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Alghauli MA, Alqutaibi AY, Wille S, Kern M. The physical-mechanical properties of 3D-printed versus conventional milled zirconia for dental clinical applications: A systematic review with meta-analysis. J Mech Behav Biomed Mater 2024; 156:106601. [PMID: 38810545 DOI: 10.1016/j.jmbbm.2024.106601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 05/12/2024] [Accepted: 05/23/2024] [Indexed: 05/31/2024]
Abstract
AIM OF STUDY This systematic review aimed to compare the physical-mechanical properties of 3D-printed (additively manufactured (AM)) zirconia compared to conventionally milled (subtractive manufactured: SM) zirconia specimens. MATERIALS AND METHODS A thorough search of Internet databases was conducted up to September 2023. The search retrieved studies that evaluated AM zirconia specimens and restorations regarding the physical-mechanical properties and mechanical behavior of zirconia. The main topic focused on 3Y-TZP. However, records of 4YSZ and 5YSZ were also included to gather more comprehensive evidence on additively manufactured zirconia ceramic. The quality of studies was assessed using the ROB2 tool, Newcastle Ottawa scale, and the Modified Consort Statement. Of 1736 records, 57 were assessed for eligibility, and 38 records were included in this review, only two clinical trials meet the inclusion criteria and 36 records were laboratory studies. There were no signs of mechanical complications and wear to antagonists with short-term clinical observation. SM thin specimens ≤1.5 mm showed statistically significant higher flexural strength than AM zirconia (p ≤ 0.01), while thicker specimens showed comparable outcomes (p > 0.5). The fracture resistance of dental restorations was dependent on the aging protocol, restoration type, and thickness. The bond strength of veneering ceramic to zirconia core was comparable. CONCLUSIONS The results pooled from two short-term clinical trials showed no signs of mechanical or biological complications of additively manufactured 3Y-TZP zirconia crowns. The flexural strength might depend on the specimens' thickness, but it showed promising results to be used in clinical applications, taking into account the printing technique and orientation, material composition (yttria content), solid loading, and sintering parameters. 3D-printed restorations fracture resistance improved when adhered to human teeth. The veneering ceramic bond was comparable to milled zirconia specimens. Long-term RCTs are recommended to confirm the mechanical behavior of 3D-printed restorations.
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Affiliation(s)
- Mohammed Ahmed Alghauli
- Department of Prosthodontic, Propaedeutic and Dental Materials, Faculty of Dentistry, Kiel University, Kiel, Germany; Department of Prosthodontics, Faculty of Dentistry, Ibb University, Ibb, Yemen.
| | - Ahmed Yaseen Alqutaibi
- Department of Prosthodontics, Faculty of Dentistry, Ibb University, Ibb, Yemen; Department of Substitutive Dental Science, College of Dentistry, Taibah University, Al-Madinah, Saudi Arabia
| | - Sebastian Wille
- Department of Prosthodontic, Propaedeutic and Dental Materials, Faculty of Dentistry, Kiel University, Kiel, Germany
| | - Matthias Kern
- Department of Prosthodontic, Propaedeutic and Dental Materials, Faculty of Dentistry, Kiel University, Kiel, Germany
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Su C, Lu ZC, Ji X, Yu H. Optical properties of recycled zirconia for dental applications. J Prosthet Dent 2024; 131:1237.e1-1237.e7. [PMID: 38418303 DOI: 10.1016/j.prosdent.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 03/01/2024]
Abstract
STATEMENT OF PROBLEM While waste zirconia can be recycled, whether the optical properties of recycled zirconia match those of commercially available zirconia is unclear. PURPOSE The purpose of this in vitro study was to evaluate the optical properties of recycled zirconia by assessing its color, translucency, and opalescence across different thicknesses and shades. MATERIAL AND METHODS Sixty specimens were prepared from 3 mol% yttria-stabilized tetragonal zirconia polycrystal blocks (Lava Plus; 3M ESPE) (group C); 60 other specimens were prepared from waste blocks of the same zirconia (group R). The specimens were further categorized into 4 subgroups (n=15) based on their thicknesses (1.0 mm or 1.5 mm) and shades (A1 or A3). Specimen color was measured with a spectrophotometer (Easyshade Advance 4.0; Vita ZahnFabrik). The parameters of color difference (ΔE00), translucency (TP), contrast ratio (CR), and opalescence (OP) were calculated. Grain size analysis was performed using scanning electron microscopy. Data were analyzed with analysis of variance (ANOVA) (α=.05). RESULTS Significant differences in translucency and opalescence were observed between groups C and R in all specimens (P<.001). Group R exhibited a range of TP (4.89 to 11.27), CR (0.74 to 0.91), and OP (3.36 to 8.65) values. The ΔE00 values between groups C and R ranged from 13.99 to 21.31. Both thickness and shade significantly affected the ΔE00 values (P<.001). The grain size in group C was not significantly different from that in group R (F=0.364, df=1, P=.555). The TP and OP values of group R decreased with increasing thickness (P<.001). CONCLUSIONS Recycled zirconia was less translucent and opalescent than commercially available zirconia. The color difference between commercially available and recycled zirconia exceeded the acceptable threshold, even when using the same staining procedure. Recycled zirconia exhibited reduced translucency and opalescence with increasing thickness.
