Flushing methods, temperature and flushing time of sodium hypochlorite affect the clearance effect on the smear layer of root canal / 中国组织工程研究

ABSTRACT

BACKGROUND:In root canal preparation, the clearance effect of sodium hypochlorite for root canal irrigation on the smear layer is associated with the contact time and contact area of irrigation fluid, the amount of irrigation fluid, irrigation fluid temperature, irrigation fluid concentration, flushing methods and so on. OBJECTIVE:To investigate the clearance effect of 3% sodium hypochlorite on the smear layer of root canal under different flushing methods, flushing temperature and flushing time. METHODS:Totaly 180 isolated front teeth with single root were colected and root canal preparation was conducted using motorized ProTaper. The root canal was flushed with 3% sodium hypochlorite. According to different flushing methods, these root canals were randomly and evenly divided into root canal active flushing group, passive ultrasound swished group and side opening flushing needle group. According to the flushing temperature and the flushing time after replacing a file, each group was randomly divided into six subgroups 20℃ 30 seconds group, 20℃ 60 seconds group, 37 ℃ 30 se group. The clearance effect on the smear layer of root canal was observed using scanning electron microscope. RESULTS AND CONCLUSION:The general clearance effect on the smear layer in the root canal active flushing group was better than that in the passive ultrasound swished group and side opening flush acupuncture group (P< 0.05). At the same time, the clearance effect on the smear layer in the 60℃ group was better that that in the 37 ℃ group and 20℃group (P < 0.05). At a certain temperature, the clearance effect on the smear layer in 60 seconds group was better than that in the 30 seconds group (P < 0.05). The clearance effect on the smear layer in the 1/3 root cap zone was better than that in the 1/3 root and 1/3 apical root zone (P < 0.05). These results show that the best clearance effect on the smear layer can be achieved as folows 3% sodium hypochlorite irrigation at 60℃ for 60 seconds.