الفهرس 
Bond degradation resistance and interface characterization of a water-expandable endodontic obturation point
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Abstract
This in vitro study was carried out to evaluate the effect of an alternative root canal obturating system on the durability of the sealer/ dentin interface using water expandable (C-Point) /Endosequence bioceramic sealer and compared it to gutta-percha / AH-plus using the micro push bond strength and nanoleakage of the two-root canal obturating systems at different time intervals namely; four hours, one day, and one month. Similarly, also the failure mode and the interfacial analysis using environmental scanning electron microscope at the same selected time intervals. Ninety freshly extracted human upper central incisors teeth with straight root canals were used in the study; they were examined to exclude any tooth with defects or cracks. The access cavities were opened. All teeth were instrumented with a crown-down technique, using a set of ProTaper rotary instruments to achieve a size # 40 apical preparation. Irrigation was performed using 3 mL of 2.5% NaOCl after every change of instrument. Following biomechanical preparation 17% EDTA was used for 1 min, followed by distilled water for 1 min. Excess water was blotted dry using paper points. The specimens were divided into two main equal groups of 30 roots each according to testing material. Each group was further divided into three subgroups according to aging period of 10 teeth each. Each subgroup was divided into three classes according to the root segment tested into coronal, middle, and apical segments. Single cone technique was used for both tested materials. The root canals were filled with C-Point ProTaper F4/Endosequence BC sealer. A radiograph was taken to confirm the position of the point. Endosequence BC sealer was supplied in a premixed-syringable paste with intra-canal