Fluoride is a mineral which in the presence of calcium and phosphate has the ability to remineralize tooth enamel. Small incipient caries (cavities) can actually reversed in this process.
As stated earlier, fluoride is a naturally occurring mineral in most drinking water. Many water districts will monitor this level daily and add fluoride to the water to reach the optimum 0.7 milligrams of fluoride per liter.
It is important to note that excessive fluoride is detrimental to a person. Consuming excessive amounts of fluoride from dental products or dietary supplements can cause nausea, vomiting, abdominal pain, diarrhea, bone pain, and even death in rare cases. Getting too much fluoride over a long period of time can lead to a condition called skeletal fluorosis. In skeletal fluorosis the bones are generally weaker than normal with stiffness and pain in the joints as the early symptoms.
Orally, It can also produce dark and light stains on teeth if ingested during the developmental phase of a child’s life. Ironically the excessive exposure to fluoride can actually weaken teeth.
Despite the negative effects of excessive exposure to fluorine, the ADA recommends fluoridation of water in municipal water systems. Studies since the 1950s have revealed properly fluoridated water systems have reduced caries (cavities) by 25%.