Effect of Laser Energy and Tip Insertion Depth on the Pressure Generated Outside the Apical Foramen During Er:YAG Laser-Activated Root Canal Irrigation.

Abstract

The risk of extrusion of irritative irrigants into the extraradicular tissue should be minimized during root canal irrigation. This study aimed to examine the pressure generated outside the apex during Er:YAG laser-activated irrigation (LAI) in comparison with passive ultrasonic irrigation (PUI) and conventional syringe irrigation (SI). LAI is reported to be efficient for root canal debridement, whereas the apical pressure generated during LAI has not been investigated in detail. Plastic root canal models (apical diameter = 0.40 mm, taper = 6%, and length = 20 mm) were irrigated with water using either LAI with an Er:YAG laser (Erwin AdvEr; 30, 50, or 70 mJ, 10 pps), PUI, or SI. The tip insertion depth was set at 2, 5, or 10 mm from the apex. The pressure generated outside the apical foramen was measured with a pressure sensor connected to the apex of the model. When the tip was positioned at 2 mm and the power setting was changed, the mean maximum pressure values were LAI (30 mJ) = PUI < LAI (70 mJ) < SI (p < 0.05). When LAI was performed at 70 mJ and the tip was positioned at 5 or 10 mm, the pressure values were PUI < LAI = SI (p < 0.05). LAI generated similar or lower pressure outside the apical foramen compared with SI, irrespective of the laser energy and tip insertion depth examined. However, LAI generated higher pressure compared with PUI.