Antibacterial properties of electron beam-sterilized Gutta-Percha cones

The purpose of the study was to determine the effect of electron beam sterilization on gutta-percha cones (GPCs) at different times after sterilization. An agar diffusion test was used with -one aerobic bacterium (Bacillus subtilis) and five oral anaerobic bacteria (Fusobacterium nucleatum, Peptostreptococcus micros, Porphyromonas gingivalis, Propionibacterium acnes, and Veillonella parvula). With each microorganism 30 agar plates were prepared, evenly distributed among three groups (group 1: unsterilized GPCs; groups 2 and 3: GPCs sterilized by electron beam irradiation 5 months and 5 yr before, respectively). One GPC of the selected group was placed in each plate. After incubation the area of inhibition was read on the agar plates. Inhibition of growth was significantly different for the tested microorganisms. However no significant difference was observed between the sterilized and unsterilized GPCs. Both the tested sterilized and unsterilized GPCs impair the growth of endodontic pathogens, with no influence of the time elapsed since sterilization.