whether SDF or SMART is suitable.
