Tin(II) fluoride

Stannous fluoride is the chemical compound with the formula SnF₂. This colourless solid is a common ingredient in toothpaste. In the enamel, it converts apatite into fluoroapatite, which is more resistant to attack by acids generated by bacteria. Sodium fluoride and sodium fluorophosphate perform similarly.

Stannous fluoride was used (under the trade name Fluoristan) in the original formulation of the toothpaste Crest, though it was later replaced with sodium monofluorophosphate.

Stannous fluoride can be used with abrasives that contain calcium, which prevents sodium fluoride from being effective.