Aim: The purpose of this in vitro investigation was to evaluate the influence of double application and application of hydrophobic layer on marginal adaptation of four self-etch adhesive systems (XENOIII, ALLBONDSE, CLEARFIL SE TRI BOND, FUTURA BOND).
Materials and methods: One hundred and twenty class V cavities were prepared on intact, extracted human premolars and were divided into three groups of ten teeth each for all four adhesives. Group 1: Application of bonding agents as per manufacturer directions. Group 2: Double application of bonding agents. Group 3: Application of hydrophobic layer. The specimens were restored with composite and light cured. After thermocycling and immersion in 2% Basic Fuchsin dye solution, the teeth were sectioned and dye penetration was observed under a stereomicroscope at 20× magnification. All the samples were scored and results were analyzed using Kruskal-Wallis and Mann-Whitney tests.
Results: Group 3, in which the adhesive systems were coated with hydrophobic layer, showed significantly decreased microleakage, followed by Group 1 and Group 2 for all the adhesive systems. And there is no significant different between Group 1 and Group 2.
Conclusion: Marginal permeability of one-step adhesives can be minimized by the application of more hydrophobic resin layer, and the double application of one-step self-etch system can be safely performed without jeopardizing the performance of adhesives.
Keywords: Double application; hydrophobic layer; marginal permeability; self-etch adhesives.