In vitro study of the effect of Er:YAG laser irradiation on the apical sealing of different root canal sealers

Effect of Nd:YAG and Diode Lasers on Apical Seal of Root Canals Filled with AH Plus and Mineral Trioxide Aggregate-Based Sealers

OBJECTIVES

Laser irradiation, as an adjunct to root canal preparation, may increase the success rate of endodontic treatments. This study aimed to assess the effect of neodymium-doped yttrium aluminum garnet (Nd:YAG) and diode lasers on the apical seal of the root canals filled with AH Plus® and mineral trioxide aggregate (MTA)-based sealers.

MATERIALS AND METHODS

This in-vitro experimental study was conducted on 96 single-rooted, single-canal extracted human teeth with closed apices. The root canals were prepared by using ProTaper® rotary instruments and were randomly divided into six groups (n=16): 940-nm diode laser and AH Plus® sealer (group 1), Nd:YAG laser and AH Plus® sealer (group 2), AH Plus® sealer (group 3), 940-nm diode laser and MTA-based sealer (group 4), Nd:YAG laser and MTA-based sealer (group 5), MTA-based sealer (group 6), as well as positive and negative control groups. A bacterial leakage model was used for microleakage assessment. Qualitative assessment was done by using a scanning electron microscope (SEM). Data were analyzed by two-way analysis of variance (ANOVA) at the significance level of 0.05.

RESULTS

There were statistically significant differences between the experimental and control groups (P=0.002). The laser-treated groups showed a lower apical microleakage compared to the non-laser-treated groups, although the difference was not statistically significant (P>0.05). No significant differences were noted between the two lasers in terms of the apical microleakage, irrespective of the type of sealer (P>0.05).

CONCLUSIONS

Laser irradiation, as an adjunct to root canal preparation, has no significant effect on the level of apical microleakage.

Bond strength of a self-adhesive resinous cement to root dentin irradiated with a 980-nm diode laser

OBJECTIVE

To assess the bond strength of Rely-X Unicem (RX), in comparison with Cement-Post (CP), to the cervical, middle and apical thirds of root canal dentin irradiated with a 980-nm diode laser.

MATERIAL AND METHODS

Forty maxillary canines were separated into four equal groups according to the cement used and the laser surface treatment: RX/laser irradiation (LI) group; RX/no irradiation (NI) group; CP/LI group; and CP/NI group. Two slices (2-mm thick) of each root third were submitted to a push-out test to assess the bond strength of the cement to the root canal dentin. The data obtained were submitted to two-way ANOVA and fracture analysis was performed by scanning electron microscopy.

RESULTS

The type of cement as well as 980-nm LI at the different root canal thirds significantly affected the bond strength values (p < 0.05). LI promoted an increase in bond strength of RX in all root thirds (p < 0.05). For all groups, bond strength to the cervical third was highest, followed by the middle and apical thirds (p < 0.05). When the cements were compared, RX always presented the highest bond strength in comparison with CP, irrespective of the laser application (p < 0.05). Fracture analysis showed a predominance of mixed failures for RX and of adhesive failure between dentin and cement for CP, irrespective of the laser application.

CONCLUSION

The 980-nm LI promoted an increase in bond strength of the self-adhesive resinous cement to root dentin.