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Silmeoglu Yagli O, Talay Cevlik E, Kurklu Arpacay D. The impact of aging and thickness on flexural strength of various zirconia ceramics. BMC Oral Health 2024; 24:967. [PMID: 39164712 PMCID: PMC11337592 DOI: 10.1186/s12903-024-04745-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 08/13/2024] [Indexed: 08/22/2024] Open
Abstract
BACKGROUND Effects of the aging process on the flexural strength of Y-TZP and different Y-PSZ ceramics of different thicknesses were investigated. METHODS 300 disc-shaped samples (12 mm diameter, 0.8 and 1.5 mm thicknesses) were made from 5 different zirconia materials 3Y-TZP LA, 4Y-PSZ, 5Y-PSZ, 3 + 5Y-PSZ and 4 + 5Y-PSZ. Experimental groups were artificially aged in an autoclave at 134 °C, 2 bar pressure for 1 and 5 h; control groups were not subjected to any treatment. Microstructural analysis was conducted using Scanning Electron Microscopy, and X-Ray Diffraction analysis determined the crystalline phase content. The impact of aging on flexural strength was investigated with the use of the biaxial flexural strength test. Data were analyzed using three-way ANOVA tests with a significance level of p < 0.05, applying Bonferroni correction for multiple comparisons. RESULTS Statistically significant differences in flexural strength were observed among the materials and the material thicknesses (p < 0.05), while there were no significant differences among the aging times (p > 0.05). The highest mean flexural strength values were recorded in the case of the 3 Y-TZP-1.5 mm-5 h group (744.1 ± 61.2 MPa), which was attributed to phase-transformation toughening. The lowest values were observed in the case of the 5 Y-PSZ-1.5 mm-5 h (338.3 ± 34.8 MPa) group. CONCLUSIONS Both material type and thickness significantly affect the flexural strength of zirconia ceramics, whereas aging time does not; thus, material selection and thickness are crucial considerations for clinicians.
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Affiliation(s)
- Oyku Silmeoglu Yagli
- Faculty of Dentistry, Department of Prosthodontics, Aydın Adnan Menderes University, Efeler, Aydın, Türkiye
| | - Esra Talay Cevlik
- Faculty of Dentistry, Department of Prosthodontics, Aydın Adnan Menderes University, Efeler, Aydın, Türkiye.
| | - Duygu Kurklu Arpacay
- Faculty of Dentistry, Department of Prosthodontics, Izmir Democracy University, Konak, Izmir, Türkiye
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Salama AA, Shehab KA, Bushra SS, Hamza FS. The effect of aging on the translucency of contemporary zirconia generations: in-vitro study. BMC Oral Health 2024; 24:744. [PMID: 38937719 PMCID: PMC11212148 DOI: 10.1186/s12903-024-04465-6] [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: 11/28/2023] [Accepted: 06/07/2024] [Indexed: 06/29/2024] Open
Abstract
BACKGROUND The translucency of different zirconia generations at each time point after thermocycling aging is still lacking. METHODS Four zirconia materials were used with a total of 60 samples produced from monolithic third generation (5Y) 5 mol% yttria-stabilized zirconia polycrystalline ceramic and fourth generation zirconia (4Y) 4 mol% yttria-stabilized zirconia polycrystalline ceramic, represented by [group1:[CM-5Y] Ceramill Zolid fx (3rd generation zirconia) (Amann Girrbach, Koblach, Austria), group 2:[CM-4Y] Ceramill Zolid HT + (4th generation zirconia) (Amann Girrbach, Koblach, Austria), group 3:[CC-5Y] Cercon XT/ML (Dentsply Sirona, Germany) (3rd generation), and group 4:[CC-4Y] Cercon HT/ML (Dentsply Sirona, Germany) (4th generation)]. The L*a*b* figures were measured by using a spectrophotometer at baseline and after 10,000, 30,000, and 50,000 cycles of thermocycling. At each interval, the translucency of the samples was estimated by using the translucency formula CIEDE2000. The Scheffe post-hoc compared differences among each of the four materials. The Repeated measures ANOVA tested the differences between the materials at each of the different thermocycling intervals (p < .001). Data analyses were evaluated at a significance level of p < .05 (CI 95%). RESULTS Two-way ANOVA revealed that at baseline the third and fourth generation's zirconia showed statistically significant differences in translucency (P < .001). Translucency values at baseline and after thermocycling exhibited statistically significant changes (p = .003). At each of the time interval; CM-4Y had the highest translucency values followed by CM-5Y, CC-4Y and CC-5Y had the least translucency values. CONCLUSIONS The third and fourth generations of zirconia displayed different translucencies. Thermocycling affected the translucency of both third and fourth generations of zirconia. At each of the time intervals group 2:[CM-4Y] had the highest TP followed by group1:[CM-5Y], while, group 3:[CC-5Y] and group 4:[CC-4Y] had the least TP.
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Affiliation(s)
- Aya A Salama
- Department of Fixed Prosthodontics, October University for Modern Sciences and Arts, Giza, Egypt.
| | - Karim A Shehab
- Lecturer of Orthodontics, October University for Modern Sciences and Arts, Giza, Egypt
| | - Sherif Samir Bushra
- Department of Fixed Prosthodontics, October University for Modern Sciences and Arts, Giza, Egypt
| | - Faisal Safwat Hamza
- Department of Fixed Prosthodontics, October University for Modern Sciences and Arts, Giza, Egypt
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Labetić A, Klaser T, Skoko Ž, Jakovac M, Žic M. Flexural Strength and Morphological Study of Different Multilayer Zirconia Dental Materials. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1143. [PMID: 38473614 DOI: 10.3390/ma17051143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/14/2024] [Accepted: 02/19/2024] [Indexed: 03/14/2024]
Abstract
Nowadays, yttria (Y3+)-stabilized ZrO2 (Y-TZP) is the most commonly used material in dental prosthetics. Y-TZP dental ceramics are mainly stabilized via the addition of 3 mol% yttrium oxide (Y2O3). These ceramics exhibit excellent mechanical properties, including high flexural strength, fracture toughness, elastic modulus, etc. Some manufacturers have recently introduced a new class of dental materials with multilayer composition with the aim of combining the advantages of adding more or less Y2O3 to the ceramic composition in one Y-TZP material. The flexural strength values of multilayer Y-TZP may vary depending on the dimensions of the specimen, layer distributions, and especially the layer exposed on the maximum tension side, i.e., loading configuration. Although previous studies have examined the flexural strength of separate Y-TZP layers, capturing the flexural strength of multilayer Y-TZP is still challenging. However, one should keep in mind that multilayer flexural strength is important for clinical indications. The objective of this study is to compare the flexural strength of three distinct multilayer translucent Y-TZP materials made up of layers with different Y3+ contents. Rectangular samples (2 mm × 2 mm × 16 mm) were prepared from CAD/CAM discs using the milling machine Programill PM7 (Ivoclar Vivadent AG). Milled bars were tested for flexural strength in a three-point bending test (ISO 6872:2015) using a universal testing machine (Inspekt Duo 5kN; Hegewald & Peschke, Nossen, Germany) at a crosshead speed of 0.5 mm/min. Representative samples of each type of material were selected for quantitative and qualitative analysis of the microstructure. Representative samples of each type of material were selected for structural, mechanical, and microstructural analyses.
