Effects of Er:YAG and Er,Cr:YSGG laser irradiation on the adhesion to eroded dentin

Abstract

Limited information is available regarding the adhesion to eroded dentin. This study aims to evaluate the effect of different surface treatments on eroded dentin morphology and on microtensile bond strength (μTBS) of adhesive systems to this substrate. Ninety-six extracted third molars were randomly divided into eight groups (n = 12) according to the type of surface treatment and the adhesive system: G1 = Control + Clearfil SE Bond [SE], G2 = Diamond bur [DB] + SE, G3 = Er:YAG laser (60 mJ, 2 Hz, 0.12 W, 19.3 J/ cm(2)) + SE, G4 = Er,Cr:YSGG laser (50 mJ, 30 Hz, 1.5 W, 4.5 J/ cm(2)) + SE, G5 = Control + Single Bond [SB], G6 = DB + SB, G7 = Er:YAG + SB, G8 = Er,Cr:YSGG + SB. The erosive cycling was performed by immersion in 0.05 M citric acid (pH 2.3, 10 min, 6x/day) and in supersaturated solution (pH 7.0, 1 h, between acid attacks), during 5 days. Blocks of composite were bonded to the samples according to the manufacturers' instructions. After 24 h-storage in distilled/deionized water (37 °C), stick-shaped samples were obtained and submitted to μTBS test. Each surface treatment was analyzed under scanning electron microscopy (n = 4) and the bond strength values (megapascal) were analyzed by two-way ANOVA and Tukey tests (α = 0.05). All surface treatments lead to changes on eroded dentin. G4 showed the highest bond strength mean (28.3 ± 9.2 MPa), which was statistically significant higher than all the other groups (p < 0.05). The surface treatment with Er,Cr:YSGG laser irradiation (4.5 J/cm(2)/50 mJ/30 Hz/140 μs) prior to bonding with a self-etching adhesive system significantly increases adhesion to eroded dentin, as compared to conventional treatment.

Bond strength of composite resin containing biomaterial S-PRG to eroded dentin

“…It infers a good reliability of the present µTBS test conditions and correlates well with the literature for eroded dentin bonded to adhesive systems 20,[30][31][32] . On the other hand, eroded dentin restored with ionomer based materials usually shows higher incidence of cohesive and mixed failure 22 .…”

“…The intense micromechanical interlocking produced by phosphoric acid etching might explain the higher bond strength observed to the Adper Single Bond 2. Contradictory results 30 found better results for self-etch approach when compared to etch-and-rinse bond strength results, which infers that the bonding effectiveness to eroded dentin might be product-dependent. Forgerini et al 21 (2017) reported that the use of an universal adhesive did not provide the same bonding efficacy on eroded dentin as on sound dentin, irrespective of the etching mode.…”

Effects of Erbium Family Laser on Shear Bond Strength of Composite to Dentin After Internal Bleaching

“…The water molecules among the hydroxyapatite crystals absorb the beams and evaporate; as a result, the internal pressure increases and microexplosions occur leading to substrate ejection and microstructural alterations. 25,28,29 Although several studies have assessed the effects of erbium family lasers on bleached enamel, 3,[30][31][32] to the best of our knowledge no study has compared the effects of Er:YAG and Er,Cr:YSGG lasers on bleached dentin. Based on our results, Er:YAG laser irradiation led to significantly higher bond strength compared to the control group.…”

“…28,32,33 Finally, reduction in microbial count due to erbium laser irradiation may also explain the higher bond strength values. 25,[34][35][36][37] Although Er,Cr:YSGG laser treatment caused an increase in bond strength compared to the control group, the amount was insignificant. The drop in shear bond strength values in the Er,Cr:YSGG group compared to the Er:YAG group may be due to the difference in the morphology of the lased dentin surface.…”

“…Evaporation of water in the tissue leads to micro-explosions and ablation of tooth structure. 3,22,24,25 In other words, the increased internal pressure due to evaporation of water results in explosive ablation. 26,27 The ablative effect of the erbium lasers may be able to accelerate the release of free radicals and neutralize the effects of bleaching agents on bond strength.…”