Introduction: The aim of this in vitro study was to evaluate the effects of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine (CHX) and hydroxyethylidene bisphosphonate (HEBP), also known as etidronate, on susceptibility to root fracture resistance (RFR) in human teeth subjected to endodontic preparation. Methods and Materials: Seventy extracted single-rooted human teeth were selected, endodontically prepared using the ProTaper Next rotary system (PTN, Dentsply, Maillefer, Ballaigues, Switzerland) and then randomly divided according to the following irrigation regimes (n=10): G1, saline solution (0.9% NaCl); G2, 2.5% NaOCl + 17% EDTA; G3, 2% CHX gel + 17% EDTA; and G4, a mixture of 5% NaOCl + 18% HEBP. After this step, all samples received a final irrigation with distilled water. The samples were subjected to axial forces by mechanical compression testing in a universal testing machine (Dynamometers KRATOS, LTDA, SP, Brazil). Data analyses included the Shapiro-Wilk normality test, analysis of variance (one-way ANOVA) and a subsequent multiple comparison test (Tukey’s test). Results: The results indicated that G1 (0.9% NaCl) presented greater resistance to root fracture. No significant differences were observed in G2 (2.5% NaOCl + 17% EDTA) and G3 (2% CHX gel + 17% EDTA). A significant difference was identified in G4 (mixture of 5% NaOCl + 18% HEBP) (P<0.05). Conclusion: A mixture of 5% NaOCl + 18% HEBP resulted in a lower fracture resistance when used to irrigate canals during endodontic instrumentation.
Keywords: Chlorhexidine; EDTA; Etidronic Acid; Root Canal Irrigant; Sodium Hypochlorite