William J. King

Volatility as a factor in the inability of certain amines and indole to increase the odour of saliva.

Abstract The present communication attempts to examine critically the influence of amines and indole on the disagreeableness of odour derived through salivary putrefaction. Methylamine and cadaverine failed to enhance the odour intensity. In fact, cadaverine depressed noticeably the odour producing activity of incubated saliva. These results suggest that at the pH and environmental conditions approximating those of the oral cavity, the amines exist primarily in the non-volatile state. Hence they cannot be considered as important malodorous constituents in head-space evaluations. Studies with radioactive tryptophan indicate that indole is produced in considerable quantities and that it is the main product of its metabolism. The inability of indole to alter the odour characteristics of fresh and incubated saliva is ascribed to its low volatility. Purging of putrefied saliva for 1 hr at RT with a constant stream of N2 removed most of the offensive odour. The indole and indolyl content of saliva, however, remained unchanged. Similarly the expurgations at 37 °C induced only a small loss of indole and indolyls, yet the putrefied saliva exhibited a major decline in the odour intensity. These findings are in agreement with the results obtained on indole-supplemented saliva systems. Indole did not impart a foul odour to fresh saliva or enhance perceptibly the odour intensity of incubated samples. The results demonstrate that the mere presence of indole or the amines tested is not a reflection of their influence on the odour intensity of saliva.

An in vivo technique for determining the effect of agents on enamel solubility in human subjects

IT is desirable to perform enamel solubility studies in viva on human subjects, since this is the ultimate test of the efficacy of compounds in increasing the resistance of enamel to acid attack under actual conditions of use. WALTER (1958), and M~~HLEMANN and WOLGENSINGER (1959) have developed a method for such an in viva determination utilizing 2 mm disks of filter paper. Etching solution is placed on this small piece of paper and enamel solubility is determined by the length of time required to change an acid-base indicator on the disk or by a phosphorus determination (WALLIS, 1961). This procedure is restricted to small, smooth, intact areas. Moreover, it would probably be difficult to perform analyses on lingual surfaces of any tooth and buccal surfaces of posterior teeth. A procedure has been developed in our laboratories to determine enamel solubility conveniently on any upper tooth in vivo. Anterior or posterior teeth which were to be extracted for either prosthetic or periodontal reasons were selected for testing. The teeth used in preliminary studies were relatively free from caries, fillings, and other obvious defects. The subject was placed in position so that the long axis of the test tooth was always perpendicular to the floor in order to prevent loss of the etching solution. A small polyethylene vessel containing a measured amount (usually 2 ml) of 0.2 M acetate buffer, pH 4.0, was placed over the tooth. The top of the container was placed in contact with the gingiva. When this was not possible, the position of the vessel was marked on the tooth surface. This procedure enables the investigator to expose the same area to multiple etchings. Isolated teeth or adjacent teeth with diastemas are best suited for study using this technique. A typical experiment is performed as follows: The subject brushes his teeth with a placebo dentifrice and rinses his mouth thoroughly with water. The teeth being studied are etched with 0.2 M acetate buffer, pH 4.0, for 5 min. The teeth are rinsed again thoroughly and the experimental agent applied. After re-rinsing, the teeth are etched once more for