Influence Of Different Irrigation Regimens On The Bond Strengthof AH-plus Root Canal Sealer To Root Canal Walldentin

Objective:To evaluate in vitro influence of different flushing methods combined with different chemical irrigations on the bond strength of AH-Plus root canal sealer to root canal wall dentin.Methods:42 single-canal mandibular premolars were selected,which were extirpated for Orthodontic treatment and their dental crowns were cut off,at 12 mm faraway from root apical.After general pulp extirpation,they were prepared with Pro Taper nickel titanium file to F2 file by taking 11 mm as working lengh.Before using new file,the root canal was irrigated by 5.25%Na Cl O solution.After root canal preparation,they were randomly divided into 2 groups according to different flushing methods.Group A: with syringe final irrigation,group B:with ultrasonic final irrigation.And then each groups were randomly assigned into 3 subgroups accoding to different final chemical irrigations.Group A1 and B1: with 3%H2O2 solution as final irrigation.Group A2 and B2: with 2% Chlorhexidine digluconate(CHX)solutionas final irrigation.Group A3 and B3: with 17% Ethylenediamine-tetraacetic acid(EDTA)solutionas final irrigation.After final irrigation slowly rinse all root canals with distilled water,so as to remove residual liquid..And then the dry root canals were filled with AH-Plus sealer by using a lentulo spiral and F2 gutta percha by using matched-taper single coneobturation technique.Seal the root canal with temporary seal.Finally the roots were soaked in 0.9% normal saline,placed in a cold and hot circulation machine,set at constant temperature for 37 ? and stored for one week.Each specimen was sectioned perpendicular the long axis into three slices from the coronal third,middle third,and apical third of root canals.The thickness of every slice was 1mm.118 samples were conformed to the experimental standard.All slices were performed with Push-out bond strength test to measure the instantaneous push-out strength by placed on universal testing machine.Calculated the bond strength according to the formula and observe the failure mode of every sample.Data were analyzed by SPSS21.0 software.The statistical description of the bonding strength by the mean and standard deviation(?X�S)said that the fracture mode with constituent ratio(%)said.This study was designed for factorial design of two factors and three levels.Two factors were irrigation and irrigation,and three was the root canal anatomy.T test or analysis of variance was used to compare the average number of groups in different groups.The LSD method was used for every other comparison.The comparison of fracture patterns among different groups was compared with ?2 test,and the results were statistically significant with P<0.05.Result:1.The main effect of the two factors was found to be significant difference(P<0.001).The bonding strength of the ultrasonic washing group was higher than that of the flushing group(P<0.001).And the adhesive strength of the different paste of the flushing fluid was also significantly different(P<0.001),the adhesion strength of the 17% EDTA group was the strongest and the 2%CHX group was the highest.The 3%H2O2 group was the weakest and the difference was statistically significant(P<0.01).2.The adhesion strength of the anatomical parts of the root canal was analyzed.The adhesion strength of the different paste was significantly different(P<0.001).The adhesion strength was the strongest in root cap 1/3,followed by the middle 1/3 of the root,and the weakest at the root tip 1/3.The difference was also statistically significant(P<0.01).3.The two factor factorial analysis found that there was an interaction between the washing method and the washing fluid on the adhesive strength(P<0.05).4.The fracture type takes mixed fracture as the main body,and the fracture between the tube wall is relatively small.According to the comparison of different anatomical parts,the composition of the sample fracture mode was statistically different(P<0.05),but there was no difference in the composition of the mode of fracture(P>0.05)under the conditions of different irrigation and different flushing fluid(P<0.05).Conclsion:1.To compared with the traditional syringe rinsing method,ultrasonic irrigation was more beneficial to improve the bond strength of AH-Plus sealer to root canal wall dentin.2.17%EDTA solution as terminal rinse solution could improve the adhesive strength of AH-Plus paste,and was superior to 2%CHX and 3%H2O2 solution.17%EDTA solution combined with ultrasonic washing treatment of root canal can significantly enhance the bonding strength of AH-Plus paste.3.The adhesive strength of AH-Plus paste was the weakest in the tip 1/3 of the root,suggesting that the mechanical and chemical preparation effect of root canal preparation was poor during root canal preparation.