In Vitro Influence Of Different Root Canal Filling Systems On The Fracture Resistance Of Roots

Objective:After the root canal preparation by using nickel titanium instruments of increased taper, this experiment evaluate the influence of root canal therap and different root canal filling systems on the fracture resistance of roots, to provide a basis to clinical root canal treatment, to minimize the occurrence of root fracture, improve the success rate of root canal therapy.Methods:68single canal premolars were selected. The crowns were removed at the cementoenamel junction. And then they were randomly divided into four groups. The root canals of groupA, B and C were instrumented to F3with handed Protaper system using crown-down technique. Group A root canals were obturated with master gutta-percha cone and Cortisomol sealer by using cold lateral compaction. Group B root canals were obturated with gutta-percha and Cortisomol sealer by using warm vertical compaction. Group C root canals were obturated with RealSeal by using cold lateral compaction. Control group root canals were not instrumented or obturated. Evaluate effect of root canal filling after root canal filling with X-ray films. All specimens were sealed with zine phosphate of2mm, then the roots were kept at normal temperature with10%formalin for1week. Each sample was examined with a microscope at20×stereomicroscopy to ensure that there were no cracks or craze lines in the roots after1week. Use a vernier caliper to record root length, buccolingual diameter and mesiodistal diameter of each sample. The samples were mounted in PVC tube (30mm high and30mm in diameter) filled with superhard gesso exposing5mm of the coronal buccal end of each root. Then placed all the samples in a universal testing machine and loaded each specimen to fracture. For each sample, we recorded the force to fracture. Once the obtained data were normally and homogeneously distributed, the results were subjected to statistical analysis using one-way analysis of variance (ANOVA). The level of significance was0.05.Results:The force required to fracture the roots of control group was significantly higher than that required to fracture the roots of all other groups. The force required to fracture the roots of Group C was significantly higher than that required to fracture the roots of Group A and B. Conclusion:1.Root canal therapy will reduce the fracture resistance of the root.2. There is no significant difference in the fracture resistance of teeth obturated with master gutta-percha cone by using cold lateral compaction and gutta-percha by using warm vertical compaction.3.Teeth obturated with RealSeal were more resistant to fracture than those obturated with the other two systems.