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Shrestha R, Reddy N, Fredeen S, Zhang Y, Kim J. Functionally graded bi-material interface for Porcelain Veneered Zirconia dental crowns: A study using viscoelastic finite element analysis. Dent Mater 2024; 40:1267-1281. [PMID: 38876830 PMCID: PMC11260237 DOI: 10.1016/j.dental.2024.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/30/2024] [Accepted: 06/03/2024] [Indexed: 06/16/2024]
Abstract
OBJECTIVES During the manufacturing of Porcelain Veneered Zirconia (PVZ) dental crowns, the veneer-core system undergoes high-temperature firing cycles and gets fused together which is then, under a controlled setting, cooled down to room temperature. During this cooling process, the mismatch in thermal properties between zirconia and porcelain leads to the development of transient and residual thermal stresses within the crown. These thermal stresses are inherent to the PVZ dental crown systems and render the crown structure weak, acting as a precursor to veneer chipping, fracture, and delamination. In this study, the introduction of an intermediate functionally graded material (FGM) layer at the bi-material interface is investigated as a potentially viable alternative for providing a smoother transition of properties between zirconia and porcelain in a PVZ crown system. METHODS Anatomically correct 3D crown models were developed for this study, with and without the FGM layer modeled at the bi-material interface. A viscoelastic finite element model was developed and validated for an anatomically correct bilayer PVZ crown system which was then used for predicting residual and transient stresses in the bilayer PVZ crown. Subsequently, the viscoelastic finite element model was further extended for the analysis of graded sublayers within the FGM layer, and this extended model was used for predicting the residual and transient stresses in the functionally graded PVZ crown, with an FGM layer at the bi-material interface. RESULTS The study showed that the introduction of an FGM layer at the bi-material interface has the potential to reduce the effects from transient and residual stresses within the PVZ crown system relative to a bilayer PVZ crown structure. Furthermore, the study revealed that the FGM layer causes stress redistribution to alleviate the stress concentration at the interfacial surface between porcelain and zirconia which can potentially enhance the durability of the PVZ crowns towards interfacial debonding or fracture. SIGNIFICANCE Thus, the use of an FGM layer at the bi-material interface shows a good prospect for enhancing the longevity of the PVZ dental crown restorations by alleviating the abrupt thermal property difference and relaxing thermal stresses.
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Affiliation(s)
- Rupesh Shrestha
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Niyati Reddy
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA
| | - Steven Fredeen
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA.
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT 06269, USA.
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Yanapa Márquez J, Chávez-Méndez MA. [Compressive stress in three types of finishing lines with lithium disilicate crowns in permanent teeth: finite element analysis]. REVISTA CIENTÍFICA ODONTOLÓGICA 2024; 12:e182. [PMID: 39015314 PMCID: PMC11247469 DOI: 10.21142/2523-2754-1201-2024-182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 12/14/2023] [Indexed: 07/18/2024] Open
Abstract
Introduction In oral rehabilitation, the use of ceramic restorations is widely accepted due to its aesthetic capacity to mimic the naturalness of the dental tissue, provide longevity of the material, and present a greater marginal fit compared to crowns with a metal structure. Termination lines are biological preparations whose function is to minimize the cervical opening of the marginal seal. Consequently, analyzing the behavior of restorative materials under compressive forces decreases the risk of fracture and increases the success of the treatment. Objective To compare the compressive stresses of lithium disilicate crowns with three different finishing lines. Methodology In silico study of the simulation of a dental preparation on a lower right first molar with chamfer (0.6 mm), shoulder (0.5 mm) and deep chamfer (0.5 mm) finish lines. Using the SolidWorks®️ version 2017 software, the maximum stresses, minimum stresses, and location of the compressive force were collected on the Megapascal (Mpa) measurement scale. Results The chamfer type termination line (0.6mm) obtained a lower compressive stress compared to the other two shoulder type termination lines (0.5mm) and deep chamfer (0.5mm). Conclusions It was shown that the chamfer type finishing line (0.6mm) presented a better force distribution, determining greater reliability in the selection of this finishing line with the use of a lithium disilicate crown in a unitary manner.
