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October 26, 1940

The Enamel of Human Teeth: An Inquiry into the Formation of Normal and Hypoplastic Enamel Matrix and Its Calcification

JAMA. 1940;115(17):1480. doi:10.1001/jama.1940.02810430070035

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The authors reject the generally accepted hypothesis of Retzius that human tooth enamel is formed in layers from within out-ward and that the organic matrix of each layer is calcified progressively as developed. According to them the organic matrix is formed in layers much as claimed by Retzius, but it is impregnated as it is produced with mineral salts in a colloidal state. The consistency of this matrix is not as soft as that of cheese or soft enough to be cut with the finger nail as described by Ebner and Beust but much firmer. Although the amount of contained mineral salts may progressively increase as the matrix grows older, there is no calcification until the full thickness of the matrix is fully formed and the enamel organ has begun to atrophy and undergo reduction. Then and then only does the relatively firm matrix with its content of colloidal minerals

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