الفهرس 
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Abstract
The aim of this study was to evaluate the effect of ascorbic acid on push-out bond strength of resin-based sealer (EndoRez) to root canal dentin after using two root canal irrigation regimens.
A total of fifty human single-rooted teeth were used in this study. Teeth were decoronated, cleaned and shaped using crown down technique. Samples were divided into five groups (10 each) according to the final irrigation protocol. In group I, samples were irrigated using saline (NaCl) for 10 minutes; group II, 5.25% NaOCl for 10 minutes; group III, 5.25% NaOCl for 10 minutes followed by 10% ascorbic acid for 10 minutes; group IV, 5.25% NaOCl for 10 minutes followed by 17% EDTA for 1 minute; group V, 5.25% NaOCl for 10 minutes followed by 17% EDTA for 1 and 10% ascorbic acid for 10 minutes.
The teeth were obturated using EndoRez sealer by lateral compaction technique. The bond strength was evaluated using the push-out test. The failure mode was analyzed using digital microscope for all the tested samples.
Results of the bond strength showed that Group V (NaOCl, EDTA and ascorbic acid) recorded the highest bond strength followed by group III (NaOCl and ascorbic acid), followed by group IV (NaOCl and EDTA), and followed by group I (saline). The lowest bond strength was recorded with group II (NaOCl).
The analysis of failure modes revealed a predominance of adhesive failure (type I) in group II. While in group I, III and V mixed failures (type III) were predominantly found. The failure mode was equally distributed between adhesive and mixed failure in group IV. None of the samples among the five groups showed type II failure.