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The last biomonitoring study in Poland on intoxication with fluoride compounds of deer was conducted almost two decades ago. Given the fact that fluoride level in air and water is not widely monitored in Poland, it is justified to undertake monitoring of F- levels in people and other long-lived mammals. This paper provides the assessment of the present level of fluoride accumulation in mineralized tissue of large herbivorous mammals. The aim of the present study was to determine fluoride concentration in teeth of deer inhabiting the areas of Poland which are industrially uncontaminated with fluoride compounds, to establish possible correlations between the analysed parameters, and to provide a comparison of the present results with those obtained in other studies. Mean concentration of fluoride in all analysed samples amounted to 231.0 F mg/kg, with the minimum value of 22.0 F mg/kg and the maximum of 935.0 F mg/kg. This results from the development of industry and a widespread use of fluoride-supplemented caries prevention products which contributes to an intense accumulation of these substances in vertebrates, predominantly in mineralized tissue., (Copyright© by the Polish Academy of Sciences.)

Increased exposure to fluorine-containing compounds leads to accumulation of fluorides in hard tissues of bones and teeth, which may result in numerous skeletal and dental disorders. This study evaluates the influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats subjected to long-term exposure to sodium fluoride in drinking water. The study was conducted in 30 3-month-old female Wistar FL rats. The animals were divided into five groups, six rats per group. The control group consisted of rats receiving only distilled water as drinking water. All other groups received NaF in the amount of 10 mg/kg of body mass/day in their drinking water. In addition, respective animal groups received: NaF + Met group--10 mg of methionine/kg of body mass/day, NaF + Met + E group--10 mg of methionine/kg of body mass/day and 3 mg of vitamin E (tocopheroli acetas)/rat/day and NaF + E group--3 mg of vitamin E/rat/day. Femoral bones and incisor teeth were collected for the study, and the fluoride concentration was determined using a fluoride ion-selective electrode. Fluoride concentration in both bones and teeth was found to be higher in the NaF and NaF + Met groups compared to the control group. In groups NaF + Met + E and NaF + E, the study material contained much lower fluoride concentration compared to the NaF group, while the effect was more prominent in the NaF + E group. The results of the studies indicate that methionine and vitamin E have opposite effects on accumulation of fluorides in hard tissue in rats. By stimulating fluoride accumulation, methionine reduces the adverse effect of fluorides on soft tissue, while vitamin E, which prevents excessive accumulation of fluorides in bones and teeth, protects these tissues from fluorosis. Therefore, it seems that combined application of both compounds would be optimal for the prevention of the adverse effects of chronic fluoride intoxication.

Current models for increasing the anti-caries effects of fluoride (F) agents emphasize the importance of maintaining a cariostatic concentration of F in oral fluids. The concentration of F in oral fluids is maintained by the release of this ion from bioavailable reservoirs on the teeth, oral mucosa and - most importantly, because of its association with the caries process - dental plaque. Oral F reservoirs appear to be of two types: (1) mineral reservoirs, in particular calcium fluoride or phosphate-contaminated 'calcium-fluoride-like' deposits; (2) biological reservoirs, in particular (with regard to dental plaque) F held to bacteria or bacterial fragments via calcium-fluoride bonds. The fact that all these reservoirs are mediated by calcium implies that their formation is limited by the low concentration of calcium in oral fluids. By using novel procedures which overcome this limitation, the formation of these F reservoirs after topical F application can be greatly increased. Although these increases are associated with substantive increases in salivary and plaque fluid F, and hence a potential increase in cariostatic effect, it is unclear if such changes are related to the increases in the amount of these reservoirs, or changes in the types of F deposits formed. New techniques have been developed for identifying and quantifying these deposits which should prove useful in developing agents that enhance formation of oral F reservoirs with optimum F release characteristics. Such research offers the prospect of decreasing the F content of topical agents while simultaneously increasing their cariostatic effect., (Copyright © 2011 S. Karger AG, Basel.)

This study examined the release of aluminium and fluoride from restorative materials placed in either deciduous or young permanent immature teeth stored in artificial saliva for 1 month. Cavities were prepared in extracted teeth, then filled with a fluoride releasing restorative (glass-ionomer, compomer or composite resin), with and without conditioning as appropriate. The teeth were then stored in artificial saliva for 1 month, after which the amount of aluminium and fluoride released was determined spectrophotometrically. With all materials tested, both aluminium and fluoride were released in all cases. Young immature teeth were associated with lower level of ion release which was attributed to the absorption of ions by the enamel. However, unconditioned samples were usually associated with similar ion release to conditioned ones, suggesting that the loss of mineral phase on conditioning has only a marginal effect on the capacity for ion uptake. The ratio of aluminium to fluoride released varied with the type of tooth, deciduous conditioned teeth generally absorbing proportionately less aluminium than young immature teeth. The overall conclusion is that interaction with ions released by restorative materials is influenced by type of tooth.