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Affiliation(s)
- Chen Su
- Postgraduate student, Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China
| | - Zhi-Cen Lu
- PhD Candidate, Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China
| | - Xiong Ji
- Postgraduate student, Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key Laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China
| | - Hao Yu
- Associate Professor and Associate Dean, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, Fujian, PR China, and Adjunct Associate Professor, Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
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Gali S, Gururaja S, Patel Z. Methodological approaches in graded dental ceramics. Dent Mater 2024; 40:e1-e13. [PMID: 38438282 PMCID: PMC7615955 DOI: 10.1016/j.dental.2024.02.016] [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: 10/14/2023] [Revised: 01/05/2024] [Accepted: 02/12/2024] [Indexed: 03/06/2024]
Abstract
BACKGROUND Functionally graded materials (FGM) with indistinct boundaries potentially eliminate the damaging stresses occurring at the interfaces. FGM applications in dental ceramics have enhanced their fatigue resistance and interfacial toughness. OBJECTIVES This scoping review aims to map graded designs in dental ceramics, distinguish their methodological approaches with their material characteristics and properties, and understand the factors affecting the outcomes of each of the graded approaches. METHODS A systematic electronic search was performed with the databases MEDLINE (PubMed), Scopus, Cochrane Library, EBSCO, and Google Scholar along with a manual search. RESULTS About 2675 articles were initially found from all the searches with no date restriction till July 2023. After rejecting duplicates and based on exclusion criteria, about 52 articles were included. SIGNIFICANCE Methodological approaches in grading such as glass-infiltration and silica-infiltration have been investigated on pre-sintered zirconia. The type of infiltration and the method of infiltrate application significantly influenced the phase transformation of zirconia, its microstructure, surface hardness, fracture toughness, flexural strength, wear, and fatigue strength of graded dental zirconia. Interlayers were accommodated between metal-ceramic and veneer-core all-ceramic layers. Fractions of zirconia-porcelain and alumina-porcelain showed high bending strength and better stress distribution. The results of finite element analysis studies predicted that using 10-layered graded layers reduced the stresses at the crown-cement-dentin interface.
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Affiliation(s)
- Sivaranjani Gali
- Dept. of Prosthodontics, Faculty of Dental Sciences, M.S.Ramaiah University of Applied Sciences, Bangalore 560054, India.
| | | | - Zulekha Patel
- Dept. of Prosthodontics, Faculty of Dental Sciences, M.S.Ramaiah University of Applied Sciences, Bangalore 560054, India
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Zhou M, Zhang X, Zhang Y, Li D, Zhao Z, Wang Q, Tang K, Niu L, Wang F. Construction of Nanostructured Glass-Zirconia to Improve the Interface Stability of Dental Bilayer Zirconia. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:678. [PMID: 36839046 PMCID: PMC9960043 DOI: 10.3390/nano13040678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/05/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Bilayer zirconia restoration is one of the most commonly used restorations in dental practice, but the high frequency of the cohesive/adhesive fracture of veneered porcelain is still a problem. This paper focuses on the development of nanostructured glass-zirconia to improve the interface stability of dental zirconia substrate and veneered porcelain. A novel SiO2-Li2O-Al2O3 (SLA) glass was prepared and infiltrated into the surface of fully sintered dental zirconia to obtain nanostructured glass-zirconia structure. The prepared glass-zirconia was analyzed with scanning electron microscopes (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD). The wettability, roughness and 3D morphology of zirconia were altered, and shear bonding strength (SBS) test demonstrated almost double increase in SBS values of the nanostructured glass-zirconia structure. The failure modes and microstructure characteristics also verified the improved interfacial stability. This investigation provides a promising method for enhancing the structural stability of bilayer zirconia restorations.
