Influence of different smear layers on bond durability of self-etch adhesives.

OBJECTIVE: The purpose of this study was to determine the influence of different smear layers on enamel and dentin bond durability of various types of self-etch adhesives.

METHODS: Two universal adhesives, Scotchbond Universal (SU) and Prime & Bond elect (PE); a conventional single-step self-etch adhesive, G-ænial Bond (GB); and two two-step self-etch adhesives, Optibond XTR (OX) and Clearfil SE Bond (SE) were used in this study. Shear bond strengths (SBS) and shear fatigue strengths (SFS) to human enamel and dentin were determined with different smear layer conditions. The prepared specimens were divided into three groups. The bonding surfaces were prepared by grinding with either (1) #180, (2) #600, or (3) #4000-SiC papers before making the bonded assemblies. For each group, 15 specimens were prepared for the SBS and 30 specimens for the SFS.

RESULTS: The two-step self-etch adhesives showed significantly higher SFS values than the single-step self-etch adhesives, regardless of the smear layer condition or substrate. Although most of the tested adhesives showed no significant differences in enamel SFS values among the smear layer groups, SU, GB, and SE showed significantly lower SFS values in the #180 in dentin groups than the #600 and #4000 groups.

CONCLUSION: The influence of different smear layer conditions on bond durability was adhesive dependent. Furthermore, the smear layers generated on different substrates also influenced the bond quality of the self-etch adhesives.

SIGNIFICANCE: Smear layer conditions of enamel and dentin influence the bond durability of universal adhesives and conventional single and two-step self-etch adhesives.