Khiavi Hassan A, Habibzadeh Sareh, Safaeian Shima, Eftekhar Mahsa
Department of Prosthodontics, Tehran University of Medical Sciences, International Campus, School of Dentistry, Tehran Islamic Republic of Iran.
Department of Prosthodontics, Tehran University of Medical Sciences, International Campus, School of Dentistry, Tehran Islamic Republic of Iran, Phone: +989125212758, e-mail:
J Contemp Dent Pract. 2018 May 1;19(5):560-567.
Since fiber posts are not recommended for teeth under lateral loads, a new alloy containing >80% copper (nonprecious gold or NPG) was introduced with a modulus of elasticity closer to that of dentin and easier preparation. This study aimed to compare the fracture strength of endodontically treated maxillary central incisors restored with nickel chromium (Ni-Cr) and NPG alloys.
Casting post and cores were fabricated of Ni-Cr and NPG alloys for 24 maxillary central incisors (n = 12). Full-metal crowns were also fabricated and placed under cyclin loading in 30 N load and 45° angle, for 250,000 cycles with 2.6 Hz frequency. The fracture strength was measured at a crosshead speed of 0.5 mm/min and 135° angle in a universal testing machine. Data were analyzed using independent t-test.
The mean fracture strength was 731.179 ± 327.47 and 1411.89 ± 313.56 N in the Ni-Cr and NPG groups respectively; this difference was statistically significant (p < 0.001). The fracture was irreparable in all teeth since the fracture line was below the cementoenamel junction (CEJ).
The fracture strength of teeth restored with cast NPG post and cores was significantly higher than that of teeth restored with cast Ni-Cr post and cores.
Due to proper mechanical properties, NPG post and cores seem to be a suitable choice for restoration of severely damaged anterior teeth, provided that other properties are proven to be acceptable.
由于不建议在侧向载荷下的牙齿使用纤维桩，因此引入了一种含铜量超过80%的新型合金（非贵金属或NPG），其弹性模量更接近牙本质且易于制备。本研究旨在比较用镍铬（Ni-Cr）合金和NPG合金修复的经根管治疗的上颌中切牙的断裂强度。
用Ni-Cr合金和NPG合金为24颗上颌中切牙（n = 12）制作铸造桩核。还制作了全金属冠，并在30 N载荷和45°角下进行循环加载，频率为2.6 Hz，循环250,000次。在万能试验机中以0.5 mm/min的十字头速度和135°角测量断裂强度。使用独立t检验分析数据。
Ni-Cr组和NPG组的平均断裂强度分别为731.179±327.47 N和1411.89±313.56 N；这种差异具有统计学意义（p < 0.001）。由于断裂线在牙骨质牙釉质界（CEJ）下方，所有牙齿的断裂均无法修复。
用铸造NPG桩核修复的牙齿的断裂强度明显高于用铸造Ni-Cr桩核修复的牙齿。
由于具有合适的力学性能，只要其他性能被证明是可接受的，NPG桩核似乎是修复严重受损前牙的合适选择。