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Affiliation(s)
- Joshua Yanapa Márquez
- Carrera de Estomatología, Universidad Científica del Sur. Lima, Perú. Universidad Científica del Sur Carrera de Estomatología Universidad Científica del Sur Lima Peru
| | - Martín Andrés Chávez-Méndez
- Facultad de Ciencias de la Salud, Carrera de Estomatología, Universidad Científica del Sur. Lima, Perú. Universidad Científica del Sur Facultad de Ciencias de la Salud Carrera de Estomatología Universidad Científica del Sur Lima Peru
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Alshahrani AM, Lim CH, Kim J, Zhang Y. Transient thermal stresses developed during speed sintering of 3 mol% yttria-stabilized tetragonal zirconia polycrystals. Dent Mater 2023; 39:522-528. [PMID: 37045719 PMCID: PMC10168597 DOI: 10.1016/j.dental.2023.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 04/05/2023] [Indexed: 04/14/2023]
Abstract
OBJECTIVES To investigate transient thermal stresses that developed in 3Y-TZP green compacts during speed sintering. METHODS A total of 312 disc-shaped green compacts (Ø17.1 ×1, 1.5, 2, 2.5, 3 mm) were cold-isostatically pressed from 3Y-TZP powder (Zpex, Tosoh Corp.) for speed sintering studies as well as compositional analysis and biaxial flexural strength measurements (both at room temperature and following heating at 90 °C/min to 500 °C). Flexural strength was determined using the piston-on-3-ball method. Phase assemblies were analyzed using the X-ray diffraction method. Effects of heating/cooling rates on transient stresses were investigated by conducting definitive sintering studies to determine the threshold for fracture. Finite element analysis (FEA) was used to validate the experimental findings using measured thermomechanical properties. RESULTS The bulk and relative density of the green compact were 2.95 ± 0.03 g/cm3 and 48.52% ± 0.45%. The flexural strength was drastically decreased from 10.3 ± 0.4 MPa to 1.09 ± 0.07 MPa following heating at 90 °C/min to 500 °C. The monoclinic and tetragonal contents were 54.9% and 45.1%, respectively. The threshold for fracture was located at 500 °C during the first heating stage with a 90 °C/min heating rate in specimens of 2.5 mm thickness or greater. No fractures occurred in the second heating stage and cooling phase. The FEA estimated that the principal transient tensile stress was ∼1.14 MPa at 500 °C during the heating phase, which exceeded the corresponding flexural strength (1.09 ± 0.07 MPa). SIGNIFICANCE Advanced FEA methods are an accurate and efficient tool to analyze the history of transient stresses during sintering of ceramic dental restorations.
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Affiliation(s)
- Abdulaziz M Alshahrani
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Restorative Dental Sciences, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Chek Hai Lim
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd, U-3037, Storrs, CT 06269, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Alves LMM, Rodrigues CDS, Ramos NDC, Buizastrow J, Campos TMB, Bottino MA, Zhang Y, Melo RMD. Silica infiltration on translucent zirconia restorations: Effects on the antagonist wear and survivability. Dent Mater 2022; 38:2084-2095. [PMID: 36446649 PMCID: PMC9928576 DOI: 10.1016/j.dental.2022.11.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 09/23/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To assess potential antagonist wear and survival probability of silica-infiltrated zirconia compared to glass-graded, glazed, and polished zirconia. METHODS Table top restorations made of 3Y-TZP (3Y), 5Y-PSZ (5Y), and lithium disilicate (LD) were bonded onto epoxy resin preparations. Each zirconia was divided into five groups according to the surface treatment: polishing; glaze; polishing-glaze; glass infiltration; and silica infiltration. The LD restorations received a glaze layer. Specimens were subjected to sliding fatigue wear using a steatite antagonist (1.25 ×106 cycles, 200 N). The presence of cracks, fractures, and/or debonding was checked every one/third of the total number of cycles was completed. Roughness, microstructural, Scanning electron microscopy, wear and residual stress analyses were conducted. Kaplan-Meier, Mantel-Cox (log-rank) and ANOVA tests were performed for statistical analyses. RESULTS The survival probability was different among the groups. Silica infiltration and polishing-glaze led to lower volume loss than glaze and glass-infiltration. Difference was observed for roughness among the zirconia and surface treatment, while lithium disilicate presented similar roughness compared to both glazed zirconia. Scanning electron microscopy revealed the removal of the surface treatment after sliding fatigue wear in all groups. Compressive stress was detected on 3Y surfaces, while tensile stress was observed on 5Y. SIGNIFICANCE 3Y and 5Y zirconia behaved similarly regarding antagonist wear, presenting higher antagonist wear than the glass ceramic. Silica-infiltrated and polished-glazed zirconia produced lower antagonist volume loss than glazed and glass-infiltrated zirconia. Silica-infiltrated 3Y and lithium disilicate restorations were the only groups to show survival probabilities lower than 85%.
