Effect Of Timing Of Post Space Preparation On The Apical Scal Of Root Canals Filling With Different Obturation Materials

ObjectiveThe purpose of this study was to compare the apical microleakage of three kinds of obturation materials(gutta-percha/Cortisomol, gutta-percha/AH-Plus, Realseal System) and to evaluate the effect of immediate and delayed post space preparation on the apical sealing ability of root canals filling with the three kinds of obturation materials through measuring the dying length in root canals.Methods1. Seventy-eight extracted human straight-rooted upper anteriorteeth were decoronated and prepared with ProTaper for hand crown-down technique.2. Seventy-two of the teeth were randomly assigned to3exprimental groups of24teeth each and filled with three obturation materials (gutta-percha/Cortisomol, gutta-percha/AH-Plus, Realseal System) separately. They were obturated with cold lateral condensation.The remained six teeth were equally divided in to negative control group(2teeth) and positive control group(4teeth). Group A,B and C were averagely divided into3subgroups of8teeth each:Group A1,Bland Cl were filled with the filling materials; Group A2,B2and C2were the immediate post space preparation groups; Group A3,B3and C3were the delayed post space preparation groups.3. Group A2,B2and C2were post space prepared with3#Peeso reamer immediately leaving5mm of apical filling. All specimens were sealed with zinc phosphate cement and exposed in37℃oven for7days. Then Group A2,B2andC2were post space prepared and sealed with zinc phosphate cement.4. Group E was coated with nail polish to entire root surface,the other specimens were coated with two coats of nail polish upon apical foramen2mm. Apical microleakage was evaluated with ink dye penetration.5. Statistical tests were performed by analysis of variance and student-Newman-Keulstes with SPSS17.0.Results1. There was statistically significant difference among the three kinds of obturation materials (P<0.05). Apical microleakage of Group A (gutta-percha/Cortisomol,2.62±0.19mm) was the highest. Group B had a less Apical microleakage than Group AApical microleakage of Group C(Realseal System,1.82±0.18mm) was the lowest.2. There was statistically signifieant difference between immediate and delayedpost space preparation for Group A and Group B(P<0.05). There was no statistically significant difference between group A (2.62±0.19mm)B1(2.24±0.21mm) and group A2(2.65±0.19mm), B2(2.25±0.17mm).For Group A3(2.88±0.16mm)and B3(2.48±0.17mm), microleakage value increased, the difference had statistical significance (P<0.05)。3. There was no statistically significant difference among immediate post spacepreparation,delayed post space preparation with pre-post space preparation forGroup C(F=0.18,P>0.05).Conclusions1. There was different apical sealing ability of the three kinds of obturation materials, Realseal System has better sealing ability than gutta-percha/AH-Plus, gutta-percha/Cortisomol was the worst.2. For gutta-percha/Cortisomol and gutta-percha/AH-Plus, immediate post spacepreparation had no influence on the apical sealing ability.The delayed post space preparation had decreased the apical seal.3. For Realseal System,neither immediate nor delayed post space preparation had influence on the apical sealing ability.