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Affiliation(s)
- Andrea Labetić
- University of Zagreb School of Dental Medicine, Gunduliceva 5, 10000 Zagreb, Croatia
| | - Teodoro Klaser
- Ruder Boskovic Institute, P.O. Box 180, 10000 Zagreb, Croatia
| | - Željko Skoko
- Department of Physics, Faculty of Science, University of Zagreb, Bijenicka, c. 32, 10000 Zagreb, Croatia
| | - Marko Jakovac
- University of Zagreb School of Dental Medicine, Gunduliceva 5, 10000 Zagreb, Croatia
| | - Mark Žic
- Ruder Boskovic Institute, P.O. Box 180, 10000 Zagreb, Croatia
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Dokuzlu SN, Subaşı MG. Effect of sintering programs and surface treatments on monolithic zirconia. J Adv Prosthodont 2024; 16:25-37. [PMID: 38455679 PMCID: PMC10917628 DOI: 10.4047/jap.2024.16.1.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/28/2024] [Accepted: 02/13/2024] [Indexed: 03/09/2024] Open
Abstract
PURPOSE To investigate the effect of sintering programs and surface treatments on surface properties, phase transformation and flexural strength of monolithic zirconia. MATERIALS AND METHODS Zirconia specimens were sintered using three distinct sintering programs [classic (C), speed (S), and superspeed (SS)] (n = 56, each). One sample from each group underwent scanning electron microscopy (SEM) and grain size analysis following sintering. Remaining samples were divided into five subgroups (n = 11) based on the surface treatments: control (CL), polish (P), glaze (G), grind + polish (GP), and grind + glaze (GG). One sample from each subgroup underwent SEM analysis. Remaining samples were thermally aged. Monoclinic phase volume, surface roughness, and three-point flexural strength were measured. Monoclinic phase volume and surface roughness were analyzed by Kruskal-Wallis and Dunn tests. Flexural strength was analyzed by two-way ANOVA and Weibull analysis. The relationships among the groups were analyzed using Spearman's correlation analysis. RESULTS Sintering program, surface treatment, and sintering × surface treatment (P ≤ .010) affected the monoclinic phase volume, whereas the type of surface treatment and sintering × surface treatment affected the surface roughness (P < .001). Type of sintering program or surface treatment did not affect the flexural strength. Weibull analysis revealed no significant differences between the m and σo values. Monoclinic phase volume was positively correlated with surface roughness in the SGG and SSP groups. CONCLUSION After sintering monolithic zirconia in each of the three sintering programs, each of the surface treatments can be used. However, for surface quality and aging resistance, G or GG can be recommended as a surface finishing method.
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Affiliation(s)
| | - Meryem Gülce Subaşı
- Department of Prosthodontics, Faculty of Dentistry, Kütahya Sağlık Bilimleri University, Kütahya, Turkey
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Hajhamid B, Bozec L, Tenenbaum H, De Souza G, Somogyi-Ganss E. Effect of artificial aging on optical properties and crystalline structure of high-translucency zirconia. J Prosthodont 2024; 33:61-69. [PMID: 36641491 DOI: 10.1111/jopr.13648] [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: 06/27/2022] [Revised: 01/10/2023] [Accepted: 01/10/2023] [Indexed: 01/16/2023] Open
Abstract
PURPOSE To investigate the effect of different in vitro aging protocols on the optical properties and crystalline structure of high-translucency (HT) zirconia. MATERIALS AND METHODS Thirty-six specimens of HT and extra-high translucency (XT) zirconia were divided into three groups: control (CO)-no treatment; hydrothermal aging (HA)-autoclave aging for 12.5 h at 134°C, 2 bar; clinically related aging (CRA)-aging in the chewing simulator for 1.2 million cycles, followed by 50,000 thermocycles (5-55°C) and immersion in HCl (pH 1.2) for 15 h. Optical properties, crystalline structure, and surface roughness were analyzed and compared using analysis of variance (5% significance level). RESULTS There was no statistically significant effect of aging on translucency (p = 0.10), but CRA promoted the development of a high contrast ratio (p = 0.03). Aging did not cause significant color changes for HT (p = 0.65) or XT (p = 0.36). The proportion of monoclinic crystals increased to 40% for HT-zirconia after HA and 5% after CRA. No monoclinic crystals were detected for XT groups. There was no effect of aging on surface roughness (p = 0.77). CONCLUSIONS Although hydrothermal aging has been widely used to verify zirconia crystalline stability, it did not generate an effect similar to clinically related aging on the optical properties and crystalline structure of zirconia. HA affected the crystalline structure of HT-zirconia, and CRA compromised the optical properties of XT zirconia.
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Affiliation(s)
- Beshr Hajhamid
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Laurent Bozec
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Howard Tenenbaum
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Grace De Souza
- Department of Comprehensive Dentistry, School of Dentistry, University of Louisville, Louisville, Kentucky, USA
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Kim SH, Oh NS, Pang NS, Jung BY. The effect of surface treatment and low-temperature degradation on flexural strength of additive manufactured zirconia. J Mech Behav Biomed Mater 2023; 148:106167. [PMID: 37837875 DOI: 10.1016/j.jmbbm.2023.106167] [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: 08/31/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/16/2023]
Abstract
This study aimed to assess the effect of low-temperature degradation (LTD) and surface treatment on the flexural strength of additive-manufactured (AM) zirconia by comparison to subtractive-manufactured (SM) zirconia. Disc-shaped zirconia specimens were fabricated using AM and SM technology, and each group was assigned to 3 subgroups according to the type of surface treatment: control, sandblasting (SB), and 9% hydrofluoric acid etching (HF). The groups were then further divided into 2 subgroups: unaged and aged. Biaxial flexural strength, crystal phase, surface topography, and surface roughness were measured to evaluate the mechanical properties. Statistical analyses were performed with 3-way ANOVA, followed by the comparison of means with Bonferroni post hoc analyses. The means and standard deviations of the biaxial flexural strength and Weibull parameters were calculated with descriptive statistics. All SM groups showed significantly greater flexural strength than the AM groups (p < .05), and LTD did not affect flexural strength except for the SMHF group (p < .05). After LTD, monoclinic phases (m-phase) were found in all groups, and SEM images showed grain pullout due to zirconia volume expansion in both control groups. Sandblasting significantly affected flexural strength (p < .05), whereas the HF group did not affect flexural strength except in the SMHF group after LTD (p < .05). No significant difference was observed in the surface roughness of AM compared to SM groups conditioned with the same surface treatment regardless of LTD. AM zirconia has comparable mechanical properties to SM zirconia, regardless of low-temperature degradation and surface treatment, which indicates the potential of the AM technique for clinical applications.
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Affiliation(s)
- So-Hyun Kim
- Department of Dentistry, Inha University School of Medicine, Inha University Hospital, Incheon, South Korea.
| | - Nam-Sik Oh
- Department of Dentistry, Inha University School of Medicine, Inha University Hospital, Incheon, South Korea.
| | - Nan-Sim Pang
- Department of Advanced General Dentistry, Yonsei University, College of Dentistry, Seoul, South Korea.
| | - Bock-Young Jung
- Department of Advanced General Dentistry, Yonsei University, College of Dentistry, Seoul, South Korea.
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Wille S, Möller R, Kern M. Influence of shading on zirconia's phase transformation and flexural strength after artificial aging. Dent Mater 2023; 39:702. [PMID: 37385942 DOI: 10.1016/j.dental.2023.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 05/17/2023] [Accepted: 06/14/2023] [Indexed: 07/01/2023]
Abstract
OBJECTIVES The aim of this study was to determine the phase transformation and the influence of aging on the flexural strength of different colored zirconia. The effect of hydrothermal aging in an autoclave was compared with the effect of mechanical stress by simulating chewing. METHODS High-strength zirconia (3Y-TZP) was investigated in three different colors: uncolored, A3, and D3. Disc-shaped specimens (N = 3) were analyzed by X-ray diffraction (XRD), and flexural strength was determined on bar-shaped specimens (N = 15) in a 4-point bending test before and after performing two different aging protocols: aging in an autoclave (134 °C, 70 h) and aging in a chewing simulator (5 kg load, 1.2 million cycles). During autoclave aging, the fraction of monoclinic phase on the surface was determined every 5 h. Once this exceeded 25 vol%, aging of the bar specimens was stopped. RESULTS While in the unstained group the mean value of the proportion of monoclinic phase already exceeded 25 vol% after 30 h in the autoclave, this was the case in both stained groups only after 70 h. No measurable phase transformation could be detected after chewing simulation. Only color A3 showed a statistically significant (p ≤ 0.05) decrease in flexural strength after aging in the chewing simulator. SIGNIFICANCE The colored zirconia showed a higher resistance to phase transformation through hydrothermal aging. The metal oxides in the staining solutions are assumed to hinder the phase transformation in the zirconia. Therefore, the significant reduction in the stained zirconia after chewing simulation is particularly interesting.
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Affiliation(s)
- Sebastian Wille
- Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany.
| | - Rüdiger Möller
- Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany.
| | - Matthias Kern
- Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany.