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Affiliation(s)
- Larissa Marcia Martins Alves
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Camila da Silva Rodrigues
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Nathalia de Carvalho Ramos
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil
| | - Jeff Buizastrow
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Tiago Moreira Bastos Campos
- Department of Physics, Aeronautics Technological Institute (ITA), Praça Marechal Eduardo Gomes, 50, 12228-900 São José dos Campos, SP, Brazil
| | - Marco Antonio Bottino
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, United States
| | - Renata Marques de Melo
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil.
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Fardin VP, Bonfante G, Coelho PG, Bergamo ETP, Bordin D, Janal MN, Tovar N, Witek L, Bonfante EA. Residual stress estimated by nanoindentation in pontics and abutments of veneered zirconia fixed dental prostheses. J Appl Oral Sci 2022; 30:e20210475. [PMID: 35476114 PMCID: PMC9041093 DOI: 10.1590/1678-7757-2021-0475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 01/10/2022] [Accepted: 01/19/2022] [Indexed: 11/22/2022] Open
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.
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Affiliation(s)
- Vinicius Pavesi Fardin
- Universidade de São PauloFaculdade de Odontologia de BauruDepartamento de Prótese e PeriodontiaBauruSão PauloBrasilUniversidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Prótese e Periodontia, Bauru, São Paulo, Brasil.
| | - Gerson Bonfante
- Universidade de São PauloFaculdade de Odontologia de BauruDepartamento de Prótese e PeriodontiaBauruSão PauloBrasilUniversidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Prótese e Periodontia, Bauru, São Paulo, Brasil.
| | - Paulo G. Coelho
- New York University College of DentistryDepartment of BiomaterialsNew YorkUnited StatesNew York University College of Dentistry, Department of Biomaterials, New York, United States.
- New York University TandonSchool of EngineeringDepartment of Mechanical and Aerospace EngineeringBrooklynNew YorkUnited StatesNew York University Tandon, School of Engineering, Department of Mechanical and Aerospace Engineering, Brooklyn, New York, United States.
- New York University Grossman School of MedicineHansjörg Wyss Department of Plastic SurgeryNew YorkUnited StatesNew York University Grossman School of Medicine, Hansjörg Wyss Department of Plastic Surgery, New York, United States.
| | - Edmara T. P. Bergamo
- Universidade de São PauloFaculdade de Odontologia de BauruDepartamento de Prótese e PeriodontiaBauruSão PauloBrasilUniversidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Prótese e Periodontia, Bauru, São Paulo, Brasil.
| | - Dimorvan Bordin
- Universidade de GuarulhosGuarulhosSão PauloBrasilUniversidade de Guarulhos (UNG) – UNIVERITAS, Guarulhos, São Paulo, Brasil.
| | - Malvin N. Janal
- New York University College of DentistryDepartment of Epidemiology and Health PromotionNew YorkUnited StatesNew York University College of Dentistry, Department of Epidemiology and Health Promotion, New York, United States.
| | - Nick Tovar
- New York University College of DentistryDepartment of BiomaterialsNew YorkUnited StatesNew York University College of Dentistry, Department of Biomaterials, New York, United States.
| | - Lukasz Witek
- New York University College of DentistryDepartment of BiomaterialsNew YorkUnited StatesNew York University College of Dentistry, Department of Biomaterials, New York, United States.
