Survivability and fracture resistance of monolithic and multi‐yttria‐layered zirconia crowns as a function of yttria content: A mastication simulation study

• Published in: Journal of esthetic and restorative dentistry 2022-06, Vol.34 (4), p.633-640
• Main Authors: Badr, Zaid, Culp, Lee, Duqum, Ibrahim, Lim, Chek Hai, Zhang, Yu, A. Sulaiman, Taiseer
• Format: Article
• Language: English
• Subjects: Aging; Crowns; Dental crowns; Dental Porcelain; Dental Restoration Failure; Dental Stress Analysis; fatigue; fracture load; gradient zirconia; Mastication; mastication simulation; Materials Testing; Mechanical loading; Mechanical properties; monolithic zirconia; multi‐yttria‐layered zirconia; Statistical analysis; yttria concentration; Yttrium; Zirconia; zirconia crowns; Zirconium
• ISSN: 1496-4155; 1708-8240
• DOI: 10.1111/jerd.12907

Objective To compare four different types of monolithic zirconia crowns in terms of survival rate and fracture resistance after thermocycling and/or thermo‐mechanical loading in a chewing simulator. Methods Partially stabilized zirconia (PSZ) crowns with fiber‐reinforced resin die assemblies (n = 80) were fabricated using: multi‐yttria‐layered 5Y‐PSZ/3Y‐PSZ, multi‐yttria‐layered 5Y‐PSZ/4Y‐PSZ, monolithic 4Y‐PSZ, and monolithic 3Y‐PSZ as control (n = 20). Half of the samples in each group were subjected to thermo‐mechanical loading under 110 N, 1.4 Hz, 1.2 million cycles with simultaneous thermocycling (10,000 cycles, 5–55°C). The other half were subjected to thermocycling alone. The samples were loaded to failure to measure their fracture resistance. The data were analyzed using by two‐way ANOVA and Tukey's HSD post‐hoc test (α = 0.05). Results All specimens survived the aging protocols. The yttria content significantly affected the fracture resistance of the crowns (p