Smear layer removal and ultramorphological changes of root canal dentin induced by erbium, chromium: Yttrium-scandium-gallium-garnet laser

Abstract

Aim: Using SEM & EDX analysis to evaluate: 1. The ability of Er;Cr;YSSG laser irradiation to the remove of smear layer from the root canal walls compared to the conventional EDTA/NaOCl irrigation technique 2. The effect of Er;Cr;YSSG laser irradiation on ultra morphologic characteristics and on the inorganic contents of root canal dentine. Materials and Methods: 18 single rooted freshly extracted human premolars) were chemomechanically prepared using protaper rotary nickel titanium (Ni-Ti) instruments (Dentsply maillefer) up to size 40/60 (F4) between each instruments 2 ml of 2.5% NaOcl were used. Samples were divided into two groups (n=8): Group A: 5 ml of 17% EDTA for 1 minute. Group B: Irradiation with Er;Cr;YSSG laser. Two teeth were used as a positive control (presence of smear layer). Teeth sections were evaluated by using the SEM and the EDX analysis. Results: It has been found that more than 70% of the examined samples in EDTA group showed significant removal of the smear layer in coronal, middle and apical third of the examined teeth. In Er;Cr;YSGG group, the coronal portion showed complete removal of the smear layer but with destruction of the inner wall of the dentin. In apical portion more than 87.5% of the samples showed the persistence of the smear layer in that region after laser treatment. When evaluating the degree of erosion, the highest degree was noted in the samples treated with Er,Cr;YSGG. Laser irradiation has less effect on the mineral contents of the root canal walls. Conclusions: The findings of the present study suggest that the use of Er;Cr;YSGG laser irradiation alone is significantly less effective in removing the apical third smear layer than the golden standard irrigation with 2.5% NaOCl and 17% EDTA.