The aim of the study was to examine quantitative fluorine content in tooth tissues with the decay process, tissues of teeth without decay and tissues with diseases different than those of decay origin. It has been found that in the examined teeth decay process the average fluorine content in hard tissues amounted to 235.6 ppm of fluorine and it was lower than in healthy teeth (304.8 ppm) extracted for orthodontic or periodontological reasons, whereas the highest fluorine content--383.5 ppm--was found in teeth with diseases of non-decay etiology. Analyzing particular teeth groups depending on the age of the patients, it was observed that the fluorine level is higher in the teeth received from younger patients, especially in the group of healthy teeth and teeth with wedge defects. Susceptibility of tooth enamel to dissolution was estimated by the CRT test with the use of discs impregnated with crystal violet (hexamethylene-4 hydrochloride of fuchsin) with the range of colour change from yellow and green to violet and blue at ph 0.1-1.5. The lengthening of the time of reaction in this test testified to lower acid sensitivity of tissues and at the same time to harder demineralization of enamel, e.g. in the process of decay. Longer time of reaction was observed in teeth with higher indicated fluorine content.

Drug interactions are the side effect of administration of two or more drugs or a drug-food combination. Although some drug interactions are intentional and beneficial to the patient, the majority are unintentional and associated with a potentially harmful effect. The aim of this study was to search for interactions in rats between fluoride and zinc administered orally for 12 weeks and to elucidate any potential toxicological and therapeutic consequences. 60 male Wistar rats were divided into six groups of ten rats each and exposed to: 1. controls (distilled water); 2. sodium fluoride (NaF); 3. low-dose zinc (Zn); 4. high-dose zinc; 5. NaF + low-dose Zn; 6. NaF + high-dose Zn. At the end of the experiment the content of F- and Zn+ in serum, urine, incisors, femur and mandible was measured and densitometry of femoral bones was performed. Serum alkaline phosphatase, alanine and aspartate aminotransferase activities, as well as bilirubin and creatinine concentrations were determined to confirm non-toxicity of fluoride dose. Animals receiving NaF only demonstrated higher content of fluorine in serum, urine bones and teeth. Zinc concentrations in serum, urine, bones and teeth were elevated in rats receiving zinc with or without NaF. Fluorine accumulation in bones and teeth was reduced by Zn, but in general the effect lacked statistical significance. Zinc slightly reduced the concentrations of fluorine in serum and urine. Sodium fluoride slightly reduced the concentration of zinc in serum and urine. Bone mineral content (BMC) was significantly increased by NaF and was not further increased by co-administration of zinc. No changes in serum alkaline phosphatase, alanine and aspartate aminotransferase activities, bilirubin and creatinine concentrations were detected. In conclusion, simultaneous administration of fluorine and zinc may be beneficial for prevention and treatment of pathologic conditions in bones and teeth and is not accompanied by an increase in fluorine levels which could be responsible for toxicological symptoms.

The purpose of this study was to examine, using backscattered electron imaging, the changes occurring in the structure of the dentine including giant tubules in the teeth of deer chronically exposed to fluoride. The primary and secondary dentine was characterised by the presence of interglobular dentine and regular bands of hypo- and hypermineralised dentine. Giant tubules in the unworn teeth of animals exposed to low and high levels of fluoride were characterised by a large lumen and hypermineralised rim in which there were calcospherites. With the occlusal wear of the teeth tubules beneath the immediate surface of the exposed dentine in teeth from fluorotic animals became occluded with mineral, but in low fluoride animals some tubules at the surface were not occluded with mineral. It is suggested that mineral which occludes the tubules may come from both intrinsic and extrinsic sources. The presence of some open tubules at the immediate surface in the worn teeth of animals exposed to low fluoride suggests an extrinsic source for this mineral.

