Marian L. Lefevre

Chemical Analysis of Tooth Samples Composed of Enamel, Dentine, and Cementum

Introduction. Although many investigators have analyzed enamel, dentine, and cementum of teeth, separately, a smaller number have analyzed whole teeth in which enamel, dentine, and cementum occurred in unknown proportions. Results of recorded analyses on whole teeth are summarized in table 1, which includes indications of the materials analyzed. Most of the authors did not report results in terms of percentages of Ca (6), P (4), Mg (5), C02 (7), H20 (1), organic matter (2), and inorganic matter (3), but percentages in the table are recalculated from data for tooth composition as originally expressed, to make the values comparable. Whenever the basis of the original calculations was stated, i.e., percentage of ash-weight, percentage of dry-weight, etc., that basis is noted by a suffixed letter, as indicated in the footnote under the table. The reported data, though abundant, lead to conclusions that are in some cases self-contradictory, in others radically discordant, and never completely congruent; and have been used to support inclusive and sweeping theoretical inferences. Thorough consideration of the data is out of place here, but among the sources of contradictions are these: (a) materials not described, (b) precision of methods not ascertained, (c) insufficient number of analyses, (d) insufficient precision of analyses, (e) conclusions not checked by known statistical principles. Our own results are offered, not in the belief that they remove the contradictions, but to (a) increase

The Chemical Nature of the Inorganic Portion of Fetal Tooth Substance

Analyses of fetal teeth were made in 1862 by Hoppe-Seyler (1) who determined the mineral content of enamel from the teeth of three term fetuses and found the calcium content to average 31.4%0, phosphorus 13.9%, with a Ca:P per cent ratio averaging 2.26. In 1931, Hess, Lewis and Roman (2) concluded from a radiographic study of tooth calcification from birth to adolescence that calcification of permanent teeth is a post-natal phenomenon and that, taken altogether, deciduous teeth prior to birth are calcified in amounts corresponding to less than one-half gram of tricalcium phosphate. These authors found, by pooling corresponding teeth from opposite sides of three infant jaws, that calcium ranged in amounts from 3.78 to 17.18 mgm. and phosphorus from 1.82 to 8.67 mgm. for single teeth, with an average Ca: P per cent ratio of 2.04. In view of the small number of analyses made on fetal teeth we have attempted to determine the nature of the tooth substance within the fetal jaw, and to compare it with other calcified structures both in the fetal and in the mature organism.

Calcium, Phosphorus and Carbon Dioxide Determinations on all the Dentin From Sound and Carious Teeth:

The recent development of a rapid quantitative method for the separation of enamel and dentin of the whole tooth (19) offers the opportunity for determination of the inorganic constituents in the separated tissues and for a comparison of these constituents on the basis of the extent of caries found in the tooth. Murray and Bowes (20) have analyzed a number of samples of separated enamel and dentin from sound and carious teeth. Their samples, however, do not represent the whole tooth for they were prepared by grinding from the enamel and dentin toward the dentino-enamel junction. Armstrong and Brekhus (1) using their flotation method for separation of the enamel and dentin have analyzed enamel and dentin from a number of sound teeth and the enamel of some carious teeth.