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Alfrisany NM, Somogyi-Ganss E, Tam L, Hatton BD, Sodhi RN, De Souza GM. Room-temperature atomic layer deposition of SiO2 on microcracked ZrO2 layers. J Mech Behav Biomed Mater 2022; 134:105410. [DOI: 10.1016/j.jmbbm.2022.105410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/28/2022] [Accepted: 08/01/2022] [Indexed: 10/15/2022]
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Dimitriadis K, Sfikas AK, Kamnis S, Tsolka P, Agathopoulos S. Influence of heat treatment on the microstructure and the physical and mechanical properties of dental highly translucent zirconia. J Adv Prosthodont 2022; 14:96-107. [PMID: 35601351 PMCID: PMC9095450 DOI: 10.4047/jap.2022.14.2.96] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/09/2022] [Accepted: 04/12/2022] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Microstructural and physico-mechanical characterization of highly translucent zirconia, prepared by milling technology (CAD-CAM) and repeated firing cycles, was the main aim of this in vitro study. MATERIALS AND METHODS Two groups of samples of two commercial highly-translucent yttria-stabilized dental zirconia, VITA YZ-HTWhite (Group A) and Zolid HT + White (Group B), with dimensions according to the ISO 6872 "Dentistry - Ceramic materials", were prepared. The specimens of each group were divided into two subgroups. The specimens of the first subgroups (Group A1 and Group B1) were merely the sintered specimens. The specimens of the second subgroups (Group A2 and Group B2) were subjected to 4 heat treatment cycles. The microstructural features (microstructure, density, grain size, crystalline phases, and crystallite size) and four mechanical properties (flexural strength, modulus of elasticity, Vickers hardness, and fracture toughness) of the subgroups (i.e. before and after heat treatment) were compared. The statistical significance between the subgroups (A1/A2, and B1/B2) was evaluated by the t-test. In all tests, P values smaller than 5% were considered statistically significant. RESULTS A homogenous microstructure, with no residual porosity and grains sized between 500 and 450 nm for group A and B, respectively, was observed. Crystalline yttria-stabilized tetragonal zirconia was exclusively registered in the X-ray diffractograms. The mechanical properties decreased after the heat treatment procedure, but the differences were not statistically significant. CONCLUSION The produced zirconia ceramic materials can be safely (i.e., according to the ISO 6872) used in extensive fixed prosthetic restorations, such as substructure ceramics for three-unit prostheses involving the molar restoration and substructure ceramics for prostheses involving four or more units. Consequently, milling technology is an effective manufacturing technology for producing zirconia substructures for dental fixed all-ceramic prosthetic restorations.
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Affiliation(s)
- Konstantinos Dimitriadis
- Division of Dental Technology, Department of Biomedical Sciences, University of West Attica, Athens, Greece
| | | | - Spyros Kamnis
- Castolin Eutectic-Monitor Coatings Ltd, Newcastle, United Kingdom
| | - Pepie Tsolka
- Division of Dental Technology, Department of Biomedical Sciences, University of West Attica, Athens, Greece
| | - Simeon Agathopoulos
- Department of Materials Science and Engineering, School of Engineering, University of Ioannina, Ioannina, Greece
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Hajhamid B, Alfrisany N, Somogyi-Ganss E. The effect of accelerated aging on crystalline structures and optical properties of different monolithic zirconia: A qualitative systematic review. Dent Mater 2022; 38:569-586. [DOI: 10.1016/j.dental.2022.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 02/14/2022] [Indexed: 11/03/2022]
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Bitencourt SB, Hatton BD, Bastos-Bitencourt NA, Micheline dos Santos D, Pesqueira AA, De Souza GM. Silica deposition on zirconia via room-temperature atomic layer deposition (RT-ALD): Effect on bond strength to veneering ceramic. J Mech Behav Biomed Mater 2022; 129:105142. [DOI: 10.1016/j.jmbbm.2022.105142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/18/2022] [Accepted: 02/23/2022] [Indexed: 10/19/2022]
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Surface and bulk properties of zirconia as a function of composition and aging. J Mech Behav Biomed Mater 2021; 126:104994. [PMID: 34864575 DOI: 10.1016/j.jmbbm.2021.104994] [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: 09/30/2021] [Revised: 11/18/2021] [Accepted: 11/21/2021] [Indexed: 01/08/2023]
Abstract
Yttria-stabilized zirconia (Y-SZ) materials with different levels of translucency have been used for indirect dental restorations. Y-SZ composition and microstructure are modified to improve translucency, and it is not clear how these materials respond to aging. This study evaluated the effect of hydrothermal aging (HA) performed in an autoclave on the properties of four dental Y-SZ materials with different compositions. Sintered bar-shaped specimens (14 x 4 x 2 mm) were prepared from four different zirconia-based materials (n = 40): low translucency 3 mol % Y-SZ (3Y-LT; Ceramill ZI, Amann Girrbach); high translucency 4 mol % Y-SZ (4Y-HT; Ceramill Zolid); and two high translucency 5 mol % Y-SZ (5Y-HT - Lava Esthetic, 3M; 5Y-SHT - Ceramill Zolid FX). Fully sintered specimens were exposed to HA for different times (control - 0 h, 5 h, 10 h, or 15 h at 134 °C, 2 bar pressure) and characterized for surface roughness, flexural strength (three-point bending), hardness and elastic modulus (nanoindentation), surface wettability (sessile drop technique) and crystalline content (x-ray diffraction, XRD). Data was analyzed by two-way ANOVA and Tukey HSD (p < 0.05). Zirconia composition significantly affected roughness (p = 0.016). Zirconia*aging interaction affected flexural strength (p = 0.012), surface wettability (p < 0.001), and hardness (p = 0.002). Zirconia composition (p = 0.011) and aging (p = 0.001) affected elastic modulus, while the interaction effect was not significant (p = 0.94). HA affects zirconia-based materials in different degrees. For 3Y-LT and 4Y-HT, surface and bulk properties were affected by aging to a similar extent. However, surface and bulk properties may change during clinical use as a result of prolonged degradation of Y-SZ.
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Surface characterization of different surface treatments associations with plasma and bonding analysis of Y-TZP and the veneering ceramic. Dent Mater 2021; 37:1873-1883. [PMID: 34702557 DOI: 10.1016/j.dental.2021.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 09/29/2021] [Accepted: 10/06/2021] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To characterize the surface of zirconia (Y-TZP) submitted to different surface treatments (with and without plasma associations) and to evaluate the shear bond strength (SBS) between veneering ceramic (VC) and Y-TZP after different aging methods. METHODS 301 Y-TZP specimens were fabricated and distributed into 7 groups: C (control): no treatment; Al: airborne abrasion with 27 μm Al2O3 particle; L: liner; P: plasma; Al + L: airborne + liner; Al + P: airborne + plasma; P + L: plasma + liner. The Y-TZP surface was characterized by SEM, EDS, AFM, surface profilometry, surface-free energy (SFE), and XRD. SBS between Y-TZP and VC was verified after three aging protocols: initial, after hydrothermal aging (autoclave for 5 h), or thermal fatigue (30,000 baths - 5-55 °C). One- (profilometry, SFE) and two-way ANOVA (SBS), and Tukey's HSD test were used. RESULTS For the plasma groups, a full globular surface coverage was observed (SEM, AFM). Si was found for Al, L, Al + L, and P + L. Roughness was lower for C, P, and Al + P. For SFE, the highest values were found when the liner was applied (>74.59 nm/Nm). The highest monoclinic content was observed for Al + L (6.96%) and Al + P (5.86%). For the initial period, Al and P + L presented the lowest SBS values (<5.85 MPa; P > 0.331). The highest SBS values were found for L, P, and P + L (hydrothermal aging) and for P, L, Al + L, and Al + P (thermal fatigue). SIGNIFICANCE Changes in Y-TZP topography and the SBS with the VC were found, according to treatments performed. Plasma treatment improved SBS and did not cause phase transformation.
