Evaluation of the effects of Er, Cr: YSGG laser usage on thermal changes, cytotoxicity and canal disinfection using different parameters in primary tooth root canals

The aim of this in vitro study was to compare the disinfecting efficacy of various endodontic irrigation solutions with Er,Cr:YSGG, to evaluate the cytotoxic effects, thermal increments and morphological changes induced by Er,Cr:YSGG laser in root canals. One hundred and twenty teeth extracted with orthodontic purposes were assigned to two groups in which E. faecalis and C. albicans were cultured. They were divided in three subgroups according to the disinfection method used (group 1; 2.5% NaOCl, group 2; 2% CHX gluconate, group 3; Er,Cr:YSGG laser). Periodontal ligament cells were isolated and cultured from an orthodontically extracted third molar and cytotoxic effects of Er,Cr:YSGG laser in four different power outputs (0.75, 1.5, 3, 4 W) were evaluated. Thermal increments were evaluated in 32 teeth with and without water spray. In addition, morphological changes were examined under SEM analysis in ten teeth. For both microorganisms evaluated, 2.5% NaOCl was the most effective method against E. faecalis. However, there was no statistically significant difference among three experimental groups against C. albicans (p>0.01). The effectiveness of Er,Cr:YSGG laser on E. faecalis was found statistically significantly higher when compared with C. albicans (p=0.000). While there was no significant difference among different power outputs evaluated in group with cell culture medium (p>0.05), 1.5, 3, and 4 W power outputs caused serious cytotoxicity (p<0.05) in group without cell culture medium with no significant difference among them (p>0.05). Thermal increments were found highest in the point of laser contact regardless of the water spray usage (p>0.05). While more regular and cleaner root canal surfaces were observed in water spray usage; rough, carbonized and cratered surfaces were observed in group without water spray usage under SEM analysis. In conclusion within the limitations of this study, Er,Cr:YSGG laser can be an adjunct, not an alternative to NaOCl and further in vitro and animal studies are needed to better understanding of this laser.