Chlorhexidine Antimicrobial Activity in Self-ligating and Conventional Orthodontic Brackets Infected with Porphyromonas gingivalis Biofilm

The present study was conducted to evaluate the adhesion of Porphyromonas gingivalis (P. gingivalis) biofilms formed on Self-Ligating (SL) and Conventional-Ligating (CL) brackets and their bacterial viability after treatment with 0.12% chlorhexidine (CHX) mouthwash. In this experimental study, 48 commercial metal brackets were divided into two equal groups based on their types (CL with elastomeric ligature and SL). The brackets were first coated with saliva, then placed in the suspension of P. gingivalis for 3 days to grow bacterial biofilms on their surfaces. Half of the brackets in each group were randomly treated with CHX mouthwash or Phosphate-Buffered Saline (PBS) for one minute. Quantitative analysis was performed by counting the number of Colony-Forming Units (CFUs). Data were analyzed using ANOVA and the Tukey test (α=0.05). There was a statistically significant difference between the two types of brackets in biofilm formation, SL brackets were colonized more than CL brackets (P <0.024). In both groups, CHX-treated brackets exhibited a significant reduction in P. gingivalis viability compared to PBS-treated brackets (P <0.001). Comparison of the antimicrobial activity of CHX in two types of brackets showed that more bacteria survived on the surface of SL brackets (P <0.001). The number of P. gingivalis CFUs on SL metal brackets was significantly higher compared to CL brackets with an elastomeric ligature. CHX significantly reduced the bacterial viability of P. gingivalis. However, more bacteria survived significantly on the SL brackets after treatment with CHX.