Effect of water storage and hydrophobic adhesive �ayer app�ication on the bond strength of all-in-one adhesives

Resumo

To prevent the rate of water absorption and degradation
of exposed collagen and the resin matrix on the hybrid layers,
the use of an additional layer of hydrophobic resin on all-in-one
adhesives is one of the approaches to improve the bond strength
and infiltration of monomers in demineralized dentin. Objectives:
To compare the microshear bond strength of different self-etching
adhesive systems, and to evaluate the effect of the application of
a hydrophobic adhesive layer on all-in-one adhesive systems after
a storage period of 48 h and 30 days in distilled water at 37oC.
Material and methods: Bovine incisor crowns were polished to
expose flat dentin surfaces. The crowns were randomly distributed
into 14 groups (n = 12) according to the adhesive system [Clearfil
SE Bond (CSEB), AdheSE (ASE), Adper Scotchbond SE (SSE), Adper
Easy Bond (EB), and Go! (GO)], and storage time. In two groups
(indicated as GO+B and EB+B), a layer of a hydrophobic adhesive
was applied on all-in-one adhesive systems. After 48h and 30 days of storage in distilled water at 37oC, microshear bond strength was
determined. The data were statistically analyzed by ANOVA and
Tukey’s test (α = 5%). Results: After 48h, EB, EB+B, CSEB, and
GO+B showed higher bond strength values. The application of a
hydrophobic layer did not influence EB and increased GO bond
strength values. After 30 days, CSEB, SSE, and EB+B showed
the highest bond strength values. Comparing groups of all-in-one
adhesives with and without a hydrophobic adhesive-resin layer, the
bond strength values showed no significant difference. Conclusion:
The application of a hydrophobic adhesive-resin layer increased bond
strength values only at 48h. With respect to bond degradation over
time, only EB showed a statistically significant decrease of bond
strength after 30 days.