In order to approach practicable indexes for assessing the effects of the products which are intended to be used to prevent endemic fluorosis, Wistar rats were fed with fluoridated water(50 mg/L) for four weeks. After only one week treated with fluoride, a higher activity of NAG(N-acetyl-beta-D-glucosaminidase) in urine, ChE(cholinesterase) in blood and increased urinary excretion of fluoride (compared with the control, P < 0.01) were observed, and these changes were lasted to the end of the fourth week of the study, but hydroxyproline in serum and urine had not been changed in both groups. After four weeks, the fluoride levels in the femora and teeth of fluoride treated group were ten times higher than that of the control group. According to the results, fluoride in bones and teeth must be taken as key indexes, the activities of NAG in urine and ChE in blood should be taken into consideration for assessing the effects of fluoride protagonist.

This paper compares fluoride pharmacokinetics (plasma, renal, and extrarenal clearances) and metabolic balances in healthy infants or children with those in young or middle-aged adults. Regardless of age, the removal of fluoride from the intra- and extracellular body fluids occurs almost exclusively by uptake in calcified tissues and excretion in the urine. While there can be considerable differences among individuals, the rates at which fluoride is cleared from plasma by calcified tissues and the kidneys in adults are approximately equal. The calcified tissue clearance of fluoride from plasma in children is substantially higher than that by the kidneys. This is due to the greater surface area of the loosely organized crystallites in the developing calcified tissues during growth. Thus, the balance of fluoride (total intake minus total excretion) is typically higher in children than in adults, but it can be positive or negative at any age. Positive balance occurs when chronic fluoride intake is sufficient to prevent plasma concentrations from declining. When positive, the fluoride content of the calcified tissues, which contain more than 99 percent of the body's fluoride, tends to gradually increase. Negative balance, which indicates net mobilization of fluoride from calcified tissues, can occur when plasma concentrations decline due to a reduction in the level of fluoride intake.

The aim of this work was to study the fluoride (F) concentration in the approximal area after using toothpicks and other F-containing products. The exposure time was standardised to 2 min. 24 subjects participated, divided into 4 groups, with 6 individuals per group. In 3 of the groups, the following 4 products were compared: (1) a toothpick impregnated in 4% NaF; (2) a dentifrice containing 0.32% NaF; (3) a mouthrinse solution containing 0.025% NaF; (4) a tablet containing 0.55 mg NaF. In the 4th group, 3 commercial F toothpicks and 2 F dental flosses were compared. In all 4 groups, the F concentration was determined up to 60 min at 4 approximal sites. On each sampling occasion, 3 triangle-shaped paper points were used, absorbing 3 x 1 microl. In general, the toothpick gave similar or somewhat higher F concentrations in the approximal area than the dentifrice, mouthrinse solution and tablet. Comparing the various commercial toothpicks and dental flosses, 2 of the toothpicks gave higher approximal F concentrations than the other 3 products. When comparing the series in which the very first sample was collected from 2-20 min after the F treatment, it was found that the sampling procedure itself reduced the subsequent approximal F concentration. The main conclusion from this study is that an F-impregnated toothpick is a promising vehicle for delivery of fluoride to the approximal area.

This study concerned the adsorption and desorption of commercial amine fluoride (AmF) preparations to hydroxyapatite (HA). The influence of pH, ionic strength, temperature, saliva and albumin, the latter as a gingival crevicular fluid analogue, on adsorption/desorption was investigated. AmF levels were determined using a surfactant electrode. AmFs 297 and 335 were found to bind immediately and irreversibly to HA in water over a range of pH values, ionic strengths and temperatures, the amounts increasing with concentration. More monovalent AmF 335 was absorbed than divalent AmF 297. Any AmF desorbed by water from HA was at the lowest end of the minimum inhibitory concentration for oral bacteria. AmF 297 was desorbed by CaCl2, and to a lesser extent by H+, OH-, NH4+, La3+, EDTA, Triton X100 and ethanol, whereas AmF 335 was only slightly desorbed by ethanol. Preadsorption of proteins on HA had little effect on subsequent adsorption or desorption of either AmF. It is postulated that both AmF 297 and AmF 335 are inactivated by an excess of proteins in the surrounding medium, supra- or subgingivally, and not by such proteins preventing or altering the mode or rate of adsorption, or interfering with antibacterial activity, when the AmFs contact a protein-coated tooth surface.

