后磨牙模拟根管模型制备与研究

目的：制备后磨牙模拟根管模型。方法：依照预实验中测试的牙本质和树脂根管模型材料的布氏硬度值（牙本质HB72,树脂块HB54）选取纯铜质铜管为材料（纯铜HB58）同时利用预实验中确认的后磨牙模拟根管模型弯曲角度的范围（70°-60°）并参照树脂根管模型相关数据,设计不同弯曲角度（70°,64°,60°）的纯铜质根管模型,将20套镍钛根管锉随机分为4组,其中3组根管锉分别预备相应角度的10个纯铜质后磨牙根管模型,另一组在临床预备10个后磨牙根管作为对照组。所有镍钛根管锉均在疲劳寿命测试装置中测试疲劳寿命。结果：选用根管长度为16mm±1mm,弯曲半径为5mm,内径为0.70mm的纯铜质铜管制作后磨牙根管模型。其中在弯曲角度为70°的后磨牙根管模型中有33%（2/6）近似临床;在弯曲角度为64°的后磨牙根管模型中有67%（4/6）近似临床;在弯曲角度为60°的后磨牙根管模型中有33%（2/6）近似临床。结论：弯曲角度为64°的纯铜制后磨牙模拟根管模型更接近于临床实际,可为体外研究镍钛根管锉各项指标提供一个较为理想的模型。

Preparation of model of simulated retromolar root canal

Objcetive：To set up a model of simulated retromolar root canal.Methods：According to the Brinell hardness values of dentin and resin obtained from the preliminary experiments,（HB72,HB54）,the pure copper with a Brinell hardness value HB58 was chosen as the material of the model.Three different angles of artificial root canals were designed,with the parameters of those of resin canal models：the length was 16 mm and the radius of curvature was 5 mm,and the inner diameter was 0.7 mm.Twenty sets of ProTaper Nickel-Titanium rotary-instruments were randomly divided into four groups with 5 sets each.Group A prepared 50 pure copper artificial root canals with an angle of curvature of 70 degrees,Group B 64 degrees and Group C 60 degrees.Group D prepared 50 retromolars.After preparation,Fatigue tests of all files were carried out in a bench device.Results：The similarity rate of Group A,B,C and Group D were 33%,67%,33% respectively.Conclusion：The pure copper artificial root canal with an angle of curvature of 64 degrees was an ideal model for the research of Nickel-Titanium rotary-instruments in vitro.