Teeth fluorosis

F excess Baltic Sea States, Belarus, Moldova, Central Yakutia, Kazakstan Excessive content of F in natural waters, > 1.0-1.5 ppm. Low content of F in soil and plants Tooth enamel dystrophy. Fluorosis and spotted teeth of human and animals... 

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]. 

A. Thylstrup, O. Fejerskov, Clinical appearance of dental fluorosis in permanent teeth in relation to histologic changes, Commun. Dent. Oral Epidemiol. 6 (1978) 315-328. 

Dental or enamel fluorosis is an irreversible dose-response effect caused by fluoride ingestion during the pre-eruptive development of teeth. The pre-eruptive maturation of crowns of the anterior permanent teeth, which are of most concern aesthetically, is complete and, together with the risk of fluorosis, is over by the age of 7-8 years [46,47]. After the enamel has completed its pre-eruptive maturation, it is no longer susceptible. Therefore, fluoride intake up to the age of 7-8 years is of most interest. Although it is usually the permanent teeth that are affected, occasionally the deciduous teeth may be also involved. 

Several methods have been developed for quantifying dental fluorosis. The most commonly used method is Dean s index [49], which classifies fluorosis on a scale of 0 to 4 as follows class 0, no fluorosis class 1, very mild fluorosis (opaque white areas irregularly covering <25% of the tooth surface) class 2, mild fluorosis (white areas covering 25-50% of the tooth surface) class 3, moderate fluorosis (all surfaces affected, with some brown spots and marked wear on surfaces subject to attrition) and class 4, severe fluorosis (widespread brown stains and pitting). The average score of the two most severely affected teeth is used to derive the classification. Other commonly used methods to rate dental fluorosis include the Thylstrup-Fejerskov Index (TFI) [50] and the tooth surface... 

Fig. 2. Teeth demonstrating fluorosis. A high level of dietary fluoride has resulted in much of the enamel becoming opaque in patches, giving a mottled appearance. (Reprinted with permission from [48]. Copyright 2002 Mosby International Limited.) (See Colour Plate Section at the end of this book.)...

Small amounts of fluoride have been proven to be effective in preventing dental caries, but excessive, chronic intake by young children can result in the development of dental fluorosis the critical period of exposure for all permanent teeth... 

Fluorine 3 g 1.5-4 mg Structure of teeth, bones Dental caries, possibly osteoporosis Dental fluorides severe fluorosis in parts of India and South Africa... 

The toxic nature of fluoride ion, F, is not confined to its presence in HF. It is toxic in soluble fluoride salts, such as NaF. At relatively low levels, such as about 1 ppm, used in some drinking water supplies, fluoride prevents tooth decay. At excessive levels, fluoride causes fluorosis, a condition characterized by bone abnormalities and mottled, soft teeth. Livestock are especially susceptible to poisoning from fluoride fallout on grazing land as a result of industrial pollution. In severe cases, the animals become lame and even die. 

The effect of fluoride in ptevenring dental caries was recognized when it was found that levels of tooth decay were low in regions of the world where the water supply naturally contained high levels of fluoride. In some regions, the levels of fluoride are so high that they cause a harmless mottling of the teeth called "fluorosis." Both the first set and the permanent set of teeth benefit from dietary fluoride. Water and other fluids account for most of our fluoride intake. 

Fluorine (F) and its metabolites are of importance in protecting teeth from caries. Fluorine is included in calcium hydroxyapatite, and it promotes the precipitation of calcium phosphate Ca(P03)2 and accelerates the remineralization. The necessary concentration of Fluorine added to drinking water to prevent caries is approximately 1 mg/L. Application of higher Fluorine concentrations (above 8 mg/L) leads to fluorosis. This is a disease that is characterized by a disturbance in the function of the thyroid gland. A long-term application of fluorine leads to intensive mineralization (possible precipitation of calcium sulfate), deformation of bones with possible accretion, and calcification of the connections. 

