What is fluoride varnish?
Fluoride varnish is a concentrated topical fluoride painted onto the teeth at the end of a cleaning. It takes under a minute, tastes like the flavor your child picked, and strengthens enamel enough to reverse the earliest stage of decay.
Your child can eat right away. Avoid hot drinks and hard or crunchy food for a few hours, and skip brushing until the next morning so the varnish has time to work.
What is silver diamine fluoride?
Silver diamine fluoride, or SDF, is a liquid painted directly onto a cavity to stop it from progressing. No drill, no needle, about a minute per tooth.
It is genuinely useful in three situations: a very young child with decay who cannot yet sit for a filling, a child with special healthcare needs for whom a filling would require sedation, and a baby tooth that will fall out before the decay would ever cause trouble.
Will silver diamine fluoride stain my child’s tooth?
Yes. The treated decay turns permanently black, and it does not fade.
On a back molar nobody will ever see it. On a front tooth it is obvious, and we will show you a photograph of what that actually looks like before you decide. A lot of families land on SDF for the back teeth and a tooth-colored filling for the front ones, which is a completely sensible answer and the one we most often recommend ourselves.
SDF is not a permanent fix. It buys time, and sometimes the time is all you need.
Last reviewed January 2026 by Brightburrow clinical staff.