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Kong MC, Park MG. Effect of sintering condition and low-temperature degradation on the flexural strength and phase transformation of zirconia. J Prosthet Dent 2021; 126:692.e1-692.e14. [PMID: 34598770 DOI: 10.1016/j.prosdent.2021.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 07/30/2021] [Accepted: 07/30/2021] [Indexed: 11/16/2022]
Abstract
STATEMENT OF PROBLEM The traditional sintering of zirconia takes an extended time, and accelerated treatments have been developed to reduce treatment time and manufacturing costs. Studies evaluating the effect of sintering time on the mechanical properties of zirconia are lacking. PURPOSE The purpose of this in vitro study was to evaluate the effect of the sintering condition and the low-temperature degradation (LTD) of zirconia on the flexural strength of monolithic zirconia. MATERIAL AND METHODS Zirconia specimens (LUXEN Enamel) were sintered at 1500 °C, 1530 °C, and 1560 °C for 4, 5, 6, 7, and 12 hours and subjected to LTD (n=10). Control specimens were assessed in the nontreated condition. The 3-point flexural strength was measured by using a universal testing machine. The crystal phases of the specimens were compared and quantitatively analyzed through X-ray diffraction (XRD) analysis, and the crystal grain size was measured by using a field emission scanning electron microscope (FE-SEM). Two-way ANOVA and the independent sample t test were used to analyze the experimental results (α=.05). RESULTS In the group not subjected to LTD, there was no difference in flexural strength according to the change in sintering temperature and sintering time (P>.05). The group subjected to LTD showed a difference in flexural strength according to sintering time difference (P<.001). The flexural strength of the zirconia with LTD exposure increased compared with that of the zirconia specimen not subjected to LTD (P<.001). With LTD exposure, cubic and monoclinic crystals increased, tetragonal crystals decreased, and the particle size increased. As the sintering temperature increased, the particle size increased, but not according to the sintering time. CONCLUSIONS At all sintering times, the flexural strength of zirconia was over 800 MPa, which is the minimum flexural strength of a 4-unit or longer prosthesis as specified in the International Organization for Standardization (ISO) 6872. With LTD exposure, the increase in the flexural strength of zirconia was associated with the phase change from tetragonal to monoclinic.
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Affiliation(s)
- Moon-Chun Kong
- Lecturer, Department of Dental Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Republic of Korea
| | - Mi-Gyoung Park
- Professor and Chairman, Department of Dental Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Republic of Korea.
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Bastos-Bitencourt NA, Soares Bombonatti JF, Bitencourt SB, Hatton BD, De Souza GM. Mechanical performance of a hybrid zirconia developed through hydrothermal treatment and Room-Temperature Atomic Layer Deposition (RT-ALD). J Mech Behav Biomed Mater 2021; 123:104783. [PMID: 34419886 DOI: 10.1016/j.jmbbm.2021.104783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/10/2021] [Accepted: 08/16/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE A silica-based nanofilm has been successfully deposited via Room-Temperature Atomic Layer Deposition (RT-ALD) on the surface of a glass. The purpose of this study was to evaluate the mechanical performance of a hybrid interface created between yttria-stabilized zirconia (Y-PSZ) transformed layer and silica-based nanofilm via RT-ALD. MATERIAL AND METHODS Fully-sintered Y-PSZ (14 × 4.0 × 1.5 mm) specimens in different translucencies (MO, MT, LT; IPS e.max Zircad, Ivoclar Vivadent) were distributed in 5 groups: control (C - no treatment); hydrothermal treatment (HT- 15h, 134°C, 2 bar); alumina blasting (B - 50 μm Al2O3); RT-ALD silica deposition (S); HT followed by silica deposition (HTS). RT-ALD cycles consisted of the sequential exposure of specimens to tetramethoxysilane orthosilicate (TMOS - 60s) and ammonium hydroxide (NH4OH - 10 min) vapors in 40 cycles. Mechanical performance was analyzed by flexural strength (FS) (n = 10) and fatigue failure load (staircase method; n = 20) tests. Surface hardness (H) and Young's modulus (YM) were analyzed by nanoindentation. For surface chemical and topographical characterization, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were performed. Data from surface H, YM, FS, and fatigue limit (FL) were analyzed by two-way analysis of variance (ANOVA). RESULTS The interaction between material and treatment had a significant effect on FS (p < 0.001). The FS values ranged from 436.23 MPa to 856.65 MPa. HT resulted in the highest FS (856.65 MPa) for LT and the lowest FS (436.23 MPa) for MO zirconia. For all materials, S and B treatments resulted in similar FS values (p > 0.410). S did not affect FL when compared to the C group (p > 0.277) for any material investigated. HTS resulted in higher FL than S for LT and MO materials (p < 0.001). Surface hardness and modulus were similar between control and S-treated specimens for all materials analyzed. XPS analysis showed homogeneous silica content after 20 and 40 RT-ALD cycles, and SEM did not show significant changes in surface morphology between C and S-treated specimens. CONCLUSION RT-ALD resulted in effective silica deposition without any deleterious effect on zirconia-based materials mechanical properties. Alumina blasting promoted higher alteration on surface topography. HT prior to S resulted in superior FL (for MO and MT) and flexural strength (MO) for some of the materials investigated.
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Affiliation(s)
- Natália Almeida Bastos-Bitencourt
- Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of Sao Paulo, Bauru, Brazil
| | - Juliana Fraga Soares Bombonatti
- Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of Sao Paulo, Bauru, Brazil
| | - Sandro Basso Bitencourt
- Department of Dental Materials and Prosthodontics, Sao Paulo State University (UNESP), School of Dentistry, Araçatuba, Sao Paulo, Brazil
| | - Benjamin D Hatton
- Materials Science and Engineering, University of Toronto, ON, Canada
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Solá-Ruíz MF, Rico-Coderch A, Montiel-Company JM, Fons-Badal C, Verdejo-Solá B, Agustín-Panadero R. Influence of the chemical composition of monolithic zirconia on its optical and mechanical properties. Systematic review and meta-regression. J Prosthodont Res 2021; 66:193-207. [PMID: 34176849 DOI: 10.2186/jpr.jpr_d_20_00218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE This systematic review set out to investigate the influence of chemical composition and specimen thickness of monolithic zirconia on its optical and mechanical properties. Meta-analysis and meta-regression analyzed the effects of variations in percentages of yttrium, aluminum, and specimen thickness of monolithic zirconia. STUDY SELECTION The review followed recommendations put forward in the PRISMA checklist. An electronic search for relevant articles published up to October 2019 was conducted in the Pubmed, Cochrane, Scopus, Scielo, and Web of Science databases, with no language limits and articles published in the last 10 years. From 167 relevant articles; applying inclusion criteria based on the review's PICO question, 26 articles were selected for qualitative synthesis (systematic review) and 24 for quantitative synthesis (meta-analysis). Experimental in vitro studies published were selected and their quality was assessed using the modified Consort scale for in vitro studies of dental materials. RESULTS The variables yttrium, aluminum and thickness were analyzed in random effects models, observing high heterogeneity ( > 75%), and finding statistically significant influences on the properties of monolithic zirconia (p<0.05). CONCLUSIONS Within the review's limitations, it may be concluded that variations in the percentage of yttrium and aluminum influence the optical and mechanical properties of monolithic zirconia, making it more or less esthetic and resistant in relation to each variable. The clinical implications of these findings can help select the most appropriate type of zirconia to meet the different clinical needs when restoring different regions (posterior or anterior).
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Affiliation(s)
| | - Aitana Rico-Coderch
- Department of Stomatology, Faculty of Medicine and Dentistry, University of Valencia, Valencia
| | | | - Carla Fons-Badal
- Department of Stomatology, Faculty of Medicine and Dentistry, University of Valencia, Valencia
| | - Blanca Verdejo-Solá
- Department of Medicine, Faculty of Medicine and Dentistry, Universidad Cardenal Herrera-CEU, Valencia
| | - Rubén Agustín-Panadero
- Department of Stomatology, Faculty of Medicine and Dentistry, University of Valencia, Valencia
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Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere. MATERIALS 2021; 14:ma14112767. [PMID: 34071126 PMCID: PMC8197138 DOI: 10.3390/ma14112767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/18/2021] [Accepted: 05/21/2021] [Indexed: 11/23/2022]
Abstract
Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.
