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Mayinger F, Ender A, Strickstrock M, Elsayed A, Nassary Zadeh P, Zimmermann M, Stawarczyk B. Impact of the sintering parameters on the grain size, crystal phases, translucency, biaxial flexural strength, and fracture load of zirconia materials. J Mech Behav Biomed Mater 2024; 155:106580. [PMID: 38759588 DOI: 10.1016/j.jmbbm.2024.106580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/06/2024] [Accepted: 05/10/2024] [Indexed: 05/19/2024]
Abstract
OBJECTIVES To investigate the influence of the zirconia and sintering parameters on the optical and mechanical properties. METHODS Three zirconia materials (3/4Y-TZP, 4Y-TZP, 3Y-TZP) were high-speed (HSS), speed (SS) or conventionally (CS) sintered. Disc-shaped specimens nested in 4 vertical layers of the blank were examined for grain size (GS), crystal phases (c/t'/t/m-phase), translucency (T), and biaxial flexural strength. Fracture load (FL) of three-unit fixed dental prostheses was determined initially and after thermomechanical aging. Fracture types were classified, and data statistically analyzed. RESULTS 4Y-TZP showed a higher amount of c + t'-phase and lower amount of t-phase, and higher optical and lower mechanical properties than 3Y-TZP. In all materials, T declined from Layer 1 to 4. 3/4Y-TZP showed the highest FL, followed by 3Y-TZP, while 4Y-TZP showed the lowest. In 4Y-TZP, the sintering parameters exercised a direct impact on GS and T, while mechanical properties were largely unaffected. The sintering parameters showed a varying influence on 3Y-TZP. Thermomechanical aging resulted in comparable or higher FL. CONCLUSION 3/4Y-TZP presenting the highest FL underscores the principle of using strength-gradient multi-layer blanks to profit from high optical properties in the incisal area, while ensuring high mechanical properties in the lower areas subject to tensile forces. With all groups exceeding maximum bite forces, the examined three-unit FDPs showed promising long-term mechanical properties.
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Affiliation(s)
- Felicitas Mayinger
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany.
| | - Andreas Ender
- Division of Computerized Restorative Dentistry, Clinic of Conservative and Preventive Dentistry, Center of Dental Medicine, University of Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland
| | - Monika Strickstrock
- Faculty of Engineering and Computer Science, Material Science and Analysis, University of Applied Sciences Osnabrück, Albrechtstraße 30, 49076, Osnabrück, Germany
| | - Adham Elsayed
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Parissa Nassary Zadeh
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Marcus Zimmermann
- Division of Computerized Restorative Dentistry, Clinic of Conservative and Preventive Dentistry, Center of Dental Medicine, University of Zurich, Plattenstrasse 11, 8032, Zurich, Switzerland
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany
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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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3
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Li Q, Yang Y, Chen K, Jiang Y, Swain MV, Yao M, He Y, Liang Y, Jian Y, Zhao K. Effect of low-temperature degradation on the fatigue performance of dental strength-gradient multilayered zirconia restorations. J Dent 2024; 142:104866. [PMID: 38281620 DOI: 10.1016/j.jdent.2024.104866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 01/16/2024] [Accepted: 01/25/2024] [Indexed: 01/30/2024] Open
Abstract
OBJECTIVES Fatigue and low-temperature degradation (LTD) are the main factors contributing to zirconia restoration failure. This study evaluated the effect of LTD on the fatigue performance of the novel "strength & shade-gradient" multilayered zirconia restorations. METHODS Discs (15 mm × 1.2 mm) of each yttria content layer from a newly developed strength-gradient multilayered zirconia were fabricated and under accelerated aging in an autoclave at 134℃ for 0 h, 32 h, and 64 h. Then, the phase transformation, microstructure, and mechanical properties after LTD were assessed. In addition, the crown samples, including the multi-Zir, 3Y-Zir, and 5Y-Zir were fabricated, and their monotonic and fatigue load before and after LTD, percentage of fatigue degradation (Sd) and the fracture morphology were investigated. Statistical analyses were performed using paired samples t-test (α' = α/3 = 0.017), one-way ANOVA and Weibull analysis. RESULTS After LTD, the phase transformation, surface roughness, depth of transformed zone, and residual stress were increased and inversely associated with the yttria content. The indentation elastic modulus and hardness after LTD decreased; however, there was no significant difference between the different yttria content layers. The monotonic and fatigue load of multi-Zir restorations decreased, but their Weibull modulus increased, and Sd decreased, similar to 3Y-Zir. The crack origin was associated with the cervical region. CONCLUSION These results show that although LTD reduces the absolute fatigue strength of strength-gradient multilayered zirconia restorations, it also reduces the effect of cyclic fatigue itself on the strength of zirconia (relative to monotonic strength), which might be due to the increase of residual stress. CLINICAL SIGNIFICANCE The novel "strength & shade-gradient" multilayered zirconia restorations show a promising performance during in vitro LTD and fatigue test and their reliability to some extent is comparable to 3Y-Zir. Yet, further in vivo longitudinal studies are warranted to confirm their precise performance.
