| Background: The goal of root canal therapy is to remove inflammatory tissues and microorganisms in root canals,to eliminate infections,and to promote healing,at the same time,the complex root canal system formed a good seal.Incomplete root canal filling is the main cause of failure in root canal therapy,including the failure to seal,overfill or underfill the irregular space such as main root canal,lateral root canal or other small curved part,which leads to the existence of interspace in root canal,causing a secondary infection.Nowadays,hot gutta-percha is more and more favored by clinicians because of its easy operation,less time to use,less apical microleakage,high accuracy and strong stability,compared with the traditional lateral compression technique,this method has obvious advantages.For complex root canal systems,the combination of cold gutta-percha and root canal sealer alone is difficult to fill every part of the root canal tightly,which provides conditions for bacteria to grow and causes infection,while hot gutta-percha softens at high temperatures,strong flow ability,easy to deformation,can be close contact with the root canal wall,in the role of vertical pressure can fully reach the bending of small and lateral root canals,forming a tight three-dimensional filling;In addition,the softened gutta-percha formed a uniform density and a stable volume after the root canal was cooled,and the combination of the root filling material and the root canal wall was better,which reduced the microleakage between the root canal wall and the gutta-percha.In recent years,the technique of hot gutta-percha root canal filling has been widely used in clinic.At present,there is little research on the effect of hot gutta-percha filling on the fracture resistance of teeth and the sealing ability of root canal sealer.We studied the effect of hot gutta-percha temperature on the fracture resistance of teeth and the sealing ability of root canal sealer in order to select a suitable filling temperature for hot gutta-percha,.Objective: The aim of this study is to investigate the effect of different temperatures of hot gutta-percha on the fracture resistance of teeth and the sealing ability of AH Plus,and to explore the optimal temperature of hot gutta-percha filling.Methods: 1.Experiment 1: The effect of different temperature of hot gutta-percha on the fracture resistance of teeth: 45 teeth with single premolars developed after orthodontic treatment were randomly divided into 3 groups,the fracture resistance test pieces were made of self-setting plastics and filled with hot gutta-percha（150℃,180℃,200℃）at different temperatures,One-way Anova was used to analyze the experimental data.2.Experiment 2: The effect of hot gutta-percha at different temperatures on the sealing ability of AH Plus sealer: forty-five root canal premolars developed after orthodontic treatment were randomly divided into three groups,filled with hot gutta-percha at different temperatures（150℃,180℃,200℃）,and placed in an incubator at 37℃ and 100% humidity for 7 days,the maximum distance from the apical foramen to the dye penetration was measured by vernier caliper and observed under microscope.The experimental data were analyzed by One-way Anova.Results: 1.The effect of hot gutta-percha at different temperatures on the fracture resistance of teeth: There was no significant difference in the effect of hot gutta-percha at different temperatures（P > 0.05）.2.The effect of hot gutta-percha at different temperatures on the sealing ability of AH Plus sealer was statistically different（P<0.05）.The temperature of hot gutta-percha affected the sealing ability of AH Plus sealer.Conclusion: 1.In experiment 1,the temperature of hot gutta-percha had no effect on the fracture resistance of teeth,and the increase of temperature could not change the fracture resistance of teeth.2.In experiment 2,the temperature of hot gutta-percha has an effect on the sealing ability of AH Plus sealer.The higher the temperature,the smaller the maximum distance of dye penetration and the better the sealing ability of AH Plus sealer.The ideal temperature of hot gutta-percha in this experiment is 200℃. |
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