Alternative interpretations of water sorption values of composite resins.

Water sorption values for direct filling resins and an unfilled resin were much more similar at 30 days when expressed as mg/g organic matrix than as mg/cm2 or weight percent. This interpretation is indicative of the water sorption characteristics of resin matrices. The values are even more indicative when solubility or leaching is taken into consideration. With the specimen sizes used in this study, the effect of the kinetics of water sorption could be minimized by using values obtained after immersion in water for 30 days.

The effect of exposure conditions upon the release of soluble copper and tin from dental amalgams.

The concentrations of soluble copper and tin which were generated by the corrosion of a number of different amalgams in both an artificial saliva and Ringer's solution are reported. Besides variations in solution composition, the effects of solution agitation and abrasive particle wear upon the release of soluble species are studied. Immersion only, moderate solution agitation, vigorous solution agitation with abrasive particle wear, and accelerated corrosion by both constant currents and cyclic voltammetry are included. The results indicate that an artificial saliva but not Ringer's solution is capable of generating high levels of soluble tin. With artificial saliva, agitation increases the amalgam weight losses and increases soluble copper and tin concentrations, whereas agitation with Ringer's solution decreases sample weight losses and decreases levels of soluble copper and tin. This latter effect is believed to be due to the increased oxygen supply to the amalgam surfaces with agitation and the greater ability for producing protective passivating films of the basic hydroxide and copper chlorides in solutions of higher chloride ion concentrations e.g. Ringer's solution. Abrasive particle wear, including pumice, alumina, glass beads, and silica gel had varied effects upon the release of soluble species. Depending upon the amalgam, the solution, and the abrasive combination, either larger increases in copper or in tin occurred or reduced concentrations.