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Affiliation(s)
- Ming Zhou
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
| | - Xiaoyu Zhang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
| | - Yaming Zhang
- School of Science, Xi’an University of Posts and Telecommunications, Xi’an 710061, China
| | - Ding Li
- School of Science, Xi’an University of Posts and Telecommunications, Xi’an 710061, China
| | - Zhe Zhao
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
| | - Qing Wang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
| | - Kai Tang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
| | - Lina Niu
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
| | - Fu Wang
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China
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Bonfante EA, Calamita M, Bergamo ETP. Indirect restorative systems-A narrative review. J ESTHET RESTOR DENT 2023; 35:84-104. [PMID: 36688803 DOI: 10.1111/jerd.13016] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/03/2023] [Accepted: 01/04/2023] [Indexed: 01/24/2023]
Abstract
OBJECTIVE The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence-based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all-ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes. OVERVIEW Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin-matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth. CONCLUSIONS Based on several clinical research, materials, and patient-related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process. CLINICAL SIGNIFICANCE The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long-term clinical trials in order to incorporate or not new materials and technological advancements.
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Affiliation(s)
- Estevam A Bonfante
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry - University of São Paulo, Bauru, SP, Brazil
| | - Marcelo Calamita
- Department of Restorative Dental Sciences at the University of Florida, Gainesville, Florida, USA
| | - Edmara T P Bergamo
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry - University of São Paulo, Bauru, SP, Brazil
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Zandinejad A, Das O, Barmak AB, Kuttolamadom M, Revilla-León M. The Flexural Strength and Flexural Modulus of Stereolithography Additively Manufactured Zirconia with Different Porosities. J Prosthodont 2021; 31:434-440. [PMID: 34580962 DOI: 10.1111/jopr.13430] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 09/01/2021] [Accepted: 09/09/2021] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Additive manufacturing (AM) technologies are capable of fabricating complex geometries with different porosities. However, the effect of such porosities on mechanical properties of stereolithography (SLA) AM zirconia with different porosities is unclear. The purpose of this in vitro study was to investigate the mechanical properties namely flexural strength, and flexural modulus of AM zirconia with different porosities. MATERIALS AND METHODS A bar (25 × 4 × 3 mm) for flexural strength test (ISO standard 6872/2015) was designed by CAD software program and standard tessellation language (STL) file was obtained. The STL file was used to fabricate a total of 80 bars in four groups. Three experimental groups each containing 20 samples were manufactured using an SLA ceramic printer (CeraMaker 900; 3DCeram Co) and zirconia material (3DMix ZrO2 paste; 3DCeram Co) with different sintering post processing to achieve different porosities including 0%-porosity (AMZ0), 20%-porosity (AMZ20), and 40%-porosity (AMZ40). The same STL file was used for subtractive manufacturing or milling of 20 zirconia bars as control group (CNCZ) with the same dimensions using a commercial zirconia. Three-point bending tests were performed for all groups following ISO standard 6872/2015 specification using a universal testing machine. Outcomes measured included load at fracture, mean flexural strength, and flexural modulus and they were compared across the experimental groups using a one-way ANOVA. Post hoc pair wise comparison between each pair of the groups were performed using Tukey test. RESULTS There was a significant difference between the four groups, in terms of fracture load, flexural strength and flexural modulus using one-way ANOVA. AM zirconia with 0% porosity (AMZ0) showed the highest value for fracture load (1132.7 ± 220.6 N), flexural strength (755.1 ± 147.1 MPa) and flexural modulus (41,273 ± 2193 MPa) and AM zirconia with 40% porosity (AMZ40) showed the lowest fracture load (72.13 ± 13.42 N), flexural strength (48.09 ± 8.95 MPa) and flexural modulus (7177 ± 506 MPa). Tukey's pairwise comparisons detected a significant difference between all the possible pairs for all variables except flexural modulus between AMZ0 and CNCZ. The Weibull moduli presented the lowest value for AMZ20 (4.4) followed by AMZ40 (6.1), AMZ0 (6.1), and the highest value was for CNCZ (8.1). CONCLUSION AM zirconia with 0% porosity showed significantly higher flexural strength and flexural modulus when compared to milled and AM zirconia with 20% and 40% porosities.
