Alkaline phosphatase activity in plasma and liver of rats submitted to chronic exposure to fluoride

The aim of this study was to compare the effect of fluoride (F) on alkaline phosphatase activity in the liver and plasma of the rats. Four groups of male Wistar rats (n=6), which received drinking water containing 5, 15 or 50 ppm F or deionized water (control) throughout the experiment were included in the study. The animals were euthanized and had their tissues and blood plasma collected for the analysis of fluoride and alkaline phosphatase. There was an increase in F concentration in most tissues in the animals treated with higher F concentrations, except for the heart. The alkaline phosphatase assay showed an increase in the activity in the liver and blood plasma of the animals treated with fluoride concentrations of 15 and 50 ppm (p<0.05). This study suggested that F at a concentration of 50 ppm in drinking water promotes increased the activity of alkaline phosphatase in the liver and blood plasma.

Effect of calcium pre-rinse and fluoride dentifrice on enamel and on dental plaque formed in situ.

PURPOSE: The aim of this in situ double-blind randomised crossover study was to investigate the effect of calcium (Ca) pre-rinse on the composition of plaque and on enamel prior to the use of fluoride (F) dentifrice. MATERIALS AND METHODS: During four phases (14 days each) of this study, 10 volunteers had agreed to wear dental appliances containing two healthy bovine enamel blocks. A fresh solution containing 20% weight/volume (w/v) sucrose was dripped on the enamel blocks ex vivo for 5 min three times a day. Subsequently, the appliances were replaced in the mouth, and the volunteers rinsed their mouth with 10 mL of a Ca (150 mmol/L) or a placebo rinse (1 min). In sequence, a slurry (1:3 w/v) of F (1030 ppm) or placebo dentifrice was dripped onto the blocks ex vivo for 1 min. During this time, the volunteers brushed their teeth with the respective dentifrice. The appliances were replaced in the mouth, and the volunteers rinsed their mouth with water. The plaque formed on the blocks was analysed for F and Ca. The enamel demineralisation as well as the incorporation of F on enamel was evaluated by cross-sectional microhardness and alkali-soluble F analysis, respectively. Data were tested using analysis of variance (P < 0.05). RESULTS: The Ca pre-rinse prior to the use of the F dentifrice led to a three- and sixfold increase in the plaque F and Ca concentrations, respectively. It also did not have any additive effect on the F content on the enamel and the demineralisation of the enamel, in comparison with the use of F dentifrice alone. CONCLUSIONS: A Ca lactate rinse used prior to the F dentifrice was able to change the mineral content in the plaque, but it was unable to prevent enamel demineralisation.

Availability of fluoride from meals given to kindergarten children in Brazil.

OBJECTIVES: The aim of this study was to evaluate the amount of fluoride supplied daily in the meals given in 44 public kindergarten schools in Bauru, Brazil. In addition, the fluoride concentration of water supplies and its impact on the amount of fluoride found in the meal samples were also investigated. METHODS: Meal samples and water were collected during 2 weeks (10 working days) in public kindergarten schools. Samples of meals were homogenized with known volumes of deionized water. Fluoride present in meal samples was analyzed with the ion-specific electrode (Orion 9609), after hexamethyldisilazane-facilitated diffusion. Fluoride in water samples was analyzed with the same electrode, after buffering with TISAB II. All the analyses were made in duplicate. RESULTS: Fluoride analyzed (mean+/-SD) was 0.50+/-0.20 microg/ml, ranging from nondetectable to 1.42 microg/ml for water samples (n=424) and 0.067+/-0.059 mg, ranging from 0.007 to 0.580 mg for meal samples (n=431). A weak but significant correlation was observed between the amount of fluoride in meals and fluoride concentration in water supplies (r=0.139, P=0.0042). CONCLUSIONS: Despite the seemingly small role played by school meals in the total daily fluoride intake, they can contribute to the total fluoride intake of children on a chronic basis, when in association with other fluoride products. Additionally, the impact of fluoridated public water supply on the final fluoride concentration of the school meals analyzed may be regarded as low.