To compare the continuous and intermittent irrigation method on the removal of dentin debris from root canals and to evaluate the dynamics of irrigant flow using computational fluid dynamics

AIM: This study aimed to compare the efficiency of continuous and intermittent irrigating methods on the removal of dentin debris from the simulated grooves and to evaluate the dynamics of irrigant using computational fluid dynamics (CFD). METHODOLOGY: Seventy-five extracted human permanent maxillary canines were selected. Access cavities were made, working length was determined, and canals were prepared by crown down technique. The teeth were split longitudinally and standard groove 2.0 mm in length was made in split halves and each groove was filled with dentin debris and the images were taken under a microscope (E200). The halves were re-assembled and divided into five groups based on different irrigation methods. Group 1: ultrasonic Irrigation with continuous flow for 3.0 min; Group 2: ultrasonic irrigation with continuous flow for 1.5 min; Group 3: ultrasonic irrigation with intermittent flow for 3.0 min; Group 4: ultrasonic irrigation with the intermittent flow for 1.5 min; and Group 5: syringe irrigation for 1 min. The root halves were again separated and re-evaluated for debris elimination after the irrigation protocol for all the groups separately. The effect of time and method of passive ultrasonic irrigation were compared. For the computational fluid analysis, a GAMBIT 2.2 (Ansys) software was used for mesh construction. FLUENT 6.2 (Ansys) software was used to set the boundary conditions and reconstruction of the canal; flow patterns and turbulence were graphically constructed. RESULTS: The continuous irrigation methods were better at debris removal than intermittent irrigation flow methods. The CFD showed that the turbulence of flow of irrigant was dependent on the inlet velocity and pressure of the irrigant. CONCLUSION: Debris removal from the simulated grooves was better with continuous irrigation compared with intermittent irrigation. CFD study revealed that the turbulence that was affected by the velocity and pressure of the irrigant introduced and is a variable entity.