The Effects Of Different Filling Technique For Fracture Resistance Of Root Canal On 06 Taper Root Canal Preparation

Objective:Root canal treatment is the main and the best treatment of pulp disease and periapical disease. But many research in recent years found that the over root canal preparation and filling pressures may result in the root longitudinal fractures of the non-vital teeth, leading to treatment failure. After the root canal preparation by using engine-driven nickel titanium instruments of increased taper, this experiment evaluate the effects of different filling technique for fracture resistance of root canal, to provide a basis to clinical root canal treatment, to minimize the occurrence of root fracture, to improve the success rate of root canal therapy.Methods:This study consists of two partsTest 1:Destructive experimental study of the effects of different root canal filling techniques for fracture resistance of root canalSelected 120 extracted due to orthodontic mandibular premolars, randomly divided into four group. The crown of sections by hard tissue after treatment, A, B, C with HERO-642 nickel-titanium root canal preparation systems with crown down shaping to prepare the root canale of the 30#06 taper. Group A with AH-PLUS+gutta-percha with lateral condensation filling technology, group B with AH-PLUS+gutta percha with the E&Q-plus Root canal filling system, group C were not filling, group D without any treatment. All specimens were sealed with zinc phosphate, stored in 37℃,100% humidity. Before the testing the specimen was embedded in acrylic resin cylindrical mold with a high 13mm,15mm diameter, Then the specimens were placed under the platform of universal testing machine, adjusted the beams to the top of the head to load on the root center that closed parts of zinc phosphate, pressed at 1 mm/min vertical speed until the root fracture. Record the pressure value of the root fracture from each group. The data using SPSS software for statistical analysis of variance.Test 2 Three-dimensional finite element method to evaluate the effects of ditterent root canal filling techniques to the stress distribution of root canal wall Selected an orthodontic complete extracted, no carious mandibular first molar. By CT scan, using the Mimics and other related software into the Ansys finite element software, restructure the formation of the mandibular first premolars basic finite element model, In the basic model,changing the diameter of the root canal to 30# 06 taper, simulating a different filling techniques in the filling process, observed the effects of ditterent root canal filling techniques to the stress distribution of root canal wall。Results:1,Destructive experimental results:(1) The fracture resistance between experimental groups (A, B) and the control groups C there were significant differences compared (P<0.01), A, B group were higher than the mean fracture resistance of group C.(2) The fracture resistance between A (cold lateral) and B (three-dimensional thermal vertical method) was no significant difference (P> 0.05), A, group were higher than the mean fracture resistance of group B.(3) The fracture resistance between C group (prepared without filling) and D (not prepared to not filling) Comparison were significantly different (P<0.01), the fracture resistance of D groupwas more than the fracture resistance of C group.(4) The experimental group (A, B) with the control group fracture resistance between D there were significant differences compared (P<0.05); D group were higher than the mean fracture resistance of group A,B group.2,Three-dimensional finite element method results:(1) When filled with vertical condensation by increasing filler, root canal wall position of the largest stress continuously moved up, Finally, focus on the root 1/3.(2) In the lateral condensation,when the process of lateral condensation, Mainly the maximum stress located in the root of 1/3.Conclusion:After root canal preparation to 06 taper, the effects of the different root canal filling techniques on the fracture resistance of root canals is difference, However, after statistically no significant difference;Root canal preparation will reduce the fracture resistanceof the root; Simulation of root canal filling techniques on root canal wall stress distribution is different.