Hassan A Khiavi1, Sareh Habibzadeh2, Shima Safaeian1, Mahsa Eftekhar1. 1. Department of Prosthodontics, Tehran University of Medical Sciences, International Campus, School of Dentistry, Tehran Islamic Republic of Iran. 2. Department of Prosthodontics, Tehran University of Medical Sciences, International Campus, School of Dentistry, Tehran Islamic Republic of Iran, Phone: +989125212758, e-mail: sareh.habibzadeh@gmail.com/s-habibzadeh@tums.ac.ir.
Abstract
AIM: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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. CLINICAL SIGNIFICANCE: 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.
AIM: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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. CLINICAL SIGNIFICANCE: 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.
Entities:
Keywords:
Endodontically treated teeth; Fracture strength; Nonprecious gold alloy Post and core.