Sealing ability of two root-end filling materials in a bacterial nutrient leakage model

To compare in vitro the sealing ability of root-end fillings with mineral trioxide aggregate (MTA) and EndoSequence BioCeramic Root Repair Material-Fast Set (BC-RRM) Putty using a novel bacterial nutrient leakage model, which provides information on whether or not intracanal bacteria are receiving nutrients from serum via leakage channels.

Sixty single-rooted decoronated mandibular incisors with instrumented root canals were subjected to root-end resection and ultrasonic preparation. The root specimens were mounted in the experimental apparatus, and the root-end cavities filled with the test materials. The positive control group used warm Gutta-percha and no sealer. In the negative controls, the entire resected surface was covered with varnish. After sterilization in ethylene oxide, the root canal was inoculated with 1.5 × 10(5) washed cells of Enterococcus faecalis. The apparatus was filled with foetal bovine serum, leaving only the apical root immersed. After 30-day incubation, samples were taken from the canal, cultured and the colony-forming units (CFUs) counted. Statistical analysis was performed using the Mann-Whitney test for quantitative and the Fisher exact test for qualitative data.

In the MTA group, 10 of 20 (50%) specimens still had detectable viable bacteria in the canals (mean, 8.97 × 10(3)  CFUs). In the BC-RRM Putty group, 5 of 18 (28%) specimens were positive for bacterial growth (mean, 2.88 × 10(4)  CFUs). There was no significant difference when comparing the quantitative or presence/absence data from the MTA and BC-RRM Putty groups. Positive and negative controls yielded the expected results.

MTA and BC-RRM Putty had similar sealing ability. The experimental model was effective in determining whether or not residual intracanal bacteria could survive by receiving nutrients from outside.