The efficacy of different endodontic irrigants against Enterococcus faecalis in an extracted human tooth model
This study was carried out To investigate, in vitro, the efficacy of sodium hypochlorite (NaOCl), super-oxidized water (Sterilox® Optident, Ilkely, UK) and chlorhexidine gluconate (CHX) as endondontic irrigants using an extracted human tooth model in a cross over Latin square study design.
Methodology
Twelve extracted, human single rooted teeth were prepared for endodontic treatment using the modified double flare method to a master apical file size 40 K-file. The roots and apices of all teeth were sealed using a dentine bonding agent. The teeth were mounted in cold cure silicone and placed in glass jars before autoclaving. An overnight sample of Enterococcus faecalis grown in brain heart infusion (BHI) was centrifuged and washed using phosphate buffered solution (PBS) before being suspended in fresh BHI. Optical density of the culture was adjusted to 0.1 units at 650 nm before inoculating 20 μL into the canals of the prepared teeth. Inoculated teeth were incubated at 37 °C for 48 h. The teeth were divided into four groups of three teeth, which were irrigated with NaOCl (1%), Sterilox, CHX (2%), and the control, PBS during cycles of experimentation. The teeth were irrigated using 5 × 200 μL of an endodontic irrigant using an electronic pipette, according to the Latin square. Irrigants were left in situ for 60 s after which teeth were flushed with PBS. Five size 40 sterile paper points were used to collect the microbial sample from the root canals. The number of viable bacteria recovered from the canals was determined through serial dilutions and plating of these onto nutrient agar. The logarithm of the colony forming units was used to carry out statistical analysis. The antimicrobial efficacy of the irrigants was compared using analysis of variance (anova) and Tukey post-hoc analysis at a significance level of P < 0.05 to determine whether there are differences in efficacy of the irrigants investigated.
Results
NaOCl, Sterilox and CHX were significantly more effective than the control, PBS, at reducing the bacterial load within the root canals. There was no significant difference between the efficacy of NaOCl, Sterilox and CHX in reducing bacterial load.
Conclusion
The study showed that using a cross over Latin square design eliminates bias in results due to the use of different teeth. NaOCl, Sterilox and CHX had a greater antibacterial efficacy that the control, PBS. Statistically there was no significant difference between NaOCl, Sterilox and CHX.
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