The Influence Of Different Concentrations Of Tween-80 For The Root Canal Smear Layer And Apical Microleakage

Objectives 1 Compare the influence of different storage methods and storage time on removal of root canal smear layer,in order to get storage methods which are similar to the experimental results of the fresh extracted teeth.2 Research the impact of different concentrations Tween-80 which is added when flush the root canal with low concentration Na Cl O and EDTA on the removal of smear layer and apical microleakage.Methods 1 65 collected single canal fresh extracted teeth for orthodontic need were randomly divided into five groups,the experimental group:use four different storage methods(n=15),group A 4?10%formaldehyde solution;group B 2% Benjamin chlorine solution;group C 4 ?distilled water;group D stored at-20?freezer.The control group(n=5):Fresh extracted teeth(within 30 minutes for the experiment).Select five samples randomly from experiment group for use on day 30?60 and 90.prepare the root canal with crown-down technique to F3,using Pro Taper nickel-titanium instruments.Research the removal of smear layer of apical 1/3 by SEM.2.Select 40 single root canal teeth which were pulled out from mouth of patients for orthodontic need,randomly divided into A,B,C,D four groups,each group includes 10 samples.Prepare the root canal with crowndown technique to F3,using Pro Taper nickel-titanium instruments,and use the corresponding irrigations each group during root canal preparation.Group A: Flush the root canal with 2%Na Cl O and 15%EDTA alternately during root canal preparation;Group B:Flush the root canal with 2%Na Cl O and 15%EDTA alternately,then wash the root canal with 1.0%Tween-80 after complete preparation;Group C: Flush the root canal with 2%Na Cl O and 15%EDTA alternately,then wash the root canal with1.5%Tween-80 after complete preparation;D:Flush the root canal with 2%Na Cl O and15%EDTA alternately,then wash the root canal with 2.0%Tween-80 after complete preparation.Use SEM after flushing.3.prepare and wash the samples as experiment 2.Fill the root canal with cold lateral condensation gutta-percha.Place the samples into microleakage model.Then detect the concentration of root exudation of glucose on day 1?2?4?7?10?15?20?30.Results 1 The experiment group :Compared with other experiment groups,the grade of smear layer of storing at-20?freezer are statistically significant(P <0.05);There is nosignificant difference between-20 ? freezer storage and fresh tooth(P>0.05),and no significant difference on day 30?60?90(P>0.05);.2 The differences of the removal of smear layer of root apical 1/3between group A?group B?group C and group D were statistically significant(P <0.05),the grade of smear layer reduces with the Tween-80 added.Compared with other three groups,the grade of 2.0%Tween-80 group is the least.3.The differences of micro-leakage between group A?B?C?D were statistically significant(P <0.05)Conclusions 1 Different storage methods and storage time of extracted tooth have no influence on the removal of smear layer.The similar storage method to fresh tooth is-20? freezer storage.2 Added with Tween-80 when using low concentration of Na Cl O and EDTA,the capacity that removes the smear layer of root apical 1/3 was enhanced.The higher,the better.3 Apical sealing ability is advanced after removing the smear layer.