Effect Of Maintaining Apical Patency On Root Canal Debridement By Using A Side-Vented Needle For Positive-Pressure Irrigant Delivery-A Vitro Study

Objective:This study was set up to investigate the effect of maintaining apical patency on apical third cleanliness by using a side-vented needle for irrigant delivery. Method:30 human single-rooted mandibular premolars were collected and divided into two groups, NP (no patency) and P (patency), each group had 15 specimens. The root canal system model was built in vitro. In both groups, the canals were instrumented with ProTaper Universal system using crown-down technique. The NP group was irrigated conventionally with 5.25% NaOCl while a size 10 K-file was used in P group to maintain the apical patency after conventional irrigation. The radiopaque irrigant and X-ray were used to observe gas bubble in the apical third of root canal after preparation and the data was analyzed by chi-square test. All specimens were decalcified and embedded in paraffin. The sections at lmm coronal to the anatomic apex were dyed with HE-stained. The cleanliness of apical third of root canal was evaluated by microscopy and the data was analyzed using T test. Result:The incidence of gas bubble was higher in NP group (73.33%) compared with P group (26.60%). The average cleanliness of section in P group (98%) was much better than NP group (83%). Significant differences were both found in the gas bubble (p<0.05) and the cleanliness of root canal (P<0.05).Conclusion:Maintaining apical patency with a size 10 K-file by using side-vented needle for positive-pressure can effectively enhance the cleanliness of human root canal.