Comparison of the smear layer removal efficiency of Er,CR:YSGG and Er:YAG laser irridation in root canals prepared with different novel nickel titanium rotary systems

Advanced NITI systems and lasers have been widely used for root canal shaping and irrigation procedures during the last years. The aim of the present study is; smear removing efficiency of final irrigation procedures including 2 laser types (Er:YAG and Er,Cr:YSGG lasers) and EDTA in root canals prepared with NITI files owing different motion types by using SEM. The study included 192 mandibular incisors randomly divided into 4 equal groups (n = 48). The samples in each group were prepared with one of NITI files; Protaper Next, One Shape, Reciproc and Twisted File Adaptive. Following shaping procedures, each group was then sub-grouped into 4 according to final irrigation protocol. No intervention was applied to the first sub-groups while Er,Cr:YSGG, Er:YAG and 17% EDTA were applied to 2nd, 3rd and 4th subgroups respectively. The presence of smear layer was examine under SEM by 2 different observers at different time intervals. The results were statistically analyzed 3-way factorial variance analysis and LSD multi comparison test. In terms of instrument type, Reciproc was found significantly superior to Protaper Next in smear removing (p < 0.05). The efficiency of irrigation protocols from highest to lowest was as; EDTA, Er,Cr:YSGG laser and Er: YAG laser. The differences among the groups were statistically significant (p < 0.05). It can be concluded that both the motion type of the instrument and the irrigation protocol are important factors for the removal of the smear.