Flouride is the reduced form (molecular derivative) of the chemical element fluorine, there are both organic and inorganic types of fluoride. There are several substances containing the element fluorine that are identified as fluoride although it is important to note their biological effects are extremely different. The types of fluoride in tooth paste and used to fluoridate water is hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2SiF6).