John Haldi

Dental pulp fluid—I: Relationship between dental pulp fluid and blood plasma in protein, glucose and inorganic element content

Abstract When a hole is drilled in the dogs tooth with a Cavitron or an Airdent, the pulp chamber can be reached or approximated without injury to the pulpal blood vessels. A capillary tube is inserted in the hole and cemented in place, whereupon a clear, colourless fluid begins to rise in the tube. Over a period of several hours a sufficient quantity of the fluid, designated as dental pulp fluid, can be collected for chemical analysis. The protein content of the dental pulp fluid is about one-fifth that of the blood plasma, whereas the glucose concentration is in equilibrium with the concentration in arterial blood plasma. Spectrographic analysis of dental pulp fluid and blood plasma showed that magnesium, iron, calcium, phosphorus, copper and sodium are present in both fluids.

Pressure within the Pulp Chamber of the Dog's Tooth Relative to Arterial Blood Pressure

In a previous communication we have shown that fluid, which we have designated as dental-pulp fluid, is produced continuously in the pulp chamber of the dogs tooth. It is reasonable to assume that this fluid, like the interstitial fluid elsewhere in the body, is derived from the blood via the capillary endothelium. The present study was undertaken to determine whether changes in the arterial blood pressure are reflected in the pulp chamber and, presumably, in the amount of fluid escaping from the capillaries.

Protein Fractions of the Blood Plasma and Dental-Pulp Fluid of the Dog

After the dog had been completely anesthetized with nembutal, a hole was drilled with an air-turbine handpiecet in the manner described elsewhere through the buccal enamel and dentin to the pulp chamber in the maxillary and mandibular canine, premolar, and first molar teeth on the same side of the jaw. A capillary glass tube was inserted in each hole and sealed in place. After several hours, clear, colorless fluid, which we have designated as dental-pulp fluid, had collected in the tubes in sufficient amount for the desired analyses. Plasma was obtained from venous blood drawn toward the end of the experiment. In numerous experiments in which this technique was employed, we could detect, upon microscopic examination, no erythrocytes or leukocytes in the dental-pulp fluid. The chairman of the Department of Oral Pathology at this institution made and examined for us histologic decalcified sections of the teeth in some of these experiments. He could find no evidence of pulpal damage. He saw no indication of inflammatory response in the pulp at the levels where the holes had been drilled. We have therefore concluded that the dental-pulp fluid is a capillary transudate. Separation of the protein fractions was effected in an electrophoresis instrument,: using filter-paper strips§ and sodium barbitone-sodium acetate buffer of pH 8.6 and 0.1 ionic strength. In preliminary trials it was found that the concentration of the protein fractions in the pulp fluid was so low as to give only faint, indistinct markings on the filter-paper strips when subjected to electrophoresis. The pulp fluid was therefore freeze-dried and then made up with distilled water to a volume that was five times as concentrated as the original. This concentrated solution and the plasma were

Relationship between Thyroid Function and Resistance to Dental Caries

A relationship between the secretary activity of the thyroid and resistance to dental caries is indicated by the studies of Muhler, Shafer, and Bixler,lA who found that the cariogenicity of a coarse-corn diet fed to albino rats was decreased by the addition of desiccated thyroid and, conversely, increased by the addition of propyl thiouracil. The purpose of the study reported in this paper was to determine whether certain mechanisms may possibly be involved in this relationship. Several possibilities were taken into consideration, and, accordingly, several different types of experiments were conducted. As the diet fed the animals in the experiments of Muhler, Shafer, and Bixler contained 60 per cent ground yellow corn, it was thought that perhaps the carious lesions might have been initiated as a result of fracture of the enamel by the coarse-corn particles. If this were the case, the reduction in, or loss of, the thyroid hormone in the bodily economy, which undoubtedly occurred when propyl thiouracil was added to the diet, might conceivably have resulted in a more brittle enamel, whereas, on the other hand, an additional amount of the hormone might have contributed to a more resistant enamel. An experiment was therefore undertaken in which albino rats were fed a finely powdered synthetic diet to which was added either desiccated thyroid or propyl thiouracil. These experiments were conducted on both intact and sialoadenectomized animals. The purpose of the latter experiments was to determine the role of the salivary glands in the thyroid-dental caries relationship. Another experiment was done to compare the effect of administering desiccated thyroid by stomach tube and by adding it to the diet. In view of the idea prevailing in some quarters that dental caries is initiated by acid which is produced in the degradation of carbohydrate, we considered the possibility that the buffering capacity of the saliva might be considerably lower when there was a reduction or loss of the thyroid hormone. In this event the pH on the teeth could conceivably fall to very low levels. To test this possibility, pH readings were taken in one experiment on the teeth of thyroidectomized and control animals before and after eating. This experiment served the purpose also of showing whether similar dental caries experience would result from thyroidectomy as from feeding propyl thiouracil.

pH on the teeth of albino rats under various conditions conducive to dental caries

Abstract The pH on the teeth of albino rats with reference to the time of eating was obtained by training the animals to eat their food allowance at scheduled times of the day. The average pH on the teeth of intact rats before eating was in the neighbourhood of 8.0. After eating a cariogenic diet, or sugar alone, it rarely fell as low as 7.0. In sialoadenectomized animals, it was lower than in intact animals. It is concluded that in the rat dental caries may occur without the pH on the teeth falling to what is regarded by many investigators as the decalcification level for human teeth. The results of these experiments raise some questions concerning the acidogenic hypothesis of the aetiology of dental caries.