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Affiliation(s)
- Qiulan Li
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yunxu Yang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Kuangyao Chen
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yingyu Jiang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Michael V Swain
- Don State Technical University, Rostov-on-Don 344000, Russia; AMME, Sydney University, Sydney, Australia
| | - Mianfeng Yao
- Xiangya Hospital Central South University, Changsha 410008, China
| | - Ying He
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yujie Liang
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
| | - Yutao Jian
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China; Institute of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China.
| | - Ke Zhao
- Hospital of Stomatology, Sun Yat-Sen University, Guangzhou 510055, China; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
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Klotz AL, Halfmann J, Rues S, Bömicke W, Rammelsberg P, Zenthöfer A. Fracture Resistance of Posterior Tooth-Supported Cantilever Fixed Dental Prostheses of Different Zirconia Generations and Framework Thicknesses: An In Vitro Study. MATERIALS (BASEL, SWITZERLAND) 2024; 17:263. [PMID: 38204115 PMCID: PMC10779861 DOI: 10.3390/ma17010263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024]
Abstract
The rehabilitation of free-end situations is a frequent indication in prosthetic dentistry. Cantilever fixed dental prostheses (cFDPs) made of 1st and 2nd generation zirconia are one treatment option. Due to a unique gradient technology, combinations of different zirconium dioxide generations are thus feasible in one restoration. However, data about these materials are rare. The purpose of this study was therefore to investigate the fracture resistance and fracture modes of tooth-supported cFDPs fabricated from different zirconia materials (gradient technology) and different framework thicknesses. A total of 40 cFDPs were fabricated using the CAD/CAM approach and belonged to five test groups. The different groups differed in the yttria content, the proportion of the tetragonal/cubic phases, or in wall thickness (0.7 mm or 1 mm). After completion, the cFDPs were subjected to thermal cycling and chewing simulation (1.2 × 106 load cycles, 108 N load). Afterwards, cFDPs were statically loaded until fracture in a universal testing machine. A non-parametric ANOVA was compiled to determine the possible effects of group membership on fracture resistance. In addition, post-hoc Tukey tests were used for bivariate comparisons. The mean fracture loads under axial load application ranged from 288 to 577 N. ANOVA detected a significant impact of the used material on the fracture resistances (p < 0.001). Therefore, the use of cFDPs fabricated by gradient technology zirconia may not be unreservedly recommended for clinical use, whereas cFPDs made from 3Y-TZP exhibit fracture resistance above possible masticatory loads in the posterior region.
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Affiliation(s)
- Anna-Luisa Klotz
- Department of Prosthodontics, Dental School, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; (J.H.); (S.R.); (W.B.); (P.R.); (A.Z.)
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Giti R, Jebal R. How could mouthwashes affect the color stability and translucency of various types of monolithic zirconia? An in-vitro study. PLoS One 2023; 18:e0295420. [PMID: 38039318 PMCID: PMC10691725 DOI: 10.1371/journal.pone.0295420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/20/2023] [Indexed: 12/03/2023] Open
Abstract
OBJECTIVES This study aimed to evaluate the color stability and translucency of various types of monolithic zirconia after immersion in chlorhexidine and Listerine mouthwashes. MATERIALS AND METHODS This experimental study was performed on 36 disk-shaped specimens fabricated from low-translucent, high-translucent, and multilayered monolithic zirconia (n = 12 per group). Each group was equally divided and immersed in either 2% chlorhexidine (CHX) or Listerine mouthwash for 2 min daily over 7 days. Changes in color (ΔE) and the translucency parameter (ΔTP) were evaluated and compared. The data were analyzed with one-way ANOVA followed by Tukey's post-hoc tests (α = 0.05). RESULTS Chlorhexidine caused a significantly lower ΔE and a significantly higher ΔTP in multilayered zirconia compared to the low-translucency (ΔE: P = 0.0027, ΔTP: P<0.001) and the high-translucency zirconia group (ΔE: P<0.001, ΔTP: P = 0.022). Listerine caused a significantly higher ΔE in the high-translucency zirconia group compared to the multilayered zirconia group (P = 0.0165). It also resulted in a significantly higher mean ΔTP in the multilayered zirconia group compared to the low-translucency (P = 0.0003) and high-translucency zirconia groups (P = 0.019). CONCLUSIONS In both mouthwashes, multilayered monolithic zirconia exhibited the highest color stability among the tested materials; albeit with the most pronounced changes in translucency. Meanwhile, high-translucency monolithic zirconia was more prone to discoloration when exposed to both mouthwashes.
