In vitro antimicrobial efficacy of laser activated different irrgation solutions on intracanal enterecoccus faecalis biofilms

The aim of this study was to evaluate the antimicrobial efficacy of erbium laser activated irrigation and Nd:YAG laser disinfection of root canals, and also that of conventional irrigation on intraradicular Enterococcus faecalis biofilms in invitro conditions by using scanning electron microscope.In this study Enterococcus faecalis biofilms were grown in 4 weeks on the prepared root canal walls of 110 standardized root halves which had been longitudinally sectioned. At the end of the 4 weeks after following reapproximation, the roots were divided into nine groups of twelve and were treated with different irrigation protocols. In group I and II, salin or %1 NaOCl solutions were activated respectively in nonablative energy level by using the Er:YAG laser irradiation in the apical third of the root canal system. In group III and IV salin or %1 NaOCl solutions were activated by Er:YAG laser in the coronal third of the root canal system. In group V and VI, Nd:YAG laser was irradiated after the conventional irrigation that was made by using salin or %1 NaCl solutions. In group VII, VIII, IX conventional irrigation was treated respectively by using %1 NaCl, %6 NaCl or salin.After the irrigation procedures the root halves were processed for scanning electron microscopy. The standard images (700x) were taken form apical, coronal and middle part of the specimens by using ESEM. Biofilm coverage were examined independently by three calibrated examiners, using a four-point scoring system.It was concluded that none of the three methods used in this study did not eliminate Enterococcus faecalis biofilms completely. Also it was found that Er:YAG laser activated irrigation eliminated much more biofilms than conventional irrigation and Nd:YAG laser disinfection of root canals. The determination showed that the antimicrobial efficacy of Er:YAG laser activated irrigation applied in the apical part of the root canal is more effective than that of Er:YAG laser activated irrigation applied in the coronal part of the root canal. The biofilm elimination efficacy was much more with NaCl solution activation than salin solution activation irrigated by Er:YAG laser irradiation. It was also determined that treating different irrigation solutions in canals did not augment the effect of Nd YAG laser irradiation on elimination of biofilms.As a result; Er:YAG laser activated irrigation that was seemed to be the most effective method in our study proved not to eliminate the biofilms from the root canal completely. However, it was clear that laser activated irrigation generated much more negative samples and left less apical biofilms than the other irigation methods.Keywords: Laser-activated irrigation, Er:YAG laser, Nd YAG laser, biofilm, Enterococcus faecalis, root canal disinfection