The most common type of fluoride found in toothpaste is part of the compound sodium fluoride, which has the chemical formula NaF. Other types, such as stannous fluoride (SnF2), are sometimes used in toothpaste. Fluoride is a negative ion of the element fluorine, which is used to help strengthen tooth enamel and prevent tooth decay.
As of 2014, all toothpastes with the American Dental Association (ADA) Seal of Acceptance contain fluoride. To meet the requirements of the ADA, the toothpaste's manufacturer must prove that the product has been shown to be safe and effective in clinical trials. In addition, the manufacturer must conduct ADA laboratory tests to show the amount of available fluoride present in the toothpaste, the amount of fluoride released in 1 minute and the amount of fluoride absorbed by the teeth.