In-vitro-Analyse der antimikrobiellen Effektivität von Octenidol, Natriumhypochlorit und Chlorhexidin gegen Enterococcus faecalis anhand eines intrakanalären Biofilm-Modells

Abstract

OBJECTIVE: The failure of primary root canal treatments is mostly due to persisting bacteria. These are mainly Enterococcus faecalis (E. faecalis). The objective of the study was the analysis of the antimicrobial effectiveness of sodium hypochlorite 1% (NaOCl), chlorhexidine-gluconate 2% (CHX) and Octenidol® for E. faecalis in root canals. An evaluation of the smear layer removal and evidence of the biofilm was additionally realized by means of a scanning electron microscope (SEM) analysis. METHODS: 60 extracted single-root human teeth were used for the in-vitro model. After a standardized root canal preparation the smear layer was removed with EDTA 17% and NaOCl 1%. Distribution to a total of seven experimental groups was made: two groups (each n = 5) served for analyzing the smear layer removal (SL) and the grown biofilm (BF) by means of scanning electron microscopy. Three groups (each n = 10) served for analyzing the rinsing solutions (NaOCl, CHX, Octenidol®). Furthermore, a positive and a negative control (each n = 10) were analyzed. A biofilm from E. faecalis was grown for 72 hours in the root canals of the NaOCl, CHX, Octenidol®, positive control and BF groups. The rinsing groups were then disinfected with NaOCl 1%, CHX 2% and Octenidol® each. Dentin particles were removed and incubated on an agar culture medium. After 24 hours the colony forming units (CFU) were counted and statistically evaluated. RESULTS: The removal of the smear layer and the growth of a biofilm were confirmed by means of the SEM analysis. Overall, all rinsing solutions reduced significantly the number of E. faecalis in root canals (p < 0.0001). NaOCl 1% eliminated significantly more bacteria than CHX 2% (p = 0.0219) and Octenidol® (p < 0.0001). Octenidol® left however more bacteria in the root canal than CHX 2% (p = 0,0002). No disinfection measure led to a complete elimination of E. faecalis from the root canal system. CONCLUSION: Conventional rinsing with Octenidol® or also with NaOCl 1% or CHX 2% is an effective method of treating an infection with E. faecalis in root canals. In this testing, NaOCl 1% showed significantly the best result and proved again to be the rinsing solution of first choice. Alternatively, in the rare case of sensitivity to NaOCI, CHX 2% or Octenidol® may be used nevertheless for disinfection of the root canal.