Polyphosphates constitute a wide variety of compounds that have beneficial effects on oral health, the most effective of these are the hexametaphosphates, tripolyphosphates and pyrophosphates and may be attached with an alkali metal, alkaline metal, ammonium or a salt.[16] Sodium tripolyphosphates as an example, are able to bind directly to the enamel as well as the mineralized sections of the teeth where it takes up the binding sites for calcium to attach, and interacts with calcium already bonded to enamel, to prevent it being able to form crystals.[2][3][17] Calcium mixed in the saliva can also be bound by sodium tripolyphosphates thus further preventing crystal formation.[14] Sodium tripolyphosphates are also beneficial for stain prevention, and can be broken down in the digestive tract and provide a source of phosphorus and allows the undeposited calcium to be available for whole body metabolism.[14][17]