Effects Of Phenoaldehyde Resin Sealing Root Canal Wall On Coronal Microleakage Of Thermoplasticized Gutta-percha Obturation Technique

Objective:In order to provide clinical basis for improving the long-term curative effect of root canal treatment,we used quantitative method with glucose to investigate the effects of phenoaldehyde resin sealing root canal wall on coronal microleakage of continuous-wave condensation technique.Methods:Forty-four human permanent teeth with a single root canal were collected in this study,forty of them were randomly divided into four experimental groups(A1B1?A1B2?A2B1?A2B2,n=10 for each group).The other four samples were divided into two control groups(n=2 for each group),Group C(positive control group)and Group D(negative control group).All crowns were removed at cement-enamel junction using a high speed bur.All canals were cleaned and shaped with K files using technique followed by using Gates-Glidden drills to flare the coronal.The root canal wall of Group A1B1,A1B2 were sealed with phenoaldehyde resin,Group A2B1,A2B2,C,D were not sealed with phenoaldehyde resin.All teeth of the experimental groups were obturated with a root canal sealer and gutta-percha points using the continuous-wave condensation technique.Group A1B1 and A2B1 used ZOE sealer,Group A1B2 and A2B2 used AH-plus sealer.In the control groups,sealer was not used,only using gutta-percha points.After obturation,excess gutta-percha from root orifice were removed to keep the length of the gutta-percha in the root canal as 10 mm.All samples were placed in an incubator at the controlled temperature of 37? with 100% humidity for 7 days.The teeth in the experimental groups and the positive control group C were coated with two layers of nail varnish except for the apical 2mm,teeth in the negative control group D had the entire root surface coated with nail varnish.Once the nail varnish was absolutely dry,Models were built to detect microleakage using quantitative method with glucose.Detecting the glucose leaking from the crown to the root with HK method at the 1st,4th,7th,14 th and 21 th day.All analyses were completed by SPSS version 21.0(SPSS Inc.,Chicago,IL,USA)with significance defined by 2-tailed total P values < 0.05.In this study,the values of coronal microleakage were expressed as(?x±s).Data were analyzed by Analysis of Variance(ANOVA)with 2×2 factorial design and the t-test.Results:1.The positive control group(group C)detected a large amount of glucose at the 1st day,and showed a fast rising trend.No glucose exudation was detected in the negative control group(group D)from day 1 to day 21.2.The effect of root canal wall(factor A)on coronal microleakage: at the 1st,4th,7th,14 th and 21 th day,root canal wall sealed with phenoaldehyde resin had no effect on coronal microleakage of thermoplasticized gutta-percha obturation technique(All P>0.05).3.The effect of root canal sealers(factor B)on coronal microleakage: at the 1st day,here was no significant difference between two root canal sealers on coronal microleakage of thermoplasticized gutta-percha obturation technique(P>0.05).However,at the 4th,7th,14 th and 21 th day,there was significant difference between two root canal sealerson coronal microleakage of thermoplasticized gutta-percha obturation technique(All P<0.05),and the value of microleakage of Group B2 was lower than Group B1.4.Effects of root canal wall with phenoaldehyde resin and root canal sealers(factor A×B): at the 1st,4th,7th,14 th and 21 th day,the factor A×the factor B was P>0.05,there was no interaction between two factors.Conclusions:1.Root canal wall sealed with phenoaldehyde resin had no effect on coronal microleakage of thermoplasticized gutta-percha obturation technique.2.The sealing abilities of AH-plus was better than ZOE.