External bleaching is indicated for teeth that are disclosed from aging, fluorosis, or staining due to the... 

In cattle, fluorosis can take the form of intermittent lameness (Figure 8.4) as well as stiffness and lesions of the bones and teeth. The clinical basis for the lameness is not well understood. Appetite is normally impaired and this may result in decreased weight gain, cachexia, and lowered milk yield. Decline in milk production may be secondary to appetite impairment or other responses. Evidence that animals may be suffering chronic F effect may be obtained from chemical analysis of the feed and elevated levels of F in urine and body tissues (Parker et al. 1979). Other effects include increased susceptibility to other environmental stresses and decrease in longevity. 

This chapter describes how individuals with severe enamel fluorosis (mottled tooth enamel) became associated with fluoride in the public water supply and protection from dental caries. A comparison of caries experience with the fluoride content of public water supplies and enamel fluorosis in adolescents indicated that 1 pg fluoride/mL (1 part/million) in the water provides caries protection with minimal enamel fluorosis (sect. 1). One mechanism is the spontaneous isomorphic replacement of apatite s hydroxide anions with fluoride, which reduces enamel solubility. A second is fluoride-mediated inhibition of enolase, which retards bacterial acid production at teeth surfaces. These findings led to the use of fluoride in toothpastes, which provides better protection from caries at tooth surfaces than water fluoridation alone (sect. 2). The chapter concludes with a discussion of potentially harmful effects of fluoride ingestion (sect. 3). 

Fluoride is both incorporated into enamel crystals and also affects the enzymes involved in enamel formation (Sect. 16.2.2), causing mottled enamel, a severe example of enamel fluorosis. Enamel fluorosis is evident as specks or white flecks on the enamel surface (Fig. 16.2b). In 1941, the public water supply of Aurora (IL) contained 1.2 ppm of fluoride (F), but only 5% of teeth exhibited fluorosis, mostly premolars and second molars. A sensitive index of... 

Fig. 16.4 Index of fluorosis. Figure depicts moderate to severe fluorosis of the lateral incisor, canine, and second molar teeth index values of 4 and 5 (Copied from the University of Oklahoma Library Collection circa 1990, Source unknown)...

Fig. 16.5 Relationship of DMFT and index of fluorosis to water fluoride content. The left y-axis indicates the number of decayed missing and filled teeth from caries (DMFT) and the right y-axis indicates the index of fluorosis, a measure of the deleterious effect of fluoride on the enamel surface (see text). The x-axis indicates the ppm fluoride found naturally in the drinking water supply. Triangles indicate DMFT and circles indicate the fluorosis index in the same populations. The curves showing the decrease in caries and decrease in fluorosis intersect at 1 ppm fluoride in the water supply on the x-axis (Copy of Fig. 3 from Hodge HC, Smith FA. (1954). Some public health aspects of water fluoridation. American Association of the Advancement of Science Publication No 19 Washington DC 1954 AAAS 1954, pp. 79-109)...

The fluoride ion can replace the hydroxide ion in a crystal without significantly altering its structure, an isomorphous ion replacement. Fluoride also affects the enzymes involved in enamel formation, causing mottled enamel, a severe example of enamel fluorosis. White opaque patches on the normally translucent enamel indicate mild fluorosis. Fluorosis is measured on a grade of 0-5 where 1 through 3 indicate an increased cover of opaque white patches on the tooth surface, and 4 and 5 indicate an increased mottling. The two worst affected teeth make up an individual s score. The community s index of fluoridation is the mean score for all individuals. As the natural or artificial fluoride concentration of the water supply increases to 1 ppm, the mean number of cavities in 10-12 year-old children decreases from 7 to 3. Above 1 ppm fluoride, caries does not decrease much more, but the index of fluorosis increases markedly. This is the reason why public water supplies are fluoridated to only 1 ppm and not more or less. 

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