Effect of smear layer deproteinization with enzyme solutions on bonding efficacy of one-step self-etch adhesives

Abstract Objective The aim of this study was to evaluate the deproteinizing/pretreatment effect of enzyme solutions on cavity adaptation and bond strengths to enamel and dentin. Materials and methods Class V cavities with enamel and dentin margins were prepared using bovine incisors. After one of four pre-treatments (bromelain, papain, HOCl-solution and none), Scotchbond Universal (SU) or Clearfil Universal Bond Quick (UQ) was applied to the cavities, followed by filling resin composite. After water storage for 24 h, the interfacial gap lengths were calculated using SS-OCT. In addition, the micro-shear bond strength (μSBS) test to flat enamel and dentin surfaces treated as mentioned above was performed. Furthermore, the enamel and dentin surfaces after the pretreatments were morphologically investigated using a scanning electronic microscopy (SEM). Results The pretreatment of bromelain and HOCl-solutions significantly increased μSBS of SU to enamel and dentin, and improved enamel-marginal and internal adaptations in the cavity (p 0.05) although they significantly increased μSBS to dentin (p 0.05). SEM observations revealed that treatments of bromelain and HOCl-solutions partially removed the dentin smear layer, while papain treatment slightly thinned it. Conclusion Pretreatment with bromelain could increase μSBS to enamel and dentin, and improve the cavity adaptation due to partial dissolution of the organic phase in the smear layer.