Residual stress estimated by nanoindentation in pontics and abutments of veneered zirconia fixed dental prostheses

Author(s)

Vinicius Pavesi Fardin ^[1] ; Gerson Bonfante ^[2] ; Paulo G. Coelho ; Edmara T. P. Bergamo ^[4] ; Dimorvan Bordin ^[5] ; Malvin N. Janal ^[6] ; Nick Tovar ^[7] ; Lukasz Witek ; Estevam A. Bonfante ^[9]

Affiliation

^[1] Universidade de São Paulo. Faculdade de Odontologia de Bauru. Departamento de Prótese e Periodontia - Brasil

^[2] Universidade de São Paulo. Faculdade de Odontologia de Bauru. Departamento de Prótese e Periodontia - Brasil

^[4] Universidade de São Paulo. Faculdade de Odontologia de Bauru. Departamento de Prótese e Periodontia - Brasil

^[5] Universidade de Guarulhos - Brasil

^[6] New York University College of Dentistry. Department of Epidemiology and Health Promotion - Estados Unidos

^[7] New York University College of Dentistry. Department of Biomaterials - Estados Unidos

^[9] Universidade de São Paulo. Faculdade de Odontologia de Bauru. Departamento de Prótese e Periodontia - Brasil

• Document type: Journal article
• Source: Journal of Applied Oral Science; v. 30, 2022-04-22.

Abstract

Abstract Glass ceramics’ fractures in zirconia fixed dental prosthesis (FDP) remains a clinical challenge since it has higher fracture rates than the gold standard, metal ceramic FDP. Nanoindentation has been shown a reliable tool to determine residual stress of ceramic systems, which can ultimately correlate to failure-proneness. Objectives: To assess residual tensile stress using nanoindentation in veneered three-unit zirconia FDPs at different surfaces of pontics and abutments. Methodology: Three composite resin replicas of the maxillary first premolar and crown-prepared abutment first molar were made to obtain three-unit FDPs. The FDPs were veneered with glass ceramic containing fluorapatite crystals and resin cemented on the replicas, embedded in epoxy resin, sectioned, and polished. Each specimen was subjected to nanoindentation in the following regions of interest: 1) Mesial premolar abutment (MPMa); 2) Distal premolar abutment (DPMa); 3) Buccal premolar abutment (BPMa); 4) Lingual premolar abutment (LPMa); 5) Mesial premolar pontic (MPMp); 6) Distal premolar pontic (DPMp); 7) Buccal premolar pontic (BPMp); 8) Lingual premolar pontic (LPMp); 9) Mesial molar abutment (MMa); 10) Distal molar abutment (DMa); 11) Buccal molar abutment (BMa); and 12) Lingual molar abutment (LMa). Data were assessed using Linear Mixed Model and Least Significant Difference (95%) tests. Results: Pontics had significantly higher hardness values than premolar (p=0.001) and molar (p=0.007) abutments, suggesting lower residual stress levels. Marginal ridges yielded higher hardness values for connectors (DPMa, MMa, MPMp and DPMp) than for outer proximal surfaces of abutments (MPMa and DMa). The mesial marginal ridge of the premolar abutment (MPMa) had the lowest hardness values, suggesting higher residual stress concentration. Conclusions: Residual stress in three-unit FDPs was lower in pontics than in abutments. The outer proximal surfaces of the abutments had the highest residual stress concentration. (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 type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 21/08018-2 - Nanomechanical layer characterization of graded ATZ and ZTA composites
• Grantee: Edmara Tatiely Pedroso Bergamo
• Support type: Scholarships abroad - Research Internship - Post-doctor
• 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 type: Research Grants - Young Investigators Grants
• FAPESP's process: 11/23177-8 - Evaluation of reliability and failure modes of ceramic crown systems depending on framework design and location of load application
• Grantee: Gerson Bonfante
• Support type: Regular Research 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 type: Multi-user Equipment Program
• FAPESP's process: 14/22859-6 - Effect of framework design of fatigued zirconia 3-unit prostheses on the nanomechanical properties
• Grantee: Vinicius Pavesi Fardin
• Support type: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 21/06730-7 - Towards sustainable zirconia recycled from milling waste and boosted by glass infiltration for restorative use, and of the development of strong, graded, and aging resistant multilayered zirconia blocks
• Grantee: Estevam Augusto Bonfante
• Support type: Research Grants - Young Investigators Grants - Phase 2
• FAPESP's process: 13/20806-0 - Evaluation of damage and failure modes of fixed partial denture of totally ceramic depending on marginal ridge load application
• Grantee: Vinicius Pavesi Fardin
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 11/16377-0 - Evaluation of reliability and failure modes of ceramic crown systems depending on framework design and location of load application
• Grantee: Vinicius Pavesi Fardin
• Support type: Scholarships in Brazil - Master