Evaluation and comparison of antibacterial effects of a licorice gel and chlorhexidine gel on Porphyromonas gingivalis, Aggregatibacter actinomycetamcomitans, and Tannerella forsythia – An in vitro study

Abstract

INTRODUCTION: Periodontitis is known to cause inflammation and progressive breakdown of tooth-supporting structures. The treatment for periodontitis includes scaling and root planing that effectively removes the disease causing plaque and antimicrobial agents such as chlorhexidine (CHX) used as an adjunct to maintain the healthy state of tissues. However, these antimicrobial agents have unpleasant side effects that have led researchers toward discovering, isolating, and developing natural herbal plant extracts as effective antimicrobial agents. Hence, the purpose of the study was to assess and compare the antimicrobial activity of the one such herbal plant extract Glycyrrhiza glabra (licorice) gel and CHX gel on periopathogens. MATERIALS AND METHODS: The hydroalcoholic root extract of G. glabra (licorice) was prepared through maceration, evaporation, and lyophilization to obtain dried crude extract. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the G. glabra extract against Porphyromonas gingivalis, Aggregatibacter Actinomycetemcomitans, and Tannerella forsythia were determined using broth dilution method and streaking on blood agar plates. The gel was then prepared accordingly using Carbopol 940. The antibacterial activity of the prepared G. glabra gel was tested and compared to CHX gel using the agar well diffusion assay. RESULTS: The MIC of G. glabra extract was found to be 15 mg against A. actinomycetamcomitans and T. forsythia and 7.5 mg against P. gingivalis. The MBC of the G. glabra extract was 30 mg for all three organisms. The antibacterial effects of the prepared licorice gel were assessed using agar well diffusion assay, and it showed that 100 μl of prepared licorice gel had a greater effect on A. actinomycetamcomitans and T. forsythia but not P. gingivalis. CONCLUSION: Licorice extract showed inhibitory activity against P. gingivalis, A. actinomycetamcomitans, and T. forsythia.