Abstract
Objective The aim of this study was to evaluate the use of 70 vol.% ethanol as a dentin pretreatment
on the bond strength (BS) of a two-step etch-and-rinse adhesive.
Materials and Methods Resin composite Class I restorations were clinically bonded to acid-etched dentin
of human sound third molars using Adper Single Bond 2 (SB, 3M ESPE) and randomly divided
into two major groups: dentin saturated with water (control) or 70 vol.% ethanol (ethanol).
The teeth were divided into two subgroups: immediately extracted and tested after
24 hours and extraction after 18 months. Bonded teeth (Adper SB 2) were cut into resin–dentin
sticks that were tested by microtensile BS, and the failure mode was thereafter evaluated.
Statistical Analysis Data were statistically analyzed using two-way analysis of variance and Holm–Sidak
post hoc test (α = 0.05). Additional bonded resin–dentin slabs from each group were examined
under light microscopy (LM) using the Masson's trichrome staining technique.
Results The lowest BS was obtained by ethanol pretreated dentin after aging, while other
groups presented similar BS. The LM analysis showed the presence of resin-sparse collagen
fibrils in groups examined immediately (24 hours) and the presence of several gaps
due to collagen degradation at the interfaces of ethanol pretreated aged specimens
(18 months).
Conclusion The use of 70 vol.% ethanol in dentin before the application of a two-step etch-and-rinse
adhesive should be avoided once it resulted in a significant drop on the BS.
Keywords
bond strength - ethanol wet bonding - hybrid layer
