(Abstract)
Zirconia(Y-TZP) had been widely used in prosthetic restorations with excellent physical properties and biocompatibility. As multi-color added zirconia blocks have been developed. It was able to produce a more natural esthetic crown. The studies on the fracture strength of the blocks is limitation in the development of zirconia crowns manufactured using the metalic oxide added block. The aim of this study was to evaluate comparing fracture strength of a multi-colored monolithic zirconia crown with non-shaded and shaded monolithic zirconia crowns(null hypothesis: A multi-layer coloured Zirconia block will represent a similar to colorless zirconia blocks on the fracture strength.)
standarddentiform for the left mandibular first molar prepared on the abutment with a hard resin. Occlusal surface of 1.5mm, margin - formed with chamfer of 0.5mm to 1.0mm above the cementoenamel junction were prepared. And axial angle was prepared using a milling machine to 6° were scanned using a dental scanner. Fifty metal die was fabricated using scanned abutment image by using the dental CAD/CAM system. Within the color distribution, CM, ZK group was used by non-shaded zirconia block, DM group was used by shaded zirconia block, and ND, DN group was used multi-colored zirconia block. Ten crowns was fabricated by using CAM in each groups.
Monolithic zirconia crowns the fracture strength was measured by a load vertically to the occlusal surface of the teeth on a universal testing machine. Statistical analysis was conducted using One-way ANOVA, Tukey multiple comparision test (α=.05).
The results of this study as follows. The fracture strength test showed the highest fracture strength in the CM group as 3512.4 ± 189.7N(P <.05), FIB analysis of the results CM group showed the most dense grain size as 0.37±0.085㎛(P <.05).
The conclusion was as follows based on the findings. All the groups showed sufficient fracture strength that can be applied in clinical posterior restorations. Grain size were influenced the fracture strength. The difference in the test group by the addition of metal oxides, but it was not affected to the results.