Fracture Strength of Endodontically treated Maxillary Central Incisors restored with Nickel Chromium and Nonprecious Gold Alloy Casting Post and Cores.

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.