Evaluation of the antimicrobial effects and cytotoxicity of various mouthwashes appropriate for the use of children, in vitro.

The study aimed to compare the antimicrobial effects and cytotoxicity of five mouthwashes containing chlorhexidine (CHX), fluoride, probiotics, and their combinations (Klorhex: 0.2 % CHX, Humble Co.: CHX+NaF, Listerine: NaF, Luvbiotics: probiotic+NaF, Henry Blooms: probiotic). In this in vitro study, the antimicrobial activity was screened against Streptococcus mutans (S. mutans) using the disc diffusion assay. To evaluate the antibiofilm efficacies, an in vitro biofilm model was used. The S. mutans biofilm was formed on the hydroxyapatite discs coated with the artificial saliva. The resulting biofilms were rinsed with mouthwashes, and the discs were examined with a confocal laser scanning microscope (CLSM). In the final part of the study, cytotoxicity of the mouthwashes was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4 sulfophenyl)-2H-tetrazolium (MTS) assay on human dermal fibroblast (HDF) cell lines. The cell cultures were exposed to three different concentrations (5%, 10%, and 20%) of the mouthwashes for 30 seconds, and the cell viability of HDFs was calculated. According to the disc diffusion assay, the highest inhibition zone values among the groups were obtained in the Klorhex, Luvbiotics, and Listerine groups, respectively, and no inhibition zones were formed in Henry Blooms and Humble Co. groups. In the CLSM analysis, the most effective antibiofilm activity was seen in Klorhex, Luvbiotics, Listerine, Henry Blooms, and Humble Co. groups, respectively. According to the MTS assay, the cell viability decreased at certain levels in Klorhex, Luvbiotics, and Listerine groups. It was observed that almost all cells died in these groups at high concentrations (10% and 20%). Also, in the Henry Blooms group, the cell viability reduced highly at 20% concentration; only the Humble Co. group showed high cell viability at all concentrations. It was found that the cell viability decreased in all groups as the concentration increased. As a result of this study, it was observed that mouthwashes with higher antimicrobial activity also had higher cytotoxicity; only the Humble Co. group had lower antimicrobial and cytotoxic effects. However, more in vitro and in vivo studies are needed for more valid results.