The Effectiveness of Continuous Versus Sequential Chelation in the Removal of Smear Layer and Their Influence On Push-Out Bond Strength of Bio-C Sealer (An in vitro study)

Abstract

Objectives: Successful endodontic treatment outcome requires effective shaping and cleaning of root canals. This study aims to evaluate the smear layer removal after continuous chelation (CC) (NaOCI\HEDP) and sequential chelation (SC) (NaOCI\EDTA) and their influence on the push-out bond strength (POBS) of Bio-C sealer. Material and Methods: Palatal roots of the maxillary first molar (n=72) were divided into four groups (n=18) as follows: 3% NaOCl, SC: 3% NaOCl followed by 17% EDTA, CC: 3% NaOCl \9% HEDP and Distilled water. Thirtytwo roots (n=8/group) were split longitudinally for smear layer evaluation using SEM. Forty roots were obturated with Guttapercha and Bio-C sealer using a single cone technique. Three sections were taken horizontally from the coronal, middle, and apical third (1.5±0.1 mm thickness) for the push-out test using a universal testing machine. The Kruskal-Wallis and Mann-Whitney tests were used to analyze the SEM data, while the One-way analysis of variance (ANOVA) test and the Tukey test were used to analyze POBS data. Z test to compare failure mode. Results: There was no difference between SC and CC in the smear layer removal at all thirds (p>0.05). The POBS in CC was significantly higher than SC in all thirds (p<0.05). Failure mode distribution was 53.3% mixed, followed by 26.6% adhesive and 20% cohesive. Conclusions: NaOCl\HEDP was as effective as NaOCl\EDTA in removing the smear layer. Neither of the two protocols could eliminate the smear layer completely. The bonding strength of Bio-C sealer was optimized by using NaOCl\HEDP combination.