The aim of the present investigation was to study two post-brushing water rinsing procedures: (1) on fluoride (F) accumulation in approximal dental plaque, and (2) on F clearance in the interdental area. Twenty subjects participated first in the accumulation study, including three experimental periods (A, B and C), each lasting for 7 days. During period A, they brushed with a 0.32% NaF dentifrice for 2 min, followed by a 1-min active mouth rinse with the toothpaste foam combined with 5 ml of water. During period B, the 2-min brushing was followed by three quick water rinses with 15 ml each. During period C, toothbrushing, which was carried out without any toothpaste, was followed by a 2-min active mouthrinse with 10 ml of a 0.05% NaF solution. All three procedures were performed in the morning (after breakfast) and in the evening (just before bedtime). The results showed that the accumulation of F in pooled approximal plaque after 7 days reached on average 2.7 times higher values after procedure A than B (p<0.001). Procedure C also resulted in more F in plaque than B (p<0.001). The same 20 subjects participated in the clearance study on a separate occasion. When measuring the F concentration in the interdental area at 3 h after the application, procedure A resulted in a significantly higher F concentration than both toothbrushing B and mouth rinse C; the AUC was 2.2 times larger for A than for B (p <0.001). Thus, both the accumulation of F in approximal plaque and the clearance of F in the interdental area are related to the mode of water rinsing after toothbrushing.

A laboratory experiment was conducted to compare the toxicological response and metabolism of inorganic fluoride by three species of wild mammals and laboratory white mice (Mus musculus L.). The experimental populations of the wild species--the short-tailed field vole (Microtus agrestis L.), the bank vole (Clethrionomys glareolus L.) and the the wood mouse (Apodemus sylvaticus L.)--were laboratory reared from wild stock, and all test animals were exposed to 0, 40 or 80 microgram F per ml in their drinking water for up to 84 days. The 40 and 80 microgram F per ml treatments induced premature mortalities in M. agrestis and C. glareolus only. Differential intakes, absorption and retention of fluoride were evident between M. musculus and M. agrestis, the two species subject to cage studies of fluoride metabolism budgets. Interspecific variation in accumulation of fluoride with time was also evident between all four species as regards the femur, molars and incisors. Severe dental lesions were apparent in species surviving the 80 microgram ml(-1) treatment for 84 days. Overall, however, there were few clear differences in inherent species sensitivity to fluoride, the interspecific variation in metabolism and accumulation rates being attributable mainly to variation in intake.

A quantitative physical model is presented for the formation of subsurface carious lesions in the presence of low levels of solution fluoride. Calculations using independently determined model parameters are in agreement with mineral density profiles measured in bovine enamel lesions. The proposed mechanism is controlled by fluoride in the following way: as fluoride diffuses into enamel, it is rapidly adsorbed to enamel crystallites, resulting in very low microenvironmental fluoride concentrations, so long as the crystals are not saturated with respect to fluoride adsorption. The result of this saturable adsorption is a widening band of fluoride-saturated crystals near the surface, beneath which the microenvironmental fluoride concentrations are negligible. In the saturated band, the microenvironmental fluoride concentration in the pore solution is high enough to suppress dissolution, while in the deeper, relatively fluoride free region, dissolution can occur. In addition to predicting observed mineral density profiles, the model also predicts the demarcation in solution conditions between the regime where subsurface lesion formation occurs and that where the dissolution pattern is that of surface erosion; and the lack of insensitivity of dissolution rate to hydrodynamics in the presence of low levels of fluoride, as contrasted to the square root of stirring rate dependency observed in the absence of fluoride.

This article briefly describes the pathogenesis of dental caries. It focuses on the relevant chemical processes and histological changes in dental enamel. Recent studies have shown that the mineral balance at the tooth-oral fluid interface are determinants for the occurrence of caries, and more important than the intrinsic tissue properties. During periods of low pH, following bacterial metabolism of fermentable carbohydrates, enamel is demineralized. However, loss of tissue may be compensated by mineral deposition from saliva during subsequent periods at neutral pH ('remineralization'). The mineral balance is positively affected by the presence of low fluoride levels in the oral fluids. Clinically this becomes manifest in the decreasing rates of caries initiation and progression. Also it may affect the appearance of incipient enamel lesions, which in turn could complicate caries diagnosis. The changing patterns of dental changes thus have implications for procedures in preventive and restorative practise.

The circulatory uptake and urinary excretion of topical fluoride were investigated by applying a sodium fluoride solution containing 18F for six min to healthy gingiva of four adult dogs. Blood and urine samples were taken a regular intervals. Maximal fluoride in blood represented 0.02-0.05% of the applied dose and occurred four min after completion of the application. By 6.0 h, 0.02-0.06% of the applied dose had been excreted in urine. Preliminary data showed that this represented about 8.8% of the fluoride absorbed through the gingiva.

