Influence of Changes in the Powder Particle Size Distribution on the Physical Properties of Luting Agents. Mainly on Influence of Pretreatments of Abutment Tooth before Final Cementation.

Our department has been researching the influences of changes in particle size distribution on the physical properties of luting agents. It is said that luting agents are largely affected by contact with water. In the present study, changes in the physical properties after contact with water at the time of cementation were determined in several types of glass-ionomer cement for Luting (Gcement), which differed in particle size distribution, by using an ivory or agar jig. The physical properties of G cement were also examined after pretreatment of the abutment tooth with a surfacetreatment agent and a temporary cement inside the ivory jig.As a result, the greater the content of fine particles was, the greater the compressive strenght, tensile strength and scratch hardness of G cement tended to be. G cement containing high proportions of fine particles was not likely to be affected by water. Pretreatment suchas temporary cementation or surface-treatment prior to cementation for crown or bridge formation was found to be effective for preventing deterioration of the physical properties of G cement.