Comparison of dentin root canal permeability and morphology after irradiation with Nd:YAG, Er:YAG, and diode lasers

Abstract

The aim of this study was to compare the effects of Nd:YAG, Er:YAG, and diode lasers on the morphology and permeability of root canal walls. The three laser wavelengths mentioned interact differently with dentin and therefore it is possible that the permeability changes caused will determine different indications during endodontic treatment. Twenty-eight human single-rooted teeth were instrumented up to ISO 40 and divided into four groups: group C, control (GC), non-laser irradiated; group N (GN), irradiated with Nd:YAG laser; group E (GE), with Er:YAG laser and group D (GD) with diode laser. After that, the roots were filled with a 2% methylene blue dye, divided into two halves and then photographed. The images were analyzed using Image J software and the percentage of dye penetration in the cervical, middle, and apical root thirds were calculated. Additional scanning electron microscopy (SEM) analyses were also performed. The analysis of variance (ANOVA) showed significant permeability differences between all groups in the middle and cervical thirds (p < 0.05). The Tukey test showed that in the cervical third, GN presented means of dye penetration statistically significantly lower than all of the other groups. In the middle third, GE and GD showed statistically higher dye penetration means than GC and GN. SEM analysis showed melted surfaces for GN, clean wall surfaces with open dentinal tubules for GE, and mostly obliterated dentinal tubules for GD. Er:YAG (2,094 nm) laser and diode laser (808 nm) root canal irradiation increase dentinal permeability and Nd:YAG (1,064 nm) laser decreases dentin permeability, within the studied parameters.

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.…”

“…Several studies demonstrated its efficacy in cleanliness and disinfection. 8,9,[11][12][13][14][15] Few studies have compared the resin-based sealers that were investigated in the present study and the influence of high-intensity laser irradiation on the adaptation and penetration into dentin tubules of these sealers. 3,5,6 Therefore, the hypothesis of this study is that the treatment of dentin prior to obturation using high intensity laser irradiation interferes with the quality of the apical seal when using resin-based sealers was accepted.…”

“…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. 12,13,18 All laser treatments were carried out according to the manufacturer's instructions. The roots treated with a laser contained sterile water and were irradiated four times with circular movements, from apex to crown at a speed of 2 mm∕s with a 20 s interval between applications.…”

“…[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.…”

“…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. Thus, the aim of the present study is to evaluate the quality of the apical seal of root canals irradiated with high-intensity lasers and filled with resin-based sealers.…”