- New York UniversityNYU Tandon School of EngineeringDepartment of Biomedical EngineeringBrooklynNYUnited StatesNew York University, NYU Tandon School of Engineering, Department of Biomedical Engineering, Brooklyn, NY, United States.
| | - Estevam A. Bonfante
- Universidade de São PauloFaculdade de Odontologia de BauruDepartamento de Prótese e PeriodontiaBauruSão PauloBrasilUniversidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Prótese e Periodontia, Bauru, São Paulo, Brasil.
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Dhital S, Rodrigues C, Zhang Y, Kim J. Metal-ceramic and porcelain-veneered lithium disilicate crowns: a stress profile comparison using a viscoelastic finite element model. Comput Methods Biomech Biomed Engin 2022; 25:412-423. [PMID: 34289770 PMCID: PMC9903966 DOI: 10.1080/10255842.2021.1955869] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/08/2021] [Accepted: 07/12/2021] [Indexed: 02/09/2023]
Abstract
Metal-ceramics (MC) are one of the oldest dental restorative systems, which are considered to be the gold standard for full crown restoration. Porcelain-veneered lithium disilicate (PVLD), on the other hand, are newer material systems that have shown high survival rate in clinical follow-ups but needs to be studied more. This study compares the stresses developed in the single crowns made from newer PVLD system against those with MC configuration. For this comparison, influence of the layer thickness and cooling rates is also taken into consideration. An experimentally validated viscoelastic finite element model (VFEM) has been developed to predict the stress profile in these systems. Three-dimensional rotationally symmetric crowns were analyzed using this validated model for both material systems, three veneer to core thickness ratios (2:1, 1:1, 1:2), and two cooling rates: slow cooling at 1.74E-5 W/mm2K (∼30 K/min) and fast cooling at 1.74E-4 W/mm2K (∼300 K/min). PVLD showed lower values of transient and residual stresses than MC. The maximum tensile residual stresses in MC systems were observed in the cusp area, whereas those in PVLD were located in the central fossa. With the reduction in veneer layer, there was reduction in residual stress in MC; however, the veneer thickness had little to no effect in PVLD. The effect of cooling rate was also evident as slow cooling resulted in lower residual and tensile stresses for both material systems.
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Affiliation(s)
- Sukirti Dhital
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT, USA
| | - Camila Rodrigues
- Graduate Program in Dental Sciences, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT, USA
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Sato TP, Arata A, de Miranda LM, Bottino MA, de Melo RM, Zhang Y, Souza ROA. Effect of Porcelain-to-Zirconia Ratio and Bonding Strategy on the Biaxial Flexural Strength and Weibull Characteristics of a Stress-Free Bilayer CAD/CAM Ceramic System. INT J PROSTHODONT 2022; 35:469-479. [PMID: 36125871 PMCID: PMC9974335 DOI: 10.11607/ijp.7551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
PURPOSE To evaluate the biaxial flexural strength of different porcelain-to-zirconia thickness ratios and bonding strategies of a stress-free bilayer CAD/CAM ceramic system. MATERIALS AND METHODS A total of 60 zirconia discs (diameter: 15 mm; thickness: 0.3 or 0.5 mm; n = 30 for each thickness) were divided into six groups (n = 10 each) according to porcelain-to-zirconia ratio and bonding strategy: VM/Zr (control): zirconia discs veneered with a feldspathic ceramic (VM 9, Vita) in 0.9-mm and 0.7-mm thicknesses using a conventional hand-layering technique; VB/Zr-SBU: zirconia discs airborne particle-abraded with 50-μm Al2O3 particles followed by an MDP primer application (Single Bond Universal, 3M) and bonded to the porcelain with a resin cement (Panavia F 2.0, Kuraray); and VB/Zr-RC: zirconia discs airborne particle-abraded with 30-μm silica-coated Al2O3 particles and silanized and bonded to the porcelain with the same resin cement. Before cementation, the VB (Vitablocs II) discs were etched with 5% hydrofluoric acid (60 seconds), followed by silane application. The bilayers (thickness = 1.2 mm) were loaded with 750 g while light curing the resin cement. Two porcelain-to-zirconia thickness ratios were evaluated: 0.9: 0.3 mm and 0.7: 0.5 mm. All groups were subjected to 106 mechanical cycles, followed by a biaxial flexural test. Data (MPa) were subjected to two-way analysis of variance (ANOVA), Tukey test (5%), and Weibull analyses. RESULTS Two-way ANOVA revealed that the factor porcelain-to-zirconia ratio (P = .0556) was not significant; however, the bonding strategy factor was statistically significant. Among the 0.5-mm zirconia groups, the VB/Zr-SBU group presented higher flexural strength (s) than the VM/Zr or VB/Zr-RC groups. Similar results were also found for the 0.3-mm zirconia groups, in which the VB/Zr-SBU group also presented higher strength than the others, which were similar in comparison (Tukey). The Weibull modulus was similar among the groups; however, the characteristic strength was significantly different (P = .000). CONCLUSION The zirconia bonding strategy with 50-μm Al2O3 airborne-particle abrasion, followed by a primer application, increases the flexural strength of a stress-free bilayer CAD/CAM ceramic system.
