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Uasuwan P, Juntavee N, Juntavee A. Flexural strength of novel glass infiltrated monochrome and multilayer high yttrium oxide containing zirconia upon various sintered cooling rates. J Prosthodont 2024; 33:47-59. [PMID: 38831534 DOI: 10.1111/jopr.13872] [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: 01/11/2024] [Accepted: 05/13/2024] [Indexed: 06/05/2024] Open
Abstract
PURPOSE The sintering technique and cooling strategy influence the strength of zirconia. This study examined the impact of altering the cooling rate of glass-infiltrated monolayer and multilayer 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) on their strength. MATERIALS AND METHODS One-hundred eighty (180) specimens (width × length × thickness = 10 × 20 × 2 mm) were prepared using monolayer (Mo: Cercon-xt) and multilayer (Mu: Cercon-xt ML) 5Y-PSZ. Randomly distributed specimens (n = 15/group) were sintered with traditional (T) versus glass infiltrated (G) technique and cooled down with different cooling rates: slow (S: 5°C/min), normal (N: 35°C/min), and fast (F: 70°C/min). Four-point bending test was used to measure flexural strength (σ). Microstructures were investigated by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Three-way ANOVA and Tamhane comparisons were determined for a significant difference of σ (p < 0.05). Weibull analysis was determined for Weibull modulus (m). RESULTS The highest σ (MPa) was seen for GMuS (696.8 ± 69.8). Mo-PSZ and Mu-PSZ showed no significant difference in σ. G-sintering presented significantly higher σ (659.9 ± 79.3) than T-sintering (426.0 ± 63.7). S-cooling (560.9 ± 126.1) had the highest σ. The highest m-value was observed in GMuN (12.1 ± 3.8). A significant difference in σ was indicated due to cooling rates and sintering techniques (p < 0.05). CONCLUSIONS Glass infiltration significantly enhanced strength through elastic gradience. F-cooling reduced grain size, impaired grain boundary integration, and increased the tetragonal to monoclinic phase transition, significantly decreasing flexural strength in traditional sintering. Nevertheless, F-cooling was recommended for glass-infiltrated 5Y-PSZ to enhance strength while reducing processing time.
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Affiliation(s)
- Pithiwat Uasuwan
- Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Niwut Juntavee
- Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Apa Juntavee
- Division of Pediatric Dentistry, Department of Preventive Dentistry, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
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Juntavee N, Juntavee A, Jaralpong C. Flexural Strength of Two Multilayered and Monochromatic High Yttria Containing Zirconia Materials Following Different Sintering Parameters. Eur J Dent 2024; 18:551-562. [PMID: 37729931 PMCID: PMC11132776 DOI: 10.1055/s-0043-1772569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2023] Open
Abstract
OBJECTIVES Sintering parameters influence the properties of zirconia. This study examined the effect of altering sintering temperature and time of monochrome and multilayer 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) on flexural strength. MATERIALS AND METHODS Three hundred specimens (width × length × thickness = 10 × 20 × 2 mm) were prepared from monolayer (ZX) and multilayer (ZM) 5Y-PSZ and randomly sintered at decreasing (TD: 1,450°C), regular (TR: 1,500°C), and increasing (TI: 1,550°C) sintering temperature, with extremely short (HE: 10 minutes), ultrashort (HU: 15 minutes), short (HS: 30 minutes), and regular (HR: 135 minutes) sintering time (n = 15/group). The precrack was induced on the tension side before testing for flexural strength (σ). STATISTICAL ANALYSIS Analysis of variance and Tukey's test were used for significant differences of σ at p < 0.05. The microstructure and crystalline (monoclinic; m, tetragonal; t, cubic; c) phase were evaluated by scanning electron microscope (SEM) and X-ray diffractometer (XRD). RESULTS ZXTIHS indicated the highest σ for ZX (315.81 ± 18.91 MPa), whereas ZMTIHS indicated the highest σ for ZM (335.21 ± 36.18 MPa). There was no significant difference for σ between ZX and ZM (p > 0.05). Sintering zirconia at TI or HR indicated significantly higher σ than sintering at TD or TR or with HS, HE, or HU for both ZX and ZM (p < 0.05). There was no significant difference for σ between TRHR and TIHS, TIHU, and TIHE (p > 0.05). SEM indicated intergranular and transgranular fractures. XRD revealed predominately c- and t-phases and minor amounts of m-phase. CONCLUSION Increasing sintered temperature with decreasing time offers acceptable strength to regular sintering. Raising sintering temperature with decreasing time is suggested to facilitate chairside restorative reconstruction.
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Affiliation(s)
- Niwut Juntavee
- Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Apa Juntavee
- Division of Pediatric Dentistry, Department of Preventive Dentistry, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Chutikarn Jaralpong
- Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
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Cesar PF, Miranda RBDP, Santos KF, Scherrer SS, Zhang Y. Recent advances in dental zirconia: 15 years of material and processing evolution. Dent Mater 2024; 40:824-836. [PMID: 38521694 PMCID: PMC11098698 DOI: 10.1016/j.dental.2024.02.026] [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: 01/26/2024] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/25/2024]
Abstract
OBJECTIVES The objective was to discuss the research on zirconia published in the past 15 years to help the dental materials community understand the key properties of the types of zirconia and their clinical applications. METHODS A literature search was performed in May/2023 using Web of Science Core Collection with the term "dental zirconia". The search returned 5102 articles, which were categorized into 31 groups according to the research topic. RESULTS The current approach to improving the translucency of zirconia is to decrease the alumina content while increasing the yttria content. The resulting materials (4Y-, 5Y-, and above 5 mol% PSZs) may contain more than 50% of cubic phase, with a decrease in mechanical properties. The market trend for zirconia is the production of CAD/CAM disks containing more fracture resistant 3Y-TZP at the bottom layers and more translucent 5Y-PSZ at the top. Although flaws located between layers in multilayered blocks might represent a problem, newer generations of zirconia layered blocks appear to have solved this problem with novel powder compaction technology. Significant advancements in zirconia processing technologies have been made, but there is still plenty of room for improvement, especially in the fields of high-speed sintering and additive manufacturing. SIGNIFICANCE The wide range of zirconia materials currently available in the market may cause confusion in materials selection. It is therefore imperative for dental clinicians and laboratory technicians to get the needed knowledge on zirconia material science, to follow manufacturers' instructions, and to optimize the design of the prosthetic restoration with a good understanding where to reinforce the structure with a tough and strong zirconia.
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Affiliation(s)
- Paulo Francisco Cesar
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
| | | | - Karina Felix Santos
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil
| | - Susanne S Scherrer
- Division of Fixed Prosthodontics and Biomaterials, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, USA
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Alshahrani AM, Lim CH, Wolff MS, Janal MN, Zhang Y. Current speed sintering and high-speed sintering protocols compromise the translucency but not strength of yttria-stabilized zirconia. Dent Mater 2024; 40:664-673. [PMID: 38378371 PMCID: PMC11015968 DOI: 10.1016/j.dental.2024.02.012] [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: 09/07/2023] [Revised: 01/05/2024] [Accepted: 02/12/2024] [Indexed: 02/22/2024]
Abstract
OBJECTIVES To investigate the impacts of speed and high-speed sintering on the densification, microstructure, phase composition, translucency, and flexural strength of yttria-stabilized zirconia (YSZ). METHODS A total of 162 disc-shaped specimens (n = 18) were cold-isostatically pressed from 3YSZ (Zpex), 4YSZ (Zpex 4), and 5YSZ (Zpex Smile) powders (Tosoh Corporation) and sintered according to the following protocols: conventional (control, ∼12 h), speed (∼28 min for 3YSZ; ∼60 min for 4YSZ and 5YSZ), and high-speed (∼18 min) sintering. Dimensions of zirconia specimens after sintering and polishing (1-μm diamond grit finish) were Ø13.75 × 1 mm. Density, microstructure, phase content, translucency parameter, and biaxial flexural strength were evaluated using Archimedes', SEM, XRD, spectrophotometric, and piston-on-3-ball methods, respectively. Data were analyzed with either one-way ANOVA and Tukey's test or Kruskal-Wallis with Dunn's test (α = 0.05). RESULTS For all YSZ compositions, conventional sintering yielded the highest density followed by speed then high-speed sintering. All sintering protocols resulted in similar strength values; however, speed and high-speed sintering protocols afforded significantly lower translucency relative to conventional sintering. XRD analysis revealed similar spectra for YSZs sintered by various protocols. The speed sintered specimens had the smallest grain size whereas the high-speed sintered 5YSZ possessed the largest grain size among all groups. SEM examination of all YSZ compositions revealed that the average pore size was an order of magnitude smaller than the average grain size. SIGNIFICANCE Speed and high-speed sintering of YSZs yield similar strength but diminished density and translucency relative to their conventionally sintered counterparts.
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Affiliation(s)
- Abdulaziz M Alshahrani
- Laboratories for Microstructure Physics & Mechanics of Materials, Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Restorative Dental Sciences, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Chek Hai Lim
- Laboratories for Microstructure Physics & Mechanics of Materials, Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mark S Wolff
- Morton Amsterdam Dean, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Malvin N Janal
- Department of Epidemiology & Health Promotion, New York University College of Dentistry, New York, NY 10010, USA
| | - Yu Zhang
- Laboratories for Microstructure Physics & Mechanics of Materials, Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Hajjaj MS, Alamoudi RAA, Babeer WA, Rizg WY, Basalah AA, Alzahrani SJ, Yeslam HE. Flexural strength, flexural modulus and microhardness of milled vs. fused deposition modeling printed Zirconia; effect of conventional vs. speed sintering. BMC Oral Health 2024; 24:38. [PMID: 38185744 PMCID: PMC10771678 DOI: 10.1186/s12903-023-03829-8] [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: 10/17/2023] [Accepted: 12/26/2023] [Indexed: 01/09/2024] Open
Abstract
BACKGROUND Various methods can be used for creating zirconia dental restorations, including 3-dimensional (3D) printing and computer-aided design/ computer-aided manufacturing (CAD/CAM) milling. The fused deposition modeling (FDM) printing method for zirconia presents numerous advantages, albeit research on the mechanical properties of these materials and resultant restorations remains scarce. Such developments are undeniably intriguing and warrant further investigation. The objective of the present study was to evaluate the impact of the sintering firing cycle (Conventional vs. Speed sintering) on the flexural strength, flexural modulus, and Vickers Microhardness of milled vs. FDM printed zirconia. METHODS A total of 60 bars (2 × 5 × 27 mm) were fabricated for flexural strength testing, along with 40 discs (12 × 1.5 mm) for Vickers microhardness testing. Half of the specimens underwent conventional sintering, while the other half underwent a speed sintering cycle. The flexural strength and modulus were determined by a three-point bending test in a universal testing machine. The microhardness of the specimens was evaluated using a Vickers microhardness tester. Statistical analysis was performed using a two-way ANOVA test with a post-hoc Tukey test (p < 0.05). RESULTS CAD/CAM milled zirconia had significantly higher flexural strength and modulus than FDM-printed zirconia. The sintering process did not significantly affect the flexural strength or modulus of milled or FDM-printed zirconia. The milled speed sintering group had significantly higher values in the Vickers microhardness test compared to the other groups. CONCLUSIONS The mechanical properties of FDM-printed zirconia specimens were not found to be comparable to those of milled zirconia. Speed sintering cycle may produce milled zirconia restorations with similar flexural strength and modulus to conventional sintering, and even higher Vickers Microhardness values.
