CORRELATION OF CHEMICAL AND HISTOLOGICAL INVESTIGATION ON DEVELOPING ENAMEL

¹ The Foundation for Dental Research of the Chicago College of Dental Surgery, Chicago, Ill.

By correlating the chemical analysis with the histological appearance of developing enamel, the main chemical components of the 2 stages in enamel development, i.e., matrix formation and calcification were established.

Insoluble enamel matrix contains 37-28 per cent water, 38-22 organic material, 23.4-30.3 calcium and 12-15.3 phosphorus. The range of components is smaller if samples which border soluble enamel are left out of consideration. It is calculated that in the enamel matrix about of the amount of mineral salts found in hard enamel is present.

In contrast to the insoluble enamel, there is presented definite proof of a gradient from occlusal to cervical in the soluble enamel which runs in crossrelation to the incremental lines. The values were found to range between about 25-6.5 per cent water, 9.5-4.0 organic material, 34.6-37.6 calcium and 26.5-18.1 phosphorus.

The chemical properties of insoluble and soluble enamel corroborate the morphologically based postulate that there is a distinct differentiation between the stages of enamel matrix formation and enamel calcification, the latter stage starting only after the first has been completed.

Solubility of enamel indicates completion of the enamel matrix and shows that calcification has progressed at least to a certain point but does not mean that enamel is mature.

Calcification of enamel is characterized by a removal of moisture and organic material and an influx of mineral salts. In this process a proteolytic enzyme and phosphatase may play leading roles.

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