Antibacterial activity of calcium hydroxide and chlorhexidine containing points against Fusobacterium nucleatum and Parvimonas micra

OBJECTIVE: Up to 90% of the flora of an infected root canal consists of obligate anaerobic bacteria. However, most studies have centred on microaerophiles. This quantitative assay investigated the antibacterial effects against Fusobacterium nucleatum and Parvimonas micra of gutta-percha (GP) points containing either calcium hydroxide (Ca(OH)(2)) or chlorhexidine (CHX) compared to those of conventional GP points. METHODS: Standardized root canals were prepared in 192 bovine incisors. The canals were sterilized and then inoculated with one of two bacterial species (n=96 teeth per bacterium). After anaerobic incubation at 37°C, the inoculum was removed and the canals were filled with one of the three points. Control teeth were filled with a saline/serum mixture. After 0, 1, 4 and 8 days of anaerobic incubation, the numbers of viable bacteria (CFU/ml) were determined on both the points and the canal wall dentin. Six replicates were carried out for each experiment. RESULTS: None of the points completely eradicated the bacteria in the canal. GP+CHX was significantly more effective than GP+Ca(OH)(2) and GP (P<.05 in each case). The inhibitory effect of GP+Ca(OH)(2) did not significantly differ from that of GP (P>.05). Compared to the controls, the antibacterial effect of the medicated points was reached initially. CONCLUSION: Within the limitations of the in vitro model, the incorporation of commonly used medicaments in GP does not offer a long-lasting antibacterial advantage over non-medicated GP.