Henry Klein

The Effects of Strontium Administration on the Histological Structure of the Teeth of Rats

The effects upon the animal organism of the feeding of strontium salts has been studied by a number of workers. Stoeltzner (1908) and Lehnerdt (1910) have reported that the feeding of strontium salts results in the production of excessive amounts of osteoid tissue in the bones. Shipley, Park, McCollum, Simmonds, and Kinney (1922) reported similar findings. They used McCollums diet 2581 as a basal one, which is composed as follows:

Physico-Chemical Studies On the Structure of Dental Enamel Viii. the Determination of the Isoelectric Point of Enamel by Means of Membrane-Potential Measurements

Introduction. Experiments dealing with effects of acidity and alkalinity on the nature of the cataphoretic charge on enamel particles, and on the enamel pore-wall,3 have indicated that the isoelectric point of enamel lies between pH 3.6 and 4.9. Previous research4 had demonstrated that a reversal of sign of the charge on the enamel pore-wall is accompanied by a reversal of direction of the membrane potential, the pore walls being negatively charged in KCI solutions, positively in CaCl2 solutions. Reversal of sign of the charge on a substance, by changing the hydrogen-ion concentration of the bathing solutions, usually indicates that this substance contains or is made up of amphoteric material which dissociates in acid solutions in such a way that the dominant charge on the substance is that of a cation (positive); in alkaline solutions, that of an anion (negative). If enamel has amphoteric properties, the enamel porewall would be positively charged in solutions on the acid side of the isoelectric point, negatively on the alkaline side. That enamel possesses such properties has been experimentally demonstrated.5 On the basis of the previously described mechanism for the pro-

The Significance of Food-Particle Size in the Etiology of Macroscopic Dental Decay in Rats

Introduction. Recent work by Hoppert, Webber and Canniff2 has suggested the possibility that size of food particle plays a role in the etiology of macroscopical dental decay in rats. Their animals ingested the following diet (adequate): ground yellow-corn, 60 parts; wholemilk powder, 30; linseed-oil meal, 6; alfalfa meal, 3; NaCl, 1. The rats on this diet developed dental decay in the molar teeth at eight weeks of age. Some of the ground yellow-corn was then sifted through a 60-mesh sieve. The portion that passed through the sieve (substituted for the ground whole-corn in the diet of the first group) was fed to another series of rats, which, fed for eight weeks, did not develop dental decay. The conclusion noted by these workers, namely, that size of food particle was the causative factor in the caries incidence, was not entirely justified by the experiments, for it may readily be noted that there are many differences aside from particle size between ground corn and that part of corn which passes through a 60-mesh sieve. Nevertheless, Hoppert, Webber and Canniff have, in this manner, offered an interesting suggestion, which was subjected to further investigation in the experiments described below. It should be noted that this paper is concerned only with macroscopic dental decay in rats; that is to say, with very obvious and easily identified holes in the molar teeth. The authors have already pointed

The Histopathology of Experimental Molar Caries in Rats

An extensive array of direct experimental evidence shows that defective tooth-structure results from the feeding of deficient diets. However, few workers have observed actual cavity production as a result of such feedings. McCollum and co-workers (3) reported the finding of macroscopic cavities (caries-like lesions) in the molars of rats on diets unbalanced in protein and mineral contents. Marshall (5) and Bunting (2) found cavities histologically in rats on diets low in calcium and vitamin A. Howe (4) observed similar lesions in guinea pigs deprived of this vitamin. Bloch (1), however, was unable to find dental caries in cases of xerophthalmia caused by deficiency in vitamin A. In the course of an investigation on the effects of unbalanced diets on the teeth of rats, it became apparent that frequent caries-like lesions were present in the molars of rachitic rats which had been fed viosterol therapeutically for long periods. The present communication is concerned with a description of the histology of such cavities. The rats used were the offspring of healthy females, which had been receiving diets adequate in all respects. At weaning the young were placed on a rachitogenic diet, and continued on this diet for nineteen days. At the end of this time 1 per cent of viosterol, equivalent to cod-liver oil,2 was added to the ration, which was fed for 87 days, until the rats were 135 days old. When the teeth of these rats were examined, the most striking defect noted was an extensive

