Relationship between enamel fluorosis severity and fluoride content.

OBJECTIVES: Enamel fluorosis is a hypomineralization caused by chronic exposure to high levels of fluoride during tooth development. Previous research on the relationship between enamel fluoride content and fluorosis severity has been equivocal. The current study aimed at comparing visually and histologically assessed fluorosis severity with enamel fluoride content. METHODS: Extracted teeth (n=112) were visually examined using the Thylstrup and Fejerskov Index for fluorosis. Eruption status of each tooth was noted. Teeth were cut into 100 µm slices to assess histological changes with polarized light microscopy. Teeth were categorized as sound, mild, moderate, or severe fluorosis, visually and histologically. They were cut into squares (2 × 2 mm) for the determination of fluoride content (microbiopsy) at depths of 30, 60 and 90 µm from the external surface. RESULTS: Erupted teeth with severe fluorosis had significantly greater mean fluoride content at 30, 60 and 90 µm than sound teeth. Unerupted teeth with mild, moderate and severe fluorosis had significantly greater mean fluoride content than sound teeth at 30 µm; unerupted teeth with mild and severe fluorosis had significantly greater mean fluoride content than sound teeth at 60 µm, while only unerupted teeth severe fluorosis had significantly greater mean fluoride content than sound teeth at 90 µm. CONCLUSIONS: Both erupted and unerupted severely fluorosed teeth presented higher mean enamel fluoride content than sound teeth. CLINICAL SIGNIFICANCE: Data on fluoride content in enamel will further our understanding of its biological characteristics which play a role in the management of hard tissue diseases and conditions.

Fluoride concentration of bottled water, tap water, and fluoridated salt from two communities in Mexico.

AIM: To determine fluoride levels in bottled water, tap water, and fluoridated salt from two communities in Mexico. DESIGN: Stratified random collection of water and salt samples from Mexico City and Veracruz, Mexico for fluoride analysis. METHODS: Samples were analysed using a combination fluoride ion-specific electrode. Results were compared using Student's t-test and mixed-model ANOVA. Water fluoride values were compared by type, community and collection area; salt fluoride values were compared by community and collection area. RESULTS: 197 tap water samples, 133 bottled water samples and 20 fluoridated salt samples were collected. The mean (+/- SD) fluoride content for all tap water was 0.20 +/- 0.17 microg F/g (ranging from 0.01 to 0.88 microg F/g) and 0.24 +/- 0.24 microg F/g for all bottled water (ranging from 0.01 to 2.80 microg F/g). This difference was not statistically significant. When results were analysed by city, the difference between tap water samples was statistically significant. Ten bottled water samples contained more than negligible fluoride (ranging from 0.7-2.8 microg F/g). Mean salt fluoride content was 230.0 +/- 49.8 microg F/g, which was within governmental regulation levels. CONCLUSION: Some water samples had amounts of fluoride exceeding the maximum recommended levels. Salt fluoride levels were within regulation limits. Monitoring of fluoride content of both bottled and tap water is strongly advised.