[The study of precedent subgingival flora colonization on four kinds of crown and bridge restorative materials]

The purpose of this in vitro study was to investigate the effects of microbial colonization on different crown or fixed bridge-used restorative materials and discuss the standards for evaluating those materials microscopically. Four kinds of restorative materials such as SDA-II type medium alloy, ceramic-fused-to-metal material, heat cure composite resin for crown restoration, Plat castable ceramics and four species of precedent subgingival flora (A. viscosus, F. nucleterm, C. ochracea, S. sanguis) were used. The material specimen had been continuously anaerobic cultured with the experimental bacterial fluid for 3, 7 and 14 days respectively, then the OD values of the specimenwashing fluid which could stand for the biomass of colonized bacteria on the surfaces of materials were measured. The results indicated that the quantity of precedent subgingival flora colonization on the surfaces of different restorative materials varied among different species of bacteria, which might concern with the surface structure, composition, property of anticorrosion and antisoluability of those materials.