Thomas M. Marthaler

Urinary fluoride excretion by children 4-6 years old in a south Texas community

This study evaluated urinary fluoride excretion by school children 4-6 years old who were living in a south Texas rural community that had concentrations of fluoride in drinking water supplies generally around the optimal level. We took supervised collections of urine samples in the morning and afternoon at school, and parents of the participating students collected nocturnal samples. We recorded the beginning and end times of the three collection periods and then determined the urinary volume and urinary flow for each of the periods. We measured urinary fluoride concentrations and calculated the urinary excretion rate per hour. The children had breakfast and lunch provided at the school, where the drinking water contained 1.0-1.3 milligrams/liter (mg/L) fluoride. Fluoride concentrations in the tested household water supplies, from wells, ranged from 0.1 to 3.2 mg/L fluoride. The childrens average urinary fluoride concentrations found for the day were similar to those for the night, with means ranging from 1.26 mg/L to 1.42 mg/L. Average excretion was 36.4 micrograms/h in the morning, 45.6 micrograms/h in the afternoon, and 17.5 micrograms/h at night. The lower nocturnal excretion rates are easily explained by low urinary flow at night. Based on the 15 hours of urine collected, the extrapolated 24-hour fluoride excretion was 749 micrograms. In conjunction with similar studies, the data from this study will help in developing upper limits for urinary fluoride excretion that are appropriate for avoiding unsightly fluorosis while providing optimal protection against dental decay.

Salt fluoridation and oral health.

UNLABELLED The aim of this paper is to make known the potential of fluoridated salt in community oral health programs, particularly in South Eastern Europe. Since 1922, the addition of iodine to salt has been successful in Switzerland. Goiter is virtually extinct. By 1945, the caries-protective effect of fluorides was well established. Based on the success of water fluoridation, a gynecologist started adding of fluoride to salt. The sale of fluoridated salt began in 1956 in the Swiss Canton of Zurich, and several other cantons followed suit. Studies initiated in the early seventies showed that fluoride, when added to salt, inhibits dental caries. The addition of fluoride to salt for human consumption was officially authorized in 1980-82. In Switzerland 85% of domestic salt consumed is fluoridated and 67% in Germany. Salt fluoridation schemes are reaching more than one hundred million in Mexico, Colombia, Peru and Cuba. The cost of salt fluoridation is very low, within 0.02 and 0.05 € per year and capita. Children and adults of the low socio-economic strata tend to have substantially more untreated caries than higher strata. Salt fluoridation is by far the cheapest method for improving oral health. CONCLUSION Salt fluoridation has cariostatic potential like water fluoridation (caries reductions up to 50%). In Europe, meaningful percentages of users have been attained only in Germany (67%) and Switzerland (85%). In Latin America, there are more than 100 million users, and several countries have arrived at coverage of 90 to 99%. Salt fluoridation is by far the cheapest method of caries prevention, and billions of people throughout the world could benefit from this method.

Daily Variations in Mitotic Activity of Adrenal Cortex, Thyroid and Oral Epithelium of the Rat.∗

Summary Daily periodicity characterizes mitotic activity in the adrenal, the thyroid and the oral epithelium of male Sherman albino rats, kept under standardized environmental circumstances. The daily times of “high” and “low” in number of mitoses are roughly synchronized for the thyroid and the oral epithelium, while the 24-hour periodicity in mitotic activity of the adrenal cortex shows a different timing.

Dissolution of dental enamel in decalcifying buffers containing different amounts of calcium and phosphorus

Crowns of intact premolars and molars were exposed for 3 hr to 10 ml of acid buffer, pH 4, containing differing amounts of calcium and phosphate at the beginning of the experiments. Acetic and phthalic acid buffers were used at 0.025 and 0.075 molar concentrations. Calcium and phosphate ions were added by dissolution of CaCl2 or Na2HPO4. The presence of calcium and phosphate alone was of little effect on the dissolution rate. A more clearly diminished dissolution rate was found when both calcium and phosphate were present in the buffers. The relative protection against dissolution by the presence of calcium and phosphate became considerably smaller when the molarity of the buffers was raised from 0.025 to 0.075. The presence of calcium or phosphorus in the acid buffers did not change the calciumphosphorus ratio of the dissolved enamel substance. Addition of NaCl or MgSO4 to acetic acid buffer already containing calcium and phosphate resulted in an increase of the enamel dissolution rate. The results are compared with certain findings in experimental caries studies.