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Affiliation(s)
- Maher S Hajjaj
- Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
- Advanced Technology Dental Research Laboratory, King Abdulaziz University, P.O. Box 80209, Jeddah, 21589, Saudi Arabia.
| | - Rana A A Alamoudi
- Prosthodontic Master Student, Department of Oral and Maxillofacial Rehabilitation, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Walaa A Babeer
- Department of Oral and Maxillofacial Rehabilitation, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Waleed Y Rizg
- Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Center of Innovation in Personalized Medicine (CIPM), 3D Bioprinting Unit, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Ahmad A Basalah
- Mechanical Engineering Department, College of Engineering and Architecture, Umm Al Qura University, Makkah, Saudi Arabia
| | - Saeed J Alzahrani
- Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Hanin E Yeslam
- Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
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Attia MA, Radwan M, Blunt L, Bills P, Tawfik A, Arafa AM. Effect of different sintering protocols on the fracture strength of 3-unit monolithic gradient zirconia fixed partial dentures: An in vitro study. J Prosthet Dent 2023; 130:908.e1-908.e8. [PMID: 37802734 DOI: 10.1016/j.prosdent.2023.09.012] [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: 05/02/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 10/08/2023]
Abstract
STATEMENT OF PROBLEM Strength-gradient zirconia combining 3 zirconia formulations with different flexural strengths has been reported to have outstanding mechanical properties. However, data concerning the effect of different sintering protocols on the fracture strength of 3-unit monolithic gradient zirconia fixed partial dentures (FPDs) are sparse. PURPOSE The purpose of this in vitro study was to test the effect of different sintering protocols on the fracture strength of 3-unit monolithic gradient zirconia FPDs. MATERIAL AND METHODS Two custom-made stainless-steel master dies were designed to replicate a mandibular right second premolar and second molar prepared to receive a 3-unit monolithic zirconia FPD. Thirty monolithic zirconia FPDs were milled from gradient zirconia blanks and allocated to 3 groups (n=10) according to the sintering protocols: high-speed sintering, speed sintering, and conventional sintering. The FPDs were cemented onto the corresponding dies with traditional glass ionomer cement. All FPDs were cyclic loaded (600 000 cycles/49 N/1.7 Hz) in a mastication simulator. Fracture load measurements for each FPD were determined by using a universal testing machine. Scanning electron microscopy (SEM) at ×80 magnification was used to examine a fractured FPD from each group. A representative specimen from each group was examined with SEM at ×30 000 magnification to determine the grain size. One-way ANOVA, pair-wise Tukey honestly significant difference (HSD), and Pearson correlation tests were used for statistical analysis of the data (α=.05). RESULTS The high-speed sintered FPDs recorded the highest statistically significant fracture load mean ±standard deviation value (2526 ±300 N), followed by the speed sintered FPDs (2136 ±127 N), while the lowest statistically significant fracture load mean value was recorded with the conventionally sintered FPDs (1361 ±181 N) (P<.001). In addition, the mean ±standard deviation grain size values were 488 ±272 nm for the high-speed sintered specimen, 578 ±409 nm for the speed sintered specimen, and 832 ±551 nm for the conventionally sintered specimen (P<.001). A significant negative correlation was found between fracture strength and grain size among the 3 groups. CONCLUSIONS The fracture strength of 3-unit monolithic gradient zirconia FPDs sintered by using a high-speed protocol was significantly higher than that of speed and conventionally sintered FPDs (P<.001). The high-speed sintering protocol reduced the mean grain size of gradient zirconia FPDs compared with that of both speed and conventional sintering protocols.
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Affiliation(s)
- Mazen A Attia
- Associate Professor, Department of Fixed Prosthodontics, Faculty of Dentistry, Beni-Suef University, Beni-Suef, Egypt.
| | - Mohamed Radwan
- Lecturer, Department of Fixed Prosthodontics, Faculty of Dentistry, Beni-Suef University, Beni-Suef, Egypt
| | - Liam Blunt
- Professor, Engineering and Physical Sciences Research Council (EPSRC) Future Advanced Metrology Hub, University of Huddersfield, Huddersfield, England, United Kingdom
| | - Paul Bills
- Professor, Engineering and Physical Sciences Research Council (EPSRC) Future Advanced Metrology Hub, University of Huddersfield, Huddersfield, England, United Kingdom
| | - Ahmed Tawfik
- PhD Researcher, Engineering and Physical Sciences Research Council (EPSRC) Future Advanced Metrology Hub, University of Huddersfield, Huddersfield, England, United Kingdom
| | - Ahmed M Arafa
- Lecturer, Department of Fixed Prosthodontics, Faculty of Dentistry, Beni-Suef University, Beni-Suef, Egypt
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Yang S, Li Q, Chen SY, Yu H. Effect of multiple firings on the marginal fit of monolithic zirconia crowns: An in vitro study. J Prosthet Dent 2023; 130:897-901. [PMID: 35181056 DOI: 10.1016/j.prosdent.2021.12.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 10/19/2022]
Abstract
STATEMENT OF PROBLEM Speed sintering was introduced to save chair time and produce monolithic zirconia restorations in a single visit. Multiple firings are usually required clinically for both speed-sintered and conventionally sintered monolithic zirconia crowns. However, the effects of multiple firings on the marginal fit of speed-sintered and conventionally sintered monolithic zirconia crowns are unknown. PURPOSE The purpose of this in vitro study was to investigate the effect of multiple firings on the marginal fit of speed-sintered and conventionally sintered monolithic zirconia crowns. MATERIAL AND METHODS Twenty conventionally sintered and 20 speed-sintered monolithic zirconia crowns were milled, sintered, and repeatedly fired by using conventional sintering and speed sintering furnaces. The absolute marginal discrepancy of the crowns was measured with a measuring microscope at ×100 magnification after sintering (T0) and after the first (T1), second (T2), and third firings (T3). Two-way repeated-measures ANOVA was used to detect the impact of multiple firings on the absolute marginal discrepancy of conventionally sintered and speed-sintered monolithic zirconia crowns and the differences between the 2 materials (α=.05). RESULTS Multiple firings improved the absolute marginal discrepancy of conventionally sintered and speed-sintered monolithic zirconia crowns (P<.001). The absolute marginal discrepancy of conventionally sintered monolithic zirconia crowns at T2 and T3 was significantly smaller than that at T1 (P=.008 and 0.016, respectively), and the absolute marginal discrepancy of speed-sintered monolithic zirconia crowns at T2 was significantly smaller than that at T1 (P=.015). The speed-sintered monolithic zirconia crowns had a better marginal fit than conventionally sintered monolithic zirconia crowns (P=.008). No significant interaction was found between the multiple firings and material types on the absolute marginal discrepancy of monolithic zirconia crowns (P=.914). CONCLUSIONS Multiple firing cycles can significantly improve the marginal fit of conventionally sintered and speed-sintered monolithic zirconia crowns. The speed-sintered monolithic zirconia crowns have a better marginal fit (both vertically and horizontally) than the conventionally sintered monolithic zirconia crowns.
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Affiliation(s)
- Song Yang
- Attending dentist and PhD candidate, Department of Prosthodontics, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China
| | - Qi Li
- Resident, Department of Stomatology, Fujian Provincial Governmental Hospital, Fuzhou, PR China
| | - Sheng-Yuan Chen
- Postgraduate student, Department of Prosthodontics, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China
| | - Hao Yu
- Associate Professor and associate dean, Department of Prosthodontics, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, PR China; Adjunct Associate Professor, Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
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Lubauer J, Schuenemann FH, Belli R, Lohbauer U. Speed-sintering and the mechanical properties of 3-5 mol% Y 2O 3-stabilized zirconias. Odontology 2023; 111:883-890. [PMID: 36859729 PMCID: PMC10492746 DOI: 10.1007/s10266-023-00796-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 02/15/2023] [Indexed: 03/03/2023]
Abstract
Ever faster workflows for the fabrication of all-ceramic restorations are of high economic interest. For that purpose, sintering protocols have been optimized for use in modern sintering furnaces, the so-called speed-sintering. However, conventional furnaces are still the most widely used equipment to sinter zirconia restorations. In this in-vitro study, we evaluated the feasibility of a speed-sintering protocol using a conventional sintering furnace to sinter different dental zirconias (stabilized with 3 mol% up to 5.4 mol% Y2O3) in comparison to a conventional sintering program. The properties evaluated were Young's modulus, Poisson's ratio, density, biaxial flexural strength, and fracture toughness. We show here that despite differences being dependent on material, the physical and mechanical properties of speed-sintered zirconia are comparable to those obtained by the conventional sintering.
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Affiliation(s)
- Julia Lubauer
- Zahnklinik 1-Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Glueckstraße 11, 91054, Erlangen, Germany
| | - Fernanda Haverroth Schuenemann
- Zahnklinik 1-Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Glueckstraße 11, 91054, Erlangen, Germany
| | - Renan Belli
- Zahnklinik 1-Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Glueckstraße 11, 91054, Erlangen, Germany.
| | - Ulrich Lohbauer
- Zahnklinik 1-Zahnerhaltung und Parodontologie, Forschungslabor für dentale Biomaterialien, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Glueckstraße 11, 91054, Erlangen, Germany
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Antón X, Liebermann A, Hampe R, Joda T, Stawarczyk B. Impact of high-speed sintering and choice of preshaded monochrome or multilayered blanks on fatigue behavior of 4 mol% yttria-stabilized tetragonal zirconia polycrystal. J Prosthet Dent 2023; 130:639-645. [PMID: 34930599 DOI: 10.1016/j.prosdent.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 10/31/2021] [Accepted: 11/01/2021] [Indexed: 11/25/2022]
Abstract
STATEMENT OF PROBLEM High-speed sintering allows the rapid fabrication of esthetic restorations with adequate flexural strength. However, data on the fatigue behavior of high-speed sintered 4 mol% yttria-stabilized tetragonal zirconia polycrystal (4Y-TZP) are lacking. PURPOSE The purpose of this in vitro study was to examine the effect of high-speed sintering and the preshading of blanks (monochrome versus multilayer) on the fatigue behavior of 4Y-TZP ceramics. MATERIAL AND METHODS Four-point flexural strength specimens (N=405) were fabricated from high-speed sintered multilayer 4Y-TZP (Zolid DRS) processed at 1580 °C for about 20 minutes and conventionally sintered at 1450 °C for about 10 hours, multilayer 4Y-TZP (Zolid Gen-x), and monochrome 4Y-TZP (Ceramill Zolid HT+PS), the control group. The specimens were loaded under 5 different dynamic test conditions for fatigue testing (P1-P5). Three were step-stress protocols (P1: 50 N for 5000 cycles; P2: 10 N for 1000 cycles, P3: 5% for 5000 cycles), 1 was tested with a constant force of 720 N (P4), and 1 was tested for different constant load levels (P5). For analysis of P1-P3, the Kaplan-Meier test and Mantel Cox test were performed (α=.05). P4 was analyzed with the Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests, and P5 by creating a load-cycle diagram. A fracture analysis was performed. RESULTS ZMLC showed better fatigue behavior than ZMLH (P≤.006) and ZMOC (P≤.002) in all 3 step-stress protocols (P1-P3). ZMLH showed results comparable with those for ZMOC (P≥.285). In P4 and P5, all materials showed comparable values (P=.163 for P4). CONCLUSIONS The multilayer technique showed a positive effect on the fatigue behavior of 4Y-TZP. In contrast, high-speed sintering negatively influenced the fatigue behavior of multilayer 4Y-TZP. The high-speed sintered material showed no deterioration compared with the conventional sintered monochrome material.
