Mineral content of different areas of human dentin in hypophosphataemic vitamin D-resistant rickets.

Calcium, phosphorus, fluoride, sodium, magnesium and zinc estimations were carried out on teeth from a patient with hypophosphataemic vitamin D-resistant rickets (HVDRR) and from a patient with acquired rickets with the aim of determining differences in the composition of dentine in these two types of rickets. Normal deciduous teeth served as controls. Mineral analyses were carried out using an electron probe micro-analyser after carefully polishing the hemisected specimens. After the analyses the specimens were coated with gold-palladium for more detailed SEM studies. The Ca, P, F and Zn contents of the calcospherites were normal, while there was more Na and less Mg in the dentine of HVDRR teeth than of controls. The significance of this remains unexplained. The mineral content of the interglobular spaces was very limited, but there was more Zn in these than in other parts of the HVDRR teeth, in the acquired rickets teeth or in the control teeth. The excess of Zn in the interglobular spaces is thought to have an effect on the mineralisation process in HVDRR teeth. The globular nature of HVDRR teeth is thought to be genetically controlled and the result of a reduction in the number of calcification nuclei. The globular nature of the HVDRR teeth was not due to lack of Ca and P, as the serum levels of these minerals were maintained within normal limits during tooth development by controlled phosphate supplementation. Because in acquired rickets the globules were seen at the developmental stage that the teeth had reached when the nutritional disturbance occurred, the fault in mineralisation is thought to be different from that in HVDRR teeth.(ABSTRACT TRUNCATED AT 250 WORDS)