Aging resistance of an experimental zirconia-toughened alumina composite for large span dental prostheses: Optical and mechanical characterization

Author(s):Show less -

Benalcazar Jalkh, E. B. ^{[1, 2]} ; Bergamo, E. T. P. ^[2] ; Monteiro, K. N. ^[3] ; Cesar, P. F. ^[3] ; Genova, L. A. ^[4] ; Lopes, A. C. O. ^[2] ; Lisboa Filho, P. N. ^[5] ; Coelho, P. G. ^{[1, 6, 7]} ; Santos, C. F. ^[8] ; Bortolin, F. ^[2] ; Piza, M. M. T. ^[2] ; Bonfante, E. A. ^[2]

Affiliation

^[1] NYU, Coll Dent, Dept Biomat & Biomimet, New York, NY - USA

^[2] Univ Sao Paulo, Dept Prosthodont & Periodontol, Bauru Sch Dent, Al Otavio Pinheiro Brisola 9-75, BR-17012901 Bauru, SP - Brazil

^[3] Univ Sao Paulo, Sch Dent, Dept Biomat & Oral Biol, Sao Paulo, SP - Brazil

^[4] Nucl & Energy Res Inst, Sao Paulo, SP - Brazil

^[5] Sao Paulo State Univ, Dept Phys, Bauru, SP - Brazil

^[6] NYU Tandon Sch Engn, Mech & Aerosp Engn, New York, NY - USA

^[7] NYU Langone Med Ctr, Hansjorg Wyss Dept Plast Surg, New York, NY - USA

^[8] Univ Sao Paulo, Bauru Sch Dent, Dept Biol Sci, Discipline Pharmacol, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS; v. 104, APR 2020.
• Web of Science Citations: 0

Abstract

Purpose: To synthesize a zirconia-toughened alumina (ZTA) composite with 85% alumina matrix reinforced by 15% zirconia and to characterize its optical and mechanical properties before and after artificial aging, to be compared with a conventional dental zirconia (3Y-TZP). Material and methods: After syntheses, ZTA and 3Y-TZP powders were uniaxially and isostatically pressed. Green-body samples were sintered and polished to obtain 80 disc-shaped specimens per group (12 x 1 mm, ISO 6872:2015). The crystalline content and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical properties were determined by the calculation of contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength test (BFS). All analyses were conducted before and after artificial aging (20h, 134 degrees C, 0.22 MPa). Optical parameters and microhardness differences were evaluated through repeated-measures analysis of variance (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). Results: The synthesis of the experimental ZTA composite was successful, with 98% of theoretical density, as shown in the SEM images. XRD patterns revealed typical zirconia and alumina crystalline phases. ZTA optical properties parameters showed no effect of aging, with a high CR and low TP values denoting a high masking-ability. 3Y-TZP presented lower masking-ability and aging significantly affected its optical properties. ZTA Vickers hardness, fracture toughness and Weibull parameters, including characteristic stress and Weibull modulus were not influenced by aging, while 3Y-TZP presented a significant decrease in characteristic stress and increase in fracture toughness after aging. The ZTA probability of survival for missions of 300 and 500 MPa was estimated at similar to 99% validating its use for 3-unit posterior fixed dental prostheses (FDP), and no different from conventional 3Y-TZP. At high-stress mission (800 MPa) a significant decrease in probability of survival was observed for aged 3Y-TZP (84%) and for immediate and aged ZTA (73 and 82% respectively). Conclusion: The ZTA composite presented a dense microstructure, with preservation of the crystalline content, optical and mechanical properties after artificial aging, which encourages future research to validate its potential use for large span FDP. (AU)

• FAPESP's process: 19/08693-1 - Experimental glass-infiltrated alumina-zirconia composites: characterization of microstructure, optical and mechanical properties.
• Grantee: Edmara Tatiely Pedroso Bergamo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/00452-5 - EXPERIMENTAL 70%Al2O3-30%ZrO2 ZTA COMPOSITES: MECHANICAL, ESTRUCTURAL AND TOPHOGRAPHICAL CHARACTERIZATION
• Grantee: Ernesto Byron Benalcazar Jalkh
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 16/24165-7 - Development and characterization of conventional ZTA composite mechanical properties for monolithic CAD / CAM prostheses
• Grantee: Fábio Bortolin
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 17/19362-0 - DEVELOPMENT, MECHANICAL AND OPTICAL CHARACTERIZATION OF 80% AL2O3 AND 20% ZRO2 ZTA COMPOSITES FOR CAD/CAM PROSTHESES
• Grantee: Adolfo Coelho de Oliveira Lopes
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• FAPESP's process: 18/03072-6 - Experimental 70% Al2O3-30% ZrO2 composites: structural characterization and survival probability before and after aging
• Grantee: Ernesto Byron Benalcazar Jalkh
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 16/18657-4 - Development and characterization of optical, topographic and crystalline phase properties of conventional ZTA composite for monolithic CAD/CAM prostheses
• Grantee: Mariana Miranda de Toledo Piza
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 19/14798-0 - Development of pre-sintered ZTA 80% Al2O3/20% ZrO2 composite blocks for milling in CAD/CAM system
• Grantee: Adolfo Coelho de Oliveira Lopes
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 12/19078-7 - Development and processing of Al2O3-ZrO2 translucent composite for CAD/CAM monolithic prostheses: the effect of aging on biaxial flexural strength
• Grantee: Estevam Augusto Bonfante
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 16/18818-8 - Multi-User Equipment approved in grant 2012/19078-7: ElectroPuls E3000 Linear-Torsion All-Electric dynamic test instrument package
• Grantee: Estevam Augusto Bonfante
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 16/17793-1 - Development and mechanical and optical characterization of 80% Al2O3 and 20% ZrO2 translucent composites for CAD/CAM monolithic prostheses
• Grantee: Adolfo Coelho de Oliveira Lopes
• Support Opportunities: Scholarships in Brazil - Master