Chemical Constitution of Enamel and Dentin

An understanding of the calcification process requires exact. knowledge of the nature and variations of composition of the mineral phase of calcified tissues. Other investigators have continued the study, begun years ago, of the composition of the inorganic salts of bone, but a comprehensive study of the results of analysis of enamel and. dentin by modern methods has not been described. Crowell, Hodge, and Line (1934) have reported the results of a very complete survey of the composition of the mineral phase of whole adult teeth. These authors present a comprehensive summary of the literature on the composition of whole teeth, enamel, and dentin. Recently Le Fevre, Bale, and Hodge (1937) described the composition of the mineral phase of whole fetal teeth. The analyses reported in both papers were made on the inorganic residue prepared by boiling the specimen in a solution of potassium hydroxide and ethylene glycol. The variations in relative amounts of enamel, dentin, and cementum in teeth make the interpretation of analyses of whole teeth difficult and it is, therefore, desirable to determine the composition of enamel and dentin separately. The older studies described the composition of only a few specimens and in many cases the analyses were made on ashed materials. Changes in composition of the mineral phase are known to result during ignition (Bowes and Murray, 1935; Howland, Marriott, and Kra-