[Temperature dependence of inner structure in dental amalgam (author's transl)]

The problem of temperature dependence of inner structure in dental amalgan has been studied by several investigators. But so far as the present authors are aware, researches of the inner structure in amalgam at successive temperatures have not been published. In the present paper, the temperature dependence of structure are observed under a hot stage microscope with monitor television and recorded by vidio tape. The specimen is placed in furnace of microscope, and rised temperature by W heater. The contrast of structure increase very much at about 50 degrees C, and even uetched specimens reveal the structure clearly. The structure change remarkably above 60 degrees C and 80 degrees C. It seems that the main reason are the decomposition of gamma 2 phase and amalgamation of residual mercuries in the specimen. The structure of specimen polished and etched after cooling from 100 degrees C are similar to that before heating very much without fine structure in the unreacted particles. It has been deduced that the resemblance of structure concern the reversibility of mechanical properties proposed by Jørgensen, Otani and Kanai.