Hojatollah Yousefimanesh - Department of Periodontology, School of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Maryam Robati - Department of Oral Medicine, School of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Atefeh Piri - Department of Periodontology, School of Dentistry, Infectious and Tropical Diseases Research Center, Health ResearchInstitute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Azardokht Khosravi Boroujeni - Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Mehrandokht Sirous - Department of Microbiology, Faculty of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran

Background: Chlorhexidine (CHX) is the gold standard chemical agent against oral pathogenic bacteria and iswidely used for plaque/gingivitis control. The aim of the present study was to compare the effect of alcoholbasedand alcohol-free CHX mouthwashes on oral microorganisms.Methods: In the present in vitro study, the standard strains of four microorganisms present in the oral cavity wereprepared, including Streptococcus mutans, Streptococcus sanguinis, Streptococcus salivarius, and Lactobacilluscasei. The serial dilutions of CHX antimicrobial agents were obtained, and the level of minimum inhibitoryconcentration (MIC) and minimum bactericidal concentration (MBC) was determined using the broth dilutionmethod. Finally, data were analyzed using the Kruskal-Wallis test, the Mann-Whitney U test, and SPSS-۱۶.Results: The MIC values of ۰.۱۲% and ۰.۲% alcohol-free CHX and ۰.۲% alcohol-based CHX for S. mutans were۱.۱۷, ۰.۴۸, and ۰.۲۴ μg/mL, respectively. The MBC values of ۰.۱۲% and ۰.۲% alcohol-free CHX and ۰.۲%alcohol-based CHX for S. mutans were ۱۸.۷۸, ۷.۸۱, and ۷.۸۱ μg/mL, respectively. The MIC and MBC values ofthe tested CHX mouthwashes for S. mutans were significant (P ≤ ۰.۰۵).Conclusions: Overall, the ۰.۲% alcohol-based CHX mouthwash had the highest antibacterial activity againstgram-positive bacteria.

Chlorhexidine, Mouthwashes, Minimum inhibitory concentration, Minimum bactericidal concentration, Alcohol