Dentin pretreatment with Er:YAG laser and sodium ascorbate to improve the bond strength of glass fiber post

Abstract

Root-filled teeth that received fiber posts most frequently fail at the adhesive interface between resin cement and dentin. The objective of this study is to evaluate the effect of Er:YAG laser and/or sodium ascorbate (SA) on bond strength, microhardness of dentin, and penetration depth of cement into dentinal tubules. Forty-eight bovine incisor roots were endodontically treated, post spaces were prepared and equally divided into four groups (n = 12): G1-distilled water (control); G2-10% SA (10 min); G3-Er:YAG laser (150 mJ/4 Hz/40 s), and G4-Er:YAG laser + 10% SA. Glass fiber posts were cemented and roots sectioned into slices. In the first slice, the push-out bond strength (MPa) and failures were analyzed by confocal laser scanning microscope (CLSM). The second slice was subjected to microhardness test (KHN) and CLSM to assess the cement penetration. ANOVA and Tukey test were used for bond strength and microhardness data and Kruskal-Wallis and Dunn tests for the cement penetration (α = .05). The SA-treated samples had higher bond strength (10.02 ± 5.45a), similar to Er:YAG laser (9.91 ± 4.62a) and Er:YAG laser + SA (8.09 ± 4.07a). The least values (P < .05) were found on control (4.02 ± 2.39b). Significant differences were observed on root thirds (P < .05): cervical > middle > apical. There was a predominance of adhesive failures. The microhardness test revealed no differences between groups (P > .05). The experimental groups (G2, G3, and G4) had highest penetration into dentinal tubules when compared to the control (G1). Dentin pretreatments with Er:YAG laser or SA improved bond strength of cement-post-dentin interfaces; however, no synergistic effect of both treatments combined was observed.

Effect of Er:YAG laser irrigation with different etching modes on the push-out bond strength of fiber posts to the root dentine

“…The wavelength of the Er:YAG laser is 2940 nm, which water and hydroxyapatite highly absorb. When it is applied on the dentine surface, the water and the hydroxyapatite of the dentine in the root canal could absorb the Er:YAG laser’s energy, causing dentine’s expansion and microexplosion, and the debris and smear layer in the root canal could be removed better than with other lasers [ 11 , 23 , 24 ]. In this study, the SEM observation showed that the smear layer in the dentine surface was removed more effectively by the irrigation method of passive ultrasonic irrigation or Er:YAG laser–activated irrigation combined with the irrigation protocols of 5.25% NaClO and 17% EDTA solutions than that by conventional syringe irrigation method.…”

“…Its emission wavelength (2.940 nm) is strongly absorbed by water; it is thus effective and efficient in dental hard tissue ablation [ 10 ]. Er:YAG-activated irrigation possibly could form steam bubbles in the root canal at sub-ablative level, through which the cavitation effect is generated and the root canal is thus cleaned [ 11 ]. Previous studies have suggested that irregular dentine surfaces and dentine tubules were opened after Er:YAG laser irradiation, which increases the bonding area between the dentine and adhesive [ 12 ].…”

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“…Prior to cementation, post spaces were irrigated using standard irrigation protocol (5.25% NaOCl followed by distilled water, then 17% EDTA, and again distilled water as a final flush) [16,17] , then dried and the posts were cemented using dual-cured self-adhesive resin cement, and light-cured [18,19] .…”

“…Preparation for push-out bond strength test Three 1.5 mm thick slices were attained from each root sample by cutting machine under water cooling (IsoMet 4000 microsaw, Buehler, USA) to represent various root levels (cervical, middle, apical) and their thickness was confirmed using a digital caliper. The push-out bond strength test was done using a universal testing machine at a cross head speed of 1 mm/min in an apico-coronal direction as shown in figure (4) [16,19] .…”

Influência da quitosana na biomodificação da dentina após remoção seletiva da lesão de cárie utilizando laser de ER:YAG. Análise clínica, da adaptação marginal da réplica da restauração e microbiológica

“…A influência do laser de Er:YAG no processo de adesão da dentina irradiada, bem como o impacto sobre as fibras colágenas, ainda não se encontra totalmente esclarecida. Estudos mostram que o pré-tratamento da dentina com o laser de Er:YAG melhora a força adesiva na interface cemento-dentina (Pelozo et al, 2018) e pode ser vantajosa para a adesão de restaurações em resina composta (Kallis et al, 2018). Outros estudos mostram que a utilização do laser de Er:YAG provoca alterações na força de ligação adesiva da restauração ao dente devido às mudanças microestruturais na dentina causadas pela irradiação, tais como aumento da profundidade de crateras dentinárias (Nahas et al, 2018), ausência de smear layer e desnaturação das fibras colágenas, o que pode dificultar a penetração do adesivo nos túbulos dentinários (Ramos et al, 2002;Giachetti et al, 2004;Dunn et al, 2005;Xu et al, 2011;Firat et al, 2012;Profeta et al, 2012;Moosavi et al, 2016).…”