Zhou Tuan-feng, Zhang Xiang-hao, Wang Xin-zhi
Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China; First Clinical Division, Peking University School and Hospital of Stomatology, Beijing 100034, China.
Second Clinical Division, Peking University School and Hospital of Stomatology, Beijing 100101, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2015 Feb 18;47(1):78-84.
To analyze the biomechanics trait of one-piece computer aided design and computer aided manufacture (CAD/CAM) zirconia post and core by the Three-dimensional finite element.
The Three-dimensional finite element models of three upper central incisors restored with one-piece CAD/CAM zirconia post and core (group 1), refabricated zirconia post and hot-pressed porcelain core (group 2), and cast gold alloy post and core (group 3) were built by geometry method respectively. 100 N vertical loading through the central incisor models long axis and 100 N loading along directing at an angle of 45° with the models long axis were used to imitate the central incisor stress state in biting and mandible physiological protraction movement.
Under vertical loading, the restored teeth without dentin ferrule, the maximum Von-Mises stress value of the tooth root in group 1 was the least(11.02 N), which was the largest (13.17 N)in group 2. The stress became weaker from the upper to the lower of the tooth root. The maximum Von-Mises stress value of the tooth root, post and core became smaller while the restored teeth with the 2.0 mm high dentin ferrule. Under directing at an angle of 45° loading, without the design of dentin ferrule in the restored teeth, the maximum Von-Mises stress value of the post and core in group 1 was the greatest(20.45 N), while that stress of post and core in group 3 was the smallest(13.61 N). With 2.0 mm high dentin ferrule design in the restored teeth, the tooth root stress became weaker. The maximum Von-Mises stress value of the tooth root was the greatest (14.10 N) in group 3, but which was the lowest (13.38 N) in group 1.
The results of the Three-dimensional finite element analysis infers that one-piece zirconia post and core restoration is more beneficial to disperse the bite force than the prefabricated zirconia post and the cast gold alloy post and core. The one-piece of zirconia post and core is good to protect the teeth and keep the restoration intact.
通过三维有限元分析一体成型计算机辅助设计与制造（CAD/CAM）氧化锆桩核的生物力学特性。
分别采用几何建模法建立三组上颌中切牙的三维有限元模型，包括一体成型CAD/CAM氧化锆桩核修复组（第1组）、再加工氧化锆桩与热压铸瓷核修复组（第2组）以及铸造金合金桩核修复组（第3组）。通过沿中切牙模型长轴施加100 N垂直载荷以及沿与模型长轴呈45°角方向施加100 N载荷，模拟中切牙在咬合及下颌生理性前伸运动时的应力状态。
垂直加载时，对于无牙本质肩台的修复牙，第1组牙根的最大von-Mises应力值最小（11.02 N），第2组最大（13.17 N）。牙根应力从根尖向根方逐渐减弱。对于有2.0 mm高牙本质肩台的修复牙，牙根、桩核的最大von-Mises应力值均减小。在45°角方向加载时，对于无牙本质肩台设计的修复牙，第1组桩核的最大von-Mises应力值最大（20.45 N），第3组桩核的该应力最小（13.61 N）。对于有2.0 mm高牙本质肩台设计的修复牙，牙根应力减弱。第3组牙根的最大von-Mises应力值最大（14.10 N），第1组最低（13.38 N）。
三维有限元分析结果表明，一体成型氧化锆桩核修复较预成氧化锆桩及铸造金合金桩核更有利于分散咬合力。一体成型氧化锆桩核有利于保护患牙并保持修复体完整。