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Affiliation(s)
- Xenia Antón
- Doctoral student, Dental Materials Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany.
| | - Anja Liebermann
- Assistant Professor, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Rüdiger Hampe
- Guest Researcher, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
| | - Tim Joda
- Professor, Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, Basel, Switzerland
| | - Bogna Stawarczyk
- Scientific Head, Dental Materials Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany
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Salah K, Sherif AH, Mandour MH, Nossair SA. Optical effect of rapid sintering protocols on different types of zirconia. J Prosthet Dent 2023; 130:253.e1-253.e7. [PMID: 37330359 DOI: 10.1016/j.prosdent.2023.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 05/07/2023] [Accepted: 05/09/2023] [Indexed: 06/19/2023]
Abstract
STATEMENT OF PROBLEM Rapid sintering protocols are available for the fabrication of zirconia restorations, but whether rapid sintering influences color or translucency is unclear. PURPOSE The purpose of this in vitro study was to investigate the effect of different rapid sintering protocols on the color and translucency of cubic and tetragonal zirconias. MATERIAL AND METHODS Sixty disk-shaped specimens of 1-mm-thick cubic (DD CubeX2) and tetragonal (DD Bio ZX2) zirconia were investigated. Specimens of each type of zirconia were divided into three groups: conventional, speed, and superspeed sintering protocols. The conventional group of each zirconia type served as the control for calculating color differences. Translucency for each group was assessed by the translucency parameter and contrast ratio. Two-way analysis of variance was used for statistical analysis of the data (α=.05). RESULTS The translucency of cubic and tetragonal zirconia decreased after speed and superspeed sintering (P<.001). Superspeed sintering resulted in a greater color change than speed sintering (P<.001). CONCLUSIONS Rapid sintering protocols produced a significant effect on the color and translucency of cubic and tetragonal zirconias.
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Affiliation(s)
- Kerolos Salah
- Former Postgraduate student, Department of Fixed Prosthodontics, Faculty of Oral and Dental Medicine, Future University, New Cairo, Egypt.
| | - Ashraf Hussein Sherif
- Professor, Department of Fixed Prosthodontics, Faculty of Oral and Dental Medicine, Future University, New Cairo, Egypt
| | - Mona H Mandour
- Professor, Department of Crown and Bridge, Faculty of Dental Medicine, Al-Azhar University, Girls' Branch, Cairo, Egypt
| | - Shereen Ahmed Nossair
- Assistant Professor, Department of Fixed Prosthodontics, Faculty of Oral and Dental Medicine, Future University, New Cairo, Egypt
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11
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Kongkiatkamon S, Rokaya D, Kengtanyakich S, Peampring C. Current classification of zirconia in dentistry: an updated review. PeerJ 2023; 11:e15669. [PMID: 37465158 PMCID: PMC10351515 DOI: 10.7717/peerj.15669] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/09/2023] [Indexed: 07/20/2023] Open
Abstract
Zirconia, a crystalline oxide of zirconium, holds good mechanical, optical, and biological properties. The metal-free restorations, mostly consisting of all-ceramic/zirconia restorations, are becoming popular restorative materials in restorative and prosthetic dentistry choices for aesthetic and biological reasons. Dental zirconia has increased over the past years producing wide varieties of zirconia for prosthetic restorations in dentistry. At present, literature is lacking on the recent zirconia biomaterials in dentistry. Currently, no article has the latest information on the various zirconia biomaterials in dentistry. Hence, the aim of this article is to present an overview of recent dental zirconia biomaterials and tends to classify the recent zirconia biomaterials in dentistry. This article is useful for dentists, dental technicians, prosthodontists, academicians, and researchers in the field of dental zirconia.
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Affiliation(s)
- Suchada Kongkiatkamon
- Department of Prosthetic Dentistry, Faculty of Dentistry, Prince of Songkla University, Songkhla, Thailand
| | - Dinesh Rokaya
- Faculty of Dentistry, Zarqa University, Zarqa, Jordan
| | - Santiphab Kengtanyakich
- Prosthodontic Section, Department of Restorative Dentistry, Naresuan University, Phitsanulok, Thailand
| | - Chaimongkon Peampring
- Department of Prosthetic Dentistry, Faculty of Dentistry, Prince of Songkla University, Songkhla, Thailand
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12
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Oyar P, Durkan R. The effects of heating rate and sintering time on the biaxial flexural strength of monolithic zirconia ceramics. BIOMED ENG-BIOMED TE 2023:bmt-2022-0338. [PMID: 36930871 DOI: 10.1515/bmt-2022-0338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 03/02/2023] [Indexed: 03/19/2023]
Abstract
The strength of zirconia ceramic materials used in restorations is dependent upon sintering. Varying sintering protocols may affect the biaxial flexural strength of zirconia materials. This in vitro study was conducted to investigate the effects of sintering parameters on the biaxial flexural strength of monolithic zirconia. Two different monoblock zirconia ceramics were used. Following coloration, samples of both types of ceramics were divided into groups according to whether or not biaxial flexural strength testing was performed directly after sintering or following thermocycling. Biaxial flexural strength data was analysed with a Shapiro Wilk normality test, followed by 1-way ANOVA, Tukey post hoc tests for inter-group comparisons, and paired samples t-tests for intra-group comparisons. A significant difference was found between the biaxial flexural strengths of Zircon X and Upcera ceramics before thermocycling (p<0.05). In both Zircon X and Upcera ceramic groups, the thermocycling process created a significant difference in the biaxial flexural strength values of the ceramic samples in Group 6 (p<0.05) which had the slowest heating rate and longest holding time. The zirconia ceramics have higher BFS at higher heating rates either before or after thermocycling. The holding time has significant effects on thermocycling and flexural strength. The zirconia achieved its optimum strength when it sintered at longer time regardless of heating rates.
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Affiliation(s)
- Perihan Oyar
- Professor, Dental Prosthetics Technology, Vocational School of Health Services, Hacettepe University, Ankara, Türkiye
| | - Rukiye Durkan
- Department of Prosthodontics, Faculty of Dentistry, Istanbul Okan University, Istanbul, Türkiye
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13
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Yan M, Ding SJ, Lin CW, Wei CL, Huang YW, Yang CC. Aging resistance of highly translucent zirconia ceramics with rapid sintering. J Oral Sci 2023; 65:15-19. [PMID: 36403959 DOI: 10.2334/josnusd.22-0264] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE Rapid sintering technology has become one of the most direct methods for shortening the manufacturing time of zirconia restorations. This study aimed to explore the aging resistance of rapid-sintered 5 mol% yttria-partially-stabilized zirconia (5Y-PSZ). METHODS Specimens were made from two types of 5Y-PSZ material and subjected to rapid sintering (RS) and conventional sintering (CS). After in vitro aging for 5 h, morphology observation, grain size measurement, and phase composition analysis were performed. The mechanical properties were evaluated by biaxial, three-point flexural tests, and the Vickers microhardness test. Results were analyzed by 3-way ANOVA. RESULTS Both the RS group and the CS group had a dense microstructure. The tested zirconia ceramics had different grain sizes, which were affected by the interaction between the sintering method and aging. Both groups revealed the same characteristic peaks of the cubic phase after aging. Regardless of the sintering method used, there was no significant difference in the mechanical properties of the tested zirconia before and after aging. CONCLUSION The rapid-sintered 5Y-PSZ materials had a microstructure, phase composition and mechanical properties similar to those of conventional sintered materials. The characteristics of the materials prepared using the two sintering methods did not change significantly after aging.
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Affiliation(s)
- Min Yan
- Institute of Oral Sciences, Chung Shan Medical University.,Department of Dentistry, Chung Shan Medical University Hospital, Chung Shan Medical University
| | - Shinn-Jyh Ding
- Institute of Oral Sciences, Chung Shan Medical University.,Department of Dentistry, Chung Shan Medical University Hospital, Chung Shan Medical University
| | - Cheng-Wei Lin
- Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology
| | - Cian-Li Wei
- Institute of Oral Sciences, Chung Shan Medical University
| | - Yi-Wen Huang
- Institute of Oral Sciences, Chung Shan Medical University
| | - Chun-Chuan Yang
- Department of Dental Technology, Shu-Zen Junior College of Medicine and Management
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14
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Miura S, Shinya A, Koizumi H, Fujisawa M. Effect of speed sintering of monolithic zirconia with different yttria contents on color and crystal phase. Eur J Oral Sci 2022; 130:e12898. [PMID: 36335285 DOI: 10.1111/eos.12898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 09/28/2022] [Indexed: 11/09/2022]
Abstract
This study evaluated the color and microstructure of monolithic zirconia crowns with different yttrium oxide (Y2 O3 ) contents treated by conventional or speed sintering. Four types of zirconia ceramics were assessed: two monolayer zirconia, and two multilayer zirconia. The monolithic zirconia crowns were fabricated using a dental computer-aided design/computer-aided manufacturing (CAD/CAM) system and in two shades (A2 and BL). After milling, the zirconia crowns were sintered using either speed sintering or conventional sintering. For each combination of zirconia (4), shade (2), and sintering condition (2), the color parameters were determined at three positions of each of nine crowns using a non-contact dental spectrophotometer. In addition, the zirconia phases in the specimens were quantified using X-ray diffractometry. Significant differences in the ΔE00 values at different measurement positions were observed for the Multi2 crown of the BL shade group. The color difference resulting from conventional and speed sintering programs was not affected by the difference in yttria content of Mono1, Mono2, and Multi1. However, in Multi2, containing 3Y-TZP and 5Y-PSZ, a color change was caused by the use of speed sintering. Therefore, when performing speed sintering with Multi2, it is necessary to select the color in consideration of these results or take measures for staining.
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Affiliation(s)
- Shoko Miura
- Division of Fixed Prosthodontics, Department of Restorative & Biomaterials Sciences, Meikai University School of Dentistry, Sakado, Saitama, Japan
| | - Akikazu Shinya
- Department of Dental Materials Sciences, School of Life Dentistry at Tokyo, The Nippon Dental University, Tokyo, Japan.,Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland
| | - Hiroyasu Koizumi
- Department of Dental Materials, Nihon University School of Dentistry, Tokyo, Japan
| | - Masanori Fujisawa
- Division of Fixed Prosthodontics, Department of Restorative & Biomaterials Sciences, Meikai University School of Dentistry, Sakado, Saitama, Japan
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15
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Effect of sintering time on the marginal and internal fit of monolithic zirconia crowns containing 3–4 mol% Y2O3. BMC Oral Health 2022; 22:493. [PMID: 36380324 PMCID: PMC9664799 DOI: 10.1186/s12903-022-02563-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 11/03/2022] [Indexed: 11/16/2022] Open
Abstract
Background Short-term sintering may offer advantages including saving time and energy but there is limited evidence on the effect that altering sintering time has on the accuracy of monolithic zirconia crowns. The purpose of this in vitro study was to investigate the effect of shortened sintering time on the marginal and internal fit of 3Y-TZP and 4Y-TZP monolithic crowns. Methods Sixty monolithic zirconia crowns were fabricated for the maxillary first molar tooth on the prefabricated implant abutment. Groups were created according to the material composition: 3Y-TZP Generation 1, 3Y-TZP Generation 2 and 4Y-TZP. Two different sintering protocols were performed: same final sintering temperature (1500 °C) and various rates of heating (10 °C/min and 40 °C/min), cooling down speed (− 10 °C/min and − 40 °C/min), holding time (45 and 120 minutes), and total sintering time (approximately 2 and 7 hours, respectively). The marginal and internal fit of the crowns were determined using the silicone replica technique. Comparisons between groups were analyzed using two-way ANOVA. Pairwise multiple comparisons were performed using t-test (p < 0.05). Results The mean marginal gap values of 4Y-TZP zirconia revealed statistically significant increase for the short-term sintering protocol (p < 0.0001), while no difference was observed between the sintering protocols for the mean marginal gap values of 3Y-TZP groups. Although all groups showed clinically acceptable gap values, altering the sintering time had an effect on marginal fit of the crowns manufactured from 4Y-TZP zirconia. Conclusions Shortening the sintering time may lead to differences within clinically acceptable limits. The manufacturer’s recommendations according to material composition should be implemented with care.