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Affiliation(s)
- Tabata Prado Sato
- Institute of Science and Technology, Universidade Estadual Paulista, São José dos Campos, Brazil
| | - Anelyse Arata
- Nanoscience and Advanced Materials Program, Federal University of ABC, Bangú, Brazil
| | - Larissa Mendonça de Miranda
- Federal University of Rio Grande do Norte, Department of Dentistry, Division of Prosthodontics, Natal, Brazil
| | - Marco Antonio Bottino
- Department of Dental Materials Institute of Science and Technology, University Estadual Paulista, São José dos Campos, Brazil
| | - Renata Marques de Melo
- Department of Dental Materials Institute of Science and Technology, University Estadual Paulista, São José dos Campos, Brazil
| | - Yu Zhang
- University of Pennsylvania, School of Dental Medicine, Department of Preventive and Restorative Sciences, Philadelphia, Pennsylvania, USA
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Blatz MB, Hariton‐Gross K, Anadioti E, Mante F, Zhang Y, Saleh N. Prospective 5-year clinical evaluation of posterior zirconia fixed dental prostheses veneered with milled lithium disilicate (CADon). J ESTHET RESTOR DENT 2022; 34:136-144. [PMID: 35083844 PMCID: PMC9934977 DOI: 10.1111/jerd.12877] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Bi-layer zirconia-based posterior fixed dental prostheses (FDPs) have reportedly a high incidence of veneering ceramic fractures. The CADon technique employs zirconia frameworks veneered with milled lithium disilicate glass-ceramic to overcome these shortcomings but long-term clinical studies are missing. This study evaluated the clinical efficacy of posterior 3-unit CADOn FDPs over a 5-year period. MATERIALS AND METHODS A total of 25 patients, 16 male and 9 female with a mean age of 55.6 years, received a total of 25 posterior three-unit CADOn FDPs. Patients were recalled for baseline and for follow-up visits at 6, 12, 24, and 60 months. Parameters evaluated were fracture, marginal adaptation, marginal discoloration, wear, polish, color match, surface staining, and retention of these restorations as well as secondary caries of the abutment teeth. RESULTS A total of 21 FDPs evaluated at 60-months revealed a 100% survival rate. All evaluated clinical parameters were satisfactory (alpha or bravo) and there was no statistically significant difference at different time points, except for surface staining, which was also worse at 60 months compared to baseline (p ≤ 0.001). CONCLUSIONS CADOn three-unit posterior FDPs demonstrate excellent fracture resistance after 5 years of clinical function. All evaluated clinical parameters were satisfactory, except for surface stain, which also increased over time. CLINICAL SIGNIFICANCE Conventionally veneered bi-layer zirconia-based posterior FDPs have limited clinical success. Based on this study, alternative methods such as zirconia frameworks veneered with milled lithium disilicate glass-ceramic provide a viable alternative with excellent long-term clinical outcomes.
