Comparative study of B content and δ11 B in the enamel of isolated teeth from brothers in the same family.

RATIONALE: The quantity of boron (B) and its isotopic ratios in tooth can provide information on dietary habits and oral health of individuals. These metrics are gradually being used in stomatology, environmental science and geochemistry. METHODS: This study measured the B concentration and δ11 B in the enamel of isolated teeth from brothers in the same family living in high-B-exposure areas at different times using inductively coupled plasma mass spectrometry (ICP-MS) and multicollector ICP-MS. RESULTS: The results demonstrate that B content in tooth samples of two brothers is related to the time of shedding. The earlier the time of shedding, the lower is the B content in tooth. The B content increased from 20.5 µg/g of the central incisor (6-7 years old) of the younger brother to 50.4 µg/g of the second molar (10-12 years old). And B content for the elder brother increased from 28.7 to 58.3 µg/g at the same positions. In the same family, the diet and environmental input of B is basically similar, and the B exposure is basically the same every year. The annual growth rate of B for the younger brother in this experiment is about 4.98 µg/g per year and that for the elder brother is about 4.93 µg/g per year. The δ11 B of shed teeth at different times from the same person is basically similar, but different from person to person. The δ11 B of shed teeth from the elder brother varies from 15.5‰ to 17.9‰ and from the younger brother varies from 5.2‰ to 6.7‰. The δ11 B is quite different for the brothers in the same family who had the same food and environmental intake of B. CONCLUSIONS: The experimental data confirmed the relationship between the information of B (B content and δ11 B) in shed teeth and B exposure. They provided an experimental basis using modern human teeth to apply B-isotope paleo-environmental significance.