Er:YAG Laser-Activated Irrigation in Comparison with Different Irrigation Systems for Cleaning the Apical Root Canal...

To evaluate the effectiveness of erbium:yttrium aluminum garnet (Er:YAG) laser-activated irrigation (LAI) for cleaning the apical root canal area beyond a ledge. This was the first study that evaluated the efficacy of LAI in debris and smear layer removal from such hard-to-reach canal areas in human teeth. Eighty-eight human maxillary molars with either a mesiobuccal or distobuccal canal with 25°-35° curvature and mature apices were used. Following instrumentation to a size 25/0.02 taper, a ledge was created at 2.2 ± 0.7 mm short of the apex and checked using microcomputed tomography. Samples were divided into four groups: syringe irrigation (SI), ultrasonic-activated irrigation (UAI), agitation with the XP-endo Finisher (XP), and LAI. Each group was subdivided based on the irrigation regimen: 9 mL of 6% sodium hypochlorite (NaOCl), and 6 mL of 6% NaOCl +3 mL of 14.3% ethylenediaminetetraacetic acid (EDTA) (n = 11). The apical 1-mm region was examined using scanning electron microscopy to evaluate the remaining debris and smear layer. Data were analyzed using the Kruskal-Wallis test and Mann-Whitney U test (a = 0.05). Regardless of the irrigants used, LAI showed significantly lower smear layer scores than SI and XP (p < 0.05), with insignificant difference as compared with UAI. LAI showed significantly better debris removal than SI (p < 0.05) when NaOCl alone was used. In the apical area of ledged canals, the cleaning efficacy of Er:YAG LAI with/without EDTA was higher than SI and XP, but was comparable with UAI. Clinical Trial Registration number D2014-33.