ABSTRACT
Objective:To compare the efficacy of six different irrigation techniques on smear layer removal.Methods:60 single-rooted teeth were prepared.The root canals were irrigated with NaOCl at 20 ℃ or 60 ℃,and activated with side-vented needle,pas-sive ultrasonic irrigation (PUI)and EndoActivator (EA)irrigation techniques respectively.Then teeth were randomly divided into 6 groups(n =1 0):20 ℃-PUI group,20 ℃-EA group,20 ℃control group,60 ℃-PUI group,60 ℃-EA group and 60 ℃ control group.Smear layer was observed under thermal field emission scanning electron microscope(FE-SEM)and scored according to the cri-teria specified by Hulsmann M.Results:The smear layer removal effect in 60 ℃ groups was better than that in 20 ℃ groups (P <0.05),and better in 20 ℃-EA and 20 ℃-PUI groups than in 20 ℃ control group(P <0.05).Conclusion:The temperature of NaOCl is the main factor influencing the smear layer removal,NaOCl at 60 ℃ is more effective than that at 20 ℃.