Physico-Chemical Studies on the Structure of Dental Enamel: III. A Method for Determining the Rate at Which a Salt May Penetrate the Enamel

Dog canines were extracted carefully without injury to the enamel. The pulp was removed, and the pulp chamber cleansed of all organic debris. The teeth were sawed through at the cemento-enamel junction, and the root portions discarded. The crown was then placed in distilled water, which was changed daily for from one to two months, to wash out salts and other soluble substances in or on the structure.

Physico-Chemical Studies On the Structure of Dental Enamel: VII. the Mechanism of Production of Membrane Potentials (Electrical Differences of Potentials) in the Enamel of Dogs

Introduction. When two different concentrations of a salt, in separated containers, are connected by a salt bridge with suitable instruments, an electrical current, known as a diffusion potential,2 is set up. When two different concentrations of the salt are separated by a membrane semipermeable for one ion, an electrical current, known as a membrane potential,3 arises. If the membrane separating two different concentrations of a salt solution contains very large pores, the diffusion potential is very slight, and arises only from differences in mobility of the different ions. This condition holds for any membrane having pores, the membrane playing no role in the production of electrical current, diffusion from the concentrated solution into the dilute being unhampered by a membrane having large pores. If the salt is 0.1 M KC1 separated from 0.02 M KCl, a membrane with large pores acts as a very slight barrier, the ensuing potential difference being due only to the difference in ionic mobilities of the K ion and the Cl ion. If, however, a membrane containing smaller pores is placed between the two different concentrations of KCI, the ensuing potential difference increases in magnitude as the pore-size diminishes. A very permeable membrane (large pores) produces only slight potentialdifferences; one that is not readily permeable (small pores) develops

A Critical Analysis of the Dental Literature Dealing with the Effects of Dietary Variations Upon the Structure of Teeth

An analysis of the dental literature dealing with the observed effects of dietary variations and deficiencies upon the structure and composition of teeth, instituted to obtain a clearer conception of the work already accomplished and its quality, revealed much interesting data. Each paper was carefully read and then grouped as to its scientific worth. We have arranged the papers into three groups. In the first are placed those papers which on the basis of well controlled experiments derive certain well-founded and cautious conclusions. This group has been designated Group A. The second is made up of those articles which, containing excellent reviews and the correlation of research accomplished by workers whose papers fall in Group A, has been designated Group B. The third group includes those papers that do not present any or at most very poor experimental evidence for conclusions stated, which conclusions are based upon poorly defined information. This includes editorials, letters and essays, all of little scientific value. Also in group C, are included papers and reviews that are repetitions, by authors in a number of journals, of work already published elsewhere; and in addition, this last group includes a few clinical papers whose conclusions are not wholly warranted by the amount of evidence presented. The papers have been judged with this point in mind: Does the article contribute new, well-founded, cautiously interpreted facts, well supported by experimental evidence? In fig. 1, papers that measure

A Lead -Sector-Disk for Expressing Density of Bone and Tooth Structure in Terms of Percentage Transmission of X-Rays

Attempts to determine densities of bone and teeth by means of an x-ray method have been made by few workers. Doubrovine2 has reported a method consisting primarily of crude comparisons of x-ray films photometrically without any attempt at calibration. More recently Bishop and Warren3 have advocated a method in which aluminum step-tablets are used as a calibration standard for determining bone densities. In their method, the bone densities are determined by comparing the density of photographic deposits produced by x-rayed bone with that produced by various thicknesses of sheet aluminum. The densities are then expressed in terms of millimeters of aluminum. In a study of the effects of dietary deficiencies upon bone and tooth structure in swine, it became necessary to evaluate tooth and bone