Energy-dispersive X-ray microanalysis and scanning electron microscopy of developing and mature cat enamel

Calcium and phosphorus distribution in forming, maturing and mature enamel of cat teeth and the microstructures manifest in all these were examined in fractured enamel from the dentine-enamel junction toward the enamel surface. concentrations of both Ca and P increased gradually from the forming enamel, through the maturing enamel and into the mature enamel. The innermost layer, adjacent to the dentine-enamel junction showed the greatest and the superficial layer the lowest concentration of Ca. Still the mature enamel of the erupted tooth was not yet completely mineralized and Ca and P concentrations only slightly higher than those in maturing enamel. Molar Ca:P ratio of each enamel stage was lower than that of pure crystalline hydroxyapatite. Simultaneously-performed SEM observations revealed microstructural changes in the enamel: in the forming-front layer of the forming enamel, the enamel was a rough, immature structure but began to show more compact, tighter structures as concentrations of Ca and P altered. The results suggest that the enamel organ exercises intense cellular control over increases of Ca and P concentration during the formation and maturation stages of amelogenesis.