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Clinical evaluation of monolithic zirconia multiunit posterior fixed dental prostheses. J Prosthet Dent 2021; 128:1258-1264. [PMID: 33902890 DOI: 10.1016/j.prosdent.2021.02.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 11/21/2022]
Abstract
STATEMENT OF PROBLEM Monolithic zirconia restorations have been evaluated with in vitro studies, but limited clinical evidence of their longevity and reliability is available. PURPOSE The purpose of this clinical study was to evaluate the clinical performance of posterior multiunit glazed monolithic zirconia fixed dental prostheses. MATERIAL AND METHODS A total of 20 participants received 33 monolithic posterior zirconia fixed dental prostheses (Zolid white; Amann Girrbach AG) with minimally invasive preparations. Bilaterally supported fixed dental prostheses with a connector area of at least 9 mm2 were luted with resin-modified glass ionomer cement. The clinical evaluations were performed after 1 week, 6 months, and then annually after completion of the treatment. The biologic outcomes were evaluated by assessing the pocket depth, attachment level, plaque control, bleeding on probing, caries, and tooth vitality. Esthetics and the functional performance of the prostheses (color match, cavosurface marginal discoloration, anatomic form, marginal adaptation) were evaluated as per the rating scales of Cvar and Ryge. An analysis of survival was made by using the Kaplan-Meier method. RESULTS After 39.8 ±16.7 months of observation, the overall survival rate of the monolithic zirconia multiunit posterior prostheses was 93.9%. No caries were found on the abutment teeth, signs of gingivitis were noted in 1 participant after 24 months, and increased probing depths of the abutment teeth were detected in 5 prostheses (15.1%). No loss of retention was detected. Two prostheses had to be replaced: 1 because of a biologic complication and 1 because of a technical complication. The remaining 31 prostheses received Alfa scores for marginal adaptation, cavosurface marginal discoloration, and caries. Twenty-seven (87.1%) prostheses were rated as Alfa and 4 (12.9%) as Bravo for anatomic form. The color match was noted as Alfa in 15 (48.3%) prostheses, and 16 (51.6%) were rated as Bravo. CONCLUSIONS Monolithic zirconia restorations demonstrated a reliable treatment option after medium-term clinical use for the replacement of missing posterior teeth.
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Fathy SM, Al-Zordk W, E Grawish M, V Swain M. Flexural strength and translucency characterization of aesthetic monolithic zirconia and relevance to clinical indications: A systematic review. Dent Mater 2021; 37:711-730. [PMID: 33581910 DOI: 10.1016/j.dental.2021.01.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/15/2020] [Accepted: 01/20/2021] [Indexed: 02/04/2023]
Affiliation(s)
- Salma M Fathy
- Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Zagazig University, Zagazig, Egypt.
| | - Walid Al-Zordk
- Fixed Prosthodontics Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt
| | - Mohammed E Grawish
- Oral Biology Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt
| | - Micheal V Swain
- Discipline of Biomaterials, Faculty of Dentistry, University of Sydney, Australia
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Juri AZ, Basak AK, Yin L. Microstructural responses of Zirconia materials to in-situ SEM nanoindentation. J Mech Behav Biomed Mater 2021; 118:104450. [PMID: 33740687 DOI: 10.1016/j.jmbbm.2021.104450] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/27/2021] [Accepted: 03/02/2021] [Indexed: 11/18/2022]
Abstract
Development of optimal shaping processes for pre-sintered and sintered zirconia materials requires a fundamental understanding of damage and deformation mechanisms at small-scale contacts with diamond tools. This paper reports on responses of zirconia materials with distinct microstructures to nanoindentation associated with diamond machining using a Berkovich diamond indenter. In-situ nanoindentation was performed in a scanning electron microscope (SEM) and in-process filmed to record small contact events. Indentation morphology was SEM-mapped at high-magnifications. Although both pre-sintered porous and sintered dense zirconia materials mechanically revealed the quasi-plastic behavior in indentation, there were distinct responses of the two materials to quasi-plasticity at the microstructural level. For pre-sintered porous zirconia, the quasi-plasticity was attributed to shear faults resulting from breaking pore networks as microstructurally discrete interfaces, to lead to compression, fragmentation, pulverization and microcracking of zirconia crystals in indentation imprints. In contrast, sintered dense zirconia had shear band-induced quasi-plastic deformation, accompanied with localized tensile microfracture. A material index associated with the mechanical properties ranked the lower quasi-plasticity for pre-sintered porous zirconia than its sintered dense state, predicting more machining-induced damage in the former than the latter. Significantly higher indentation imprint volumes induced in indented pre-sintered porous zirconia than sintered dense state previses higher machining efficiency for the former than the latter. The microstructure-dependent indentation mechanisms provide the fundamental knowledge into micromechanics of abrasive machining of zirconia materials and may lead to a new microstructural design for zirconia materials to achieve a balanced machining efficiency and damage control.
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Affiliation(s)
- Afifah Z Juri
- School of Mechanical Engineering, The University of Adelaide, Adelaide, 5005, SA, Australia.
| | - Animesh K Basak
- Adelaide Microscopy, The University of Adelaide, Adelaide, 5005, SA, Australia
| | - Ling Yin
- School of Mechanical Engineering, The University of Adelaide, Adelaide, 5005, SA, Australia.
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Effects of Aging on the Color and Translucency of Monolithic Translucent Y-TZP Ceramics: A Systematic Review and Meta-Analysis of In Vitro Studies. BIOMED RESEARCH INTERNATIONAL 2021; 2021:8875023. [PMID: 33575352 PMCID: PMC7857873 DOI: 10.1155/2021/8875023] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/08/2020] [Accepted: 01/11/2021] [Indexed: 11/27/2022]
Abstract
Background Monolithic restorations made of translucent yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) have become popular over the past few decades. However, whether aging affects the color and translucency of monolithic translucent Y-TZP is unclear. Objective The aim of this systematic review and meta-analysis of in vitro studies was to evaluate the effects of aging on the color and translucency of monolithic translucent Y-TZP ceramics. Materials and Methods This systematic review/meta-analysis was reported according to the PRISMA statement and registered in the OSF registries (https://osf.io/5qjmu). Four databases including Medline via the PubMed, Embase, and Web of Science databases and the Cochrane Library were searched using no publication year and language limits. The last search was executed on November 20, 2020. In vitro studies comparing the translucency and/or color of monolithic translucent Y-TZP ceramics before and after simulated aging were selected. Meta-analyses were performed using Review Manager software (version 5.3, Cochrane Collaboration, Oxford, UK) with random-effects models at a significance level of 0.05. A risk-of-bias assessment was also performed for the included studies. Results Of the 188 potentially relevant studies, 13 were included in the systematic review. The hydrothermal aging duration ranged from 1 to 100 h at relatively similar temperatures (~134°C). In the general meta-analyses, the aged Y-TZP ceramics exhibited similar translucency parameter (TP), L∗, and b∗ values compared with the nonaged controls (P = .73, P = .49, and P = .62, respectively). Moreover, there was a significant difference between the aged and nonaged Y-TZP ceramics in the a∗ value (P = .03; MD = −0.26; 95% CI = −0.51 to − 0.02), favoring the nonaged Y-TZP ceramics. The subgroup analyses showed that the duration of aging contributed to changes in the translucency and color of the Y-TZP ceramics. Conclusions The optical properties of monolithic translucent Y-TZP ceramics were stable after hydrothermal aging at 134°C and 0.2 MPa for ≤20 h. Moreover, clinically unacceptable changes in the translucency and color of monolithic translucent Y-TZP ceramics were found after hydrothermal aging for >20 h.
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Effect of cementation and aging on the marginal fit of veneered and monolithic zirconia and metal-ceramic CAD-CAM crowns. J Prosthet Dent 2020; 125:323.e1-323.e7. [PMID: 33176924 DOI: 10.1016/j.prosdent.2020.06.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 10/23/2022]
Abstract
STATEMENT OF PROBLEM Marginal fit of zirconia restorations is an important criterion for their long-term success. However, in spite of the wide use of zirconia in dentistry, the relationship between marginal fit and low-temperature degradation from aging is unclear. PURPOSE The purpose of this in vitro study was to compare the marginal adaptation of veneered and monolithic zirconia and metal-ceramic computer-aided design and computer-aided manufacturing (CAD-CAM) crowns before and after cementation and to evaluate the influence of artificial aging on the adaptation of zirconia crowns. MATERIAL AND METHODS Seventy-two standardized dies were prepared to receive a posterior crown and randomly divided into 6 groups (n=12) as per the material and the presence or not of cement: metal-ceramic, veneered zirconia, and monolithic zirconia. The zirconia groups were subjected to accelerated low-temperature degradation through hydrothermal aging in an autoclave at 131 °C and 0.17 MPa for 5 and 20 hours. A scanning electron microscope with a magnification of ×1000 was used for marginal adaptation measurements, and X-ray diffraction (XRD) was used to characterize phase transformation degradation. The data were statistically analyzed using 2-way ANOVA, repeated measures ANOVA with Greenhouse-Geisser correction, and the t test (α=.05). RESULTS No significant differences in the marginal discrepancy were recorded among the analyzed groups. The presence of cement did not influence marginal fit in any treatment group. No significant differences were observed in the marginal adaptation values before and after aging (P>.05). After 20 hours of aging, the monoclinic phase increase to 8.3% on veneered zirconia and to 3.1% on monolithic crowns. CONCLUSIONS Monolithic and bilayer CAD-CAM zirconia crowns showed marginal gaps that were within an acceptable range of clinical discrepancy, regardless of cementation. Marginal adaptation was not influenced by aging. Low-temperature degradation did not lead to a significant transformation from the tetragonal to monoclinic phase.
