EFFECT OF DIFFERENT IRRIGATION PROTOCOLS ON BOND STRENGTH OF ROOT CANAL SEALER TO DENTIN

Abstract

The aim of this study was to evaluate the effect of different irrigation protocols on the push-out bond strength of zinc oxide-eugenol based sealer; Kerr Pulp Canal Sealer EWT to root canal dentin and to determine the mode of bond failures that have occurred after dislodgment of the filling material. A total of 60 human permanent single rooted teeth were used in this study. Teeth were decoronated, cleaned and shaped using;ProTaper rotary system till # F5. Samples were divided into six groups (10 each) according to the final irrigation regimen used: Group Ι; root canals were finally irrigated with 5ml 2.5% NaOCl for 1 min, followed by rinsing with 5ml distilled water for 1 min. Group ΙΙ; root canals were finally irrigated with 5ml 17% EDTA for 1 min. Group ΙΙΙ; root canals were finally irrigated with 5ml 17% EDTA for 1 min, followed by 5ml 2% CHX for 2 min. Group ΙV; root canals were finally irrigated with 5ml BioPure MTAD according to the manufacturer’s instructions: 1ml of BioPure MTAD was placed in the canal for 3 min, followed by rinsing the canal with 4ml of MTAD. Group V; root canals were finally irrigated with 5ml BioPure MTAD with the same manner as in Group ΙV, followed by 5ml 2% CHX for 2 min. Group VΙ; root canals were finally irrigated with 5ml 2% CHX for 2 min. Kerr Pulp Canal Sealer EWT was used for obturating all samples using cold lateral compaction technique. The bond strength of the tested sealer was measured by the push-out test, and the mode of bond failure was determined under a scanning electron microscope. The results of the push-out test showed that there was no statistically significant difference between mean push-out bond strength of Group III(EDTA+CHX) and Group V(MTAD+CHX); both showed the statistically significantly highest mean values. There was no statistically significant difference between Group I(NaOCl), Group II (EDTA) and Group IV (MTAD); all showed lower mean values. Group VI (CHX) showed the statistically significantly lowest mean push-out bond strength. The apical bond strength in Groups; I (NaOCl),ΙΙΙ (EDTA+CHX) and V (MTAD+CHX) were significantly higher than the middle and coronal bond strength. The results of mode of bond failure examination revealed that groups;I (NaOCl), II (EDTA) and ΙΙΙ (EDTA+CHX) exhibited mixed types of failure, while groups;ΙV (MTAD), V (MTAD+CHX) and VΙ (CHX) exhibited adhesive types of failure. Based on the results obtained from this study it can be concluded that: 1) The bond strength of Kerr Pulp Canal Sealer EWT to dentin was affected by the type of final irrigant. 2) To obtain the highest bond strength values with Kerr PCS EWT/ gutta-percha; EDTA+CHX or MTAD+CHX can be used as a final irrigant. 3) The push-out bond strength of Kerr PCS EWT/ gutta-percha after different irrigation protocols appeared to increase from coronal to apical direction.  Recommendations: 1) Testing the effect of different irrigation regimens on the bond strength of dentin when using different root canal sealers is recommended. 2) Testing the effect of Q mix, Green tea, Apple vinegar and MorindaCitrifolia on the bond strength of dentin when using different root canal sealers is recommended. 3) Effect of final irrigation activation techniques on the bond strength of dentin/ different root canal sealers is recommended.