Abstract
Objective: This study aimed to compare the antibacterial efficacy of 10% nisin, 2% chlorhexidine (ChX), and 2.5% sodium hypochlorite (NaOCl)against Enterococcus faecalis biofilm in vitro.Methods: Petri dishes containing brain heart infusion agar were seeded with E. faecalis (ATCC 29212) and were incubated overnight at 37°C. Thecellulose nitrate filter membrane was inoculated with E. faecalis for 72 h to grow a biofilm, and we performed the direct contact test between the testsolutions and the biofilm for 10 min. The DNA was quantified using real-time polymerase chain reaction with propidium monoazide additive to countthe living cells.Results: The number of E. faecalis bacteria in the 2% ChX group was the lowest (8.36×103 CFU/mL) while the highest number of bacteria - among theantibacterial substances tested - in the nisin 10% group (5.55×106 CFU/mL).Conclusion: The antibacterial effects against E. faecalis biofilm of 10% nisin were not comparable with those of 2% ChX and 2.5% NaOCl.
Highlights
Enterococcus faecialis is an organism often found in a failed endodontic treatment [1], at a level 9 times greater than that found in primary endodontic cases [2]
Compared with other antibacterial agents, we found the highest number of bacteria - among the antibacterial substances tested - in the nisin 10% group (5.55×106 CFU/mL)
Based on the percentages of live bacteria, we found that ChX had the lowest percentage at 0.11%, followed by NaOCl at 0.99% and nisin as 2.48%, against the control at 100%
Summary
Enterococcus faecialis is an organism often found in a failed endodontic treatment [1], at a level 9 times greater than that found in primary endodontic cases [2]. By bonding to the dentine and invaginating the root canal, Enterococcus faecialis is able to survive for a long time without any nutritive substrate; it has lysis enzyme, sitolisyn, agregatsubstant, feromon, and lipoteichoic uses the serum as a nutritive substrate, and competes with other cells, forming a biofilm [3,4,5,6]. The aim of endodontic retreatment is to eliminate bacterial infection and, the E. faecalis biofilm which is located in the root canal, to facilitate the healing process. An important aspect of cleaning the root canal is the irrigating solution in endodontic treatment [8]. The irrigating solution should have an antibacterial effect without being toxic to the periapical tissue
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