Effect of double coating of one-step self-etching adhesive on micromorphology and microtensile bond strength to sound vs demineralized dentin

Abstract

Aim: The purpose of the present study was to evaluate (1) the one-step adhesive system application method (doubling the adhesive coatings) in regard to microtensile bond strength (MTB) and (2) the interfacial morphology of one-step adhesives to sound vs demineralized dentin. Materials and methods: Forty dentin fragments were randomly allocated to 2 groups: D. demineralized dentin and S. sound dentin. Specimens were also subdivided into 2 groups (n = 10), according to the one-step adhesive [AEO (Adper Easy One), 3M ESPE] application method: M, According to the manufacturer's instructions, and D, based on the application of two consecutive layers. After adhesive light polymerization, a resin composite block (Filtek Z250, 3M ESPE) was built on the dentin surface. Resin-tooth blocks were sectioned into 0.9 mm thick slabs, and one slab of each block was prepared for adhesive interface analysis by scanning electron microscopy (SEM). The remaining slabs were sectioned into 0.8 mm2 sticks that were subjected to tensile stress (0.5 mm/min). Data were subjected to two-way ANOVA and Tukey's test (α = 0.05). Results: The application of two consecutive layers of AEO adhesive system did not influence MTB values for sound dentin. When two consecutive layers of one-step adhesive system were applied, MTB was statistically greater in demineralized vs sound dentin. SEM analysis demonstrated that the application of two consecutive adhesive layers to sound and demineralized dentin produced longer resin tags. Conclusion: It can be concluded that the application of two consecutive adhesive layers improved bond strength to demineralized dentin, but no such effect was observed for sound dentin. Clinical significance: Application of double coats of one-step self-etching adhesive improved bond strength to demineralized dentin.