Tin(II) fluoride

Tin(II) fluoride, also known as stannous fluoride, is a chemical compound. Its chemical formula is SnF2. It contains tin and fluoride ions. The tin is in its +2 oxidation state.
Properties.
Tin(II) fluoride is a colorless crystalline solid. It dissolves in water. It is a reducing agent. It can be oxidized to solid tin(IV) fluoride, which does not work for dentistry.
Preparation.
It is made by reacting tin or its oxide with hydrofluoric acid. 
Uses.
It is commonly used in toothpastes as a source of fluoride ions. The fluoride ions react with the enamel of the tooth, making it harder to attack by bacteria. It also stops gingivitis. Some mouthwashes have tin(II) fluoride in them.