Compounds containing fluoride are used for the prevention of tooth decay. Most commonly found in toothpaste and mouthwash, it is also added to the public drinking water in the US.
Fluoridation develops low concentrations of fluoride ions in saliva and helps the formation of fluorapatite that remineralizes teeth enamel. Adding calcium to fluoride treatments helps reduce cavities even more,
While harmful in high concentrations, a low concentration can be found in many products like mouthwash or contact lens solution. It is used to fight against fungi and enveloped viruses. For dental use it most effective for reducing plaque and oral bacteria. Chlorhexidine lasts longer than other mouth washes and is the preferred treatment for gingivitis.
There are some negative effects of long term use of Chlorhexidine including stains on teeth and may alter taste sensations.