This study was to evaluate the load bearing capacity of monolithic dental zirconia crowns, and the effect of surface finishing on fracture strength. (1) The zirconia plates were divided into 5 groups and polished by various types of polishing bur, every specimen was analyzed by surface roughness testing, and X-ray diffraction (XRD). (2) The zirconia crowns were classified into 4 groups corresponding to different surface treatments and thickness. All the crowns were cemented and subjected to a load of 7 kg for 5 min. Stored in distilled water at 37°C for 24 h. Observe the typical surface using field emission scanning electron microscopy (FE-SEM). The cycling and fracture tests were carried out. The data was statistically analyzed. The groups had better fracture strength after polishing. This suggests the monoclinic phase can be eliminated by optimizing the polishing process. Moreover, the fracture strength increased with occlusal thickness (p<0.05).
Keywords: Fracture strength; Monoclinic phase; Polishing; Surface roughness; Zirconia crown.