Abstract
Purpose: Resin cements utilizing universal adhesives have been marketed in order to simplify clinical procedures and overcome the technique sensitivity of multiple-step resin cement systems. However, the influence of light irradiation on the bonding performance of resin cement is not known. The purpose of this study was to monitor the chronological changes of dentin bond strength of resin cement using a universal adhesive.
Methods: Two dual-cure resin-based cements, a combination of universal adhesive/resin cement (Scotchbond Universal/RelyX Ultimate Resin Cement, RXU; 3M ESPE) and conventional type resin cement (Clearfil Esthetic Cement, CEC; Kuraray Noritake Dental), were used. Bovine dentin was wet-ground with #600 SiC paper. Resin columns (4 mm in diameter, 2 mm in height) were cemented and light-irradiated with the power density of 600 mW/cm2 or not irradiated (chemical-cured). The shear bond strengths of 10 specimens per group were measured at a cross-head speed of 1.0 mm/min after 15 min, 1, 6, 12, and 24 h storage in a chamber at 37±1°C, 90±5 RH%. Statistical analysis was done to test for the presence of a significant difference between the mean bond strength at each test time at a significance level of 0.05.
Results: The dentin bond strength increased with prolonged specimen storage time. When the specimens were light-irradiated, higher bond strengths were obtained compared to those specimens without irradiation. When the specimens were without light irradiation, dentin-cement interface failures were observed for RXU and CEC. When the specimens were light irradiated, cohesive failures within resin and dentin were observed for RXU, and dentin-cement interface failures were observed for CEC.
Conclusions: From the results of this study, it was concluded that the chronological change in the dentin bond strength of resin cement was affected by the presence or absence of light irradiation of the specimen. Light irradiation might be necessary to achieve greater dentin bond strength, even in materials with a dual-cured setting reaction.
