Assessment of apical extrusion in regenerative endodontics: a comparative study of different irrigation methods using three-dimensional immature tooth models.

To investigate the apical extrusion of sodium hypochlorite in immature permanent teeth caused by conventional syringe irrigation (CSI), EDDY, XP-endo Finisher file (XP-F), and a new laser irrigation activation system [shock-wave-enhanced-emission-photo-acoustic-streaming (SWEEPS)]. Three-dimensionally printed forty-nine teeth with immature central incisor morphology were randomly assigned to seven experimental groups, based on the irrigation activation methods and insertion depths (1 mm and 2 mm short of the working length) as follows: CSI-1, CSI-2, EDDY-1, EDDY-2, XP-1, XP-2, and SWEEPS. Prior to the irrigation activation process, samples were placed in metacresol mixed agar gel in Eppendorf tubes. To evaluate NaOCI extrusion into the gel, each sample was digitally photographed, and the area of apical extrusion was analyzed using ImageJ software. To examine potential significant differences between the continuous variables, the Mann-Whitney U test and Kruskal-Wallis H test, were applied (P = .05). The SWEEPS resulted in a greater amount of apical extrusion compared to the CSI method, regardless of the insertion depth (P < 0.001). The SWEEPS resulted in greater apical extrusion scores compared to EDDY-2 (P < 0.001). The EDDY-1 resulted in greater amount of apical extrusion scores compared to EDDY-2 (P < 0.001). This study, the first to show the effect of the novel SWEEPS technology on NaOCI extrusion, found that irrigation activation can cause different levels of apical extrusion depending on the method and distance from the working length. It is crucial to consider the potential occurrence of apical extrusion when applying activation methods to immature teeth.