Characterization and aqueous extraction of calcium hydroxide materials.

Analysis of two single and eight dual product systems showed the former to be calcium hydroxide dispersed in an aqueous gel in methyl ethyl ketone solution of an acrylic polymer and the latter were cements based on the polymerization occurring when mixing salicylate esters with calcium hydroxide. Using water as an extractant under controlled conditions, specimens of the prepared materials produced marked differences in pH values over 24 hours and conductivity over 72 hours; also cumulative extractions over 26 weeks showed substantial variation in the amount of calcium hydroxide and other solubles.

Potential toxicants in alginate powders.

Twenty-five dental alginate impression powders were obtained locally and analysed for Pb, Zn, Ba, Cd, As, Be, Hg, Sb, and V contents by atomic absorption spectroscopy; also total fluoride was determined by a conventional wet-way procedure. In addition, some lead containing powders were investigated for the lead content of the aerosol and that extractable from the surface of the set material by aqueous solutions. The results are detailed and concern is expressed at a possible hazard to health, mainly by inhalation of these materials.

A survey of the elemental composition of alloy for dental amalgam.

Analyses of 51 alloys (conventional, 41, and high-copper, 10) currently available in Australia were made. A rapid and precise procedure was developed that relied on wet-way methods for silver and tin while copper, zinc, mercury, indium and low-level constituents, such as lead, cadmium and antimony, were determined by atomic absorption spectroscopy. The conventional alloys, with two minor exceptions, all complied with the compositional requirements of modern standards and little quantitative variations was noted when the range of the major component was compared with the values obtained in two surveys made over thirty years ago. The high-copper contained, among other factors, an average copper concentration about four times that of conventional alloys. Rather surprising were the contents of mercury, indium, and cadmium found in some of the alloys as well as the low-level concentration of lead, and in a few cases antimony. Other elements were not detected by the sensitive technique used. It is justifiable to recommend that the maximum zinc content to be permitted in zinc-free type alloys should not be greater than 0.01%, and this value was subsequently incorporated in the revised Australian standard 2110-1977: Alloy for Dental Amalgam.

A rapid spectrophotometric assay of amide type dental anaesthetic agents.

A spectrophotometric procedure for the determination of lignocaine in ointments was investigated and standardized for general application to local anaesthetic solutions of the amide type commonly used for dental injection, namely, lignocaine, prilocaine, mepivacaine, pyrrocaine and tolycaine. The method is based on the controlled formation of a copper complex and the Beer-Lambert law was found to be obeyed over a useful range. Results indicated that the method would be accurate, convenient and rapid, saving substantial time over wet-way methods conventionally used. For confirmation of the identify of the anaesthetic agent, infrared spectroscopy was shown to be a rewarding technique.