Comparison of in vitro Antimicrobial Efficacy of Octenidine against Staphylococcus epidermidis (S. epidermidis) for Root Canal Disinfection

Introduction

Bacteria have been identified as the main cause of pulp infection and periapical disease. There are over 700 bacterial species in the oral cavity, with any individual harbouring 100–200 species. Irrigants have varying degrees of antimicrobial activity and it has been established that irrigants, coupled with mechanical instrumentation, are mandatory to ensure the elimination or greatest possible reduction of pathogens from the infected root canal. The characteristics of an ideal endodontic irrigant includes good antimicrobial activity, non-cytotoxicity towards the surrounding periapical tissue, and the ability to inactivate endotoxins, to act as a lubricant, and to dissolve organic tissue remnants.

Aim

The present study compared the antimicrobial efficacy of octenidine dihydrochloride (OCT) with chlorhexidine (CHX) and sodium hypochlorite (NaOCl) against Staphylococcus epidermidis (S. epidermidis) for root canal disinfection.

Study Sample

• Non-carious single-rooted human mandibular premolars obtained from patients by extraction for orthodontic or periodontal reasons were processed to obtain 6 mm dentin blocks

Materials and Methods

• The minimum inhibitory concentration (MIC) was obtained using the serial dilution method.
• The agar diffusion method was then used to determine the zones of inhibition for each irrigant.
• Lastly, forty 6-mm dentin blocks were prepared from human mandibular premolars and inoculated with S. epidermidis.
• Samples were randomly divided into four groups of ten blocks and irrigated for 3 minutes with saline (control), 2% CHX, 3% NaOCl, or 0.1% OCT.
• Dentin samples were then collected immediately for microbial analysis, including an analysis of colony-forming units (CFUs).

Results

• The MIC values of each tested irrigant were 0.05% for CHX, 0.25% for NaOCl, and 0.0125% for OCT.
• All tested irrigants showed concentration-dependent increase in zones of inhibition, and 3% NaOCl showed the largest zone of inhibition amongst all the tested irrigants (p<0.05).
• OCT in 0.0125% solution showed a significantly larger zone of inhibition than 0.5% and 1% CHX (p<0.05), and 0.025% OCT showed a similar zone of inhibition with 2% CHX and 1% NaOCl.
• There were no significant differences among the CFU measurements of 2% CHX, 3% NaOCl and 0.1% OCT showing complete elimination of S. epidermidis in all samples.

Conclusion

• OCT at lower concentrations effectively inhibited antimicrobial growth of S. epidermidis compared with CHX and NaOCl, implying its possible applicability as an endodontic irrigant in terms of the antimicrobial properties that were evaluated.

Restor Dent Endod. 2019 Feb;44(1):e8