Effect of dietary iron deficiency on the pigmentation and iron content of rat incisor enamel.

Abstract

abstract— The enamel of rat incisors is characterized by a pigmented, iron‐rich surface layer. The Fe content and degree of mineralization of this enamel layer in rats fed an Fe‐deficient diet were studied using the electron microprobe. Four groups of eight 24‐day‐old rats were fed a milk diet, Fe‐fortified milk diet, Cu‐fortified milk diet, and Fe+Cu‐fortified milk diet, respectively, for 10 weeks. At the end of the experimental period, incisor pigmentation was markedly reduced in the animals fed the Fe‐deficient diets. Close to the enamel surface, the Fe content averaged 1.9% in the midsagittal area, as opposed to 9.9% Fe in the controls. Variation of Cu supply had no effect on hemoglobin values or Fe content of incisor enamel. In a second experiment, rats were fed a milk diet with and without Fe supplementation. Nearly colorless incisors from animals sacrificed after 16 weeks on the milk diet contained 1.9% Fe (range 1.4–2.5%) close to the enamel surface. In this region, the Ca content averaged 33.7% and P 17.2%. Normally orange‐colored incisors from animals receiving the Fe‐supplemented diet contained, in the same region, 9.9% Fe (9.3–10.5%), 28.9% Ca, and 16.0% P. While pigmentation and Fe content of incisor surface enamel were markedly reduced as a result of the Fe‐deficient diet, the Ca and P contents had increased to values similar to those found in non‐pigmented subsurface enamel. The Ca/P weight ratio of incisor surface enamel was 1.96 in the iron‐deficient animals and 1.81 in the controls.