Nd:YAG laser irradiation effect on apical intracanal dentin - a microleakage and SEM evaluation

Abstract

The purpose of this in vitro study was to evaluate the effect of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation on intracanal dentin surface by SEM analysis and its interference in the apical seal of filled canals. After endodontic treatment procedures, 34 maxillary human incisors were randomly assigned to 2 groups. In the negative control group (n=17), no additional treatment was performed and teeth were filled with vertically condensed gutta-percha; in the laser-treated group (n=17), the root canals were irradiated with Nd:YAG laser (1.5 W, 100 mJ, 15 Hz) before filling as described for the control group. Two specimens of each group were prepared for SEM analysis to evaluate the presence and extent of morphological changes and removal of debris; the other specimens were immersed in 0.5% methylene blue dye (pH 7.2) for 24 h for evaluation of the linear dye leakage at the apical third. SEM analysis of the laser-treated group showed dentin fusion and resolidification without smear layer or debris. The Student's t-test showed that the laser-treated group had significantly less leakage in apical third than the control group. Within the limitations of this study, it may be concluded that the morphological changes on the apical intraradicular dentin surface caused by Nd:YAG laser resulted in less linear dye apical leakage.

Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers

“…Treatment of the wall of the canal prior to obturation may affect the apical sealing ability of root canal sealers, as demonstrated in previous studies using different approaches and materials from EDTA to laser irradiation. [3][4][5]10,12,13,16,17 It is well-known that high intensity laser intracanal irradiation has other advantages. Several studies demonstrated its efficacy in cleanliness and disinfection.…”

“…These results concur with other reports in the literature. 9,[15][16][17][18][19] On the other hand, Er: YAG laser irradiation caused ablation of the dentin surface, which was more evident in the intertubular than the peritubular dentin. This resulted in more exposed dentinal tubules as previously reported.…”

“…Teeth in Group Neodymium had the root canals irradiated with a 1064-nm Nd:YAG laser (Pulse Master 1000; American Dental Technologies, Southfield, Michigan) operated at 1.5 W, 100 mJ, 15 Hz, and 124;34 J∕cm 2 , in pulsed mode. 9,11,16 Group diode was irradiated with an 808-nm diode laser (Zap Softlase; Zap Lasers Ltd., Pleasant Hill, California) with a setting of 2.5 W in continuous mode. 5,6,19,20 In the fourth group (Erbium), the root canals were irradiated with a 2940 nm Er:YAG laser (KavoKey laser 2; KaVo Co., Biberach, Germany) operated at 1 W, 100 mJ, 10 Hz, and 38;03 J∕cm 2 in pulsed mode.…”

“…[2][3][4][5][6][7] As an adjunct in endodontic treatment, the use of high intensity laser devices has demonstrated significant intracanal disinfection and morphological changes of the dentin surface that interfere with dentin permeability and root canal sealing. 5,6,[8][9][10][11][12][13][14][15][16] The interaction between laser wavelengths and irradiated tissues will assume the level of energy absorbed by the latter and therefore the intensity of tissue alteration. 3,9,11-,15-18 Wavelengths between 800 and 1100 nm (i.e., diode and Nd:YAG lasers) have poor interaction with dental hard tissues like enamel and dentin.…”

“…These lasers can melt their surfaces, creating a new pattern and occluding dentinal tubules. 9,11,13,[15][16][17][18][19] On the other hand, wavelengths in the range of 2700 and 3000 nm (Er, Cr:YSGG and Er:YAG lasers) have an optimal interaction with water and hydroxyapatite, and therefore the laser energy is highly absorbed by dental structures causing surface ablation. 3,10,12,13,18 Despite the favorable properties of the methacrylate resinbased sealers and high intensity laser irradiation, it is not well understood if the association of these two resources improves the root canal seal, and therefore might enhance the success of root canal treatment.…”