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Affiliation(s)
- Markus B. Blatz
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Karina Hariton‐Gross
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Evanthia Anadioti
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Francis Mante
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Najeed Saleh
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
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Shelar P, Abdolvand H, Butler S. On the behaviour of zirconia-based dental materials: A review. J Mech Behav Biomed Mater 2021; 124:104861. [PMID: 34600431 DOI: 10.1016/j.jmbbm.2021.104861] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 11/28/2022]
Abstract
Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability. However, premature clinical failures of veneering porcelains raise a concern about their integrity. Extensive studies have been performed over a decade to resolve this issue, but it is challenging to reference all information effectively. A single source identifying the significance of potential parameters on material performance has not previously been available. An evidence-based meta-narrative review technique was used to review the characteristic parameters that can affect the overall behaviour of zirconia-based materials. Keywords were chosen to assess manuscripts based on scientific coherence with this paper's research objective. Online keyword searches were carried out on ScienceDirect, PubMed, and SAGE databases for relevant published manuscripts from year 1985-2020.261 out of 3170 identified manuscripts were included. A total of 10 parameters were identified and classified into the material, manufacturing, and geometric aspects. The effect of every parameter was reviewed on the performance of the material. A discrepancy in findings was observed and is attributed to the fact that there is no standard methodology. This review acts as a single source that summarizes various parameters' contribution to zirconia-based dental materials' performance. This review facilitates manufacturing improvements by accounting for every parameter's effect on overall performance.
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Affiliation(s)
- Prashant Shelar
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Hamidreza Abdolvand
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Sheila Butler
- Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
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Rodrigues CS, Dhital S, Kim J, May LG, Wolff MS, Zhang Y. Residual stresses explaining clinical fractures of bilayer zirconia and lithium disilicate crowns: A VFEM study. Dent Mater 2021; 37:1655-1666. [PMID: 34481666 DOI: 10.1016/j.dental.2021.08.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To understand the stress development in porcelain-veneered zirconia (PVZ) and porcelain-veneered lithium disilicate (PVLD) crowns with different veneer/core thickness ratios and cooling rates. To provide design guidelines for better performing bilayer restorations with the aid of Viscoelastic Finite Element Method (VFEM). METHODS The VFEM was validated by comparing the predicted residual stresses with experimental measurements. Then, the model was used to predict transient and residual stresses in the two bilayer systems. Models with two different veneer/core thickness ratios were prepared (2:1 and 1:1) and two cooling protocols were simulated (Fast: ∼300 °C/min, Slow: ∼30 °C/min) using the heat transfer module, followed by stress analysis in ABAQUS. The physical properties of zirconia, lithium disilicate, and the porcelains used for the simulations were determined as a function of temperature. RESULTS PVLD showed lower residual stresses than PVZ. The maximum tensile stresses in PVZ were observed in the cusp area, whereas those in PVLD were located in the central fossa. The 1:1 thickness ratio decreased stresses in both layers of PVZ. Slow cooling slightly decreased residual stresses in both systems. However, the cooling rate effect was more evident in transient stresses. SIGNIFICANCE Slow cooling is preferable for both systems. A thinner porcelain layer over zirconia lowers stresses throughout the restoration. The different stress distributions between PVZ and PVLD may affect their failure modes. Smaller mismatches in modulus, CTE, and specific heat between the constituents, and the use of low Tg porcelains can effectively reduce the deleterious transient and residual tensile stresses in bilayer restorations.
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Affiliation(s)
- Camila S Rodrigues
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, 777 Eng. Francisco José Longo Av, 12245-000, São José dos Campos, SP, Brazil
| | - Sukirti Dhital
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd., U-3037, Storrs, CT 06269, USA
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd., U-3037, Storrs, CT 06269, USA
| | - Liliana Gressler May
- Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, 1000 Roraima Av., T Street, Building 26F, 97105-900, Santa Maria, RS, Brazil
| | - Mark S Wolff
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA 19104, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA 19104, USA.
