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Objective: The aim of this study was to investigate the calcium, phosphorus, fluorine and magnesium content of primary teeth among three caries experience groups using Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS).
Materials and Methods: Thirty extracted primary teeth were equally divided into three groups: low, moderate and high caries experience. A caries-free smooth surface was used to represent the whole tooth in each group. Each tooth was longitudinally sectioned. The cut surface was cleaned by immersion in 5.25% sodium hypochlorite for 12 hours, and placed in an ultrasonic cleanser for 10 minutes. It was left to dry at room temperature for three days and processed for SEM examinations. Two areas, outer and inner, of the enamel and dentin were examined. The atomic% (at.%) of calcium, phosphorus, fluorine and magnesium were measured using the EDS technique. The means and standard deviations of these four elements were analyzed using two-way ANOVA (p≤0.05).
Results: The enamel, in general, in the low caries experience group had a significantly greater calcium and phosphorus content than in the moderate and high caries experience groups. However, there was no significant difference in fluorine, magnesium or calcium-to-phosphorus ratio between any of the caries experience groups. On the other hands, the outer enamel had greater calcium, phosphorus and fluorine content than did the inner enamel. The outer dentin had greater fluorine content than did the inner dentin. Surprisingly, the inner dentin had greater calcium and phosphorus content than did the outer dentin. The deeper the measurement depth in the dentin, the greater was the magnesium content.
Conclusions: Our findings raise the possibility that the caries resistance of enamel depends upon calcium and phosphorus, but not fluorine or magnesium, content. However, further investigations are still needed.
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