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16
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Shahbazi A, Vafaei F, Hooshyarfard A, Nosrati E, Nazari M, Farhadian M. Effect of Sintering Temperature on Flexural Strength of Two Types of Zirconia. Front Dent 2022; 19:31. [PMID: 36865949 PMCID: PMC9971647 DOI: 10.18502/fid.v19i31.10803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 08/15/2022] [Indexed: 03/04/2023] Open
Abstract
Objectives: Any change in the sintering process can directly affect the micro-structure and properties of zirconia. This study sought to assess the effect of sintering temperature on flexural strength of IPS e.max ZirCAD MO Ivoclar (EZI) and CopraSmile White Peaks Symphony (WPS) zirconia blocks. Materials and Methods: In this in vitro, experimental study, 30 EZI and 30 WPS zirconia blocks measuring 10 x 10 x 1 mm were milled and sintered at 1440, 1500 and 1530°C in three subgroups. The flexural strength of the specimens was measured by a testing machine with piston-on-3-ball method according to ISO2015. Data were analyzed using one-way ANOVA. Results: The mean flexural strength was 1.31±0.49, 1.09±0.24 and 1.29±0.48 MPa in 1440, 1500, and 1530°C subgroups of EZI, and 1.44±0.61, 1.18±0.35, and 1.33±0.54 MPa in 1440, 1500, and 1530°C subgroups of WPS zirconia, respectively. Two-way ANOVA revealed that the effects of zirconia type (P=0.484), temperature (P=0.258) and their interaction (P=0.957) on flexural strength were not significant. Conclusion: Increasing the sintering temperature from 1440°C to 1530°C did not increase the flexural strength of EZI or WPS zirconia.
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Affiliation(s)
- Armaghan Shahbazi
- Department of Prosthodontics, Faculty of Dentistry, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Fariborz Vafaei
- Dental Implants Research Center, Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran,Corresponding author: Dental Implants Research Center, Department of Prosthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
| | - Amirarsalan Hooshyarfard
- Dental Materials Research Center, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran,Department of Periodontics, Faculty of Dentistry, Shahed University, Tehran, Iran
| | | | | | - Maryam Farhadian
- Department of Biostatistics, School of Public Health and Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran
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17
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Mohaghegh M, Baseri S, Hassan Kalantari M, Giti R, Ahmad Ghoraishian S. Influence of Sintering Temperature on the Marginal Fit and Compressive Strength of Monolithic Zirconia Crowns. JOURNAL OF DENTISTRY (SHIRAZ, IRAN) 2022; 23:307-313. [PMID: 36506887 PMCID: PMC9719600 DOI: 10.30476/dentjods.2021.90024.1459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/24/2021] [Accepted: 09/22/2021] [Indexed: 12/15/2022]
Abstract
Statement of the Problem Increasing the sintering temperature is suggested by some manufacturers as a way to enhance the translucency of monolithic zirconia crowns. Meanwhile, its effect on the marginal fit and compressive strength of the restoration is not fully understood. Purpose This study aimed to evaluate the effect of sintering temperature on the marginal fit and compressive strength of monolithic zirconia crowns. Materials and Method In this in vitro study, thirty crowns of pre-sintered monolithic zirconia were milled and sintered in a special furnace at either 1450°C or 1550°C (n=15 per group). The marginal gaps were measured at 18 spots on the dies with a digital microscope. To evaluate the compressive strength, the specimens were cemented on brass dies by using conventional glass ionomer cement. Vertical load was applied by a universal testing machine until fracture. One-way ANOVA test was used to analyze the results (α=0.05). Results The marginal gap was not significantly different between the two groups (p= 0.062). A significantly higher mean value of compressive strength was observed in crowns sintered at 1550°c (1988.27±635.09 N) than those sintered at 1450 °c (1514.27±455.11 N) (p= 0.026). Conclusion Although increasing the sintering temperature would not affect the marginal gap of monolithic zirconia crowns, it could significantly improve the compressive strength of zirconia restorations.
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Affiliation(s)
- Mina Mohaghegh
- Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Sajjad Baseri
- Postgraduate Student, Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | - Rashin Giti
- Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seyed Ahmad Ghoraishian
- Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
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18
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Conventional, Speed Sintering and High-Speed Sintering of Zirconia: A Systematic Review of the Current Status of Applications in Dentistry with a Focus on Precision, Mechanical and Optical Parameters. J Clin Med 2022; 11:jcm11164892. [PMID: 36013131 PMCID: PMC9409711 DOI: 10.3390/jcm11164892] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/04/2022] [Accepted: 08/17/2022] [Indexed: 01/17/2023] Open
Abstract
The aim of this systematic review was to provide an overview of the technical and clinical outcomes of conventional, speed sintering and high-speed sintering protocols of zirconia in the dental field. Data on precision, mechanical and optical parameters were evaluated and related to the clinical performance of zirconia ceramic. The PICOS search strategy was applied using MEDLINE to search for in vitro and in vivo studies using MeSH Terms by two reviewers. Of 66 potentially relevant studies, 5 full text articles were selected and 10 were further retrieved through a manual search. All 15 studies included in the systematic review were in vitro studies. Mechanical, precision and optical properties (marginal and internal fit, fracture strength and modulus, wear, translucency and opalescence, aging resistance/hydrothermal aging) were evaluated regarding 3-, 4- and 5-YTZP zirconia material and conventional, high- and high-speed sintering protocols. Mechanical and precision results were similar or better when speed or high-speed sintering methods were used for 3-, 4- and 5-YTZP zirconia. Translucency is usually reduced when 3 Y-TZP is used with speed sintering methods. All types of zirconia using the sintering procedures performed mechanically better compared to lithium disilicate glass ceramics but glass ceramics showed better results regarding translucency.
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19
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Kongkiatkamon S, Peampring C. Effect of Speed Sintering on Low Temperature Degradation and Biaxial Flexural Strength of 5Y-TZP Zirconia. Molecules 2022; 27:molecules27165272. [PMID: 36014509 PMCID: PMC9416714 DOI: 10.3390/molecules27165272] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/03/2022] [Accepted: 08/15/2022] [Indexed: 11/16/2022] Open
Abstract
Translucent zirconia is becoming the material of choice for the esthetic restorative material. We aimed to evaluate the surface structure, phase determination, translucency, and flexural strength of 5Y-TZP Zirconia (Katana STML Block and Disc) between the regular sintering and the speed sintering with and without low-temperature degradation (LTD). A total of 60 zirconia discs (30 per group; regular sintering and speed sintering) were used in this study. A CAM machine was used to mill cylinders out of the zirconia blanks and then cut into smaller discs. For the speed sintering, the zirconia blocks were milled into smaller discs. The zirconia discs were subjected to regular and speed sintering with and without LTD. Scanning electron microscopy was used to characterize the zirconia specimens and the zirconia grain size. Furthermore, the zirconia specimens were analyzed for elemental analysis using energy dispersive spectroscopy and phase identification using X-ray diffraction. The zirconia specimens were subjected to translucency measurements and biaxial flexural strength testing. The results of the zirconia specimens were compared among the groups. Statistical analysis was completed using SPSS version 20.0 to detect the statistically significant differences (p value = 0.05). A one-way ANOVA with multiple comparisons was performed using Scheffe analysis among the groups. The speed sintering presented smaller grain sizes. The zirconia specimens with and without LTD in regular and speed sintering presented a similar surface structure. Regular sintering showed more translucency compared to speed sintering. Multiple comparisons of the translucency parameter were a significant difference (p value < 0.05) between the various groups except for the comparison between speed sintering and speed sintering LTD. The regular sintering showed bigger gain sizes and slightly more translucency compared to speed sintering. The speed sintering showed higher biaxial flexural strengths compared to regular sintering. This shows that speed sintering can be considered a suitable method of sintering zirconia.
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20
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Kulyk V, Duriagina Z, Kostryzhev A, Vasyliv B, Vavrukh V, Marenych O. The Effect of Yttria Content on Microstructure, Strength, and Fracture Behavior of Yttria-Stabilized Zirconia. MATERIALS 2022; 15:ma15155212. [PMID: 35955147 PMCID: PMC9369764 DOI: 10.3390/ma15155212] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 07/18/2022] [Accepted: 07/26/2022] [Indexed: 02/01/2023]
Abstract
Yttria-stabilized zirconia (YSZ) is well-known as a material with perfect mechanical, thermal, and electrical properties. It is used for manufacturing various high-temperature components for aerospace and energy generation, as well as wear- and corrosion-resistant devices in medicine. This work investigated the effect of a Y2O3 addition to ZrO2 on the microstructure and mechanical properties of YSZ ceramics produced by one sintering schedule. ZrO2 ceramics doped with 3, 4, 5, 6, 7, and 8 mol% Y2O3 (designated 3YSZ through to 8YSZ) were prepared by using conventional sintering at 1550 °C for 2 h in argon. The effect of yttria content was analyzed with respect to grain size, morphology of the microstructural features, phase composition, parameters of fracture surface, and flexural strength. The 7YSZ ceramics sintered at 1550 °C for 2 h showed the highest level of flexural strength due to the formation of the fine-grained microstructure containing mainly the monoclinic and tetragonal zirconia phases. The fracture micromechanism in the studied YSZ ceramics is discussed.
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Affiliation(s)
- Volodymyr Kulyk
- Department of Materials Science and Engineering, Lviv Polytechnic National University, 12 S. Bandera str., 79013 Lviv, Ukraine; (Z.D.); (V.V.)
- Correspondence:
| | - Zoia Duriagina
- Department of Materials Science and Engineering, Lviv Polytechnic National University, 12 S. Bandera str., 79013 Lviv, Ukraine; (Z.D.); (V.V.)
- Department of Materials Engineering, John Paul II Catholic University of Lublin, 14 Racławickie Al., 20-950 Lublin, Poland
| | - Andrii Kostryzhev
- Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia; (A.K.); (O.M.)
| | - Bogdan Vasyliv
- Department of Hydrogen Technologies and Alternative Energy Materials, Karpenko Physico-Mechanical Institute, 5 Naukova str., 79060 Lviv, Ukraine;
| | - Valentyna Vavrukh
- Department of Materials Science and Engineering, Lviv Polytechnic National University, 12 S. Bandera str., 79013 Lviv, Ukraine; (Z.D.); (V.V.)
| | - Olexandra Marenych
- Centre for Microscopy and Microanalysis, University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia; (A.K.); (O.M.)
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21
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Mayinger F, Buser R, Laier M, Schönhoff LM, Kelch M, Hampe R, Stawarczyk B. Impact of the material and sintering protocol, layer thickness, and thermomechanical aging on the two-body wear and fracture load of 4Y-TZP crowns. Clin Oral Investig 2022; 26:6617-6628. [PMID: 35840737 DOI: 10.1007/s00784-022-04616-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 07/04/2022] [Indexed: 11/03/2022]
Abstract
OBJECTIVES The aim of this study is to investigate the influence of the material and corresponding sintering protocol, layer thickness, and aging on the two-body wear (2BW) and fracture load (FL) of 4Y-TZP crowns. MATERIALS AND METHODS Multi-layer 4Y-TZP crowns in three thicknesses (0.5 mm/1.0 mm/1.5 mm) were sintered by high-speed (Zolid RS) or conventional (Zolid Gen-X) sintering. 2BW of ceramic and enamel antagonist after aging (1,200,000 mechanical-, 6000 thermal-cycles) was determined by 3D-scanning before and after aging and subsequent matching to determine volume and height loss (6 subgroups, n = 16/subgroup). FL was examined initially and after aging (12 subgroups, n = 16/subgroup). Fractographic analyses were performed using light-microscope imaging. Global univariate analysis of variance, one-way ANOVA, linear regression, Spearman's correlation, Kolgomorov-Smirnov, Mann-Whitney U, and t test were computed (alpha = 0.05). Weibull moduli were determined. Fracture types were analyzed using Ciba Geigy table. RESULTS Material/sintering protocol did not influence 2BW (crowns: p = 0.908, antagonists: p = 0.059). High-speed sintered Zolid RS presented similar (p = 0.325-0.633) or reduced (p < 0.001-0.047) FL as Zolid Gen-X. Both 4Y-TZPs showed an increased FL with an increasing thickness (0.5(797.3-1429 N) < 1.0(2087-2634 N) < 1.5(2683-3715 N)mm; p < 0.001). For most groups, aging negatively impacted FL (p < 0.001-0.002). Five 0.5 mm specimens fractured, four showed cracks during and after aging. CONCLUSIONS High-speed sintered crowns with a minimum thickness of 1.0 mm showed sufficient mechanical properties to withstand masticatory forces, even after a simulated aging period of 5 years. CLINICAL RELEVANCE Despite the manufacturer indicating a thickness of 0.5 mm to be suitable for single crowns, a minimum thickness of 1.0 mm should be used to ensure long-term satisfactory results.
