Antimicrobial effects of chlorhexidine gel associated with hyaluronic acid or cetylpyridinium chloride in a multispecies biofilm

Chlorhexidine (CHX) and cetylpyridinium chloride (CPC) are commonly used as mouthwashes due to their antimicrobial effect. More recently, hyaluronic acid (HA) has also been associated to oral health products aiming to improve their anti-inflammatory and antimicrobial effects. This study aimed to evaluate the effect of three different CHX-based commercially available products on the subgingival microbial composition and metabolic activity using a multispecies biofilm model. A biofilm model composed of 33 bacterial species with 7 days of maturation on a Calgary plate device was used. The multispecies biofilm was treated with CHX 0.2% (positive control), CHX 0.2% + CPC (test 1), CHX 0.2% + HA 1% (test 2), and culture medium (negative control). The metabolic activity of the multispecies biofilm was measured using a spectrophotometric assay and the microbial composition by checkerboard DNA-DNA hybridization. The studied groups were compared using ANOVA and post hoc Bonferroni tests. The significance level was established at 5%. The CHX+CPC gel was more effective than the other treatments in reducing proportions of red complex species and increasing bacterial species associated with periodontal health (p<0.05). A reduction of approximately 54% was observed in the microbial metabolic activity of biofilms treated with CHX and CHX + CPC, and 26% in biofilms treated with CHX+HA. The CHX+CPC gel seems to have a superior antibacterial potential when compared to a gel containing CHX only, or CHX+HA, in an in vitro multispecies biofilm model.