Comparation The Effectiveness Of Smear Layer Removal By The Agitation Techniques, The Temperature And The Agitation Time Of Sodium Hypochlorite

ObjectivesThe alternate use the different agitation techniques, the temperature and the agitation time of sodium hypochlorite (NaOCl) to compare the effectiveness of smear layer removal.MethodsExtracted single-rooted, non-carious anterior human teeth were collected. The teeth were decoronated to standardize the root length at15mm. ISO#10K-files were inserted into root canals until the files were just visible at the apical foramina. The working lengths (WL) were established by deducting1mm from this point. Root canals were prepared with the crown-down technique using Protaper Ni-Ti rotary instruments according to the manufacturer’s manual. All samples were prepared to F3size.After each instrumentation, all the root canals were irrigated by1ml3%NaOCl, and then all samples were flushed with5ml distilled water. After the preparation,1ml17%EDTA was introduced as final rinse1min. Finally, all samples were flushed with5ml distilled water and dried the canals with the paper tip.The specimens were divided into18equal groups (n=10) according to different agitation techniques, the temperature and the agitation time of NaOC1.EndoActivator (EA) group:After each instrumentation, all the root canals were irrigated by1ml3%NaOCl at20℃or37℃or60℃with the EA were inserted into the canals for agitation at10,000cpm for30s or60s.①A20℃30s group:EA agitated the3%NaOCl at20℃for30s;②A20℃60s group:EA agitated the3%NaOCl at20℃for60s;③A37℃30s group:EA agitated the3%NaOCl at37℃for30s;④A37T:60s group:EA agitated the3%NaOCl at37℃for60s;⑤A60℃30s group:EA agitated the3%NaOCl at60℃for30s;⑥A60℃60s group:EA agitated the3%NaOCl at60℃for60s,Passive ultrasonic irrigation (PUD group:After each instrumentation, all the root canals were irrigated by1ml3%NaOCl at20℃or37℃or60℃with the PUI were inserted into the canals for agitation for30s or60s.⑦UI20℃30s group:PUI agitated the3%NaOCl at20℃for30s;⑧UI20℃60s group:PUI agitated the3%NaOCl at20℃for60s;⑨UI37℃30s group:PUI agitated the3%NaOCl at37℃for30s;⑩UI37℃60s group:PUI agitated the3%NaOCl at37℃for60s;(?)UI60℃30s group:PUI agitated the3%NaOCl at60℃for30s;(?)UI60℃60s group:PUI agitated the3%NaOCl at60℃for60S。The side-vented needle group (The control group):After each instrumentation, all the root canals were irrigated by1ml3%NaOCl at20℃or37℃or60℃with the side-vented needle were inserted into the canals for agitation for30s or60s.(?)20℃30s control group:3%NaOCl flushed with the side-vented needle at20℃for30s;(?)20℃60s control group:3%NaOCl flushed with the side-vented needle at20℃60fors;(?)37℃30s control group:3%NaOCl flushed with the side-vented needle at37℃30fors;(?)37℃60s control group:3%NaOCl flushed with the side-vented needle at37℃60fors;(?)60℃30s control group:3%NaOCl flushed with the side-vented needle at60℃30fors;(?)60℃60s control group:3%NaOCl flushed with the side-vented needle at60℃for60s。Smear layer was quantified using a scoring system by Hulsmann using a thermal field emission scanning electron microscope. Results:There was statistical significance among groups EA and groups PUI (P<0.05).A comparison of the groups showed a significant difference between the groups with agitation using the NaOCl at60℃((⑤⑥(?)(?)(?)(?)group) and the agitation using the NaOCl at37℃(③④⑨⑩(?)(?)group)(P<0.05). And there was statistical significance among agitation using the NaOCl at37℃groups(③④⑨⑩(?)(?)(?) group)and agitation using the NaOCl at20℃(①②⑦⑧(?)(?)group)(P<0.05).There was statistical significance among flushed using NaOCl for60s groups (②④⑥⑧⑩12141618group) and flushed using NaOCl for60s groups (①③⑤⑦⑨11151317group) In all the18group the scores of canal thirds arranged as coronal<middle<apical thirds (P<0.05)Conclusions:1. EndoActivator could improve the efficacy of smear layer removal than the PUI and side-vented needle.2. Increasing the temperature of NaOCl to60℃, does increase the effectiveness of smear layer removal.3. Improved the temperature of NaOCl could improve the effectiveness of smear layer removal.4. In the apical thirds, the smear layer could not be effectively removed, no matter which protocol was used.