Objective: Clinical applications of crown and bridge prosthodontics using zirconium ceramics have been expanding due to their advantages in terms of aesthetics and metal allergy. However, the application of bridges results in great flexural stress at the connection to the abutment teeth. Therefore, in the present study, a measurement comparison of the bending strengths of zirconium and zirconium fused with porcelain ceramics was conducted. Materials & Methods: For the production of test samples, Cercon (Dentsply,Germany) and Vintage ZR (Shofu Inc., Kyoto, Japan) were used as zirconium and porcelain ceramics, respectively. zirconium specimens 30 mm (L) x 4„b0.25 mm (W) x 0.5 mm (T) were subjected to a test method based on ISO testing methods. The porcelain-fused samples were produced by 1.0 mm porcelain (opaqueƒydentinƒyenamel) to the zirconium samples. Twelve samples of each material (total, 24 samples) were produced, and a biaxial flexural strength test was conducted using an Autograph (Shimazu, Kyoto) at a crosshead speed of 1„b0.5 mm/min. Results: The Levene's test was performed to confirm the equality of variance of the measured values, followed by a t-test, which indicated that the porcelain-fused zirconium samples had significantly higher values. Mean flexural strengths were 16.17 kgf for zirconium and 39.40 kgf for porcelain-fused zirconium. Macroscopic observation of the fracture surface of the porcelain-fused zirconium revealed a fracture where the porcelain had separated from the zirconium. Conclusion: The flexural strength of porcelain-fused zirconium samples was 2.3 times greater than that of zirconium.

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