Antimicrobial action of chlorhexidine digluconate in self-ligating and conventional metal brackets infected with Streptococcus mutans biofilm.

Abstract

ObjectivesThe objectives of this study were to assess the adherence of Streptococcus mutans biofilms grown over conventional ligature (CL) or self-ligating (SL) metal brackets and their bacterial viability after 0.12% chlorhexidine (CHX) digluconate treatment.Materials and methodsThe sample consisted of 48 metallic orthodontic brackets divided randomly into two groups: CL (n=24) and SL brackets (n=24). S. mutans biofilms were grown over the bracket surface (96 h) and treated with CHX (positive control) or 0.9% phosphate-buffered saline (PBS) (negative control) for 1 min each. Quantitative analysis was assessed by colony-forming units, and fluorescence microscopy was performed aiming to illustrate the outcomes. The tests were done in triplicate at three different times (n=9). Data were analyzed using ANOVA and Tukey test (P<0.05).ResultsThere were significant differences in brackets’ biofilm formation, being CL largely colonized compared with SL, which was observed by colony-forming unit counting (P<0.05) and microcopy images. Significant reduction in the viability of S. mutans was found in both brackets treated with CHX compared to PBS (P<0.05).ConclusionThe antimicrobial activities of CHX were similar for CL and SL brackets (P>0.05). In conclusion, a lower colonization was achieved in SL brackets and S. mutans biofilms were susceptible to CHX treatment to both studied brackets.