ABSTRACT
New palladium-based dental materials were examined in a wide spectrum of pH values from 3.8 to 9.6 at 37 degrees C for 315 h. Palladium dissolves in acid (pH 3.8) media with subsequent passivation (formation of complex compounds); areas of passiveness of palladium and its alloys for other pH values were found. The potentials of passiveness currents emerging in such cases were defined for all media, and corrosion curves of the alloys plotted. A film of palladium oxide appearing on the surface of the alloy was found to prevent further corrosion. High corrosion resistance in artificial saliva and high chemical inertness of palladium-indium alloy was revealed. The mechanisms of selective corrosion of the examined alloys and passiveness currents are discussed from the viewpoint of modern physical chemistry, and experimental data are explained. Use of such alloys in dentistry is shown to hold good promise.
Subject(s)
Dental Alloys/chemistry , Indium/chemistry , Palladium/chemistry , Corrosion , Electrochemistry , Hydrogen-Ion Concentration , Materials Testing/methods , SolutionsABSTRACT
A method for estimation of pore sizes in acrylic plastic dentures is described. Size-distribution of pores may be a very informative characteristic of not only strength, esthetic, and hygienic characteristics of dentures, but an indicator of a plastic polymerization process in various humidity and temperature conditions.
Subject(s)
Acrylic Resins/chemistry , Dental Materials/chemistry , Materials Testing/methods , Mercury , Polymers , Porosity , TemperatureSubject(s)
Acid Etching, Dental , Citrates/pharmacology , Dental Bonding , Dentin/drug effects , Phosphoric Acids/pharmacology , Adolescent , Adult , Citric Acid , Humans , In Vitro Techniques , Microscopy, Electron, Scanning , Middle Aged , Solutions , Spectrophotometry, Infrared , Surface PropertiesABSTRACT
The further progress in electron microscope autoradiography and the extent of its employment in histology and cytology are associated with the development of reliable methods of analysis. The essence of the main approaches to the analysis of high resolution autoradiograms is shortly reviewed. The examples given illustrate the usage of el electron microscope autoradiography as a quantitative method of research at the subcellular level.