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Affiliation(s)
- Felicitas Mayinger
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany.
| | - Ramona Buser
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany.,Department of Reconstructive Dentistry and Gerodontology, University of Bern, Freiburgstrasse 7, 3007, Bern, Switzerland
| | - Maximilian Laier
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Lisa Marie Schönhoff
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Matthias Kelch
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Rüdiger Hampe
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany
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22
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Lim CH, Vardhaman S, Reddy N, Zhang Y. Composition, processing, and properties of biphasic zirconia bioceramics: relationship to competing strength and optical properties. CERAMICS INTERNATIONAL 2022; 48:17095-17103. [PMID: 37701057 PMCID: PMC10497227 DOI: 10.1016/j.ceramint.2022.02.265] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
A study is made of relationships between composition, processing, structure and properties of biphasic zirconia bioceramics. The focus is on zirconia compositions with different yttria dopant contents used in modern dental restorations, namely 3 - 5 mol% yttria stabilized zirconia (3YSZ, 4YSZ, and 5YSZ). Crystallographies and densities are surveyed, sintering conditions examined, and microstructures characterized. Strength and optical tests are conducted on each YSZ, and dependencies on sintering temperature, cubic content and grain size analyzed. Strength correlates with the amount of tetragonal zirconia (t-ZrO2) crystals with large lattice distortions (tetragonality). YSZ translucency correlates with content of cubic zirconia (c-ZrO2) and t-ZrO2 with low levels of tetragonality. Consistent with literature reporting, the materials rank in decreasing order 3YSZ, 4YSZ to 5YSZ for strength but increasing order for translucency. However, for a given composition, the data suggest that the strengths of densely sintered 3YSZ and 4YSZ actually increase with translucency, although that of 5YSZ remains undiminished. These trends are in apparent contradiction to prevailing experience, and offer potential future processing routes to optimization of clinical materials.
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Affiliation(s)
- Chek Hai Lim
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Sonaj Vardhaman
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Niyati Reddy
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
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23
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The effect of aging on the wear performance of monolithic zirconia. Dent Mater 2022; 38:e136-e146. [DOI: 10.1016/j.dental.2022.04.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 03/06/2022] [Accepted: 04/01/2022] [Indexed: 11/24/2022]
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24
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Yılmaz Savaş T, Akın C. Effects of sintering protocol and dipping time on the optical properties of monolithic zirconia. J Prosthet Dent 2022; 127:801.e1-801.e8. [DOI: 10.1016/j.prosdent.2021.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 10/19/2022]
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25
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Dyakonenko EE, Sakhabieva DA, Axelrod IB, Lebedenko IY. [Comparative evaluation of traditional and speed sintering of dental ceramics based on zirconium dioxide]. STOMATOLOGIIA 2022; 101:106-113. [PMID: 35362712 DOI: 10.17116/stomat2022101021106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This study analyzed the traditional and high-speed firing of dental ceramics based on zirconia. The types of furnaces for sintering zirconia, the basic principles of traditional, high-speed and super-speed firing, as well as the effect of the sintering protocol on the structure, physical, mechanical, optical properties, wear and marginal fit of zirconia were evaluated. The analysis showed that it`s necessary to develop a special optimal sintering technique using particular protocols in specific types of furnaces for each dental ceramic material based on zirconia, taking into account the composition and structure of the ceramics. To write this review, articles from the electronic databases of Medline, PubMed and the websites of dental journals were used.
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Affiliation(s)
- E E Dyakonenko
- Central Research Institute of Dentistry and Maxillofacial Surgery, Moscow, Russia
| | - D A Sakhabieva
- Peoples' Friendship University of Russia, Moscow, Russia
| | - I B Axelrod
- Central Research Institute of Dentistry and Maxillofacial Surgery, Moscow, Russia
| | - I Yu Lebedenko
- Central Research Institute of Dentistry and Maxillofacial Surgery, Moscow, Russia
- Peoples' Friendship University of Russia, Moscow, Russia
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26
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Al-Surkhi O, Hamad Z. Influence of firing temperature and duration on the hardness of dental zirconia for optimum selection of sintering conditions. J Appl Biomater Funct Mater 2022; 20:22808000221114218. [PMID: 35876066 DOI: 10.1177/22808000221114218] [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: 11/16/2022] Open
Abstract
OBJECTIVE In order to optimize the properties of dental zirconia, the sintering process involves firing zirconia to elevated temperatures for an extended time that can take several hours. The aim of this study is to investigate the effect of firing temperature and firing duration on the hardness of dental zirconia to indicate the optimum sintering conditions. METHODS Thirty-six zirconia specimens in shape of bars were randomly assigned to nine groups. The zirconia specimen groups were sintered using a sintering furnace with different firing temperatures (900°C, 1200°C, and 1800°C) and firing durations (6, 9, and 12 h). A total of 108 hardness measurements were conducted for all specimens (12 hardness readings per group). For each of the specimen groups, micro Vickers hardness test was performed using a load of 1 Kgf (9.807 N) and the Vickers hardness number was computed. Statistical analysis using Kruskal-Wallis test was conducted to examine the significant differences on Vickers hardness number HV among the specimen groups according to the firing parameters with 0.005 p-value used as an indicator. RESULTS Results suggest that there is an association between the increase in the hardness number and the increase in firing duration at a given firing temperature. The results also indicate that there is an association between the increase in the hardness number and increase in firing temperature at a given firing duration. CONCLUSIONS The greatest rate of hardness increase with time is associated with groups of firing temperature 1200°C. The highest rate of hardness increase with temperature happened during the first 6 h of sintering process. On the other hand, there is no significant increase in the hardness number when increasing the firing temperature beyond 1200°C.
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Affiliation(s)
- Omar Al-Surkhi
- Faculty of Engineering, Al-Quds University, Jerusalem, Palestine
| | - Zeina Hamad
- Faculty of Engineering, Al-Quds University, Jerusalem, Palestine
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27
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Influence of high-speed sintering protocols on translucency, mechanical properties, microstructure, crystallography, and low-temperature degradation of highly translucent zirconia. Dent Mater 2021; 38:451-468. [PMID: 34961644 DOI: 10.1016/j.dental.2021.12.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 12/15/2021] [Accepted: 12/15/2021] [Indexed: 01/24/2023]
Abstract
OBJECTIVES Impacts of high-speed sintering on the optical and mechanical properties, microstructure, crystallography, and low-temperature degradation of commercial yttria-partially stabilized zirconia (Y-PSZ) were investigated. METHODS Five commercial Y-PSZ products (KATANA HT, KATANA STML, KATANA UTML, Zpex 4, and Zpex Smile) were investigated. Specimens were sintered following speed-sintering (~90 min) and conventional-sintering protocols (~7 h), and a group of KATANA STML was super-speed-sintered (18 min). Dimensions of the zirconia specimens after sintering were 14.5 mm (diameter) and 1.2 mm (thickness). Translucency was assessed using a colorimeter. Biaxial flexural strength was measured using a universal testing machine, followed by Weibull analysis. Scanning electron microscopy was used for microstructure assessments. X-ray diffraction was used to analyze the crystallography before and after hydrothermal aging. Low-temperature degradation (LTD) tests were performed at 134 °C under 2-3 bar water vapor in an autoclave. RESULTS The translucency and flexural strength were not affected significantly by the sintering programs (p > 0.05). The conventionally sintered KATANA STML and speed-sintered Zpex 4 presented the highest and lowest Weibull modulus, respectively. The conventionally-sintered Y-PSZ had a larger average grain size and smaller fraction of fine grains than those of the speed-sintered specimens. The fractographic analysis of the speed- and conventionally sintered Y-PSZ yielded comparable results. The speed-sintered Y-PSZ exhibited a lower c-ZrO2 content than that of conventionally-sintered Y-PSZ, except for KATANA HT and KATANA STML. LTD tests indicated that some of the speed and conventionally-sintered Y-PSZ exhibited similar monoclinic volume fractions. SIGNIFICANCE Speed-sintering programs are acceptable for Y-PSZ zirconia.
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28
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Plyushch A, Mačiulis N, Sokal A, Grigalaitis R, Macutkevič J, Kudlash A, Apanasevich N, Lapko K, Selskis A, Maksimenko SA, Kuzhir P, Banys J. 0.7Pb(Mg 1/3Nb 2/3)O 3-0.3PbTiO 3 Phosphate Composites: Dielectric and Ferroelectric Properties. MATERIALS 2021; 14:ma14175065. [PMID: 34501154 PMCID: PMC8433962 DOI: 10.3390/ma14175065] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/28/2021] [Accepted: 09/01/2021] [Indexed: 12/01/2022]
Abstract
Composite materials with 83 wt.% of the 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 distributed in phosphate-bonded ceramics were prepared at three different pressures. A phosphate matrix comprises a mixture of an aluminum phosphate binder and melted periclase, MgO. All samples demonstrate a homogeneous distribution of the ferroelectric perovskite phase and are thermally stable up to 900 K. At higher temperatures, the pyrochlore cubic phase forms. It has been found that the density of the composites non-monotonously depends on the pressure. The dielectric permittivity and losses substantially increase with the density of the samples. The fabricated composites demonstrate diffused ferroelectric–paraelectric transition and prominent piezoelectric properties.
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Affiliation(s)
- Artyom Plyushch
- Faculty of Physics, Vilnius University, Sauletekio 9, LT-10222 Vilnius, Lithuania; (N.M.); (R.G.); (J.M.); (J.B.)
- Institute for Nuclear Problems, Belarusian State University, 220006 Minsk, Belarus; (S.A.M.); (P.K.)
- Correspondence:
| | - Nerijus Mačiulis
- Faculty of Physics, Vilnius University, Sauletekio 9, LT-10222 Vilnius, Lithuania; (N.M.); (R.G.); (J.M.); (J.B.)
| | - Aliaksei Sokal
- Faculty of Chemistry, Belarusian State University, Nezalezhnastsi Ave. 4, 220030 Minsk, Belarus; (A.S.); (A.K.); (N.A.); (K.L.)
| | - Robertas Grigalaitis
- Faculty of Physics, Vilnius University, Sauletekio 9, LT-10222 Vilnius, Lithuania; (N.M.); (R.G.); (J.M.); (J.B.)
| | - Jan Macutkevič
- Faculty of Physics, Vilnius University, Sauletekio 9, LT-10222 Vilnius, Lithuania; (N.M.); (R.G.); (J.M.); (J.B.)
| | - Alexander Kudlash
- Faculty of Chemistry, Belarusian State University, Nezalezhnastsi Ave. 4, 220030 Minsk, Belarus; (A.S.); (A.K.); (N.A.); (K.L.)
| | - Natalia Apanasevich
- Faculty of Chemistry, Belarusian State University, Nezalezhnastsi Ave. 4, 220030 Minsk, Belarus; (A.S.); (A.K.); (N.A.); (K.L.)
| | - Konstantin Lapko
- Faculty of Chemistry, Belarusian State University, Nezalezhnastsi Ave. 4, 220030 Minsk, Belarus; (A.S.); (A.K.); (N.A.); (K.L.)
| | - Algirdas Selskis
- Department of Structural Analysis of Materials, Center for Physical Sciences and Technology, Sauletekio 3, LT-10257 Vilnius, Lithuania;
| | - Sergey A. Maksimenko
- Institute for Nuclear Problems, Belarusian State University, 220006 Minsk, Belarus; (S.A.M.); (P.K.)
| | - Polina Kuzhir
- Institute for Nuclear Problems, Belarusian State University, 220006 Minsk, Belarus; (S.A.M.); (P.K.)
