Antibacterial effects of resinous retrograde root filling materials

The effect of three resinous retrograde root filling materials on the growth of four obligate anaerobic bacteria associated with endodontic infections was determined by using the agar diffusion inhibitory test. Samples of the following resinous materials (resin-modified, glass-ionomer cement, Fuji II LC; compomer, Dyract; and composite resin, Spectrum) were incubated for 1 week with the following anaerobic bacteria: Fusobacterium nucleatum, Porphyromonas gingivalis, P. endodontalis, and Prevotella intermedia. The freshly mixed and set resinous materials were placed into the prepared wells of agar plates inoculated with the test microorganisms for 1 week. After the end of the incubation period, the zone of growth inhibition was observed and measured. Analysis of variance of the mean diameter of the zone of inhibition indicated no statistically significant overall differences in the response of the black-pigmented Bacteroides species (p > 0.05). For F. nucleatum, Spectrum had more antibacterial effect against this bacteria than Dyract (p < 0.05). Additionally, Fuji II LC was ineffective against F. nucleatum (p < 0.05). However, positive control plates showed bacterial growth in all cases. Our data suggest that the antibacterial potency of polymerized materials varied considerably, depending on the type and the product tested.