Amounts of fluoride in self-administered dental products: safety considerations for children.

With the increased use of various fluoride preparations for caries prevention, all dental personnel should know their potential toxicity and the margins of safety associated with their use. An understanding of the body's mechanisms for handling fluoride provides a rational basis for assessing the possible risks of excessive fluoride ingestion. Five to 10 g of sodium fluoride is considered a certainly lethal dose for a 70-kg adult. One quarter of the certainly lethal dose can be ingested without producing serious acute toxicity and is known as the safely tolerated dose. Comparisons of certainly lethal and safely tolerated doses for commonly used fluoride agents and procedures show that they can be applied with little or no risk of adverse acute effects, as long as they are used judiciously. If their use is abused, there is a risk of illness or even death. If amounts of fluoride close to the certainly lethal dose are ingested, the speed of initiating proper treatment is critical for survival. Vomiting should be induced, if it is not spontaneous; fluoride-binding liquids, such as milk or liquid or gel antacids, administered; and the patient taken to the nearest hospital for emergency care. Frequent ingestion of low but excessive quantities of fluoride during the period of tooth formation can lead to dental fluorosis. Particular concern is warranted for the ingestion of fluoride-containing toothpastes by young children and the inappropriate use of dietary fluoride supplements in communities with sufficient fluoride already present in drinking water.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of fluoride ingestion on white-tailed deer (Odocoileus virginianus).

The effects of the addition of 25 or 50 ppm fluoride (F), as sodium fluoride (NaF), to the rations of 5-mo-old male white-tailed deer were similar to those observed in domestic cattle fed similar amounts of fluoride. The ingestion of 50 ppm F for 2 yr resulted in the accumulation of over 7,000 ppm F in bone ash. Accumulation of fluoride in antlers was extensive and occurred more rapidly than in skeletal tissue. Fluoride ingestion resulted in lesions on the developing incisors that were similar, but not identical to those seen in other species. Increased molar wear in the deer fed 50 ppm F was minimal, and no gross pathology of the mandible was observed. Only mild hyperostosis of the long bones was evident.

Dental fluorosis in bovine temporary teeth.

Deciduous incisors from calves born to dams fed an average of 40 mg of fluoride/kg of forage ration (40 ppm) were compared with incisors from calves born to dams fed a normal dairy ration. Skeletal fluoride concentration in the calves born to fluoride-fed dams was increased 5 to 8 fold, but enamel mottling and hypoplasia, typical of permanent bovine incisor dental fluorosis were not seen by gross, histologic, or radiologic examination. Decreases in the amount of enamel on the tooth or hardness of the enamel were not observed. These data do not support recent reports of widespread dental fluorosis of deciduous bovine teeth as a clinical sign of fluoride toxicity.

Histological, macroscopic and microhardness observations of fluoride-induced changes in the enamel organ and enamel of sheep incisor teeth.

When aged 8.5 months, 10 sheep born in the same week were given 4 mg fluoride (F)/kg body weight orally for 26 days. Three sheep received no F. Sheep were killed at the end of the treatment period and later at selected stages of tooth development. The macroscopic changes in the enamel of one incisor were related to the cellular changes in the enamel organ of the contralateral tooth. A break in enamel continuity, hypoplasia, was seen on the labial enamel of 9 of the 10 F-treated sheep. Pitting of the enamel was associated with shortening of some ameloblasts and aggregations of cysts affecting cells late in their secretory phase in the first-killed sheep. In sheep killed later, these changes were associated with cells which had progressed into their maturation phase. A more extensive absence of enamel with ledge formation cervically, seen in one sheep, was associated with displacement or death of almost all the cells in their secretory phase during F treatment and consequent retention of the organic matrix. The hypoplastic lesions resulted from secretory-cell reaction during the period of F dosing. Diffuse patchy opacities, characterized by an irregular hypomineralized surface zone, were only apparent in the enamel of the later-killed sheep and were associated in one sheep with abnormal ameloblast regression in the contralateral tooth. These defects possibly resulted from the long-continued release of F stored in the bones during the period of F dosing.

The relationship between plasma fluoride, urinary excretion rate and urine fluoride concentration in man.

The fluoride concentration in urine is commonly used for monitoring fluoride exposure, e.g., in aluminium plants. Hitherto this parameter does not seem to have been related to the actual fluoride concentration in plasma following fluoride exposure. In the present study the fluoride concentration in urine, the urinary excretion rate of fluoride and the fluoride concentration in plasma have been studied in five volunteers after intake of 10 mg of fluoride in the form of sodium fluoride (NaF) tablets. In pharmacokinetic analyses of the data calculation of the half-life of fluoride from plasma data and from the urinary excretion rate yielded almost identical results; 5.78 hours (plasma) and 5.11 hours (urine). It was found that plasma fluoride levels were correlated with the fluoride concentration in urine (r = .7532; n = 70), but even more with the urinary excretion rate of fluoride (r = .9651; n = 63). The data suggest that plasma fluoride levels or urinary excretion rates of fluoride may give a more correct picture of occupational fluoride exposure than fluoride concentrations in urine.

Dose-response relationship between water fluoride levels and the category of questionable dental fluorosis.

There is a dose-response relationship between the prevalence of the questionable category of dental fluorosis as reported by various authors and the drinking water fluoride level. While the possibility that chance could have produced this trend cannot be conclusively ruled out, a distinct pattern of increasing prevalence with increasing water fluoride level can be discerned. Such a pattern is not compatible with the concept of a threshold level for the action of fluoride ion on the enamel organ.

Enamel mineralization disturbances in 12-year-old children with known early exposure to fluorides.

Enamel changes and caries experience were studied in 134 12-year-old children with a known early exposure to fluoride tablets and/or fluoride containing toothpaste. The influence of birth weight and breast-feeding period was also analyzed. A clinical intact enamel was found in 32% of the children. Enamel fluorosis was found in 45% and localized opacities or hypoplasias in 40%. Children who had consumed fluoride tablets for a period of at least 12 months from the age of 6 months ran a 5.4 times greater risk of developing enamel fluorosis than children with no such consumption. No such risk could be shown in children who at 6 or 12 months of age started to use fluoride toothpaste. There was no statistically significant reduction in the prevalence of smooth surface caries or fillings in children with an exposure to fluoride tablets.

[Controversial caries prevention using fluorine]. / Umstrittene Karies-Prophylaxe mit Fluor

Fluorine as an essential trace element is necessary for life. The artificial increase of the natural fluoride-content of drinking water up to a maximum of one milligram per litre has been proved a prophylactic step against dental caries. The available material is examined to find out how far side effects of this fluoride concentration as well as any higher fluoride doses can be brought in connection with special defects and patterns of diseases. A comprehensive review of scientific findings concerning physiological reactions caused by fluoride is given.