Influence of the Ash of the Cacao Bean on the Cariogenicity of a High-Sucrose Diet

A number of studiesl-8 have provided evidence that the mineral content of a diet may affect its cariogenicity. It may have been such investigations as these which led Rozeik, Cremer, and Hannover9 to consider the possibility that the minerals in the cacao bean might account for some of the results obtained in the Vipeholm experiments.0 In these experiments the subjects who ate 8 toffees daily between meals over a 2-year period had an increase in caries activity more than twice that of those who ate almost the same amount of sugar between meals in the form of milk chocolate. In experiments by Rozeik, Cremer, and Hannover on sialoadenectomized white rats, there was considerably less dental caries in the animals fed a diet containing cacao-bean ash than in those on the control diet. These observations led the authors to conclude that the ash of the cacao bean is caries-inhibitory. It should be noted, however, that there were several differences in the composition of the control and test diets, apart from the ash content of the latter. The control diet consisted of 200 gm. barley groats, 100 gm. fish meal, and 100 gm. powdered sugar. The test diet was composed of 100 gm. barley groats, 100 gm. fish meal, 100 gm. powdered sugar, 66 gm. vitaminized margarine, 12 gm. casein, 12 gm. starch, and 6 gm. cellulose, to which was added 5.25 gm. of the cacao-bean ash. One notable difference between the two diets was the addition of fat in the form of vitaminized margarine to the experimental diet, whereas the margarine was omitted from the control diet. Other investigators have found that when fat was added to a synthetic cariogenic diet, the diet was less conducive both to smooth-surface caries2 and to fissure caries in the albino rat. In view of these considerations, two different experiments have been conducted in our laboratories to determine (1) whether the addition of cacao-bean ash to a synthetic high-sucrose cariogenic diet would render the diet less cariogenic and (2) whether supplementation of this ash-containing diet with fat in the form of vitaminized margarine would affect its cariogenicity.

Effect of Sialoadenectomy on Weight Gain and Body Composition of Albino Rats

It has been noted in various laboratories 2 that sialoadenectomized rats gain less weight than their unoperated controls. Examination of the daily food consumption has suggested to Bixler, Muhler, and Shafer that the retardation in weight gain of their sialoadenectomized animals may have been attributable to a lower food intake than that of their littermates. However, it should be noted that, while the test males had eaten less food than their controls, there had been no difference in the food intake of the test and control females. Shaw and Wollman2 have reported that the recorded food consumption of the sialoadenectomized rats had been greater, while the weight gain had been considerably less than that of the controls-. In the above-mentioned experiments, feeding had been ad libitum. In our earlier-experiments3 in which the sialoadenectomized rats gained less weight than their controls, the animals had been pair-fed. It has been observed in our laboratories that sialoadenectomized rats scratch an appreciable amount of food out of the feeding cups, thereby making it impossible to determine accurately the food consumption even when the animalsare pair-fed. In order to avoid this source of error, the present experiments were undertaken in which the animals were fed by stomach tube. This procedure gave unequivocal assurance that the daily food intake of each sialoadenectomized rat was the sameas that of its littermate, sham-operated control. In addition to obtaining data on weight gain under these conditions, the composition of body constituents of the test and control animals was determined by chemical analysis. In order to determine whether there was a difference in utilization of food, i.e., in digestion and/or absorption in the two groups, the feces of each animal were collected throughout the experiment and the caloric value obtained by burning them in a bomb calorimeter.

Comparative Concentration of Various Constituents of Blood Plasma and Dental-Pulp Fluid

Although the significance of the dental-pulp fluid with reference to the vitality of the tooth is at present unknown, it is nevertheless highly desirable that our knowledge of the constituents of the pulp fluid be expanded. With this thought in mind, the experiments reported in this paper were undertaken to ascertain the relative concentrations of various constituents of the pulp fluid and of the blood plasma. It was thought that information of this nature might also throw light on the mechanisms involved in the production of the dental-pulp fluid.

Dental Caries in Albino Rats Fed Diets Containing Different Amounts of Calcium and Phosphorus with the Same Ca/P Ratio

In earlier experiments it was found that the cariogenicity of a high-sucrose diet was reduced when the Ca/P ratio of the diet was changed by the addition of phosphate to the diet without altering the calcium content.1 Later it was shown that the diet could likewise be made less cariogenic when the Ca/P ratio was changed by adding calcium to the diet and keeping the phosphorus at a constant level.2 In the first experiment a progressive decrease in the number of carious lesions and the caries score occurred up to a certain point with a progressive decrease in the Ca/P ratio, whereas in the second experiment this relationship was reversed: a decrease in caries conduciveness of the diet was associated with an increase in the Ca/P ratio. These findings were taken to indicate that the changes induced in the cariogenic properties of our high-sucrose diet, by altering the calcium and phosphorus content, were due to differences in the actual calcium and phosphorus content of the diets and not to differences in their Ca/P ratios. The evidence for this deduction, however, was admittedly indirect, inasmuch as in each experiment the Ca/P ratio was altered when either calcium or phosphorus was added to the diet. In the present study our conclusion drawn from our previous experiments was submitted to a direct test by increasing the calcium and phosphorus of the diet without changing the Ca/P ratio.

Sulfanilamide and Penicillin in the Pulp Fluid of the Dog Following Administration of these Compounds

In previous studies,-3 the concentration of glucose, protein (N X 6.25), urea, chlorides, alkaline phosphatase, and magnesium was found to be approximately the same in the blood plasma and dental pulp fluid of the dog, whereas calcium and inorganic phosphorus were at a lower level in the pulp fluid than in the blood plasma. The experiments reported in this paper were undertaken to determine whether the administration of the chemotherapeutic agent sulfanilamide and the antibiotic penicillin would be followed by an accumulation of these substances in the dental pulp fluid.