Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer

Abstract

This study evaluated the effect of flowable composite resin application on the microtensile bond strength (microTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37 degrees C for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm(2) in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5% significance level. Placement of a low-viscosity resin to the hybridized dentin increased the microTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher microTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest microTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on microTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.

Effect of adhesive system and application strategy on reduction of dentin permeability

“…5,7,8,10,16 To overcome this early degradation, some investigations have revealed that the application of more hydrophobic resins over hybridized tissues provides better sealing of acid-etched dentin 9,18-21 and higher bond strength of composite to dentin. 19,20,22 In this study, the use of flowable resin or an additional layer of more hydrophobic adhesive did not improve the percentage dentin sealing of any type of adhesive.…”

“…16,17 To improve the sealing ability of one-step self-etching adhesives, some authors have suggested the application of an additional layer of hydrophobic material in an attempt to reduce the concentration of hydrophilic monomers to be light cured. 9,[18][19][20][21][22] The importance of studying dentin permeability in relation to the sealing ability of adhesive systems is that, besides bonding the restorative material to the tooth, adhesive systems are responsible for sealing the resin-dentin interface against microleakage and avoiding restorative material debonding, which could compromise the restorations. 2,16,17 The objective of this study was to measure fluid flow through the adhesive-dentin interfaces created by eight bonding agents using a permeability device.…”

&lt;sup&gt;99m&lt;/sup&gt;Tc in the evaluation of microleakage of composite resin restorations with SonicFill&lt;sup&gt;TM&lt;/sup&gt;. An &lt;i&gt;in vitro&lt;/i&gt; experimental model

“…According to Yuasa et al these adhesive systems have the advantage of saving time, reducing procedural errors and with their lower etching ability, decreasing the potential for iatrogenic damage to dental hard tissue [23]. De Goes et al advocate that Clearfil TM SE BOND presents significantly higher bond strengths than other self-etching adhesives [24]. The enamel was etched previously with 35% phosphoric acid gel, increasing the bond strengths significantly [25].…”

The effect of the elastic modulus of low-viscosity resins on the microleakage of Class V resin composite restorations under occlusal loading

“…It has been reported that the incompatibility of one-step selfetching adhesive with resin composite 37) and the lack of hydrophobic resins for hybrid layer formation of this adhesive compromised the dentine bond 38) . Furthermore, an additional intermediate flowable composite was used and reported to increase the adhesion 39) . According to that result, marginal sealing may be improved by the application of the flowable composite.…”