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To evaluate the effect of two passive ultrasonic irrigation methods on removal of dentin debris from root canal systems using computational fluid dynamics study model

Annil Dhingra, Panna Mangat, Anjali Miglani, Saurabh Kalkhande, Harkanwal Kaur Bhullar


Objectives: The aim was to evaluate the effect of passive ultrasonic irrigation (PUI), on removal of dentin debris from root canals comparing intermittent and continuous flow methods using a computational fluid dynamics (CFD) study model. Methods: A total of 75 freshly extracted single-rooted maxillary canines with mature apices were selected. The root canals were prepared to a master apical size of F4 and the teeth were then split longitudinally through the canal forming two halves. A standard groove was made and filled with dentin debris. Images of the groove were taken using a Nikon microscope at ×40 magnifi cation without and with dentin debris. The two halves were re-assembled and teeth were divided into five groups and irrigated accordingly. Group 1: UI with continuous flow or 3.0 min, Group 2: UI with continuous flow for 1.5 min, Group 3: UI with intermittent flow for 3.0 min, Group 4: UI with intermittent fl ow for 1.5 min. Group 5: Syringe irrigation for 1 min. The root halves were separated and re-evaluated for the debris elimination after the irrigation protocol, for all the groups separately. The effect of time and method of PUI were compared. For the computational fluid analysis, GAMBIT 2.2 (Ansys) software was used for the mesh construction and the FLUENT 6.2 (Ansys) software to set the boundary conditions and the reconstruction of the canal. The velocity inlet boundary conditions were set for the entrance of the irrigant. The flow patterns and turbulence were graphically constructed. Results: The PUI and activation of sodium hypochlorite inside the root canal exhibited better debris removal than syringe irrigation both at 1% and 5% level of significance. However, the continuous irrigation methods were better at debris removal than intermittent irrigation flow methods. The time used for the various irrigation regimens had slight difference in the efficacy, which did not exhibit any statistical significance at 1% level of significance, but exhibited statistical significance at 5% level of significance. The CFD showed that the turbulence of flow of irrigant was dependent upon the inlet velocity and pressure of the irrigant. Conclusion: Within the limitations of this study, the debris removal from the canals was better with the PUI when compared with syringe irrigation. Passive continuous irrigation demonstrated better debris removal than the passive ultrasonic intermittent irrigation. In both methods, the eff ect of time did not have signifi ant statistical diff erence. CFD removal depended on the turbulence that was affected by the velocity and pressure of the irrigant introduced and is a variable entity.


Computational fluid dynamics; continuous irrigation; dentin debris; intermittent

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