THE CHEMICAL NATURE OF THE INORGANIC PORTION OF FETAL TOOTH SUBSTANCE

¹ Departments of Biochemistry and Pharmacology, and Medicine (Radiology), School of Medicine and Dentistry, University of Rochester, Rochester, New York

1. Normal values for fetal tooth substances are as follows: (per cent) moisture, 6.81 ± 2.0; inorganic residue, 80.4 ± 3.2; Ca, 34.5 ± 2.3; Mg, 1.1 ± 0.6; P, 16.9 ± 0.5; CO₂, 3.3 ± 0.1; residue solution number, 13.4 ± 2.4; Ca:P per cent ratio, 2.04 ± 0.16.

2. Per cents of Ca, P, inorganic residue are constant and per cents of Mg, moisture and residue solution numbers are variable.

3. Central incisors, upper and lower, have a higher inorganic residue than other teeth; otherwise, there is no relation between tooth type and per cent composition.

4. There is a definite relation between the moist weight of the fetal tooth and its morphological type.

5. Ca per cent, Ca:P per cent ratio and moisture per cent are lower for fetal than for adult teeth.

6. It is impossible to state on the basis of chemical analysis whether fetal and adult tooth substance have the same molecular structure since certain calculations show similarities in constitution and others show differences.

7. X-ray diffraction patterns for fetal and adult tooth substance are identical; this is strong presumptive evidence that the principal constituents are identical.