ABSTRACT
Objective:To examine the effects of different endodontic irrigation methods on root canal morphology.Methods:We collected 20 extracted single-root premolars from elderly patients(≥60 years)with periodontitis and randomly divided them into 5 groups.Group A: syringe irrigation; Group B: P5 ultrasonic irrigation, Group C: 0.20 W Er: yttrium aluminum garnet(YAG)laser irrigation; Group D: 0.30 W Er: YAG laser irrigation; and Group E; 0.35 W Er: YAG laser irrigation.Changes in the smear layer in the root canal and the hardness of the root canal were assessed.Results:After treatment with different root canal cleaning methods, the scores of smear layer removal for Groups A, B, C, D and E were(4.67±0.27), (3.08±0.57), (2.83±0.43), (1.17±0.19)and(2.87±0.50), respectively.There were statistically significant differences between them( F=35.946, P<0.01). Among them, Group B, C, D and E had better smear layer removal than Group A, and the differences were statistically significant(all P<0.01). Group D had better removal of the smear layer than Groups B, C and E, and the differences were statistically significant( P<0.01); Values for dentin microhardness of Groups A, B, C, D and E were(58.98±5.54), (55.19±5.71), (56.04±3.96), (66.65±3.23)and(45.68±7.58), respectively, with statistically significant differences( F=5.83, P<0.05), and for laser-based irrigation, the value for dentin microhardness of Group D was higher than those of groups C and B(all P<0.05). Conclusions:Laser-based root canal irrigation is better than traditional irrigation methods, with 0.30 W Er: YAG laser achieving maximal removal of the smear layer and at the same time having the least impact on root canal hardness.