B. J. Kruger

Synthetic hydroxyapatite-solubility product and stoichiometry of dissolution.

Abstract The solubility product of a well-characterized sample of hydroxyapatite (Ca:P ratio of 1.664 ± 0.002) was constant over the pH range 4.56 to 9.67, ionic strength range 0.0003 to 1.03 and solid:solution range 0.0625 to 5.55 g/250 ml in spite of non-stoichiometric dissolution of the solid. The mean product for 61 equilibrations was 2.91 × 10 −58 with 95 per cent confidence limits of 0.51 × 10 −58 and 7.89 × 10 −58 . The hydroxyapatite sample also yielded solubility product values far in excess of 2.91 × 10 −58 if (a) an irreversible surface layer formed during preparation was not removed, or (b) during successive equilibrations at high solid:solution ratios, the suspension was subjected to a large increase in solution pH.

Lipid and protein histochemistry of enamel--effects of fluoride.

SummaryStaining reactions for a number of histochemical procedures for lipophilic staining and protein were studied in the enamel matrix along the length of rat incisors. Sudan Black gave a positive stain across the whole thickness of very early enamel (up to 30 μm) but this staining only continued as a narrow band close to the ameloblasts as the enamel matured. A variety of tests for protein produced almost identical staining patterns in enamel matrix up to 100 μm thick. Since the pattern of “lipid” staining persisted, after using a number of procedures which could normally be expected to remove lipid, it is suggested that Sudan Black positive staining may be due to lipophilic protein rather than lipid itself. Fluoride did not significantly alter the staining reactions for “lipid” and protein but did proceduce matrix which was much more effectively stained by cross-linking agents FFDNB and FF sulphene.

Effects of a Single Intravenous Dose of Sodium Fluoride on Plasma Electrolytes and Metabolites in Rats, Rabbits, and Cockerels

This study assessed the effect of a single intravenous dose of sodium fluoride (20 mglkg body wt.) on plasma ionic fluoride and on some other plasma electrolytes and metabolites in rats, rabbits, and cockerels. At any given time following sodium fluoride administration, the plasma ionic fluoride was highest in rabbits and lowest in cockerels. The rate of removal of fluoride from plasma was slower in rabbits as compared with that in the other two species. Plasma sodium, chloride, total protein, albumin, total globulins, and osmolality were not significantly altered by sodium fluoride in any of these three species. However, plasma phosphate (inorganic), urea, creatinine, and glucose were elevated, and plasma calcium was reduced in the rats and the rabbits, but none was significantly altered in the cockerels. The analyses indicated that species variability does exist in fluoride toxicity.

Statistical Evaluation of a Multiple Response Experiment: Alterations to the Morphology of Rat Molars

SYNOPSIS IN INTERLINGUA EVALUTATION STATISTIC DE UN EXPERIMENTO A RESPONSA MULTIPLE; ALTERATIONES AL MORPHOLOGIA DE MOLARES DE RATTO.-Quando il existe multe mesuramentos pro cata unitate experimental, il es multo plus efficace determinar le variantia per methodos de analyse a multiple variabiles que per separate analyses a un sol variabile. In le presente studio, separate analyses a un sol variabile monstrava que le administration de fluoruro alterava 6 de 8 characteristicas de molares del ratto. Methodos a multiple variabiles confirmava ille conclusion, sed illos etiam monstrava que le plus grande parte del effecto general poteva esser explicate per alterationes in non plus que 2 del characteristicas. Le altere characteristicas non experien- tiava alterationes independente. Fluoruro in le presentia de molybdenum e molybdenum sin fluoruro produceva differente resultatos.

Influence of Boron, Fluorine, and Molybdenum on the Morphology of the Rat Molar

Boron, fluorilne, and molybdenum, administered during amelogenesis, will reduce the caries susceptibility of rat molars (B. J. Kruger, Australian D. J., 3:236, 298, 374, 1958). How this is effected is not completely understood. This project studied the effect of the trace elements on the morphology of the first mandibular rat molar. The enamel of this tooth forms between birth and the eleventh day, when the young are dependent on the mother for sustenance. Within-litter effects were measured. The elements were injected intraperitoneally into the young as normal saline solutions of suitable salts; littermate controls received normal saline. Daily amount injected into a boron rat was approximately 25 ug B, as boric acid, into a fluoride rat approximately 108 pug F, as sodium fluoride, and into a molybdenumt rat approximately 7 jug Mo, as ammonium molybdate. The treatments did not affect gain in xveight. Animals were killed at age 21 days. The occlusal surface of each molar was photographed and enlarged (17X) by means of a standardized technique.

Differences in fluoride levels in the blood between sheep, rabbit and rat

The various techniques for measuring F levels in serum with the fluoride electrode were compared to select a suitable procedure for monitoring F in the sera of animals after the administration of an insult dose of fluoride. F was present in the sera in two forms-ionic and bound. In the the sera of sheep and rabbit, the bound F was released by diffusion with, e.g. HClO4 but in rat sera was only released by ashing before diffusion.

Dose-Dependent Ultrastructural Changes Induced by Tetracycline in Developing Dental Tissues of the Rat

Tetracycline was administered to rats in varying doses in order to study the likelihood of ultrastructural alterations to ameloblasts and to study odontoblasts and dentin as well. The changes caused by tetracycline to the mineralization of dentin and the ultrastructural changes to the odontoblasts and ameloblasts increased with larger doses.

The effect of intravenous sodium fluoride and synthetic salmon calcitonin on plasma total calcium, inorganic phosphate, and ionic fluoride

SummaryVarious doses of sodium fluoride (NaF), salmon calcitonin (CT) and NaF combined with CT were given intravenously to rats (236±2 g). Blood plasma samples were collected at various times up to 24 hours and measured for total calcium (adjusted for variation in plasma albumin), inorganic phosphate, ionic fluoride, urea, and creatinine. Following injection of NaF alone, significant hypocalcemia and hyperphosphatemia was observed. In contrast, CT injections resulted in hypocalcemia and hypophosphatemia. NaF and CT given in combination generally resulted in the hypocalcemia being equal to or greater than that calculated from the simple addition of their individual effects. Significant increases in both plasma creatinine and plasma urea were observed following treatment with NaF alone or with CT and NaF together, whereas CT alone had negligible effect. These results suggest that NaF does not mimic the effects of CT; rather that NaF and CT interact to modify their individual effects. The influence of NaF probably occurs via an effect on kidney function.

A microspectrophotometric analysis of the effect of fluoride on immature enamel matrix protein of rat molar teeth.

SummaryOver a 24-h period, Wistar rats from 4 litters, 6 to 9 days old, were given five intraperitoneal injections of a solution of 0.9% sodium chloride containing sodium fluoride (3 mg F/kg body weight). Within-litter controls were used. All rats were killed by decapitation 2 h after the final injection and the rat heads, cut sagittally, were processed for protein histochemistry.The intensity of staining of the protein in the enamel matrix of the upper jaw molar tooth buds was quantified using the two-wavelength method of microphotometry. A significant increase in the intensity of staining of fluoride-treated tissues over controls was observed with the histochemical methods specific for arginine (P<0.01), tyrosine (P < 0.05), and cysteine (P<0.05). Other histochemical methods specific for amino acid groups failed to show any significant difference between fluoride and non-fluoride-treated enamel matrix.