Efficacy of antimicrobial solutions against polymicrobial root canal biofilm

Abstract Aim To evaluate the antibiofilm activity of 2.5% sodium hypochlorite (Na OC l), 2% chlorhexidine ( CHX ), 2% alexidine ( ALX ) and 0.2% cetrimide ( CTR ) alone and in combination on mature polymicrobial root canal biofilms on human dentine using confocal laser scanning microscopy ( CLSM ). Methodology Twenty‐eight human dentine specimens were infected for 21 days with microbial samples collected from infected root canals of three volunteers. Antibiofilm activity of the irrigating solutions was evaluated after 3 min of contact time under CLSM . For quantification purposes, bioimage_L software was used. The variables evaluated were the log 10 of total biovolume (μm 3 ) and percentage of live cells (green) population. Statistical analysis of both variables was performed using an anova test and a post hoc Duncan test to determine significant clusters amongst groups. The variable green population percentage was previously subjected to the normalized Anscombe transformation. Results The Na OC l group had a total biovolume and percentage of live cells significantly lower than the other groups ( P ˂ 0.001). The addition of 0.2% CTR significantly increased the antimicrobial effect of 2% CHX ( P ˂ 0.001). There were no significant differences between 0.2% CTR , 2% ALX and the combination of both ( P ˂ 0.05). Conclusions Overall, 2.5% Na OC l dissolved and killed bacteria significantly more efficiently when used against polymicrobial mature biofilm on human dentine. Cetrimide improved the antimicrobial activity of chlorhexidine and alexidine.