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Shelar P, Butler S. Effect of thermal gradient on structural relaxation and characterization of thermal stresses in dental porcelains - A finite element study. J Mech Behav Biomed Mater 2021; 122:104693. [PMID: 34293694 DOI: 10.1016/j.jmbbm.2021.104693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 06/29/2021] [Accepted: 07/02/2021] [Indexed: 10/20/2022]
Abstract
Zirconia-based materials veneered with glassy porcelain have become the material of choice for both dentists and their patients. This restoration material is now extensively used in clinical practice for the following reasons: material closely resembles tooth appearance, biofunctionality, biocompatibility and affordability. However, premature clinical failures due to the combination of subsurface flaws and tensile stresses within porcelains raise a concern about their reliability and integrity. This study evaluates structural relaxation in dental porcelain to form a suitable explanation for subsurface tensile stresses. Finite Element Method (FEM) is used for this analysis. User material subroutines, UEXPAN, and UTRS, were developed and integrated into a finite element solver to study the effects of structural relaxation on thermal stresses in veneer during final heat treatment. The predictions of the model were validated through qualitative and quantitave means. A validated model was used for Finite Element Analysis (FEA). Faster cooling rates and high veneer thickness predicted high subsurface tensile stresses due to ineffective structural relaxation. Slow cooling rates and lower veneer thickness showed desired compressive stresses in subsurface areas with visible structural relaxation. This work, emphasizing structural relaxation in veneering dental porcelain, provides a way forward for effective designing of dental restorations. Accordingly, it is useful to tailor the desired stress state for extended life in veneered dental porcelains on zirconia frameworks.
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Affiliation(s)
- Prashant Shelar
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Sheila Butler
- Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
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Lima JMDC, Tribst JPM, Anami LC, de Melo RM, Moura DMD, Souza ROA, Bottino MA. Long-term fracture load of all-ceramic crowns: Effects of veneering ceramic thickness, application techniques, and cooling protocol. J Clin Exp Dent 2020; 12:e1078-e1085. [PMID: 33262875 PMCID: PMC7680567 DOI: 10.4317/jced.57352] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/02/2020] [Indexed: 11/14/2022] Open
Abstract
Background To evaluate, in vitro, the effects of the cooling protocol, application technique, and veneering ceramic thickness on the fracture resistance of ceramic crowns with Y-TZP frameworks.
Material and Methods 80 frameworks were made from zirconia by the CAD/CAM technique and divided into 8 groups (n = 10) according to the factors: “application technique” (stratified-L and pressed -P), “thickness” (1 mm and 2 mm), and “cooling protocol” (slow-S and fast-F) of the feldspathic veneering ceramic. After, all crowns were cemented over G10 preparations with resin cement (Panavia F, Kuraray), mechanically cycled (2x106 cycles, 200 N, 3Hz), and subjected to the axial compression resistance test (0.5 mm/min, 10 kN). The data (N) underwent descriptive statistical analysis by 3-way ANOVA and Tukey’s test (5%). Fracture analysis was performed to determine the possible origin of failure.
Results The factors “cooling protocol” (P=0.0058) and “application” technique (P=0.0001) influenced the fracture resistance of the crowns. For pressed veneer technique, the P2S (4608.9±464.5). A presented significantly higher results than that P2F(3621.1±523.0)BCD (Tukey’s test). For the stratified technique, this difference was not observed (P>0.05). The thickness of the veneering ceramic was not significant regardless of the cooling protocol and technique (P>0.05). The predominant failure mode was chipping of the ceramic veneer originating in the subsurface.
Conclusions The pressed technique, used with a slow-cooling protocol, leads to the best outcome for the veneering of all-ceramic crowns. Key words:Zirconia, ceramics, cooling protocol, thickness, application technique.
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Affiliation(s)
| | - João-Paulo-Mendes Tribst
- DDs, MSc, PhD, Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, São Paulo, Brazil
| | - Lilian-Costa Anami
- DDs, MSc, PhD, Departmentof Dentistry, Santo Amaro University, São Paulo, SP, Brazil
| | - Renata-Marques de Melo
- DDs, MSc, PhD, Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, São Paulo, Brazil
| | - Dayanne-Monielle-Duarte Moura
- DDs, MSc, PhD, Department of Dentistry, Division of Prosthodontics, Federal University of Rio Grande do Norte (UFRN), Natal/RN, Brazil
| | - Rodrigo-Othávio-Assunção Souza
- DDs, MSc, PhD, Department of Dentistry, Division of Prosthodontics, Federal University of Rio Grande do Norte (UFRN), Natal/RN, Brazil
| | - Marco-Antonio Bottino
- DDs, MSc, PhD, Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos, São Paulo, Brazil
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