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DE SOUZA RH, KAIZER MR, BORGES CEP, FERNANDES ABF, CORRER GM, DIÓGENES AN, ZHANG Y, GONZAGA CC. Flexural strength and crystalline stability of a monolithic translucent zirconia subjected to grinding, polishing and thermal challenges. CERAMICS INTERNATIONAL 2020; 46:26168-26175. [PMID: 33716378 PMCID: PMC7946154 DOI: 10.1016/j.ceramint.2020.07.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The objective of this study is to investigate the magnitude of structural degradation of a monolithic translucent zirconia caused by clinically relevant grinding and polishing procedures, when associated or not with low temperature degradation (LTD), induced by accelerated hydrothermal aging using autoclave or thermocycling Ninety disks (Ø12 × 1 mm) were prepared from dental zirconia for monolithic restorations (Vipi Block Zirconn Translucent, Vipi). The specimens were divided into 3 groups (n = 30) according to surface treatment: As Sintered (untreated), Grind (diamond bur), Grind + Polish (diamond bur + polish); and then subdivided according to aging method (n = 10): Baseline (no aging), Autoclave (134°C, 2.2 kgf/cm2 pressure for 5 h), and Thermocycling (200,000 cycles, 5°C and 55°C, for 15 s each). Roughness, biaxial flexural strength and percentage of monoclinic phase were evaluated. Regarding surface treatment, the Grind group presented higher roughness and greater flexural strength compared to As Sintered group, while Grind + Polish showed intermediate roughness and flexural strength similar to Grind group. Aging had little effect on roughness, but yielded a significant reduction in flexural strength. Tetragonal to monoclinic phase transformation was observed in all groups, caused by both mechanical stresses (grinding and polishing) and LTD, which was similarly induced by the traditional autoclave method, as well as the thermocycling method The use of diamond burs to grind zirconia surface may result in deleterious effects on the surface quality of monolithic zirconia restorations, yet has a potential toughening effect by phase transformation. However, when zirconia is exposed to LTD, regardless of the surface treatment, degradation of the surface quality and strength are observed.
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Affiliation(s)
- Raisa Hintz DE SOUZA
- School of Health Sciences, Graduate Program in Dentistry, Universidade Positivo, Curitiba, PR 81280, Brazil
| | - Marina R KAIZER
- School of Health Sciences, Graduate Program in Dentistry, Universidade Positivo, Curitiba, PR 81280, Brazil
| | | | | | - Gisele Maria CORRER
- School of Health Sciences, Graduate Program in Dentistry, Universidade Positivo, Curitiba, PR 81280, Brazil
| | | | - Yu ZHANG
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
| | - Carla Castiglia GONZAGA
- School of Health Sciences, Graduate Program in Dentistry, Universidade Positivo, Curitiba, PR 81280, Brazil
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Hajhamid B, Mohammad Rahimi R, F Bahr D, M De Souza G. Effect of ionizing radiation and chewing simulation on human enamel and zirconia. J Prosthodont Res 2020; 65:67-72. [PMID: 32938881 DOI: 10.2186/jpr.jpor_2019_592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE To evaluate the effect of ionizing irradiation on human enamel and zirconia after chewing simulation. METHODS Twenty enamel and twenty translucent Yttria-stabilized zirconia (Y-PSZ) specimens were divided in 4 groups: Co (control) - no irradiation on enamel cusps/opposing zirconia slabs; E70 - irradiated (70 Gray) enamel cusps/opposing irradiated enamel slabs; Z70 - irradiated zirconia cusps/opposing irradiated zirconia slabs; EZ70 - irradiated enamel cusps/opposing irradiated zirconia slabs. Cusps were abraded against slabs in a chewing simulator (CS - one million cycles, 80 N, artificial saliva, 37˚C). Wear and roughness of zirconia and enamel were analyzed using a stylus profilometer. The abraded enamel was analyzed by Electron probe micro-analyzer (EPMA) and zirconia was characterized by nanoindentation and X-ray diffraction. One-way analysis of variance (ANOVA) and Tukey test were used for analysis of wear, Repeated Measures and Bonferroni test for roughness, and hardness and modulus values were compared using Wilcoxan Mann Whitney rank sum test (overall 5% significance). RESULTS Significantly higher volume loss was presented by cusps in the E70 group (p<0.001). Wear was similar between Co and EZ70 groups. There was no significant effect of irradiation on roughness of enamel or zirconia slabs (p=0.072). Irradiated Y-PSZ slabs had significantly higher hardness and modulus than non-irradiated ones and a 7% increase in m phase content was detected after irradiation. CONCLUSIONS The opposing surface characteristics played a more significant role on enamel wear than did ionizing radiation. However, radiation affects Y-PSZ crystalline composition, hardness and modulus of elasticity.
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Affiliation(s)
- Beshr Hajhamid
- Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, ON M5G1G6
| | - Raheleh Mohammad Rahimi
- School of Materials Engineering, Purdue University, 701West Stadium Avenue, West Lafayette, IN 47907-2045
| | - David F Bahr
- School of Materials Engineering, Purdue University, 701West Stadium Avenue, West Lafayette, IN 47907-2045
| | - Grace M De Souza
- Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, ON M5G1G6
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Papageorgiou-Kyrana K, Fasoula M, Kontonasaki E. Translucency of Monolithic Zirconia after Hydrothermal Aging: A Review of In Vitro Studies. J Prosthodont 2020; 29:489-500. [PMID: 32275345 DOI: 10.1111/jopr.13174] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 04/03/2020] [Accepted: 04/03/2020] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Recent modifications in composition, structure, and fabrication methods have led to monolithic zirconia ceramics of superior translucency. However, during aging, intrinsic microstructural features, such as grain boundaries and pores, may affect light scattering and consequently the translucency of zirconia. The aim of this study was to systematically review if hydrothermal aging affects the translucency of monolithic zirconia. MATERIALS AND METHODS An electronic search in Medline and Scopus was conducted to identify the effect of hydrothermal aging on the translucency of zirconia. The search was limited to English-language publications and in vitro studies. The following search terms were used alone or in combination: "monolithic zirconia," "full contour zirconia," "Y-TZP zirconia," "tetragonal zirconia," "cubic zirconia," "aging," "hydrothermal aging," "steam autoclave," "translucency," "translucency parameter," and "contrast ratio." From the titles found after searching the electronic databases, only 10 articles met the inclusion criteria and were included in this review. The translucency parameter or total transmittance was used to extract data from the studies. RESULTS Aging reduced the translucency of monolithic zirconia in most of the studies; however, the differences varied according to the brand tested and the microstructure and thickness of the specimens. The thinner specimens presented higher translucency alterations. Although in all studies a change in translucency was recorded, its mean values suggest that the differences are within the acceptability threshold in most cases, independent of the color system used to calculate translucent parameter, so they are clinically undetectable. For longer aging times, beyond the perspective clinical life of the restorations, the change in translucency is higher than the acceptability threshold. CONCLUSIONS There is a controversy regarding how aging affects the translucency of monolithic zirconia ceramics; however, this may not be clinically important, as in most cases, changes (either decrease or increase) in translucency were within the acceptability thresholds.
