Effect of Nd: YAG laser irradiation on the apical seal of root canal-treated teeth

Good apical seal plays a critical role in the success of endodontic treatment and the smear layer reduces the efficacy of the apical seal. The aim of this study was to evaluate the effect of Nd:YAG laser irradiation on the apical seal of root canal-treated teeth using the fluid filtration technique. In this in vitro study, 44 human maxillary central incisors were selected. After preparation, the specimens were randomly assigned to 4 groups: group A, the control group (n=20); group B, the laser-treated group (n=20); group C, the positive control group (n=2); and group D, the negative control group (n=2). All the groups were prepared using the crown-down technique. Group B was irradiated with Nd:YAG laser before obturation. Groups A, B and D were obturated with gutta-percha and sealer and group C was obturated with gutta-percha and without sealer. The coronal end of the specimens were sealed with amalgam and then stored in an incubator for one week. Then, the outer surface of groups A, B and C, except for 2 mm in the apical area, and group D were entirely covered with two layers of nail polish and one layer of sticky wax. Apical microleakage was then evaluated using fluid filtration technique. Data were analyzed with SPSS 18, using Kolmogorov-Smirnov and independent t-test (α=0.05). The means of apical leakage in the laser and control groups were 4.35±2.88 and 5.34±3.13 µL/min/cm H2O, respectively, with no significant differences (p value = 0.305). Under the limitations of this study, use of Nd:YAG laser in root canal therapy had no significant effect on apical microleakage.