The effects of electric currents on the uptake of fluoride ions by human teeth, in vitro were determined by measuring the change in fluoride ion concentration of the electrolyte in which teeth were subjected to the electrochemical treatment. There was an enhanced uptake when the gold electrode embedded in the tooth was polarized anodically. Evidence that the fluoride ions were taken upon by the teeth was shown by subsequent cathodic polarization of the gold electrode in a fluoride free electrolyte and by measurement of fluoride release into the solution.

A study has been made to determine the inhibitory action upon the progress of dental caries of two trace elements (fluorine and molybdenum) combined with chlorohexidine with the goal of increasing the efficiency of fluoride treatment. However, the results obtained show that the chosen combination of trace elements did not lead to a substantial increase in cariostatic action. Combined use of fluorides and chlorohexidine was seen to exert an inhibitory action on the progress of dental caries.

Bone meal (containing 500 ppm F) was added to the diet of growing rats in an amount corresponding to that recommended ingested by children. Addition of bone meal did not influence body weight increment, or growth and ash content of bone and teeth. Fluoride in bone and teeth increased as compared to control animals, but the increase was 2-4 times less than if fluoride had been given as NaF. Analyses of feces disclosed significantly increased values of Ca and F in animals fed the bone meal supplemented diet, indicating low absorption of these minerals from bone meal.

Effect of high fluoride ingestion on the tooth matrix glycosaminoglycans was studied in rabbits administered 10 mg NaF/kg body weight orally at 24-h intervals for a period of 9 months. Fluoride-treated tooth showed a significant reduction in glycosaminoglycan content as compared to the normal tooth. Sephadex G-75 chromatography and DEAE-cellulose ion exchange chromatography revealed the presence of small molecular weight glycosaminoglycan molecules and an increase in the charge density heterogeneity in the sulphated glycosaminoglycans of the fluoride-treated rabbit tooth as compared to the controls. These changes may be related to the dedifferentiated tooth matrix and an increase in the dermatan sulphate content in the fluoride-treated tooth matrix reported earlier.

The fluoride (F) concentrations in hard tissues and blood plasma were determined in biopsy and autopsy specimens from fetuses, infants, and children on varying F intake. In newborn autopsy cases specimens consisting of rib, jawbone with teeth, and blood plasma the F concentrations of bone and dentin were of the same order, those of the enamel lower. Correlations between individual F values in different tissues were all positive, highest for enamel/dentin. Low birth weight entailed only slightly reduced F contents, high water F significantly increased F contents. In the biopsy material (rib and blood plasma) the maximal rib/ash concentration was about 400 parts/10(6) F. A negative correlation between rib F and plasma F is specially commented on. The possible influence of F on bone development as expressed by blood plasma F and phosphatase activity was investigated in three groups of infants aged 2-6 months, either breast-fed or fed dry-milk formulas diluted with drinking waters of different F content. The children of these groups were calculated to ingest F in the ratio of about 1:10:50. The highest F group had higher plasma F values than the two other groups, whereas its alkaline phosphatase was significantly higher than that of the lowest F group only. The influence of disturbances in the skeletal development on F retention studied in physically handicapped children aged 4-15 years living in a city with about 1 part/10(6) F in the drinking water. The severely handicapped showed a higher urinary F excretion than the controls.

A variety of methods has been employed to produce artificial caries-like enamel lesions. The aim of this paper was to use a pH-cycling regime to compare the de-/remineralization behavior of lesions prepared by two methods. Lesions were produced by use of either an acidified undialyzed gelatin system or a buffered solution. Enamel sections, each containing four lesions, were allocated to four groups (A, B, C, D) and subjected to a daily pH-cycling regime of 16-hour demineralization and eight-hour remineralization. Groups A & B contained gelatin-prepared lesions, whereas Groups C & D contained solution-prepared lesions. To the remineralizing solutions used in Groups B & D, 2 ppm fluoride was added. The mineral content in the lesions was assessed, by means of microradiography/microdensitometry, at baseline and at intervals for six weeks. The lesions in all four groups exhibited net demineralization. In terms of the total mineral lost from the lesion (the delta z parameter), the demineralization rates of the solution-prepared lesions were significantly greater than those of the corresponding gelatin-prepared lesions. All sections in the non-fluoride groups showed subsurface demineralization in initially sound enamel, whereas only one section in the fluoride groups showed an area of mineral loss. Laminations in the mineral content profiles were apparent only in Group D. The results of this study indicate that the method of lesion preparation affects the subsequent behavior of lesions when exposed to de- and remineralizing protocols.