- Department of Physics and Matematics, Institute of Photonics, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Juras Banys
- Faculty of Physics, Vilnius University, Sauletekio 9, LT-10222 Vilnius, Lithuania; (N.M.); (R.G.); (J.M.); (J.B.)
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29
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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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30
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Effect of sintering process on microstructure, 4-point flexural strength, and grain size of yttria-stabilized tetragonal zirconia polycrystal for use in monolithic dental restorations. J Prosthet Dent 2021; 125:824.e1-824.e8. [PMID: 33775390 DOI: 10.1016/j.prosdent.2021.01.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 01/27/2021] [Accepted: 01/27/2021] [Indexed: 11/22/2022]
Abstract
STATEMENT OF PROBLEM Modifications have been made in the microstructure and sintering parameters of monolithic zirconia to improve esthetics qualities and avoid chipping of 2-layer restorations. However, how these modifications affect the physical and mechanical properties of zirconia is unclear. PURPOSE The purpose of this in vitro study was to compare the influence of different sintering parameters on the microstructure, 4-point flexural strength, density, and grain size of 2 commercially available zirconia advocated for the fabrication of monolithic dental prostheses and 1 commercially available zirconia for use as a core material. MATERIAL AND METHODS Three presintered blocks (Ceramill Zolid, Prettau, and IPS e.max ZirCAD) were used. Specimens were cut and sintered as per the manufacturer's recommendation or as per a modified heating protocol. Ceramill Zolid (Z1450) was sintered at 1450 °C, Prettau (P1600) was sintered at 1600 °C, and IPS e.max ZirCAD (I1530) was sintered at 1530 °C by following the manufacturer's heating protocol. Groups Ceramill Zolid Z1530 and Z1600 were sintered at temperatures higher than the manufacturer's recommendation. Specimens from each group (n=13) were analyzed with X-ray diffraction (XRD), density calculus, average grain size measurement, and 4-point flexural tests. Data were compared by using ANOVA (α=.05). RESULTS XRD analysis showed the presence of a tetragonal metastable phase in all groups before and after sintering. No significant differences were found in relative density values for the 3 Ceramill groups (5.98 g/cm3). Groups I1530 (6.03 g/cm3) and P1600 (6.03 g/cm3) had similar density results greater than 6.00 g/cm3. The average grain size of all groups remained lower than 1 μm. P1600 had the highest grain size (0.817 μm), and Z1450 presented the lowest grain size (0.465 μm). P1600 showed the most homogeneous flexural strength and the highest Weibull modulus (m=8.22). Z1530 presented the lowest Weibull modulus (m=4.58). IPS e.max ZirCAD (I1530) had the highest flexural strength (1057.41 ±150.54 MPa), and Ceramill Zolid Z1450 had the lowest (621.01 ±138.08 MPa). CONCLUSIONS The flexural strength, microstructure, crystal phase, and grain size of the analyzed zirconia varied as per the sintering processing. The IPS e.max ZirCAD had the highest flexural strength (1057.41 ±150.54 MPa), followed by Prettau zirconia (864.18 ±118.21), with a statistically significant difference (P<.05). The Ceramill Zolid zirconia presented the lowest flexural strength, as well as the lowest reliability for all sintering parameters used (Z1450: 621.01 ±138.08 MPa and m=5.42; Z1530: 713.10 ±175.44 MPa and m=4.58; Z1600: 630.15 ±112.08 MPa and m=6.87). At a lower heating rate (8 °C/min), the final density increased and excessive grain growth in group Z1530 was prevented.
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31
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Yurdakul A. Production and Characterization of Ceramic Bushings from Alumina-Toughened Yttrium-Stabilized Tetragonal Zirconia Composites for Projection Welding Applications. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2021. [DOI: 10.1007/s13369-020-05160-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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32
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Rosentritt M, Preis V, Schmid A, Strasser T. Multilayer zirconia: Influence of positioning within blank and sintering conditions on the in vitro performance of 3-unit fixed partial dentures. J Prosthet Dent 2020; 127:141-145. [DOI: 10.1016/j.prosdent.2020.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/20/2020] [Accepted: 11/20/2020] [Indexed: 10/22/2022]
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33
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Vojtko M, Puchy V, Múdra E, Milkovič O, Kovalčíková A. Coarse-grain CeO2 doped ZrO2 ceramic prepared by spark plasma sintering. Ann Ital Chir 2020. [DOI: 10.1016/j.jeurceramsoc.2020.05.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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34
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Michailova M, Elsayed A, Fabel G, Edelhoff D, Zylla IM, Stawarczyk B. Comparison between novel strength-gradient and color-gradient multilayered zirconia using conventional and high-speed sintering. J Mech Behav Biomed Mater 2020; 111:103977. [DOI: 10.1016/j.jmbbm.2020.103977] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 11/29/2022]
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35
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Oyar P, Durkan R, Deste G. Effects of sintering time and hydrothermal aging on the mechanical properties of monolithic zirconia ceramic systems. J Prosthet Dent 2020; 126:688-691. [PMID: 33039187 DOI: 10.1016/j.prosdent.2020.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 10/23/2022]
Abstract
STATEMENT OF PROBLEM The flexural strength of zirconia restorations is partially dependent on the sintering process. Changes in sintering protocols as well as hydrothermal aging may affect the flexural strength of zirconia materials. PURPOSE The purpose of this in vitro study was to investigate how changes in sintering parameters and hydrothermal aging affect the biaxial flexural strength of monolithic zirconia. MATERIAL AND METHODS Specimens were produced from 2 translucent monolithic zirconia ceramics (Zircon X ST, Upcera YZ HT). After coloring, specimens of both ceramics were distributed into groups and subjected to 1 of 6 different sintering protocols. Half were subjected to biaxial flexural strength tests directly after sintering, and the remaining specimens were subjected to hydrothermal aging and then to biaxial flexural strength testing. Biaxial flexural strength data were analyzed by using a statistical software program. Normality of distribution was determined by the Shapiro-Wilk test. Biaxial flexural strength data were compared among groups by using 1-way ANOVA and Tukey post hoc tests, and intragroup data were compared by using paired specimens t tests (α=.05). RESULTS The highest overall biaxial flexural strength value was obtained in UW-II. The highest biaxial flexural strength for Zircon X was obtained in ZX-VI and ZX-HTA-VI, whereas the highest biaxial flexural strength for Upcera was obtained in UW-II before hydrothermal aging and in UW-HTA-V after aging (P<.05). CONCLUSIONS The biaxial flexural strength of Zircon X increased with longer sintering times. Upcera specimens were more fracture-resistant than Zircon X both before and after hydrothermal aging. Based on these findings, longer sintering times are recommended to increase the strength of monolithic zirconia.
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Affiliation(s)
- Perihan Oyar
- Associate Professor, Department of Dental Prosthetics Technology, Vocational School of Health Services, Hacettepe University, Ankara, Turkey.
| | - Rukiye Durkan
- Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Afyon Kocatepe University, Afyonkarahisar, Turkey
| | - Gonca Deste
- Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Bursa Uludağ University, Bursa, Turkey
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Ahmed WM, Shariati B, Gazzaz AZ, Sayed ME, Carvalho RM. Fit of tooth-supported zirconia single crowns-A systematic review of the literature. Clin Exp Dent Res 2020; 6:700-716. [PMID: 32885613 PMCID: PMC7745068 DOI: 10.1002/cre2.323] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study is to systematically map all the factors that influence the fit and adaptation of zirconia crowns and/or copings. MATERIALS AND METHODS The investigational strategy involved carrying out an electronic search between December 1, 2009 and September 1, 2019 through the Embase and Medline databases using Boolean operators to locate appropriate articles. RESULTS A total of 637 articles were discovered after the removal of duplicates, and 46 of these were selected for evaluation. Further, a quality assessment was performed using GRADE evaluation criteria. CONCLUSIONS Shoulder finish line preparations had slightly better marginal fit compared to chamfer finish lines. Crowns obtained from digital impressions had comparable to superior marginal adaptation compared to conventional impressions. Increasing cement space showed to improve zirconia crown adaptation. Cementation and veneering zirconia frameworks found to increase the marginal and internal gaps. Limited information is available on the effect of the alteration of sintering time/Temperature and/or sintering techniques on the adaptation of zirconia crowns. Most of the selected studies had a moderate quality assessment evaluation. Future studies could investigate the chair-side, ultra-fast sintering effect on the marginal gap of zirconia crowns.
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Affiliation(s)
- Walaa Magdy Ahmed
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.,Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Batoul Shariati
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Arwa Z Gazzaz
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.,College of Dentistry, King Saud University, Riyadh, Saudi Arabia
| | | | - Ricardo M Carvalho
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada
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37
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Juntavee N, Uasuwan P. Flexural Strength of Different Monolithic Computer-Assisted Design and Computer-Assisted Manufacturing Ceramic Materials upon Different Thermal Tempering Processes. Eur J Dent 2020; 14:566-574. [PMID: 32791528 PMCID: PMC7535961 DOI: 10.1055/s-0040-1713957] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Objective
Strength of ceramics related with sintering procedure. This study investigated the influence of different tempering processes on flexural strength of three monolithic ceramic materials.
Materials and Methods
Specimens were prepared in bar-shape (width × length × thickness = 4 × 14 × 1.2 mm) from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP, inCoris TZI [I]), zirconia-reinforced lithium silicate (ZLS, Vita Suprinity [V]), and lithium disilicate (LS
2
, IPS e.max CAD [E]), and sintered with different tempering processes: slow (S), normal (N), and fast (F) cooling procedure (
n
= 15/group). Flexural strength (σ
)
was determined using three-point bending test apparatus at 1 mm/min crosshead speed.
Statistical Analysis
The analysis of variance and Bonferroni’s multiple comparisons were determined for significant difference (α = 0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristics strength (σ
o
). Microstructures were evaluated with scanning electron microscope and X-ray diffraction.
Results
The mean ± standard deviation (MPa) of σ, m, and σ
o
were: 1,183.98 ± 204.26, 6.23, 1,271.80 for IS; 1,084.43 ± 204.79, 5.76, 1,170.08 for IN; 777.19 ± 99.77, 8.78, 819.96 for IF; 267.15 ± 32.71, 9.11, 281.48 for VS; 218.43 ± 38.46, 6.40, 234.23 for VN; 252.67 ± 37.58, 7.20, 269.23 for VF; 392.09 ± 37.91, 11.37, 409.23 for ES; 378.88 ± 55.38, 7.45, 403.11 for EN, and 390.94 ± 25.34, 16.00, 403.51 for EF. Thermal tempering significantly affected flexural strength of Y-TZP (
p
< 0.05), but not either ZLS or LS
2
(
p
> 0.05). Y-TZP indicated significantly higher flexural strength upon slow tempering than others.
Conclusion
Enhancing flexural strength of Y-TZP can be achieved through slow tempering process and was suggested as a process for monolithic zirconia. Strengthening of ZLS and LS
2
cannot be accomplished through tempering; thus, either S-, N-, or F- tempering procedure can be performed. Nevertheless, to minimize sintering time, rapid thermal tempering is more preferable for both ZLS and LS
2
.
