Microtensile bond strength and interfacial analysis of bulk-fill resin composite versus incrementally-packed resin composite with dentin substrate : An In-vitro study / Abdullah Mohammad Mahmoud ; Supervised Heba Hamza , Asmaa Yassen

Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Operative Dentistry

This study was conducted to evaluate the effect of two different resin composite materials, bulk-fill and incremental, on microtensile bond strength to dentin immediately after 24-hours and after one-month storage in distilled water. The study compared two resin composite systems, of which one intervention and one served as control. Twenty extracted molars were collected, divided into two main equal groups according to resin composite systems (10 in each); each group was further subdivided into two subgroups according to storage Periods (5 in each). To prepare the specimens, their occlusal surfaces were reduced to obtain flat dentin surfaces. The tested resin composite systems were applied according to manufacturer's instructions onto each substrate using a 4-mm thick acrylic mold. To evaluate microtensile bond strength, prepared teeth were sectioned to obtain 0.9x0.9mm beams consisted of dentin, adhesive and resin composite. For each tested subgroup, 20 Beams where stressed to failure under tensile loading using a universal testing machine. Fractured specimens from microtensile bond testing were collected and examined under Stereomicroscope to analyze the modes of failure. Ultra-morphological analysis of the resin/dentin interface was done. Representative specimens were prepared and interfaces were analyzed under Environmental Scanning Electron Microscope at high magnifications (500X- 3000X)

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