Caries fluoride effects

Mild tooth staining has been observed after use of stannous fluoride products. The ADA Council on Dental Therapeutics endorses fluorides for their caries-inhibiting effect but not for plaque inhibition. 

G.N. Pakhomov, K. Ivanova, I.J. Moller, M. Vrabcheva, Dental caries-reducing effects of a milk fluoridation project in Bulgaria, J. Public Health Dent. 55 (1995) 234-237. 

P.P. Hagen, R.G. Rozier, J.W. Bawden, The caries-preventive effect of full- and halfstrength topical acidulated phosphate fluoride, Pediatr. Dent. 7 (1985) 185-191. 

Because of the low natural levels of fluoride in some water supplies and correspondingly high levels of dental caries, many authorities worldwide have permitted, or instigated, fluoridation of water supplies, although this has met some opposition, partly because of the potential health or dental effects including fluorosis. In order to prevent dental caries, fluoride is deliberately added to salt or milk in some countries. 

In general, saliva (as well as plaque fluid) is supersaturated with respect to calcium-phosphate salts, and they prevent tendency to dissolve mineral crystals of teeth. Moreover, precipitation of calcium-phosphate salts that include hydroxyapatite may also occur (remineralization) in early lesions of tooth surfaces injured by acidic bacterial products (i.e., lactic acid). Salivary fluoride facilitates calcium-phosphate precipitation, and such crystals (i.e., fluorapatite) show lower acid solubility properties that lead to an increased caries preventive effect. The increase of pFI (i.e., buffer capacity and pH of saliva, as well as ureolysis in dental plaque) also facilitates crystal precipitation and remineralization (4, 13). 

Substantial research has been performed on the caries-inhibiting effect of fluoride mouthrinse products. The effectiveness of these topically applied fluorides varies with patient compliance. 

DePaola, P.F. Lax, M. The caries-inhibiting effect of acidulated phosphate-fluoride chewable tablets a two-year double-blind study. JADA 1968, 76, 554-557. 

Fluoride is tenaciously held by the inorganic phase of enamel. In solution at concentrations of less than 100 ppm it replaces hydroxyl ions in the apatite lattice, which is partially converted to fluorapatite. Above this level a second phase of calcium fluoride is formed. These substances have been demonstrated, both in vitro and on the enamel surface where the concentration of fluoride is highest, to be for practical purposes less soluble in slightly acid solutions than is unsubstituted hydroxyapatite. Fluoride likewise becomes concentrated in regions of local demineralization such as enamel defects and areas of incipient caries. Here it replaces hydroxyl ions on the surface of damaged hydroxyapatite crystals, the fluorapatite surface so formed being less vulnerable to further acid attack than if it had remained as hydroxyapatite. Thus in both healthy and carious enamel, fluoride effectively decreases solubility and promotes remineralization of the inorganic phase. 

Moreover, the best analytical procedures available have failed to reveal an increase in the fluorine content of topically treated teeth, although most of the studies of topical applications of fluoride to tooth surfaces have demonstrated caries-preventive effects. The most likely explanation seems to be that fluorine influences the physical and biochemical properties of teeth and particularly of enamel surfaces in vivo perhaps by the surface absorption of minute amounts of fluorine by the OH-apatite of the enamel with the production of a protective layer of acid-resisting fluorapatite. Studies with radioactive fluorine have shown that enamel, dentine, bone, and OH-apatite absorb fluorine according to the Freundlich adsorption isotherm.That physicochemical changes do occur which confer acid-... 

The daily fluoride intake in many areeis of the United States is not sufficient to afford optimal protection against dental caries. Fluoridation of water supplies is the simplest and most effective method of providing such add protection, although it is possible to add fluorine to milk, cereals, and salt, or to take it in tablet form eis sodium fluoride. 

Mechanical removal of plaque is the most effective measure against plaque-caused diseases, dental caries, and periodontal diseases. Even before the advent of fluoride treatments, it was assumed that a clean tooth does not decay. A toothbmsh is effective in removing dental plaque and, for those individuals who optimize its use, it usually can adequately control plaque. Despite the proven efficacy of mechanical plaque removal, the amount of patient involvement is such that only about 30% of the population in developed countries and considerably less in undeveloped countries can be expected to adequately remove plaque (1). Hence, supplementary measures such as dentifrices and dental rinses are necessary. 

Eluoride added to a compatible dentifrice base at a level of 1000 ppm has been clinically proven to reduce the incidence of dental caries by about 25% on average, even in areas where the water supply is fluoridated (4). Elevation to 1500 ppm increases the protection. Sources of fluoride approved for use in dentifrices are sodium fluoride [7681-49-4] (0.22%), sodium monofluorophosphate (0.76%), and stannous fluoride [7783-47-3] (0.41%). The Eood and Dmg Administration regulates fluoridated dentifrices as dmgs and has estabUshed parameters for safe and effective products. CompatibiUty of the fluoride with the abrasive is an important requirement. 

Dissolved mineral salts The principal ions found in water are calcium, magnesium, sodium, bicarbonate, sulphate, chloride and nitrate. A few parts per million of iron or manganese may sometimes be present and there may be traces of potassium salts, whose behaviour is very similar to that of sodium salts. From the corrosion point of view the small quantities of other acid radicals present, e.g. nitrite, phosphate, iodide, bromide and fluoride, have little significance. Larger concentrations of some of these ions, notably nitrite and phosphate, may act as corrosion inhibitors, but the small quantities present in natural waters will have little effect. Some of the minor constituents have other beneficial or harmful effects, e.g. there is an optimum concentration of fluoride for control of dental caries and very low iodide or high nitrate concentrations are objectionable on medical grounds. 

