08 June 2022

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Chlorhexidine-containing mouthwashes with different formulations influence Streptococcus mutans biofilm viability: an in vitro study

Authors: A.C. Ionescu, G. Gloria Cazzaniga, M. Ottobelli, M. Basso, E. Brambilla

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Alteration of the equilibrium between the oral tissues and the biofilm that permanently colonizes the mouth cavity could lead to dysbiosis and is responsible for most oral cavity pathologies, such as caries, gingivitis and periodontitis.

Among microorganisms, Streptococcus mutans (S. mutans), plays a key role in the development of oral cavity pathologies and, above all, caries. The control of the development of a pathogenic oral biofilm has become crucial in preventing such pathologies. The gold standard among the oral antimicrobial agents is chlorhexidine (CHX) which has shown a wide spectrum of action against gram-

positive, gram-negative and yeast bacteria. However, other two promising active ingredients are sodium hyaluronic acid and polyvinylpyrrolidone-vinyl ace- tate (PVP-VA).

The purpose of this in vitro study was to evaluate the effect of different mouthwashes formulations on the development of a S. mutans biofilm with the use of biore- actor under continuous flow (MDFR).

MATERIALS AND METHODS

48 polystyrene standardized discs were prepared and a monospecific biofilm of S. mutans was obtained in a bioreactor under continuous flow conditions for 20h. Once the biofilm was stable, the discs were exposed for two minutes to different mouthwash formulations indicated as A) Curasept Impianti; B) Dentosan® 0,20%; Group C) Curasept Perio; D) Dentosan® 0,12%; E) Control 1; F) Control 2 and two additional formulation containing CHX 0,20% (positive control) and sterile PBS solution (negative control). Additional 4 h of incubation were waited before the amount of viable adherent biomass on polystyrene surfaces was assessed by plate count. Results obtained were statistically analyzed with One-Way Anova test and Tukey post-hoc test and statistical significance was set for p<0.05.

RESULTS

The 0,2% CHX solution (positive control) showed a reduction of UFC number comparable to that of mouthwash formulation A, B, C, D (respectively p=1,000, p=0,995, p=1,000, p=0,242). All mouthwashes containing CHX, independently from the concentration, revealed a more effective antimicrobial activity compared to the ones without CHX, such as formulation E and F. Further, E and F formulation showed a reduced amount of vital bacteria cells compared to the negative control, thus indicating a weak antimicrobial effect (p<0,001).

CONCLUSIONS

Results of the in vitro study showed that mouthwash formulations containing CHX associated with PVP-VA are able to produce a more affective antimicrobial activity thus, the results were not statistically significant compared to the commercial mouthwash available on the market containing CHX alone. Further studies are necessary to validate the obtained results and to study the modification produced by the different additives included in mouthwashes formulations.

CLINICAL SIGNIFICANCE

The anti-biofilm efficacy depends not only on the active principle chosen, but also on the other compounds included in the formulation. They are supposed to be able to interact with the main ingredient and to power or reduce its antimicrobial effect. The creation of a more effective mouthwash with the association of CHX and a polymer able to create an adherent film on most oral tissues could be a helpful solution in controlling oral biofilm formation over time and promoting reduced bacteria growth on exposed surfaces.