The effects of fluoride ingestion (3.5 mg/kg of body weight) were evaluated in 9 ewes at 6 through 9, 10 through 13, or 14 through 17 months of age (3 ewes/age group). In the 3 groups, the plasma fluoride concentration rapidly increased to 0.45, 0.46, and 0.50 microgram/ml, respectively, and decreased rapidly to 0.1 microgram/ml after fluoride was removed from the ration. In 5 of the 9 ewes, this short-term exposure caused symmetrical, moderate damage to the molars, which is characteristic of fluorosis in sheep. In 7 of the 9 ewes, abnormal gaps were found between incisors, which are not characteristic of fluorosis in sheep. Fluoride accumulation was higher in the roots of the incisors and in the dentine of the molars and was particularly evident in teeth that were developing when fluoride was administered; however, the fully developed teeth and teeth that developed several months after administration of fluoride also were affected. The increase in fluoride concentration in the enamel was confined to a maximum of 2 molars. The abnormal wear of the molars was not directly linked to fluoride accumulation.

A recently conceived calcium fluoride-containing remineralization system was tested using human teeth in vitro. The influence of several variables (surface pretreatment, demineralization time, and remineralization time) was studied. Appreciable levels of fluoride taken up by pumiced human teeth were found at depths up to 50 micrometers when remineralization was carried out in either the remineralizing solution or saliva. The successful performance of the delivery device in these laboratory studies is encouraging and indicates that the logical evolution of the crude devices studied thus far could lead to clinically practical fluoride delivery devices.

Fluoride therapy has been credited with remarkable success in reducing the incidence of tooth decay. Medium to high doses of fluoride have been used in the treatment of osteoporosis. The precise mode of action of fluoride on teeth and bone has yet to be elucidated. It is often assumed that, except in rare circumstances, plasma and extracellular fluid levels of ionic fluoride will not reach concentrations capable of interfering with the normal functioning of human cells. However, fluoride accumulates in skeletal tissues and may be concentrated in the surface layers of the lacunae and canaliculae of bone. Such a hypothetical mechanism may help to clarify the pathogenesis of the osseous lesions in skeletal fluorosis. This hypothesis should be tested in view of recent findings which show that sodium fluoride has a genotoxic effect on embryonic cell culture lines, and can interfere with DNA synthesis in human oral keratinocytes.

Laboratory studies were carried out on a newly conceived fluoride-containing remineralizing system with bovine teeth. The prototype fluoride delivery device involved micronized calcium fluoride maintained at the tooth surface with a cellulose film. Together with salivary calcium and phosphate (or simulated saliva), this system was able to generate and maintain the appropriate thermodynamic activity driving force for significant fluorapatite deposition in a reasonably short time (approximately 48 hr).

Grass can absorb and retain gaseous fluoride from ambient air. This fluoride then is absorbed by cattle eating the grass. The accumulation of this fluoride in their teeth and bones can damage their health and productivity. Critical concentrations of fluoride in grass have been defined. New data describing the relationship between amount of fluoride in air and fluoride in leaves of grass have been assembled and expressed by a regression equation. This equation can be used to predict fluoride accumulation in grass near a planned industrial project, and the likelihood of effect or damage in grazing cattle can be judged.

Cadmium injections during molar tooth development in the rat were strongly caries-promoting in female rats. Cadmium also partially negated the cariostatic effect of fluoridated drinking water in both male and female rats. The mechanism for the caries-promoting properties of cadmium is unknown, but may be related to cadmium uptake into enamel and dentin. Cadmium was taken up into molar enamel and dentin in proportion to the amount of cadmium administered, but cadmium did not influence uptake of fluoride onto eruted enamel. Calcium and ash concentrations in molar enamel were not altered by cadmium administration.

The fluoride distributions in the incisal, middle and cervical regions of the facial surfaces of six maxillary central incisors were determined by three successive acid etch biopsy procedures. The fluoride concentrations were adjusted to standardized depths of 0--10 micron, 10--20 micron and 20--30 micron. In the biopsy areas the enamel fluoride concentrations decreased with increasing depth. In all the teeth the fluoride content was lowest in the incisal region and highest at the cervical third.