The effect of low temperature degradation on color stability of two types of monolithic translucent zirconia crowns

Document Type : Original Article

Authors

1 Lecturer of Crown & Bridge, Department of Crown & bridge, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt

2 Professor of Crown & bridge, Faculty Of Dentistry Suez Canal University

3 Professor of Crown & Bridge, Department of Crown & bridge, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt

Abstract

Objective: To investigate the effect of artificial aging on the shade of two types of monolithic translucent zirconia crowns, manufactured using two different CAD/CAM systems.
Materials and methods: A sound human maxillary first premolar was selected to receive all ceramic crown preparation. The prepared premolar was then duplicated to produce twenty epoxy dies divided into two groups (n=10) according to the constructed crowns.. Twenty Standardized monolithic translucent zirconia (10 Prettau, & 10 Incoris TZI crowns) were CAD/CAM fabricated onto the epoxy dies and cemented using Panavia F 2.0. Vita Easy-Shade digital spectrophotometer was used to measure the color shade differences (ΔE) value between the selected color shade (A3 classical shade) and the color shade of the cemented CAD/CAM crowns before and after aging. The samples were aged under standard autoclave conditions for ten hours. XRD analysis was used to analyze the microstructure of both ZrO2 types before and after accerlated aging. SEM was done to examine the surface changes before and after aging. Results were tabulated and statistically analyzed using Kruskal-Wallis test and post hoc analysis .
Results: The results showed that the Prettau crowns had higher ΔE (4.26 ± 0.51) values than that of Incoris TZI crowns before (3.56 ± 0.28) aging. Also after aging Prettau showed higher ΔE (5.6 ± 0.47) than that of Incoris TZI (4.36 ± 0.34). Statistical analysis showed statistical significant difference between the groups.
Conclusions: This study concluded that Incoris TZI crowns better color shade results than Prettau crowns before and after aging.

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