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Affiliation(s)
| | - Maria Fasoula
- Postgraduate Student, Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eleana Kontonasaki
- Associate Professor, Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Vila-Nova TEL, Gurgel de Carvalho IH, Moura DMD, Batista AUD, Zhang Y, Paskocimas CA, Bottino MA, de Assunção E Souza RO. Effect of finishing/polishing techniques and low temperature degradation on the surface topography, phase transformation and flexural strength of ultra-translucent ZrO 2 ceramic. Dent Mater 2020; 36:e126-e139. [PMID: 32008750 DOI: 10.1016/j.dental.2020.01.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/24/2019] [Accepted: 01/14/2020] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To investigate the effect of different surface finishing and polishing regimes and low temperature degradation on flexural strength, phase transformation and surface topography of ultra-translucent ZrO2 ceramic. METHODS 300 (n=15/group) of conventional zirconia (Z: Ice Zirkon Transluzent) and ultra-translucent zirconia (UT: Prettau Anterior) bar-specimens were made and divided according to the "Finishing/Polishing" - (C - Control, B - diamond rubber polishers, P - adjusting with burs, PB - adjusting with burs+diamond polishers, PG - adjusting with burs+glaze), "Low temperature Degradation (LTD)" (with or without a treatment at 127°C, 1.7bar/24h). Then, a 3-point mini flexural test was performed in a universal testing machine (1mm/min, 500kgf load cell). SEM, EDS, XDR, AFM, optical profilometry and Weibull analysis were performed. Data were analyzed by 3-way ANOVA and Tukey's post-test (5%). RESULTS Groups ZPBD (1670±253MPa), ZBD (1664±217MPa), and ZB (1655±3678MPa) showed significantly higher flexural strength than the UTPG group (372±56MPa). The Weibull modulus was significantly higher for the ZPD group compared to the UB, UCD, UPD and UPBD, while UTB, UTCD and UTPD had the lowest value. Monoclinic phases were observed only in the conventional zirconia groups and were more evident after LTD. Diamond rubber polishers presented less roughness for both zirconias. SIGNIFICANCE The use of diamond rubber polishers is the most suitable finishing/polishing method for zirconia ceramic restorations and that final glazing reduces the fracture resistance of these materials.
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Affiliation(s)
- Taciana Emília Leite Vila-Nova
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP: 59056-000, Brazil.
| | - Isabelle Helena Gurgel de Carvalho
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Division of Prosthodontics, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, 59056-000, Brazil.
| | - Dayanne Monielle Duarte Moura
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Division of Prosthodontics, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, 59056-000, Brazil.
| | - André Ulisses Dantas Batista
- Federal University of Paraíba (UFPB), Department of Restorative Dentistry, Conj. Pres. Castelo Branco III, João Pessoa, PB, 58033-455, Brazil.
| | - Yu Zhang
- New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY, 10010, United States.
| | - Carlos Alberto Paskocimas
- Federal University of Rio Grande do Norte (UFRN), Department of Material Engineering, Av. Salgado Filho, 3000, Lagoa Nova, Natal, RN, Brazil.
| | - Marco Antonio Bottino
- São Paulo State University (UNESP), Institute of Science and Technology, Av Engenheiro Francisco José Longo, 777, Jardim São Dimas, São José dos Campos, São Paulo, São José dos Campos, CEP: 12245-000, Brazil.
| | - Rodrigo Othávio de Assunção E Souza
- Adjunct Professor at Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Division of Prosthodontics, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, 59056-000, Brazil.
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Kelesi M, Kontonasaki E, Kantiranis N, Papadopoulou L, Zorba T, Paraskevopoulos KM, Koidis P. The effect of different aging protocols on the flexural strength and phase transformations of two monolithic zirconia ceramics. J Appl Biomater Funct Mater 2020; 18:2280800020982677. [DOI: 10.1177/2280800020982677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Introduction: The aim of the present study was to investigate how different aging protocols can affect the flexural strength and phase transformations of yttrium-stabilized zirconia ceramics (Y-TZP) for monolithic restorations. Materials and methods: Bar-shaped specimens from two zirconia ceramics bars were divided into three groups: a. no treatment (c), b. aging in an autoclave (a), and c. thermal cycling (t). The flexural strength was determined by the 3-point bending test and statistical analysis was performed to determine significant differences ( p< 0.05). Weibull statistics was used to analyze the dispersion of strength values while surface microstructural analysis was performed through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Results: Aging did not significantly affect the flexural strength but differences were recorded between the two groups, with group A presenting higher strength values and m-phase percentages. Conclusions: The observed differences between the two ceramics could be attributed to variations in composition and processing.
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Affiliation(s)
- Maria Kelesi
- Laboratory of Prosthodontics, Dentistry Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eleana Kontonasaki
- Laboratory of Prosthodontics, Dentistry Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Nikolaos Kantiranis
- Geology Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Lambrini Papadopoulou
- Geology Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Triantafyllia Zorba
- Physics Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - K M Paraskevopoulos
- Physics Department, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Petros Koidis
- Laboratory of Prosthodontics, Dentistry Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Moqbel NM, Al-Akhali M, Wille S, Kern M. Influence of Aging on Biaxial Flexural Strength and Hardness of Translucent 3Y-TZP. MATERIALS 2019; 13:ma13010027. [PMID: 31861613 PMCID: PMC6981501 DOI: 10.3390/ma13010027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/02/2019] [Accepted: 12/13/2019] [Indexed: 11/16/2022]
Abstract
The purpose of this research was to evaluate the influence of aging and surface treatment on surface roughness, biaxial flexural strength (BFS), and Vickers hardness (VHN) of translucent dental zirconia. Half of 80 disc-shaped zirconia specimens (1.2 mm thickness and 12 mm diameter) were aged (group A) in an autoclave for 20 h (134 °C and 0.2 MPa) and the other half were not aged (group N). Specimens were subjected to: no surface treatment (SIN), particle air-abrasion with 50 µm alumina particles at 1 bar (0.1 MPa) and 2.5 bar (0.25 MPa), or polishing down to 1 µm (POL). Specimens were analyzed using X-ray diffraction, laser scanning microscope, BFS, and VHN tests. Three groups (N-SIN, N-POL, and A-POL) showed almost no monoclinic phase. While other groups showed monoclinic phase ratios ranging from 7.5 vol. % ± 2.4 vol. % (N-0.1 MPa) to 41.5 vol. % ± 0.3 vol. % (A-0.1 MPa). Aging and particle air-abrasion increased significantly the BFS, ranging from 720 ± 37 MPa (N-SIN) to 1153 ± 92 MPa (N-0.1 MPa). The hardness was not influenced significantly by aging. A certain amount of monoclinic phase at the surface strengthens the high translucent dental zirconia, while hardness and roughness are not influenced. The pressure of particle air-abrasion showed no influence on the evaluated properties.
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Affiliation(s)
- Nawal M. Moqbel
- Correspondence: ; Tel.: +49-0431-500-264-10; Fax: +49-0431-500-264-04
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Kelch M, Schulz J, Edelhoff D, Sener B, Stawarczyk B. Impact of different pretreatments and aging procedures on the flexural strength and phase structure of zirconia ceramics. Dent Mater 2019; 35:1439-1449. [PMID: 31399228 DOI: 10.1016/j.dental.2019.07.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/14/2019] [Accepted: 07/15/2019] [Indexed: 02/04/2023]
Abstract
OBJECTIVE To test the impact of zirconia pretreatment and aging on flexural strength and phase structure. METHODS For flexural strength measurements, 180 3Y-TZP0.25 specimens were fabricated and pretreated: (i) air-abraded (105-μm alumina, 0.25MPa), (ii) air-abraded (50-μm alumina, 0.25MPa), (iii) air-abraded (30-μm silica-coated alumina, 0.28MPa) (iv) non-pretreated. Each pretreated group (n=15) was aged: (a) hydrothermal (134°C, 0.23MPa, 2h) (b) in a mastication simulator (1,200,000×, 5/55°C) and (c) not aged. The fractured specimens were stored dry for 5 years (23°C) for analysis of phase transformation. Additionally, specimens were fabricated from 3Y-TZP0.25 (n=12) and 3Y-TZP0.05 (n=8), pretreated (i, ii, iii, iv), and hydrothermally aged. Each air-abrasion method was alternated using 0.05, 0.25 and 0.4MPa pressure. The phase transformation was examined by Raman spectroscopy and surface topography by scanning electron microscope. Data were analyzed using univariate ANOVA with the Scheffé post hoc test and partial-eta-squared (ƞp²) (α=0.05). RESULTS The highest impact on flexural strength was exerted by the pretreatment (ηP²=0.261, p<0.001), followed by interactions between pretreatment and aging (ηP²=0.077, p=0.033). Non-pretreated and non-aged specimens showed the lowest monoclinic percentage. Hydrothermal aging and 5 years of storage at room temperature increased the monolithic percentage of 3Y-TZP0.25. The highest phase transformation was observed in groups air-abraded with 105-μm alumina particles. Increasing pressure during the air-abrading process increased the content of the monoclinic phase in zirconia surfaces. SIGNIFICANCE Air-abrasion with 30-μm silica-coated alumina powder can be recommended for pretreatment of 3Y-TZP0.25 and 3Y-TZP0.05. For air-abrasion using alumina powder lower pressure should be used.
