Evaluation and comparison of the antimicrobial effect of two different mouthwashes on selected periodontal pathogens: An in vitro study

Introduction: Antimicrobial mouth rinses as an adjunct to nonsurgical periodontal therapy can play an important role in maintaining oral health. Aim: The aim of this study is to evaluate the antimicrobial effect of Listerine and HiOra® mouthrinses and compare their efficacy on four specific standard bacterial strains, namely, Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), and Fusobacterium nucleatum (Fn). Settings and Design: Ethical clearance for the study was granted by the Institutional Ethics Committee. Materials and Methods: Aa, Pg, Pi, and Fn were maintained on enriched tryptic soy agar. Listerine and HiOra were tested against these bacterial strains using agar diffusion and broth dilution assay method where minimal inhibitory concentrations (MICs) were defined as the lowest concentration of test agent, either showing no or few bacterial growth colonies and by lack of turbidity, respectively. Distilled water was used as the control group. The tests were run three times for each mouthrinse against each organism. The results obtained were compared by their median values. Results: All the strains showed sensitivity towards both the test solutions. Listerine showed a lower MIC value than HiOra against all the strains, except Fn where the MIC value by broth dilution was 3.12 mcg/ml and by agar method was 90% concentration for both the test solutions. Both the test solutions had antibacterial effect at various concentrations. Conclusion: Listerine, the essential oil-based mouthrinse, was observed to be more potent than the herbal mouthrinse HiOra where both had antimicrobial effect.