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Affiliation(s)
- Rashin Giti
- Department of Prosthodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
| | - Reza Jebal
- Student Research Committee, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
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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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Musa DB, Ereifej NS. The influence of core-build up materials on biaxial flexural strength of monolithic strength-gradient zirconia; an in-vitro study. BMC Oral Health 2023; 23:873. [PMID: 37978509 PMCID: PMC10657006 DOI: 10.1186/s12903-023-03635-2] [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: 08/17/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Since their introduction, there has been limited research regarding the mechanical properties of novel strength-gradient monolithic zirconia. In addition to that, studies evaluating the effect of different core-build materials on the strength of indirect restorations are scarce. Therefore, the aim of this study was to investigate the effect of using different core build-up materials on biaxial flexural strength of a new monolithic multilayered zirconia material. METHODS Forty zirconia discs were fabricated from IPS e.max ZirCAD Prime (Ivoclar Vivadent AG, Schaan, Liechtenstein) and divided into 2 groups (n = 20). Forty composite discs were prepared from Tetric N-Ceram (Ivoclar Vivadent AG, Schaan, Liechtenstein) and MultiCore Flow (Ivoclar Vivadent AG, Schaan, Liechtenstein). The zirconia discs were adhesively cemented to the 2 types of composite forming 2 groups (Zirconia-Tetric N-Ceram and Zirconia-MultiCore Flow). Biaxial flexural strength was determined using a piston-on-3-ball test. The data were statistically analyzed with an independent t-test for significant differences (p = 0.05). RESULTS Tetric N-Ceram had significantly higher strength than MultiCore Flow (p < 0.001) but no statistically significant differences were found in strength values between Zirconia-Tetric N-Ceram and Zirconia-MultiCore Flow bilayered samples (p = 0.27). CONCLUSIONS It was concluded that although the tested composite core materials significantly differ in their biaxial flexural strength values, they had no influence on the biaxial flexural strength of the overlying zirconia.
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Affiliation(s)
| | - Nadia S Ereifej
- Department of Prosthetic Dentistry, Faculty of Dentistry, The University of Jordan, Queen Rania Street, Amman, 11942, Jordan.
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Erdinç G, Bülbül M, Özcan M. Fracture strength and energy-dispersive spectroscopy analysis of 3-unit fixed partial dentures fabricated from different monolithic zirconia materials. J Prosthet Dent 2023:S0022-3913(23)00178-6. [PMID: 37024356 DOI: 10.1016/j.prosdent.2023.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 04/08/2023]
Abstract
STATEMENT OF PROBLEM Mastication forces in different regions affect the survival of multiunit posterior restorations. The fracture strength of 3-unit posterior monolithic zirconia fixed partial dentures (FPDs) and their fracture patterns require investigation. PURPOSE The purpose of this in vitro study was to evaluate and compare the fracture strength and fracture pattern of 3-unit posterior FPDs fabricated from different monolithic zirconia materials. MATERIAL AND METHODS Thirty 3-unit FPDs were fabricated from BruxZir, FireZr, and Upcera (n=10 per group). Energy-dispersive spectroscopy analysis was performed on 2 selected specimens from each group. All specimens were exposed to a mastication simulator for 1.2×106 cycles and then monotonically loaded to fracture at a crosshead speed of 1 mm/min. The surfaces of a selected fractured specimen were examined at magnifications of ×25 and ×500 with scanning electron microscopy. Conformity to normal distribution was evaluated with the Shapiro-Wilk test. One-way analysis of variance was used to compare the normally distributed initial crack formation load F initial (Fi) and catastrophic failure strength F maximum (Fm) means by group. Weibull statistics were calculated by using the maximum likelihood estimation method. The chi-square test was used to compare shape and scale parameters (α=.05). RESULTS The mean Fm values were fail1878.9 N for Upcera, 2177.8 N for BruxZir, and 2229.4 N for FireZr. Upcera and BruxZir showed statistically significant differences for the Fm mean values (P=.039). The differences between the fracture type distributions according to the groups were statistically similar (P>.05). For Fi, Upcera presented the highest Weibull modulus value (2.199), FireZr had the lowest (1.594), while for Fm, BruxZir had the highest Weibull modulus value (9.267) and FireZr the lowest (6.572). CONCLUSIONS Using the zirconia materials BruxZir, FireZr, and Upcera resulted in high Fm values after aging procedures. With all materials, the fractures were most commonly found in the connector areas in the tested FPDs.