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Affiliation(s)
- Niwut Juntavee
- Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Pithiwat Uasuwan
- Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
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Cokic SM, Vleugels J, Van Meerbeek B, Camargo B, Willems E, Li M, Zhang F. Mechanical properties, aging stability and translucency of speed-sintered zirconia for chairside restorations. Dent Mater 2020; 36:959-972. [PMID: 32493658 DOI: 10.1016/j.dental.2020.04.026] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/10/2020] [Accepted: 04/30/2020] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To evaluate the performance of zirconia ceramics sintered in a speed sintering induction furnace by comprehensive understanding of their optical and mechanical properties, microstructure, phase composition and aging stability, in comparison to ceramics sintered in a conventional furnace. METHODS Speed sintered (SS) Katana STMLSS (Kuraray Noritake) (total thermal cycle/sintering time/dwell temperature: 30min/16min/1560°C) and CEREC Zirconia (CEREC ZrSS) (Dentsply Sirona) (15min/2min/1578°C) were compared to conventionally sintered (CS) Katana STMLCS (6.8h/2h/1550°C) and inCoris TZICS (4h/2h/1510°C). The translucency parameter (TP) and contrast ratio (CR) were measured with a spectrophotometer. The chemical composition of the materials was determined by XRF and phase composition was characterized using XRD. Hydrothermal aging behavior was evaluated by measuring the tetragonal-to-monoclinic ZrO2 phase transformation after accelerated hydrothermal aging in steam at 134°C. The indentation fracture toughness, Vickers hardness and biaxial strength of the sintered ceramics were assessed. RESULTS Speed and conventionally sintered zirconia revealed similar density, microstructure, average strength and hydrothermal aging stability. Both Katana STMLSS/CS 5Y-PSZ ceramics were characterized with a higher content of cubic phase (≈53wt%), which resulted in a higher amount of Y2O3 in the remaining tetragonal ZrO2 phases compared to the 3Y-TZP CEREC ZrSS and inCoris TZICS (8 and 20wt%, respectively). The sintering program did not affect the hydrothermal aging behavior of Katana STMLSS and CEREC ZrSS. TP of Katana STMLSS (TP≈32) was not affected by speed sintering, while the translucency of CEREC ZrSS (TP=14) was significantly reduced. Hardness, fracture toughness and Weibull characteristic strength of Katana STMLSS and CEREC ZrSS also reached the optimal level, but speed sintering substantially lowered their mechanical reliability. SIGNIFICANCE Speed sintering of 3Y-TZP and 5Y-PSZ in a speed sintering induction oven appeared suitable for clinical applications. However, further studies should focus on improving of translucency and mechanical reliability of the speed-sintered zirconia ceramics.
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Affiliation(s)
- Stevan M Cokic
- KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & UZ Leuven (University Hospitals Leuven), Dentistry, Leuven, Belgium
| | - Jef Vleugels
- KU Leuven (University of Leuven), Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, B-3001 Leuven, Belgium
| | - Bart Van Meerbeek
- KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & UZ Leuven (University Hospitals Leuven), Dentistry, Leuven, Belgium.
| | - Bernardo Camargo
- KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & UZ Leuven (University Hospitals Leuven), Dentistry, Leuven, Belgium
| | - Evita Willems
- KU Leuven (University of Leuven), Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, B-3001 Leuven, Belgium
| | - Maoyin Li
- KU Leuven (University of Leuven), Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, B-3001 Leuven, Belgium
| | - Fei Zhang
- KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & UZ Leuven (University Hospitals Leuven), Dentistry, Leuven, Belgium; KU Leuven (University of Leuven), Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, B-3001 Leuven, Belgium
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39
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Wiedenmann F, Pfefferle R, Reichert A, Jerman E, Stawarczyk B. Impact of high-speed sintering, layer thickness and artificial aging on the fracture load and two-body wear of zirconia crowns. Dent Mater 2020; 36:846-853. [PMID: 32414506 DOI: 10.1016/j.dental.2020.04.004] [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: 09/27/2019] [Revised: 03/18/2020] [Accepted: 04/13/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To investigate the impact of high-speed sintering, layer thickness and artificial aging in a chewing simulator on the fracture load (FL) and two-body wear (2BW) of 4Y-TZP crowns. METHODS 4Y-TZP crowns (Ceramill Zolid HT+, Amann Girrbach AG) in three different layer thicknesses (0.5, 1.0, 1.5; N=192, n=64/group) were manufactured using CAD/CAM technology and sintered at 1580°C (high-speed sintering) or 1450°C (control group). Specimens were polished in two-steps and bonded to standardized CoCr abutments with Multilink Automix (Ivoclar Vivadent). 2BW after 6000 thermo- and 1,200,000 chewing-cycles employing enamel antagonists was determined using best fit machining. FL was tested before and after artificial aging. Univariate ANOVAs, post hoc Scheffé, unpaired t-, Kruskal-Wallis- and Mann-Whitney-U-test were computed (p<0.05). RESULTS High-speed sintering resulted in less 2BW of the zirconia than the control group (p=0.013). High-speed sintering (p=0.001-0.006) and an increase in layer thickness (p<0.001-0.012) resulted in higher FL values, while artificial aging led to a reduction of FL (p<0.001). SIGNIFICANCE As high-speed sintering resulted in less two-body wear of the zirconia and comparable or even higher fracture load results than the control group, this cost- and time efficient alternative presents promising mechanical results.
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Affiliation(s)
- Felicitas Wiedenmann
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336 Munich, Germany.
| | - Regina Pfefferle
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336 Munich, Germany
| | - Axel Reichert
- Research & Development, Amann Girrbach GmbH, Herrschaftswiesen 1, 6842 Koblach, Austria
| | - Eva Jerman
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336 Munich, Germany
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336 Munich, Germany
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40
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Ahmed WM, Troczynski T, Stojkova BJ, McCullagh AP, Wyatt CC, Carvalho RM. Dimensional Changes of Yttria-stabilized Zirconia under Different Preparation Designs and Sintering Protocols. J Prosthodont 2020; 29:699-706. [PMID: 32237048 DOI: 10.1111/jopr.13170] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 03/20/2020] [Accepted: 03/24/2020] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To evaluate the linear and volumetric dimensional changes that occur throughout the fabrication process of monolithic 4.5-6% yttria-stabilized zirconia copings under the influence of different preparation designs and two sintering protocols. MATERIALS AND METHODS A titanium master die was fabricated using Atlantis core file implant-abutment. Six copings were designed virtually according to different finish line offsets and coping thicknesses, with four equidistant occlusal posts for linear measurements. Zirconia copings were milled using IPS e.max ZirCAD LT zirconia blanks. The experimental groups according to the coping designs were the following: G1: 0.5 mm finish line offset, 0.5 mm thickness; G2: 0.5 mm finish line offset, 1.0 mm thickness; G3: 0.5 mm finish line offset, 1.5 mm thickness; G4: 1.2 mm finish line offset, 0.5 mm thickness; G5: 1.2 mm finish line offset, 1.0 mm thickness; G6: 1.2 mm finish line offset, 1.5 mm thickness. Six samples per group were sintered by standard sintering (SS) and the other six by fast sintering (FS). Linear and volumetric measurements were taken at the three fabrication stages (virtual design, milling stage, and sintering) by using an intraoral scanner and imported as the .stl file to Meshmixer software for analysis. Statistical analysis was performed by a linear mixed effect model via statistical software R (R Core team, 2018). RESULTS There was a significant interaction between the coping design group, stage of fabrication and sintering protocol on the linear (F = 4.451, p < 0.001) and volumetric (F = 2.716; p < 0.001) dimensional changes. Standard sintering G1 showed the smallest linear and dimensional changes among the groups compared to the reference design. Sintered copings had shrunk on average 1.32% within SS and 1.54% within FS linearly and 3.82% within SS and 3.90% within FS volumetrically compared to the initial design parameters. CONCLUSION The linear and volumetric dimensional changes did not differ significantly between standard and fast sintering protocols, and the preparation designs had more influence on the dimensional changes compared to sintering protocols.
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Affiliation(s)
- Walaa Magdy Ahmed
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada.,Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Tom Troczynski
- Faculty of Applied Science, The University of British Columbia, Vancouver, BC, Canada
| | | | - Anthony P McCullagh
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada
| | - Chris C Wyatt
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada
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41
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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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42
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Coskun ME, Çelenk MF. Structural Alterations of Zirconia Depending on Sintering Parameters and Effects on Bond Strength After Different Surface Treatments. CUMHURIYET DENTAL JOURNAL 2019. [DOI: 10.7126/cumudj.583267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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43
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Elisa Kauling A, Güth JF, Erdelt K, Edelhoff D, Keul C. Influence of speed sintering on the fit and fracture strength of 3-unit monolithic zirconia fixed partial dentures. J Prosthet Dent 2019; 124:380-386. [PMID: 31780110 DOI: 10.1016/j.prosdent.2019.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 09/02/2019] [Accepted: 09/17/2019] [Indexed: 02/02/2023]
Abstract
STATEMENT OF PROBLEM Speed sintering has been introduced to enable single-visit monolithic zirconia prostheses. However, the fit and fracture load of zirconia 3-unit monolithic fixed partial dentures (FPDs) after speed sintering are unknown. PURPOSE The purpose of this in vitro study was to test the properties of zirconia 3-unit monolithic FPDs after speed sintering and to compare the properties with conventional sintering. MATERIAL AND METHODS A calibrated operator digitized an in vitro model with a complete coverage preparation of a maxillary right second premolar and second molar (n=12) by using the CEREC AC Omnicam (Dentsply Sirona) scanner. Twelve zirconia FPDs were designed (CEREC SW 4.1.1), and for each data set (n=12), 1 FPD was designed and milled 4 times (MCXL Premium; CEREC Zirconia; Dentsply Sirona), resulting in 4 identical monolithic FPDs (N=48). The FPDs were divided into 2 groups according to the sintering procedure (n=24): speed sintering (group S) by using the SpeedFire (Dentsply Sirona) and the conventional sintering (group C) by using the inFire HTC speed (Dentsply Sirona). All the FPDs were glazed by using glaze-spray and fired according to the sintering group. The SpeedFire (Dentsply Sirona) was used for group S, and the VACUMAT 6000M (VITA Zahnfabrik) was used for group C. The fit of the FPDs was evaluated with the replica technique by using polyvinyl siloxane and analyzed according to the measurement areas: marginal gap, chamfer area, axial wall, and occlusal area. Subsequently, groups S and C were further subdivided, and 12 specimens per group underwent artificial aging by thermomechanical loading in a mastication machine (50 N for 1.2×106 times at a frequency of 1.7 Hz and a thermal change in distilled water from 5 °C to 50 °C every 120 seconds), resulting in additional subgroups: group SA and group CA. For all the FPDs (groups S, C, SA, and CA), a fracture load measurement was conducted. The Kolmogorov-Smirnov test was used to examine the values of the fit and fracture load for normal distribution. The Mann-Whitney U test for the fit and a 2-way ANOVA for the fracture load were used to detect the differences among the groups (α=.05). RESULTS Group S showed a better marginal (P=.018) and occlusal (P<.001) fit than group C. For the fracture load values, no significant difference was found because of the sintering procedure (P=.070) or the interaction of the sintering procedure and artificial aging (P=.484). Artificial aging showed an impact (P=.024) with significantly lower values after aging. CONCLUSIONS Speed-sintered FPDs had equal and better values for the fit and fracture load than conventional sintering.
