Define fluorides Metabolism?
Soluble fluorides, even at high intake levels are almost completely absorbed from gastrointestinal tract. These include aqueous solutions of fluorides, sodium fluoride (NaF) used in toothpastes, and sodium fluorosilicate used in water fluoridation. However, its availability from solid foods is only about 50%-80% of that absorbed from aqueous solutions. This is because in foods, it may be bound to proteins and on hydrolysis by enzyme proteases, may still be less available for absorption, Peak plasma concentrations occur within 30-60 minutes of ingestion. Fluoride absorption occurs through diffusion.
Once absorbed, the fluoride passes into the blood for distribution chiefly to the calcified tissues. Most of the ionic fluoride enters the bone and developing teeth where the fluoride ion replaces the hdroxyl or bicarbonate in the hydroxyapatite and forms fluoroapatite. About half of the fluoride absorbed each day is deposited in the skeleton or teeth within 24 hours. Nearly 99% of the fluoride in the body is in the calcified tissues. Fluoride in the bone is in a reversible pool and can exchange for other ions such as hydroxyl ions during the process of bone remodelling. The only positive role clearly demonstrated for fluoride, however, is in the prevention of dental caries.