Evaluation of the efficacy of Er:YAG laser–activated irrigation in a simulated accessory canal

Aim: The aim of this study was to evaluate the effect of laser-activated irrigation (LAI) on the removal of debris-mimicking hydrogel from a simulated accessory canal. Materials and Methods: The simulated accessory canal was located 3 mm from the apex, perpendicular to the straight main canal. Gelatin hydrogel as a substitute of debris was used to fill the simulated accessory canal. The root canals were irrigated for 20 or 40 seconds by LAI using an erbium: yttrium aluminum garnet (Er:YAG) laser (30 mJ, 20 pps) or for 40 seconds by syringe irrigation (SI). During LAI, the cone-shaped tip of the laser was positioned stationary at 3 or 10 mm from the apex. Irrigation was performed using 5% NaOCl. The distance over which the hydrogel was removed from the accessory canal entrance was measured and compared between the irrigation procedures. Results: Using NaOCl as the irrigant, a significant increase was observed in the distance over which the hydrogel was removed by LAI compared with that by SI. A longer irradiation period with LAI resulted in significantly greater amount of hydrogel removal. There was no significant difference in hydrogel removal when the laser tip was positioned at 3 and 10 mm from the apex. Conclusion: Within the limitations of this in vitro model, LAI removed more hydrogel from the accessory canal than SI, when using NaOCl as the irrigant. Furthermore, the irradiation time influenced the cleaning efficacy, but the tip position did not.