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Affiliation(s)
- Ana Elisa Kauling
- Doctoral student and Visiting Researcher, Department of Prosthetic Dentistry, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany
| | - Jan-Frederik Güth
- Associate Professor, Department of Prosthetic Dentistry, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany
| | - Kurt Erdelt
- Research Engineer, Department of Prosthetic Dentistry, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany
| | - Daniel Edelhoff
- Director and Chair, Department of Prosthetic Dentistry, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany
| | - Christine Keul
- Assistant Professor, Department of Prosthetic Dentistry, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany.
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44
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Zimmermann M, Ender A, Mehl A. Influence of CAD/CAM Fabrication and Sintering Procedures on the Fracture Load of Full-Contour Monolithic Zirconia Crowns as a Function of Material Thickness. Oper Dent 2019; 45:219-226. [PMID: 31738694 DOI: 10.2341/19-086-l] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The purpose of this in vitro study was to analyze the effect of computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication and sintering procedures on the fracture load of monolithic zirconia crowns with different material thicknesses adhesively seated to methacrylate dies fabricated with stereolithography technology. METHOD Monolithic zirconia crowns were fabricated from inCoris TZI C material with a chairside CAD/CAM system (CEREC MCXL) comprising three material thicknesses (0.5/1.0/1.5 mm, n=8 each). Two CAD/CAM fabrication procedures (milling, MI; grinding, GR), two chairside sintering procedures (superspeed, SS; speedfire sintering, SF), and one labside sintering procedure (classic, CL) were evaluated. In total, 144 crowns were fabricated. Restorations were adhesively seated to methacrylate dies fabricated with SLA technology. Thermomechanical cycling (TCML) was performed before fracture testing. Loading forces until fracture were registered and statistically analyzed with one-way analysis of variance (ANOVA), post hoc Scheffé test, and three-way ANOVA (α=0.05). RESULTS Test groups showed statistically significant differences (p<0.05). The highest mean value was found for 1.5-mm crowns of group GR_SF with 3678.6 ± 363.9 N. The lowest mean value was found for group 0.5-mm crowns of group MI_SF with 382.4 ± 30.7 N. There was a significant three-way interaction effect between thickness, sintering, and processing [F(4,126)=9.542; p<0.001; three-way ANOVA, significance level α=0.05]. CONCLUSIONS CAD/CAM fabrication and sintering procedures influence the maximum loading force of monolithic zirconia crowns with different material thicknesses. A material thickness of 0.5 mm should be considered as a critical thickness for monolithic zirconia crown restorations.
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45
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Jansen JU, Lümkemann N, Letz I, Pfefferle R, Sener B, Stawarczyk B. Impact of high-speed sintering on translucency, phase content, grain sizes, and flexural strength of 3Y-TZP and 4Y-TZP zirconia materials. J Prosthet Dent 2019; 122:396-403. [DOI: 10.1016/j.prosdent.2019.02.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 02/19/2019] [Accepted: 02/19/2019] [Indexed: 01/24/2023]
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46
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Lawson NC, Maharishi A. Strength and translucency of zirconia after high-speed sintering. J ESTHET RESTOR DENT 2019; 32:219-225. [PMID: 31515932 DOI: 10.1111/jerd.12524] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/25/2019] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To compare the strength and translucency of CAD/CAM zirconia blocks, with traditional and high-speed sintering, to lithium disilicate. MATERIALS AND METHODS Three zirconia materials (Katana STML Block, Prettau Anterior, and Zpex Smile) were tested with either traditional (7 hours) or high-speed (18 or 30 minutes in a SpeedFire furnace) sintering. A lithium disilicate material (IPS e.max CAD) was tested as a reference. Three-point bend flexural strength specimens (16 mm × 4 mm × 1.2 mm, n = 10) were tested on 14-mm-separated supports and loaded to failure at 1 mm/min. Specimens (1 mm thick, n = 10) were measured in a Color-i7 spectrophotometer against a black and white background to calculate translucency parameter. Zirconia specimens were thermally etched and a grain structure was observed with scanning electron microscopy. Data were analyzed with 1-way ANOVA and Tukey's post hoc analysis (α = 0.05). RESULTS There were significant differences between materials for flexural strength, translucency parameter, and grain size (P < .001). Grains became significantly larger and pores were present when two of the zirconia materials (Prettau Anterior and Zpex Smile) were sintered with a high-speed sintering program. CONCLUSIONS Two of the zirconia materials (Prettau Anterior and Zpex Smile) became less translucent and less strong using a high-speed sintering program, whereas another (Katana STML Block) was unaffected.
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Affiliation(s)
- Nathaniel C Lawson
- Division of Biomaterials, University of Alabama at Birmingham, Birmingham, Alabama
| | - Anvita Maharishi
- Division of Biomaterials, University of Alabama at Birmingham, Birmingham, Alabama
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47
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Öztürk C, Çelik E. Influence of heating rate on the flexural strength of monolithic zirconia. J Adv Prosthodont 2019; 11:202-208. [PMID: 31497267 PMCID: PMC6718841 DOI: 10.4047/jap.2019.11.4.202] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/17/2019] [Accepted: 08/02/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Fabrication of zirconia restorations with ideal mechanical properties in a short period is a great challenge for clinicians. The purpose of the study was to investigate the effect of heating rate on the mechanical and microstructural properties of monolithic zirconia. MATERIALS AND METHODS Forty monolithic zirconia specimens were prepared from presintered monolithic zirconia blanks. All specimens were then assigned to 4 groups according to heating rate as Control, Group 15℃, Group 20℃, and Group 40℃. All groups were sintered according to heating rates with the sintering temperature of 1500℃, a holding time of 90 minutes and natural cooling. The phase composition was examined by XRD analysis, three-point bending test was conducted to examine the flexural strength, and Weibull analysis was conducted to determine weibull modulus and characteristic strength. Average grain sizes were determined by SEM analysis. One-way ANOVA test was performed at a significance level of 0.05. RESULTS Only tetragonal phase characteristic peaks were determined on the surface of analyzed specimens. Differences among the average grain sizes of the groups were not statistically significant. The results of the three-point bending test revealed no significant differences among the flexural strength of the groups (P>.05). Weibull modulus of groups was ranging from 3.50 to 4.74. The highest and the lowest characteristic strength values were obtained in Group 20℃ and Control Group, respectively. CONCLUSION Heating rate has no significant effect on the flexural strength of monolithic zirconia. Monolithic zirconia restorations can be produced in shorter sintering periods without affecting the flexural strength by modifying the heating rate.
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Affiliation(s)
- Caner Öztürk
- Department of Prosthodontics, Faculty of Dentistry, Hatay Mustafa Kemal University, Hatay, Turkey
| | - Ersan Çelik
- Department of Prosthodontics, Faculty of Dentistry, Ordu University, Ordu, Turkey
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48
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Ahmed WM, Troczynski T, McCullagh AP, Wyatt CCL, Carvalho RM. The influence of altering sintering protocols on the optical and mechanical properties of zirconia: A review. J ESTHET RESTOR DENT 2019; 31:423-430. [PMID: 31140674 DOI: 10.1111/jerd.12492] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/17/2019] [Accepted: 05/20/2019] [Indexed: 01/01/2023]
Abstract
OBJECTIVE As a result of advancements in chairside technology and speed sintering techniques and increased esthetic demands of patients, efforts have been made to produce monolithic zirconia restorations that are highly translucent, strong, and dense. While methods for processing zirconia are well known, there is a tendency to modify the process parameters with the aim of decreasing the overall processing time and, in particular, the sintering time. This review provides clinicians with scientific evidence of the effects of altering sintering parameters used for dental zirconia on its microstructure, phase transformation, and mechanical and optical properties. MATERIALS AND METHODS A systematic search of Embase and Medline using Boolean operators was performed to locate relevant articles. RESULTS Eleven articles were selected for this review. The following characteristics of monolithic zirconia have been confirmed to be affected by alterations in sintering: the microstructure, mechanical properties, optical properties, wear behavior, and low thermal degradation. CONCLUSIONS The alteration of sintering parameters has been found to alter the grain size, wear behavior, and translucency of zirconia. There is a lack of clinical studies that investigate the influence of altering sintering parameters or methods on the clinical performance of monolithic zirconia restorations. CLINICAL SIGNIFICANCE Alteration of sintering parameters alters the microstructural, mechanical, and optical properties of zirconia. This will consequently impact the clinical performance of zirconia prostheses. Future clinical investigations are encouraged to support these in vitro findings.
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Affiliation(s)
- Walaa M Ahmed
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.,Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Tom Troczynski
- Faculty of Applied Science, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony P McCullagh
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Chris C L Wyatt
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Ricardo M Carvalho
- Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada
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49
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Coskun M, Sarı F. Effects of Speed Sintering on Multilayered Monolithic Zirconia. CUMHURIYET DENTAL JOURNAL 2019. [DOI: 10.7126/cumudj.510393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Ahmed WM, Abdallah MN, McCullagh AP, Wyatt CCL, Troczynski T, Carvalho RM. Marginal Discrepancies of Monolithic Zirconia Crowns: The Influence of Preparation Designs and Sintering Techniques. J Prosthodont 2019; 28:288-298. [PMID: 30656786 DOI: 10.1111/jopr.13021] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2019] [Indexed: 11/29/2022] Open
Abstract
PURPOSE The marginal fit is an essential component for the clinical success of prosthodontic restorations. The aim of this study was to investigate the influence of different abutment finish line widths and crown thicknesses on the marginal fit of zirconia crowns fabricated using either standard or fast sintering protocols. MATERIALS AND METHODS Six titanium abutments were fabricated for receiving zirconia molar crowns. Crowns were designed virtually and milled from partially sintered zirconia blanks and divided into 12 groups (n = 10/group). Crowns in groups 1 to 6 were sintered by standard sintering, while those in groups 7 to 12 were sintered by fast sintering. Groups were further categorized according to abutment finish line and crown thickness: G1/G7 (0.5 mm chamfer, 0.8 mm thick); G2/G8 (0.5 mm chamfer, 1.5 mm thick); G3/G9 (1.0 mm chamfer, 0.8 mm thick); G4/10 (1.0 mm chamfer, 1.5 mm thick); G5/G11 (1.2 mm chamfer, 0.8 mm thick); G6/G12 (1.2 mm chamfer, 1.5 mm thick). The marginal gaps were assessed at 8 locations using digital microscopy. The linear mixed effect model analysis was performed at a significance level of 0.05. RESULTS All vertical marginal gaps were within the clinically acceptable range (∼11-52 μm). G8 (FS, 0.5 mm chamfer, 1.5 mm thick) demonstrated the largest gaps (47.95 μm, 95% CI: 44.57-51.23), whereas G3 (SS, 1.0 mm chamfer, 0.8 thick) had the smallest marginal gap (14.43 μm, 95% CI: 11.15-17.71). A linear mixed effect models showed significant differences for the interaction between finish line × crown thickness × sintering (F = 18.96, p < 0.001). The lingual surfaces showed the largest gaps in both sintering protocols, while the mesial and mesiobuccal surfaces demonstrated the smallest gaps. CONCLUSIONS There was a significant interaction between finish line widths, crown thickness, and sintering protocol on the marginal gaps in both sintering protocols; 1.0 mm finish line preparations with either 0.8 mm or 1.5 mm occlusal reduction had better marginal fit in both sintering protocols compared to 0.5 mm or 1.2 mm finish lines. Smaller marginal discrepancies were observed for standard sintering crowns with a 0.5 mm finish line and 1.5 mm occlusal reduction. Conservative occlusal reduction should be accompanied with a 1.2 mm finish line to obtain better marginal fit for full-contoured zirconia crowns.
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Affiliation(s)
- Walaa Magdy Ahmed
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada.,Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Anthony P McCullagh
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada
| | - Chris C L Wyatt
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada
| | - Tom Troczynski
- Faculty of Applied Science, The University of British Columbia, Vancouver, BC, Canada
| | - Ricardo M Carvalho
- Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada
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