EndoREZ sealer and Enterococcus Faecalis: a bacterial leakage study

Objective. The purpose of this study was to investigated the coronal bacterial leakage, over a 50-day period, of root canal filling with EndoREZ, a new sealer containing methacrylate, and to compared with a conventional obturation technique, mixed lateral and warm vertical condensation, using zinc oxide and eugenol cement (ZOE) and gutta-percha points. Materials and methods. Fifty human extracted single-rooted teeth were used, including negative and positive controls. Forty teeth were randomly divided into two test groups of 20 canals each. Group 1: the specimens were instrumented using steel files Endo-Eze and filled using EndoREZ sealer. Group 2: the coronal and middle third of each root canal was prepared using Gates Glidden drills, the apical third was instrumented with hand K-files and filled with conventional gutta-percha points in combination with ZOE, using lateral and warm vertical compaction. The 5 teeth that were instrumented but not obturated were used as positive controls to demonstrate bacterial leakage trough the entire length of the canal. The negative controls (5 teeth) were instrumented but not obturated and sealed externally with nail polish for the entire root surface. The roots of both groups were impermeabilized by nail varnish to external root surfaces, except for the apical 3 mm around the apical foramen, to prevent lateral microleakage. All specimens were sterilized in ethylene oxide and mounted on a device for the evaluation of the bacterial leakage. The apical 3 mm of the roots were immersed in brain-heart infusion culture medium. The coronal access of each specimen was inoculated, every 72 hours, with a suspension of Enterococcus faecalis ATCC 29212, used at concentration of 108 Colony Forming Units mL-1. The samples were incubated a 37°C for 50 days and monitored daily for the appearance of turbidity in the BHI broth. When the broth showed turbidity, 10 μl of the culture broth was subcultured onto MacConkey without crystal-violet agar to confirm the purity of E. faecalis. Statistical analysis of the data was accomplished using the Fisher exact test. A value of P less than 0.05 was statistically significant. Results. All positive controls leaked within 24 h; none of the negative controls leaked. 7 teeth leaked in group 1, whereas 15 teeth leaked in group 2. The Fisher exact test showed that there were statistically significant differences in the number of teeth that leaked at the end of the observation period between two different groups (P<0.05). Conclusions. Under the conditions of this study, over a 50 days period, the mixed lateral and warm vertical compaction produced a greater number of specimens with coronal leakage than the EndoREZ system, that showed a better resistance to bacterial penetration. Then, the EndoREZ sealer has potential to provide a good obturation system because the leakage can be prevented in canals filled with this technique.