Influence of Different Curing-Modes of Self-Etching Adhesives on Interface Morphology
Most of the currently available self-etching bonding systems are not recommended for use in combination with self- or dual-curing composites. For some self-etching bonding systems additional dual-cure Activators are available. Objective: To investigate the influence of different curing-modes on interface morphology and shear bond strength of two self-etching two step adhesive systems. Methods: The adhesives tested were AdheSE (Ivoclar Vivadent AG, Schaan, Liechtenstein) in combination with an experimental dual-cure Activator and Optibond-Solo Plus Self-Etch Adhesive System (Kerr, Orange, USA) with the corresponding dual-cure Activator. Three curing-modes were used with each system: light-, dual- and self-curing according to manufacturers instructions. For each group 8 bovine incisors (5 for shear-bond-test, 3 for CLSM investigations) were polished with P1000 grit to expose dentin respectively enamel. The adhesives were applied according to the particular protocol. The composite was built up to a 4-mm height and after 24h of storage in water at 37°C SBS was measured according to ISO/TS11405. ANOVA was used to determine inter-group differences. For CLSM Measurements the Primer components of all samples were fluorescence-labeled by rhodamin B isothiocyanate. The samples for CLSM were sectioned and examined using a CLSM in fluorescent mode. Results: The CLSM data gave evidence for a relationship between hybrid-layer formation and curing-mode of both adhesives. The bond strength of AdheSE (light-cure 21.5MPa/dual-cure 24.3MPa/self-cure 21.5MPa) are not statistically different for all curing-modes, whereas the bond strength values of Optibond-Solo (light-cure 19.3MPa/dual-cure 9.3MPa/self-cure 2.2MPa) are significantly higher for the light-cure-mode compared to the dual-cure- or self-cure-mode. (p<0.05) Conclusion: The shear bond values for both systems are comparable using the light-cure-mode, but using the self- or dual-cure-mode AdheSE with additional Activator showed significantly higher shear bond values compared to the Optibond-Solo System with Activator.