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Affiliation(s)
| | - Omprakash Das
- College of Engineering, Texas A&M University, College Station, TX
| | | | | | - Marta Revilla-León
- College of Dentistry, Texas A&M University, Dallas, TX.,School of Dentistry, University of Washington, Seattle, WA.,Revilla Research Center, Madrid, Spain
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Ramos GF, Ramos NC, Alves LMM, Kaizer MR, Borges ALS, Campos TMB, Melo RM. Failure probability and stress distribution of milled porcelain-zirconia crowns with bioinspired/traditional design and graded interface. J Mech Behav Biomed Mater 2021; 119:104438. [PMID: 33798936 DOI: 10.1016/j.jmbbm.2021.104438] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 09/14/2020] [Accepted: 02/26/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To evaluate the failure probability and stress distribution of traditional and bioinspired porcelain-zirconia milled crowns, with and without silica infiltration (graded zirconia). METHODS Traditional crown design had a zirconia infrastructure veneered with porcelain; Bioinspired, had a porcelain infrastructure with translucent-zirconia veneer; Graded and Graded Bioinspired crowns had their zirconia layer infiltrated by silica (n = 25). The cameo surface of each crown (porcelain or zirconia) was glazed. The restoration layers were fused by a vitreous connector and the crowns were adhesively cemented to dies. The specimens were then mechanically cycled in a sliding machine using 100 N load at 4 Hz. The specimens were tested until 2 × 106 cycles, and every 0.5 × 106 cycles the crowns were evaluated under stereomicroscopy for the presence of failures. The stress distribution was inspected with Finite Element Analyses. RESULTS The predominant failure modes for the Traditional and Graded crowns were delamination and cracking, respectively. The Weibull parameters beta and eta were, respectively: Traditional 1.30 and 2.3 × 106 cycles, and Graded 1.95 and 2.3 × 106 cycles. Thus, the Traditional and Graded crowns presented greater susceptibility to failure due to fatigue, while the Bioinspired and Graded Bioinspired crowns showed no fatigue effect using 100N load, showing beta = 1 and eta of approximately 17 × 106 cycles. Also, through finite element analyses, it was verified that the Bioinspired and Graded Bioinspired crowns presented the best stress distribution on both crowns and dental structures. SIGNIFICANCE Bioinspired and Graded Bioinspired crowns had the lowest failure probability and better stress distribution and may be considered robust long lasting restorations.
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Affiliation(s)
- G F Ramos
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José Dos Campos, SP, Brazil.
| | - N C Ramos
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José Dos Campos, SP, Brazil; College of Dentistry, Sao Francisco University (USF), 218 Sao Francisco de Assis Avenue, 12916-900, Bragança Paulista, SP, Brazil.
| | - L M M Alves
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José Dos Campos, SP, Brazil.
| | - M R Kaizer
- College of Dentistry, Positivo University (UP), 5300 Prof. Pedro Viriato Parigot de Souza Street, 81280-330, Curitiba, PR, Brazil.
| | - A L S Borges
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José Dos Campos, SP, Brazil.
| | - T M B Campos
- Physics Department, Technological Institute of Aeronatics (ITA), 50 Praça Marechal Eduardo Gomes, 12228-900, São José Dos Campos, SP, Brazil.
| | - R M Melo
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, 777 Eng. Francisco José Longo Avenue, 12245-000, São José Dos Campos, SP, Brazil.
