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United States Department of Agriculture

Agricultural Research Service

Research Project: MINERAL INTAKES FOR OPTIMAL BONE DEVELOPMENT AND HEALTH Title: Histomorphometric and microchemical characterization of maturing dental enamel in rats fed a boron-deficient diet

Authors
item Haro Durand, Luis - NATL ATOMIC ENERGY COMM
item Mesones, Ross - UNIV OF SALTA, ARGENTINA
item Nielsen, Forrest
item Gorustovich, Alejandro - NATL RESEARCH COUNCIL

Submitted to: Biological Trace Element Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 24, 2009
Publication Date: June 10, 2010
Repository URL: http://handle.nal.usda.gov/10113/58075
Citation: Haro Durand, L.A., Mesones, R.V., Nielsen, F.H., Gorustovich, A.A. 2010. Histomorphometric and microchemical characterization of maturing dental enamel in rats fed a boron-deficient diet. Biological Trace Element Research. 135:242-252.

Interpretive Summary: Numerous experimental findings indicate that boron is beneficial for bone formation and strength. However, whether boron is beneficial to the formation of the highly mineralized and hardest of all tissues, dental enamel has not been determined. Thus, an experiment with rats, which have continuously erupting rat incisors (teeth), was performed to determine the effect of boron deprivation on enamel formation. Nutritional boron deficiency for only for 14 days did not significantly decrease incisor enamel thickness and the calcium/phosphorus ratio in enamel crystals that were formed. However, the boron-deficient compared to boron-supplemented rats exhibited lower enamel thickness values at each of the 5 sites examined. Because dental enamel formation cells take about 7.5 days to secrete the enamel layer and another 12-14 days for the enamel crystals to mature, 14 days may have not been enough time on the boron-deficient regimen to induce a significant difference. Further study is needed to determine whether extended boron deficiency during tooth development changes the maturation of dental enamel such that it changes the shape of teeth, or makes teeth more susceptible to caries and dentine sensitivity.

Technical Abstract: Few reports are available in the literature on enamel formation under nutritional deficiencies. Continuously erupting rodent incisors have considerable potential to serve as a model system for amelogenesis. Thus, we performed a study to determine the effects of boron (B) deficiency on the maturing dental enamel by using this model. Male Wistar rats, 21 days old, were used throughout. They were divided in two groups, each containing 10 animals: +B (adequate; 3 mg B/kg diet), and -B (boron-deficient; 0.07 mg/kg diet). The animals were maintained on their respective diets for 14 days and then euthanized. The mandibles were resected, fixed, and processed for embedding in paraffin and/or methyl methacrylate. Oriented histological sections of the continuously erupting incisor were obtained at the level of the mesial root of the first molar allowing access to the maturation zone of the developing enamel. Dietary treatment did not affect food intake and body weight. Histomorphometric evaluation using undecalcified sections found no statistical significant differences in the enamel thickness between the groups (P>0.05). In addition, no alterations in enamel mineralization, in terms of Ca/P ratio, were observed. The results of the present study provide evidence, for the first time, that B nutritional deficiency did not elicit alterations in the maturing dental enamel.

Last Modified: 12/22/2014
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