Saturday, November 26, 2011

Fracture strength of incisor crowns after intracoronal bleaching with sodium percarbonate

Kuga, M. C., dos Santos Nunes Reis, J. M., Fabrício, S., Bonetti-Filho, I., de Campos, E. A. and Faria, G. (2011), Fracture strength of incisor crowns after intracoronal bleaching with sodium percarbonate. Dental Traumatology. doi: 10.1111/j.1600-9657.2011.01077.x

Abstract – Objectives:  To compare the fracture resistance of bovine teeth after intracoronal bleaching with sodium percarbonate (SPC) or sodium perborate (SP) mixed with water or 20% hydrogen peroxide (HP). Materials and methods: Fifty extracted bovine teeth were divided into four experimental groups (G1–G4) and one control (= 10) after endodontic treatment. Following root canal obturation, a glass ionomer barrier was placed at the cemento–enamel junction. After that, the pulp chambers were filled with: G1 – SP with water; G2 – SP with 20% HP; G3 – SPC with water; and G4 – SPC with 20% HP. No bleaching agent was used in the control group. Coronal access cavities were sealed with glass ionomer and specimens were immersed in artificial saliva. The bleaching agents were replaced after 7 days, and teeth were kept in artificial saliva for an additional 7 days, after which the pastes were removed and the coronal access cavities were restored with glass ionomer. Crowns were subjected to compressive load at a cross head speed of 0.5 mm min−1 applied at 135° to the long axis of the root by an EMIC DL2000 testing machine, until coronal fracture. Data were statistically analysed by anova and Tukey test. Results: No differences in fracture resistance were observed between the experimental groups (> 0.05). However, all experimental groups presented lower fracture resistance than the control group (< 0.05). Conclusion: SPC and SP led to equal reduction on fracture resistance of dental crowns, regardless of being mixed with water or 20% HP.

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