In Vitro Study of Four Endodontic Irrigation Protocols on Smear Layer Removal in Curved Canals / 天津医药

ABSTRACT

Objective To investigate the effective endodontic irrigation protocols on smear layer removal from curved canals. Methods Forty extracted mandibular first molars with curved mesial root canal were selected and decoronat-ed. Mesiobuccal root canal was instrumented to F3 using handed ProTaper system, and randomly divided into four groups ac-cording to final irrigation protocols syringe irrigation (group A), #30K file agitation (group B), passive ultrasonic irrigation (PUI, group C) and combination of #30K file agitation and PUI (group D). The ultrasonic file was located within 0.5 mm coro-nal from start of the curvature. All root canals were mesio-distally split, snicked at the start of the curvature and 2 mm apical-ly from the start of the curvature, and divided into three sections. They wereⅠ,ⅡandⅢfrom coronal to apical. The smear layer of each section of root canal was examined under scanning electron microscope (SEM). Results Group D presented small amounts of scattered or thin smear layers and obtained the lowest score at each section of root canal wall. At sectionⅠandⅡ, there was no significant difference in smear layer score between group D and group C. The smear layer scores were both significantly lower in group D and group C than those of group A and group B (P<0.05). At sectionⅢ, the smear layer score was significantly lower in group D than that of group A, group B and group C, and which was significantly lower in group B and group C than that of group A (P<0.05). Conclusion When ultrasonic file was located coronal from the start of the curvature, K file, which was the same size as dimension of apical portion preparation to agitate and PUI can remove smear layer from curved canals efficiently.