Design: Phase III multisite randomised, blind, placebo-controlled trial with two applications six months apart
Population: 830 children aged 12-71 months with severe early childhood caries and active cavitated lesions, mean dmft 11.4
Primary outcome: Proportion of lesions arrested at six months after one application
Effect: Arrest 54.0% vs 22.5% at six months, difference 31.5 percentage points (99.9% CI 21.5-41.6); 57.5% vs 18.8% at three months and 50.2% vs 17.4% at eight; no difference in pain or in treatment-related adverse events

Severe early childhood caries in a one- to five-year-old usually means restorative dentistry, and in a small, frightened child that often means a general anaesthetic. This phase III placebo-controlled trial enrolled 830 children aged 12 to 71 months with active cavitated dentine lesions from clinics and subsidised preschool programmes, and randomised them to 38% silver diamine fluoride or placebo, painted on at baseline and again at six months.

By intention to treat, silver diamine fluoride arrested 57.5% of lesions at three months, 54.0% at six and 50.2% at eight, against 18.8%, 22.5% and 17.4% with placebo. The difference at six months was 31.5 percentage points (99.9% CI 21.5-41.6). There was no difference in pain, and adverse events were similar between the groups — 47.3% versus 43.3%, mostly mild to moderate, with four severe events across the whole trial.

What this offers is a painless, drill-free, chairside way to stop active decay in children who are too young, too anxious or too far from a paediatric dentist for restorative care. It is not a restoration: arrested lesions are still cavities, they stain black permanently, and the child still needs dental follow-up. But halting the process in half of lesions with a brush-on application changes what a paediatrician in a place with no paediatric dental service can offer — from advice alone to treatment.

Silver diamine fluoride arrests lesions; it does not restore the tooth, and dental follow-up is still needed
Warn parents in advance that treated lesions stain black permanently — this is the commonest reason for complaint
Two applications six months apart were used here
Consider it first where general anaesthesia is the alternative for a very young child
Around 30% of this trial's participants were lost to follow-up, some to the pandemic

Why it matters

It converts severe early childhood caries from a problem that needs an operating list into one that can be treated in a clinic room.

The statistics, in plain English

The intervals here are 99.9% rather than the usual 95%, a stricter threshold that makes the result harder to achieve and therefore more convincing when met: the difference at six months is between 21.5 and 41.6 percentage points. Roughly a fifth of lesions arrested spontaneously in the placebo group, which is why the comparison rather than the raw arrest rate is the number that matters. Thirty per cent loss to follow-up is substantial and intention-to-treat analysis handles it conservatively rather than eliminating the concern.