Effect of Nd:YAG (1064-nm) and Diode Laser (980-nm) EDTA Agitation on Root Dentin Ultrastructure Properties

Objective: The purpose of this study was to analyze the effects of agitation of 17% ethylenediaminetetraacetic acid (EDTA) with 1064 nm Nd:YAG and 980 nm diode laser on root dentin microhardness and superficial roughness (with confocal laser scanning microscopy [CLSM]). Background data: Root canal irrigants are used in an attempt to minimize the negative effects of smear layer. Materials and methods: Twenty-five bovine roots were sectioned longitudinally and divided into five groups ( n =10 each): (1) deionized water, (2) 17% EDTA, (3) 17% EDTA with 60 sec manual agitation, (4) 17% EDTA with 50 sec diode laser (2 W) agitation, and (5) 17% EDTA with 50 sec Nd:YAG (1.5 W) laser agitation. Microhardness and superficial roughness values were calculated before and after the procedures at the cervical, middle, and apical root thirds. Microhardness was statistically analyzed using two way ANOVA, paired t test, and Tukey's tests ( α =0.05). Roughness was statistically analyzed using Kruskal–Wallis, paired t test, and Student–Newman–Keuls tests ( α =0.05%). Results: Statistically significant differences in microhardness and roughness were observed between the deionized water group and others. EDTA with 1064 nm Nd:YAG or 980 nm diode laser presented the lowest microhardness and the highest roughness values and was significantly different from EDTA with manual agitation and EDTA only ( p 0.05). CLSM analysis showed that the control samples exhibited smoother surfaces than that of the EDTA groups. Conclusions: Nd:YAG 1064 nm and 980-nm diode laser EDTA agitation caused greater reduction in microhardness and increased roughness of root dentin than EDTA only or EDTA with manual agitation.