Article Type

Original Article


Objective: To evaluate the micro-tensile bond strength (μTBS) and micro-morphological analysis of composite dentin interface of dual-cure resin composites bonded to dentin. Materials and Methods: For the micro-tensile bond strength test, sixty sound human maxillary and mandibular molars were collected. After embedding the selected molars in an acrylic resin block, the occlusal enamel and superficial dentin of each tooth were removed, exposing the mid-dentin area. They were assigned randomly into three groups (n=20) according to the restorative system. Then both groups were further divided into two subgroups; subgroup 1 for immediately tested specimens after 24 h (n=10), and subgroup 2 for delayed tested specimens after 6 months (n=10). Resin composite build-ups were made incrementally 2mm up to reach full thickness. The blocks were sectioned and then subjected to a micro-tensile (μTBS) test at 24h and after 6 months. Two specimens from each subgroup were used for the micro-morphological analysis of the adhesive/dentin interface using a scanning electron microscope (SEM) (n=12) . Results: Regarding the (μTBS) test, the One-way ANOVA test showed a significant difference among all groups(p=0.002). Tukey post hoc multiple comparison test showed that All-bond universal adhesive had the highest mean bond strength, which was significantly different from Tetric N bond UA and Futurabond M+ UA. Also, Tetric N bond UA showed the lowest mean bond strength values. All-bond universal and Futurabond M+ universal adhesives produced hybrid layers with high resin tag infiltration. While the Tetric N-bond universal adhesive showed the typical micro-morphological pattern of the hybrid component of this material. Conclusions: The present study is based on the outcome of the ( μTBS) test, for universal adhesives, the addition of a dual-curing activator did not influence bond strength to dentin, and there was no relation between the micro-tensile bond strength and the micro-morphological patterns in all tested adhesives. Aging affects negatively the bond strength.