RESUMO
Objective: This study compared the potential for apical extrusion of sodium hypochlorite (NaOCl) when using needle irrigation (NI), passive ultrasonic irrigation (PUI), passive subsonic irrigation (PSI), and negative pressure system (NP). Materials and Methods: One hundred freshly extracted human permanent anterior teeth with complete root formation were embedded rigidly in agarose gel-containing cresol purple. Teeth were randomly allocated to six groups: G1-NI; G2-PUI; G3-PSI; G4-NP; G5-positive control; and G6-negative control. The chemomechanical preparation was completed and 12 ml of 3% NaOCl was delivered for 180 s in all groups. Dye diffusion was standardized by doing gel photography after the NaOCl final irrigation the Chi-square test and Kruskal-Wallis one-way analysis of variance test were used for the data analysis. Results: G1 had statistically significant apical extrusion compared to G2 (P = 0.001), G3 (P = 0.001), and G4 (P = 0.001) groups. G4 showed the least amount of apical extrusion. Conclusions: pH-sensitive gel model is useful in evaluating NaOCl extrusion. NP produced least NaOCl extrusion as compared to the other three systems. Due consideration should be given to the potential for apical extrusion of the irrigant before the selection of an irrigation system.