Lasers have been widely used in Endodontics. The morphologic changes on dentin walls caused by Nd:YAG, Diode and Er:YAG laser irradiation could improve seal and cleanliness. The objective of this study is to verify the effects of laser energy on intracanal dentin surface, analyzing the morphologic changes and removal of debris in the cervical, middle and apical third of 80 extracted human teeth, prepared and irradiated with Nd:YAG laser, Diode laser and Er:YAG laser. The protocol used for the Nd:YAG laser irradiation is 1.5W, 100mJ and 15Hz, in pulsed mode; for Diode laser, 2.5W in continuous mode; and for Er:YAG laser 1 W, 100mJ and 10 Hz in pulsed mode. Each specimen will be irradiated 4 times with 2mm/s speed and 20s interval between the applications. After this, the teeth will be cut, dehydrated and sputtered for SEM (scanning electron microscope) analysis. SEM images will be acquired in 1500X magnification at 3mm, 6mm and 9mm from the apical border (apical, middle and cervical thirds respectively). Five calibrated examiners will score the morphologic changes and debris removal using a four-grade scale for each canal third. Statistical analysis will test the agreement between examiners (Kappa test) and a non-parametric test will be used to analyze the results (p<0.05).
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