Scanning electron microscopic study on the use of different kinds of irrigants in ultrasonic root canal instrumentation

Objective To evaluate the cleaning ability of different kinds of irrigants used as ultrasonic root canal irrigant.Methods Twenty-four with single-canal were randomly divided into three groups.All root canals were prepared with crown-down technique.Each group of specimens received a final irrigation with ultrasound for one minute:Group A,2% chlorhexidine solution(CHX);Group B,2.5%sodium hypochlorite solution(NaClO);Group C,distilled water.The teeth were split along buccolingual direction,the presence of debris and smear layer in the cervical,middle and apical third of the root canals were evaluated with a scanning electron microscope.The data were analyzed statistically by One-way ANOVA.Results Statistical analysis showed that there was no significant difference among the three groups for debris removal(P0.05),but there was significant difference among the three groups for smear layer removal(P0.05).Both Group A and B had significantly less smear layer and more visible open dentinal tubules compared with group C(P0.05).The difference of smear layer between group A and B was statistical significance(P0.05).Conclusion Ultrasonic irrigation is one of effective techniques for debris removal.Both 2.5%NaClO and 2% CHX can remove the smear layer.The cleaning ability of 2.5% NaClO to smear layer is better than 2% chlorhexidine solution as an ultrasonic irrigant of root canals.