Effect of accelerated aging and double application on the dentin bond strength of universal adhesive system

Abstract

Background: Despite the many advantages of simplified adhesive systems, there are concerns
about the durability of the adhesive layer over time. The aim was to investigate the effects of various
aging methods and double application of an adhesive layer on the bond strength of the universal
adhesive system using etch‑and‑rinse (ER) and self‑etch (SE) strategies.
Materials and Methods: In this in vitro study, the occlusal enamel of 120 extracted, intact human
third molars was removed to expose the dentin. Then, the samples were randomly divided into four
groups of thirty according to All‑Bond Universal (ABU) adhesive application strategy (ER and SE)
and the number of adhesive layers (1 or 2). Then, each group was subdivided into three subgroups
of ten according to aging method (control, thermal cycling, and 10% sodium hypochlorite [NaOCl]).
The shear bond strength was measured at the strain rate of 0.5 mm/min. Data were analyzed using
three‑way ANOVA and Tukey’s post hoc tests (P < 0.05).
Results: The effect of adhesive application strategy (P < 0.001) and aging method (P < 0.001) on the
bond strength was statistically significant, but the effect of the double application was not statistically
significant (P > 0.05). In addition, the interactive effect of adhesive application strategy–aging method
was significant (P = 0.005).
Conclusion: Using ABU with ER strategy leads to higher dentin bond strength compared to the
SE method in the control and thermal cycling groups. However, no significant differences were
observed between ER and SE strategies after aging with the NaOCl. Furthermore, the double
application might not have any effect on the bond strength and durability.
Key Words: Adhesives, aging, all‑bond system, dentin, sodium hypochlorite