Hamilton, I. R. (1977). The effects of fluoride on enzymatic regulation of bacterial carbohydrate metabolism. Caries Research, 11 (Supplement 1), 321-7. 

Aluminium ions released from the dental silicate cement are also absorbed by hydroxyapatite and have a similar beneficial effect to that of fluoride (Halse Hals, 1976 Putt Kleber, 1985). Thus, the dental silicate cement confers protection against caries (dental decay) on surrounding tooth material. 

It is superior to the zinc phosphate cement for bonding orthodontic bands to teeth (Clark, Phillips Norman, 1977). It has greater durability and there is less decalcification in adjacent tooth enamel. This latter beneficial effect must arise from the release of fluoride which is absorbed by the enamel, so protecting it in a clinical situation where caries-produdng debris and plaque accumulate. 

Controlled and sustained drug delivery has recently begun to make an impression in the area of treatment of dental diseases. Many researchers have demonstrated that controlled delivery of antimicrobial agents, such as chlorhexidine [128-130], ofloxacin [131-133], and metronidazole [134], can effectively treat and prevent periodontitis. The incidence of dental caries and formation of plaque can also be reduced by controlled delivery of fluoride [135,136]. Delivery systems used are film-forming solutions [129,130], polymeric inserts [132], implants, and patches. Since dental disease is usually chronic, sustained release of therapeutic agents in the oral cavity would obviously be desirable. 

The most important form of protection against caries involves avoiding sweet substances (foods containing saccharose, glucose, and fructose). Small children in particular should not have very sweet drinks freely available to them. Regular removal of plaque by cleaning the teeth and hardening of the dental enamel by fluoridization are also important. Fluoride has a protective effect because fluoroapatite (see A) is particularly resistant to acids. 

Fluorides are widely used in caries prevention, for which they have been highly effective. Systemic administration of fluorides for caries prevention is available via drink-... 

Chlorhexidine (C) is generally effective against all bacteria, but Streptococcus mutans and Actinomyces viscosus, two bacteria particularly associated with dental lesions, are especially susceptible to its action. Stannous fluoride (D) is widely used in caries prevention, and many studies have proven its effectiveness. 

Fluorine is an essential element involved in several enzymatic reactions in various organs, it is present as a trace element in bone mineral, dentine and tooth enamel and is considered as one of the most efficient elements for the prophylaxis and treatment of dental caries. In addition to their direct effect on cell biology, fluoride ions can also modify the physico-chemical properties of materials (solubility, structure and microstructure, surface properties), resulting in indirect biological effects. The biological and physico-chemical roles of fluoride ions are the main reasons for their incorporation in biomaterials, with a pre-eminence for the biological role and often both in conjunction. This chapter focuses on fluoridated bioceramics and related materials, including cements. The specific role of fluorinated polymers and molecules will not be reviewed here. 

T. Tanabe, T. Aoba, E.C. Moreno, M. Fukae, Effect of fluoride in the apatitic lattice on adsorption of enamel proteins onto calcium apatites, J. Dent. Res. 67 (1988) 536-542. C. Robinson, S. Connell, J. Kirkham, S.J. Brookes, R.C. Shore, A.M. Smith, The effect of fluoride on the developing tooth. Caries Res. 38 (2004) 268-276. 

When fluoride therapy was first used it was widely assumed that its effect was systemic. In particular, it was assumed to become incorporated into the tooth during development, forming the less acid-soluble fluorapatite rather than hydro-xypatite [18,19]. There was evidence to support this view. For example, studies showed that incidence of caries was lower in areas with fluoridated water and that fluoride concentration was higher in the surface of teeth of subjects in high fluoride areas [20,21]. However, over the last three decades or so, there has been a shift in our understanding, and it is now known that the principal effects of fluoride take place after eruption of the tooth [22],... 

Remineralisation occurs when partly dissolved crystals are induced to grow by precipitation of the mineral-forming ions Ca + and POl". This is a natural process that occurs as a result of the concentration of these ions in saliva [23] and it serves to oppose the demineralising effects of caries. The processes involved are complex [24] and involve dynamic activity at the interface between the tooth, the saliva, the pellicle and the plaque. Fluoride plays a role in enhancing these processes, and though this is not the only contribution that fluoride makes to protect the tooth from caries, it is nonetheless an important one. 

In the presence of fluoride, calcium ions have been found to be more firmly anchored than in pure hydroxyapatite [67]. This enhances the overall resistance to dissolution. Thus, the presence of a thin stable film of fluorapatite on the surface of hydroxyapatite crystals has two effects, namely (i) resistance to diffusion and dissolution of the anion and (ii) firmer binding of calcium ions into the surface. Both of these make the resulting apatite structure more resistant to dissolution, regardless of the pH of the external medium, and they thereby increase the resistance of the mineral phase to the onset of caries. 

Although not the most important effect of fluoride, the effect on hypersensitivity is further evidence of generally beneficial role of this element. More important is its effect of caries. The rest of the chapter is concerned with the ways in which fluoride can be delivered to the teeth of individuals in various populations and how its positive effects are harnessed to promote improved oral health. 

In general, moderate and severe fluorosis is rare. However, mild fluorosis has been detected at significant levels, for example, in 26% of subjects in one recent study [93]. However, the mildness of the fluorosis detected is associated with only very slight changes in the appearance of the teeth, which suggests that, even at these levels, it is not a major public health problem. Nonetheless, it is appropriate to ensure that parents or guardians of children continue to receive sound advice on safe levels of fluoride for those in their care to be exposed to and, since the cariostatic effect of fluoride is known to occur well after enamel formation during tooth development, treatment to reduce caries should concentrate on those measures that carry the lowest possible risks of fluorosis [91]. 

Fluoridation of drinking water has been shown to be highly effective in reducing the incidence of childhood dental caries [128,129], Earlier results were better,... 

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