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Affiliation(s)
- Matthias Kelch
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336 Munich, Germany.
| | - Julian Schulz
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336 Munich, Germany
| | - Daniel Edelhoff
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336 Munich, Germany
| | - Beatrice Sener
- Clinic of Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336 Munich, Germany
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Nam MG, Park MG. Changes in the flexural strength of translucent zirconia due to glazing and low-temperature degradation. J Prosthet Dent 2019; 120:969.e1-969.e6. [PMID: 30545472 DOI: 10.1016/j.prosdent.2018.07.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 07/29/2018] [Accepted: 07/30/2018] [Indexed: 02/04/2023]
Abstract
STATEMENT OF PROBLEM Surface glazing and low-temperature degradation (LTD) can affect the mechanical properties of zirconia, which is used to fabricate monolithic ceramic crowns. PURPOSE The purpose of this in vitro study was to assess the changes in flexural strength of monolithic ceramic crowns fabricated from translucent zirconia due to surface glazing and LTD. MATERIAL AND METHODS Sixty plates of zirconia (25×4×1.2 mm) were milled and sintered. They were classified into 4 groups according to glazing and LTD (n=15): control, glazing, LTD, and LTD after glazing. A 3-point flexural test was performed with a universal testing machine. X-ray diffraction (XRD) was used to observe changes in the crystal structures of each group, and field emission scanning electron microscopy was used to observe the sizes of the crystal grains. Two-way analysis of variance was used to evaluate the results of the flexural strength tests, and the Tukey honestly significant difference test was performed for post hoc analysis (α=.05). RESULTS The flexural strength showed significant differences due to glazing (P<.01). No significant differences were found due to LTD (P>.05). The crystal grain size increased with decreasing flexural strength of the specimens. XRD showed monoclinic phases in the groups subjected to LTD. CONCLUSIONS Glazing significantly reduced the flexural strength of translucent zirconia. LTD decreased the flexural strength of glazed translucent zirconia, but not to a significant extent.
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Affiliation(s)
- Min-Gyeong Nam
- Lecturer, Department of Dental Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Republic of Korea
| | - Mi-Gyoung Park
- Associate Professor and Chairman, Department of Dental Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan, Republic of Korea.
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Khosravani MR. Mechanical behavior of restorative dental composites under various loading conditions. J Mech Behav Biomed Mater 2019; 93:151-157. [PMID: 30798181 DOI: 10.1016/j.jmbbm.2019.02.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 02/07/2019] [Accepted: 02/11/2019] [Indexed: 12/12/2022]
Abstract
Mechanical engineering and its scientific principles constitute an essential core in medical science. Currently, different composite resins are widely used as restorative dental materials. However, their lack of adequate strength and toughness has led to research that is aimed at improving the mechanical properties of dental composites. In the present study, the behavior of three different dental materials is investigated under static and dynamic loading conditions. In the experimental tests, a split Hopkinson pressure bar is utilized which corresponds to the most commonly used experimental setup for examining material behavior under a high rate of loading. The examined dental composites experience impacts during their service life and also during car accidents or sport injuries. Hence, in the study, impact loading is modeled in an experiment. A series of compression tests is conducted from low to high strain rates up to 40s-1, and the dynamic elastic moduli of three different dental composites are measured. Furthermore, studies on the compressed surface of the dental composite specimens are performed to improve the analysis with respect to the hardness of the materials. The responses of the examined composites to dynamic loadings verify the impact resistance of the materials. The results indicate the load-carrying capabilities of the dental composites. These results can be used for materials development and existing computational models.
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Ebeid K, Wille S, Salah T, Wahsh M, Zohdy M, Kern M. Bond strength of resin cement to zirconia treated in pre-sintered stage. J Mech Behav Biomed Mater 2018; 86:84-88. [PMID: 29960247 DOI: 10.1016/j.jmbbm.2018.06.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/14/2018] [Accepted: 06/19/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE Aim of this study was to evaluate the tensile bond strength (TBS) between resin cement and zirconia surface treated in different sintering stages. MATERIALS AND METHODS Eighty zirconia discs having final dimensions of 12 mm diameter and 3.2 mm thickness were milled then divided into three main groups according to the type of surface treatment performed (group 1: air abrasion using 50 µm Al2O3 particles, group 2: silica coating using Rocatec soft, and group 3: a control group receiving no surface treatment). Groups 1 and 2 were divided into two subgroups each according to the stage in which the surface treatment was performed (subgroup A; surface treatment performed in the pre-sintered stage and subgroup B; surface treatment performed in the post-sintered stage). Discs were later bonded to composite core materials using resin cement then tested for TBS either being subjected to 3 days of water storage or 150 days of water storage and 37,500 thermal cycles. RESULTS Long-term aging caused a significant decrease in TBS of all subgroups except the subgroup air-abraded in the post-sintered stage. After long-term aging, the group silica coated in the pre-sintered stage showed the significantly lowest TBS compared to all other groups. There was also no significant difference between the subgroups air-abraded and silica coated in the pre-sintered stage. All specimens in the control group debonded during long-term aging. SIGNIFICANCE Air-abrading zirconia with Al2O3 at a reduced pressure in the pre-sintered stage may result in durable bond strength to resin cement.
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Affiliation(s)
- Kamal Ebeid
- Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany; Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Egypt.
| | - Sebastian Wille
- Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany
| | - Tarek Salah
- Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Egypt
| | - Marwa Wahsh
- Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Egypt
| | - Maged Zohdy
- Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Egypt
| | - Matthias Kern
- Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany
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Amaral M, Weitzel ISSL, Silvestri T, Guilardi LF, Pereira GKR, Valandro LF. Effect of grinding and aging on subcritical crack growth of a Y-TZP ceramic. Braz Oral Res 2018; 32:e32. [PMID: 29723335 DOI: 10.1590/1807-3107bor-2018.vol32.0032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/09/2018] [Indexed: 11/22/2022] Open
Abstract
This study aimed to investigate slow crack growth (SCG) behavior of a zirconia ceramic after grinding and simulated aging with low-temperature degradation (LTD). Complementary analysis of hardness, surface topography, crystalline phase transformation, and roughness were also measured. Disc-shaped specimens (15 mm Ø × 1.2 mm thick, n = 42) of a full-contour Y-TZP ceramic (Zirlux FC, Amherst) were manufactured according to ISO:6872-2008, and then divided into: Ctrl - as-sintered condition; Ctrl LTD - as-sintered after aging in autoclave (134°C, 2 bar, 20 h); G - ground with coarse diamond bur (grit size 181 μm); G LTD - ground and aged. The SCG parameters were measured by a dynamic biaxial flexural test, which determines the tensile stress versus stress rate under four different rates: 100, 10, 1 and 0.1 MPa/s. LTD led to m-phase content increase, as well as grinding (m-phase content: Ctrl - 0%; G - 12.3%; G LTD - 59.9%; Ctrl LTD - 81%). Surface topography and roughness analyses showed that grinding created an irregular surface (increased roughness) and aging did not promote any relevant surface change. There was no statistical difference on surface hardness among different conditions. The control group presented the lowest strength values in all tested rates. Regarding SCG, ground conditions were less susceptible to SCG, delaying its occurrence. Aging (LTD) caused an increase in SCG susceptibility for the as-sintered condition (i.e. G < G LTD < Ctrl < Ctrl LTD).
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Affiliation(s)
- Marina Amaral
- Department of Dentistry, Universidade de Taubaté - Unitau, Taubaté, SP, Brazil
| | | | - Tais Silvestri
- Post Graduation Program in Dental Science, Prosthetic Dentistry Unit, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil
| | - Luis Felipe Guilardi
- Post Graduation Program in Dental Science, Prosthetic Dentistry Unit, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil
| | | | - Luiz Felipe Valandro
- Post Graduation Program in Dental Science, Prosthetic Dentistry Unit, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS, Brazil
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Wille S, Zumstrull P, Kaidas V, Jessen LK, Kern M. Low temperature degradation of single layers of multilayered zirconia in comparison to conventional unshaded zirconia: Phase transformation and flexural strength. J Mech Behav Biomed Mater 2018; 77:171-175. [DOI: 10.1016/j.jmbbm.2017.09.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/06/2017] [Indexed: 12/22/2022]
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