Effectiveness of KTP laser versus 980nm diode laser to kill Enterococcus faecalis in biofilms developed in experimentally infected root canals

This study aimed to evaluate the antibacterial action of KTP (potassium-titanyl-phosphate) laser irradiations (compared with 980nm diode laser), associated with conventional endodontic procedures, on Enterococcus faecalis biofilms. Fifty-six dental roots with single canals were prepared with Ni-Ti rotary instruments, autoclaved, inoculated with an E.faecalis suspension and incubated for 72h. They were randomly allocated to control and treatment groups. Laser parameters were as follows: power 2.5W, Ton 35ms, Toff 50ms (KTP laser); power 2.5W, Ton 30ms, Toff 30ms (980nm diode laser). To evaluate the residual bacterial load, BioTimer Assay was employed. The chemo-mechanical treatment together with laser irradiations (KTP and 980nm diode lasers) achieved a considerable reduction of bacterial load (higher than 96% and 93%, respectively). Regarding both laser systems, comparisons with conventional endodontic procedures (mortality rate of about 67%) revealed statistically highly significant differences (P≤0.01). This study confirms that laser systems can provide an additional aid in endodontic disinfection. © 2014 Australian Society of Endodontology.