Er:YAGレーザーを用いた根管洗浄時に生じる根尖孔外の圧力

Abstract

Although root canal irrigation is an important process for successful root canal treatment, there is a high risk of irrigant extrusion into the periapical region. However, periapical pressure generated by laser-activated irrigation (LAI) using an Er:YAG laser has not been studied yet. The aim of this study was to investigate the root canal irrigation pressure generated outside the apical foramen during LAI using an Er:YAG laser in comparison with passive ultrasonic irrigation (PUI) and conventional irrigation (CI).A plastic root canal model shaped to a working length of 20 mm with an apical diameter of 0.40 mm was used. They were assigned into the following three groups:1) LAI group: Distilled water was activated by Er:YAG laser (Erwin AdvErL, Morita, Japan, 70 mJ 10 pps) with a cone-shaped tip (R200T, Morita, φ = 200 μm) positioned 2 mm short of the working length for 20 seconds.2) PUI group: PUI was performed for 20 seconds with an ultrasonic file, which was positioned 2 mm short of the canal end and driven by an ultrasonic device (Piezon Master 400, EMS, Switzerland, highest power setting).3) CI group: Hand irrigation with 1 ml of distilled water was performed using a 27 gauge conventional flat needle (Nipro needle and syringe, Nipro, Japan) positioned 2 mm short of the working length for 20 seconds.Each irrigation was performed ten times repeatedly. The mean maximum pressure caused by the irrigation was measured using a pressure sensor (AP-12S, Keyence, Japan) connected via a plastic tube to the model. Data were analyzed by one-way ANOVA and Tukey-Kramer test at a significance level of p = 0.05.The mean maximum pressure caused by LAI and PUI was significantly lower than that caused by CI (p < 0.05), and that caused by PUI was significantly lower compared to LAI (p < 0.05). Under the conditions of this preliminary study, the pulsed Er:YAG laser did create irrigation pressure outside the simulated apical foramen. Although it was smaller than that caused by CI, possible irrigant extrusion through the apical foramen should be considered also in LAI.