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Moreira Bastos Campos T, Marques de Melo Marinho R, de Oliveira Pinto Ribeiro A, Larissa do Amaral Montanheiro T, Carolina da Silva A, Thim GP. Microstructure and mechanical properties of fully sintered zirconia glazed with an experimental glass. J Mech Behav Biomed Mater 2020; 113:104093. [PMID: 33022517 DOI: 10.1016/j.jmbbm.2020.104093] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 10/23/2022]
Abstract
The need for improved mechanical properties in regions of higher masticatory loads led to the introduction of zirconia in dentistry. However, zirconia needs a characterization and glaze to have a more natural, tooth-like appearance. An experimental glass was produced based on the sol-gel method to exhibit a thermal expansion coefficient similar to that presented by zirconia. The experimental glass was used as glazing material on the previously sintered zirconia (vita YZ) surface. There was a significant reduction in the roughness and hardness of the material, caused by the formation of smooth, void-free and highly uniform glass coating. The glass infiltrated among superficial zirconia grains and caused the formation of monoclinic zirconia at the zirconia/glass interface. A consequent decrease in surface roughness and an increase in flexural strength and reliability was then observed in the experimental glass group. On the other hand, a significant decrease in the reliability of conventionally glazed group was observed. Therefore, the use of experimental glass instead of conventional glaze can improve the mechanical properties, smoothness, and mechanical reliability of fully sintered zirconia.
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Affiliation(s)
- Tiago Moreira Bastos Campos
- Physics Department, Aeronautics Technological Institute (ITA), 50 Marechal Eduardo Gomes Square, 12228-900, São José dos Campos, SP, Brazil.
| | - Renata Marques de Melo Marinho
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, São José dos Campos, São Paulo, Brazil.
| | - Amanda de Oliveira Pinto Ribeiro
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, São José dos Campos, São Paulo, Brazil.
| | - Thais Larissa do Amaral Montanheiro
- Physics Department, Aeronautics Technological Institute (ITA), 50 Marechal Eduardo Gomes Square, 12228-900, São José dos Campos, SP, Brazil.
| | - Ana Carolina da Silva
- Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Institute of Science and Technology, São José dos Campos, São Paulo, Brazil.
| | - Gilmar Patrocínio Thim
- Physics Department, Aeronautics Technological Institute (ITA), 50 Marechal Eduardo Gomes Square, 12228-900, São José dos Campos, SP, Brazil.
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A simple 3-point flexural method for measuring fracture toughness of the dental porcelain to zirconia bond and other brittle bimaterial interfaces. J Prosthodont Res 2020; 64:391-396. [PMID: 32063538 DOI: 10.1016/j.jpor.2019.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/25/2019] [Accepted: 11/05/2019] [Indexed: 11/22/2022]
Abstract
PURPOSE Porcelain fused to zirconia prostheses are widely used, but porcelain chipping, fracture, spalling and delamination are common clinical problems. Conventional bond strength testing is inherently unsuited for studying interfacial failure by cracking in brittle materials. Instead, fracture toughness is a more meaningful parameter because it can assess the robustness of the interface when subjected to loading, but fracture mechanics approaches have only rarely been used. Our purpose was to develop a novel, simple, 3-point flexural methodology and mathematical analysis to measure the fracture toughness of the porcelain to zirconia interface. METHODS Equations were derived to estimate the fracture toughness of the bond by computing the interfacial energy release rate for a novel simple 3-point flexural test model. The test was validated using two different configurations of layered zirconia/porcelain beams (n = 10), approximating the dimensions of a fixed dental prosthesis, fabricated from a tetragonal polycrystalline zirconium dioxide partially stabilized with yttria and a feldspathic dental porcelain. RESULTS Cracking along the bimaterial interface was produced and measured as a discrete event. Fracture toughness means (standard deviations) computed from the measured energy release rate, for the porcelain to zirconia interface in two different specimen configurations were 7.9 (1.3) and 5.3 (1.6) J/m2. CONCLUSIONS Equations were derived to measure interfacial fracture toughness of brittle materials using a novel simple 3-point flexural test method. The test was then validated; estimates for the fracture toughness for the porcelain to zirconia bond, overlapped with previously published data derived from more complex 4-point notched tests.
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