Mechanisms of Action of Fluoride for Caries Control

Abstract

Fluoride was introduced into dentistry over 70 years ago, and it is now recognized as the main factor responsible for the dramatic decline in caries prevalence that has been observed worldwide. However, excessive fluoride intake during the period of tooth development can cause dental fluorosis. In order that the maximum benefits of fluoride for caries control can be achieved with the minimum risk of side effects, it is necessary to have a profound understanding of the mechanisms by which fluoride promotes caries control. In the 1980s, it was established that fluoride controls caries mainly through its topical effect. Fluoride present in low, sustained concentrations (sub-ppm range) in the oral fluids during an acidic challenge is able to absorb to the surface of the apatite crystals, inhibiting demineralization. When the pH is re-established, traces of fluoride in solution will make it highly supersaturated with respect to fluorhydroxyapatite, which will speed up the process of remineralization. The mineral formed under the nucleating action of the partially dissolved minerals will then preferentially include fluoride and exclude carbonate, rendering the enamel more resistant to future acidic challenges. Topical fluoride can also provide antimicrobial action. Fluoride concentrations as found in dental plaque have biological activity on critical virulence factors of S. mutans in vitro, such as acid production and glucan synthesis, but the in vivo implications of this are still not clear. Evidence also supports fluoride's systemic mechanism of caries inhibition in pit and fissure surfaces of permanent first molars when it is incorporated into these teeth pre-eruptively.

Impact of Experimental Nano-HAP Pastes on Bovine Enamel and Dentin Submitted to a pH Cycling Model

“…The constant presence of low fluoride concentration in the oral fluids during an acidic challenge favors its absorption to the surface of the apatite crystals, inhibiting demineralization. When the pH is reestablished, traces of fluoride in oral fluid will make it highly supersaturated with respect to fluorhydroxyapatite, which will speed up the process of remineralization (25). Further studies should be performed to test the remineralizing effect and the dentin obliteration potential of the experimental F paste.…”

Water fluoridation: It really is this simple

“…The fluorapatite crystals are more symmetric and stack better than hydroxyapatite, resulting in the formation of stronger teeth with shallower fissures, and enamel that is more resistant to decay. [73] After topical exposure to fluoride in dental products (e.g. toothpaste) or water, fluoride can be found in several compartments in the oral cavity: ionized in saliva and plaque fluid, bound as calcium fluoride, bound to enamel, and bound to soft tissues.…”

“…toothpaste) or water, fluoride can be found in several compartments in the oral cavity: ionized in saliva and plaque fluid, bound as calcium fluoride, bound to enamel, and bound to soft tissues. [74] A constant low level of fluoride ion in saliva and plaque fluid reduces the rate of enamel demineralisation during the caries process and promotes the remineralisation of early caries lesions [72,73] The usual levels in saliva are 0.03 mg/L fluoride or less, dependent on the use of fluoride products and fluoride in the drinking water. Models have predicted that a concentration of 0.1 mg/L fluoride in saliva would be almost completely protective against caries progression.…”

“…Although fluoride is not essential for tooth development, enamel containing fluoroapatite is more resistant to acids (dissolves at a lower pH) than enamel containing only hydroxyapatite. [73,209] However, studies of fluoride supplementation in pregnancy have not shown them to be effective, and because of the possibility of increased risk of fluorosis, fluoride supplements are no longer recommended.…”

Children with orofacial clefts : dental caries and health-related quality of life

“…In addition, development disturbances in dental hard tissues with less mineral in enamel and dentine, increases the vulnerability for demineralization (Oliveira, Chaves et al 2006, Targino, Rosenblatt et al 2011, Vargas-Ferreira, Salas et al 2015. On the contrary, frequent local fluoride exposures will inhibit demineralization and stimulate remineralization of tooth minerals in enamel and dentine (Fejerskov, Thylstrup et al 1981, Buzalaf, Pessan et al 2011, ten Cate 2013. Moreover, good oral hygiene, with less amount of biofilm, reduces the amount of acid producing bacteria.…”