Studies on the Respiration of the Tooth Germ

Publisher Website
Google Scholar
Abstract
It has been recognized by both early and recent investigators of the mechanism of the calcification that the glycolytic process of the Embden-Meyerhof-Parnas scheme occurs in calcifying tissues, in general (1–4). In 1950, Gutman and Yu (5) found the significant fact that phlorizin, monoiodoacetate, and fluoride, the well-known inhibitors of glycolysis, decreased the calcification rate of rachitic cartilage in vitro, and based on this fact, they postulated that the glycolytic process is directly related to the calcification mechanism. That is, the energy-rich phosphate in phospho-pyruvate derived from glycolysis may be transphosphorylated to the matrix in which mineralization occurs. On the other hand, while the presence of a large amount of citrate in the calcified tissue has been known for a long time (6), Dixon and Perkins (7), and recently Less and Kuyper (8), found the presence of the enzymes and intermediates concerned in the TCA cycle. Tulpule and Patwardhan (9) discovered that vitamin D increased the pyruvate oxidation which had previously decreased in the case of rachitic metaphysis. In addition, it was found that respiration was necessary for the biosynthesis of chondroitin sulfate, which is considered to be an important portion of the organic matrix for calcification (10). Thus the respiratory system has become another important subject of research because of its possibly important role in process of calcification, particulary in the period of matrix formation. These experiments were performed on the tissues other than tooth such as cartilage (preosseous or rachitic), bone, callus after fracture, etc. The biological activities of the tooth after it is completely formed are very slight, so that there is only a small probability for the tooth to recover when it once get caries. However, the tooth germs have the most active calcifying ability and carry out intense calcification in a relatively short period. Also the metabolism responsible for tooth formation might be different from that of other hard tissues. In order to gain a better insight into the biochemistry of calcification metabolism, especially in the case of the tooth, the author intends, in the present study, to investigate the respiratory activity of tooth germs. In his previous research, Pincus (11) found the presence of respiration in human tooth pulp, and that the mean Q02 value was 0.31. Flieder and Fisher (12) found a Qoa value of 0.56 for bovine tooth pulp. However, it may be supposed that these pulp tissues were not directly concerned in calcification, because they did not contain odontoblasts and the teeth were almost completely calcified.