Microscopic investigation of apical Microleakage after laser-assisted root canal treatMent

Purpose: This in vitro study was conducted in order to assess using optical microscopy the apical sealing in Nd:YAG laser irradiated root canals in comparison with the conventional treatment method. Material and Methods: 34 extracted teeth with one straight root canal, closed apices and extracted for periodontal reasons were used in this study. All teeth had the root canals biomechanically instrumented at an apical size 30 and .06 taper. The root canals were irrigated with 2 ml 2,5% NaOCl solution. The teeth were divided in two study groups, each of 17 teeth: group A, Nd:YAG laser irradiation after the biomechanical preparation and group B, only biomechanical preparation. The laser irradiation was performed using an Nd:YAG laser (Fidelis Plus II; Fotona d.d., Slovenia; optical fiber of 250 micrometers) and the following parameters: 1,5 W, 15 Hz, 3 exposures/procedure. All roots were filled with AH Plus endodontic sealer and guttapercha points, using cold lateral condensation and vertical compaction techniques. The samples were then stored in 100% humidity, at 37°C for 72 hours and then embedded in acrylic resin using specially designed cylindrical conformators. For each sample 6 examinations were performed from the apex to 3 mm in coronal direction, by slicing 0,5 mm after each examination. The microscopic examination was performed using an optical metallographic microscope, in both reflected and polarized light. Results: The microscopic examination evidenced the presence of voids inside the root canal, microleakage areas being detected between the root canal sealer and the dentine root canal wall, but also at the guttapercha – sealer interface, mostly in the group were only conventional biomechanical preparation of root canal was performed. Conclusions: The results of this study demonstrated a reduction of microleakage in the apical area when using Nd:YAG laser irradiation in combination with the conventional biomechanical root canal preparation.