Antibiofilm activity of three irrigation protocols activated by ultrasonic, diode laser or Er:YAG laser in vitro

AimTo investigate the impact of three irrigation protocols, activated by three different methods, on mature biofilms of Enterococcus faecalis in vitro. MethodologyRoot canals in 280 single-rooted teeth were instrumented using a rotary Ni-Ti system. Biofilms of E.faecalis were generated based on a previously established protocol. Samples were randomly divided into three experimental (n=80) and one control (n=40) group based on the irrigation protocol employed: group 1 (NaOCl+Etidronic acid), 1:1 mixture of 6% NaOCl and 18% etidronic acid; group 2 (NaOCl-EDTA), 3% NaOCl followed by 17% EDTA; group 3 (NaOCl-EDTA-NaOCl), 3% NaOCl followed by 17% EDTA and a final flush of 3% NaOCl. Saline served as the control. Samples were further divided into four subgroups (n=20) based on the activation method: subgroup A, no activation; subgroup B, ultrasonic activation; group C, diode laser; group D, Er:YAG laser. Confocal laser scanning microscopy was used to assess bacterial viability in situ. Root dentine powder was obtained for determining the colony-forming units (CFUmL(-1)). Data were analysed by appropriate statistical analyses with P=0.05. ResultsAll experimental irrigation protocols caused complete destruction of the biofilm in the root canal lumen. Within the dentinal tubules, all groups had a significantly higher percentage of dead bacteria than the saline control (P<0.05). There was no significant difference between NaOCl+etidronic acid and NaOCl-EDTA-NaOCl (P>0.05), whereas both groups brought about more bacterial reduction than NaOCl-EDTA (P<0.05). There was no significant difference between diode laser and Er:YAG laser in any of the groups (P>0.05). Both diode and Er:YAG laser were more effective than ultrasonic activation and conventional syringe irrigation in reducing E.fecalis biofilms (P<0.05). ConclusionsThe use of NaOCl after or in combination with a chelator caused the greatest reduction of E.faecalis. Diode laser and Er:YAG laser activation were superior to ultrasonics in dentinal tubule disinfection.