Aim:To compare the changes in microhardness of root dentin caused by two novel irrigation regimens with conventional irrigation.Materials and Methods:Forty extracted human permanent incisor teeth were selected. Decoronated roots were separated longitudinally to get 80 specimens that were embedded in autopolymerizing acrylic resin and grounded flat with silicon carbide abrasive papers. Of these, 60 root segments without any cracks or defects were selected and divided into four groups according to the irrigation regimen used (n = 15). Group I: 5% sodium hypochlorite (NaOCl) + 17% ethylenediaminetetraacetic acid (EDTA) + 0.2% chlorhexidine digluconate (CHX) (conventional). Group II: 6% Morinda Citrifolia Juice + 17% EDTA (MCJ). Group III: 5% NaOCl + Q Mix 2 in 1 (QMix). Group IV: Distilled water (control). Irrigation regimens were performed for 5 minutes. Dentin microhardness was measured with a Vickers indenter under a 200-g load and a 20-s dwell time at the midroot level of root dentin. The data were analyzed using Kruskal Wallis test and Dunn's multiple comparison tests.Results:A significant difference was seen in the median values of the four groups. The control group showed the least reduction in microhardness when comparison with the other groups. Except for Group III (Q Mix), the other groups that were tested (MCJ and conventional regimens) showed statistically significant difference from the control group.Conclusion:Within the limitation of this study, it was concluded that NaOCl + Q Mix were least detrimental to root dentin microhardness when compared with MCJ and conventional irrigation regimens.

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Aim: The aim of the study was to assess the reaction of different final irrigants to the bond strength of root dentin exposed to chloroform. Materials and Methods: Fifty extracted maxillary central incisors were selected. Working length was determined, and canal was instrumented with ProTaper rotary system (Dentsply Maillefer) till F4 file. The specimens were then divided into five groups ( n = 10). Group 1: not disclosed to any root canal solvent, Group 2: disclosed to chloroform for 5 min, Group 3: chloroform for 5 min followed by absolute alcohol, Group 4: chloroform for 5 min followed by chlorhexidine (CHX), And Group 5 – chloroform for 5 min followed by saline. The canals were obturated with F4 gutta-percha cones with AH Plus sealer. The samples will be sectioned horizontally into 1 ± 0.1 mm thick slices. The push-out bond strength was performed in a universal testing machine. Results were statistically analyzed by one-way analysis of variance. Results: There existed a significant difference between the mean push-out bond strength of different groups. Irrigation with chloroform negatively affected the bonding between root canal sealer and root dentine. Absolute alcohol significantly improved the bond strength values. Conclusion: Exposure with chloroform during the retreatment will decrease the bonding between sealer (AH Plus) and root dentine. The use of absolute alcohol as a final irrigant improved the bonding between sealer and dentin. CHX and saline showed no improvement in bond strength.