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Affiliation(s)
- Gülbahar Erdinç
- Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Karabük University, Karabük, Turkey.
| | - Mehmet Bülbül
- Professor, Department of Prosthodontics, Faculty of Dentistry, İstanbul Aydin University, İstanbul, Turkey
| | - Mutlu Özcan
- Professor and Head, Division of Dental Biomaterials, Clinic for Reconstructive Dentistry, Center for Dental and Oral Medicine, University of Zurich, Zurich, Switzerland
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Strasser T, Wertz M, Koenig A, Koetzsch T, Rosentritt M. Microstructure, composition, and flexural strength of different layers within zirconia materials with strength gradient. Dent Mater 2023; 39:463-468. [PMID: 36907821 DOI: 10.1016/j.dental.2023.03.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 02/01/2023] [Accepted: 03/03/2023] [Indexed: 03/12/2023]
Abstract
OBJECTIVES The aim of this study was to compare composition, microstructure, and mechanical strength of current multilayer zirconia blanks. METHODS Bar shaped specimens were made from several layers of multilayer zirconia blanks (Cercon ht ML, Dentsply Sirona, US; Katana Zirconia YML, Kuraray, J;SHOFU Disk ZR Lucent Supra, Shofu, J; priti multidisc ZrO2 Multi Translucent, Pritidenta, D; IPS e.max ZirCAD Prime, Ivoclar Vivadent, FL). Flexural strength was determined in a three-point bending test on extra-thin bars. X-ray diffraction (XRD) with Rietveld refinement was used to assess crystal structure and scanning electron microscopy (SEM) imaging to visualize the microstructure of each material and layer. RESULTS Mean flexural strength varied between 467.5 ± 97.5 MPa (top layer, IPS e.max ZirCAD Prime) and 898.0 ± 188.5 MPa (bottom layer, Cercon ht ML) with significant (p ≤ 0.055) differences between the individual layers. XRD indicated 5Y-TZP for enamel-layers, 3Y-TZP for dentine-layers, individual mixtures of 3Y-TZP, 4Y-TZP, or 5 Y-TZP for intermediate layers. SEM analysis showed grain sizes between approx. 0.15 and 4 µm. Grain size tended to decrease from top to bottom layers. SIGNIFICANCE The investigated blanks differ predominantly in the intermediate layers. In addition to dimensioning of restorations, the milling position in the blanks must also be taken into account when using multilayer zirconia as restorative material.
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Affiliation(s)
- Thomas Strasser
- Department of Prosthetic Dentistry, University Hospital of Regensburg, 93053 Regensburg, Germany.
| | - Markus Wertz
- Department of Prosthodontics and Material Sciences, Leipzig University, 04103 Leipzig, Germany
| | - Andreas Koenig
- Department of Prosthodontics and Material Sciences, Leipzig University, 04103 Leipzig, Germany
| | - Torsten Koetzsch
- Institute of Mineralogy, Crystallography and Materials Science, Leipzig University, 04275 Leipzig, Germany
| | - Martin Rosentritt
- Department of Prosthetic Dentistry, University Hospital of Regensburg, 93053 Regensburg, Germany
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Machry RV, Dapieve KS, Cadore-Rodrigues AC, Werner A, de Jager N, Pereira GKR, Valandro LF, Kleverlaan CJ. Mechanical characterization of a multi-layered zirconia: Flexural strength, hardness, and fracture toughness of the different layers. J Mech Behav Biomed Mater 2022; 135:105455. [PMID: 36148725 DOI: 10.1016/j.jmbbm.2022.105455] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/30/2022] [Accepted: 09/06/2022] [Indexed: 10/31/2022]
Abstract
This study compared the flexural strength under monotonic (static - sσ) and cyclic load application (fatigue - fσ), hardness (H) and fracture toughness (KIC) of different layers of a multi-layered zirconia (IPS e.max ZirCAD MT Multi, Ivoclar). Each layer was sectioned, classified into three groups according to yttria content (4-YSZ, 4/5-YSZ and 5-YSZ), and shaped on samples for flexural strength and fracture toughness tests (bars: 1.0 × 1.0 × 11 mm); and Vickers hardness test (plates: 1.5 × 4.0 × 5.0 mm). Flexural strength under monotonic load application (sσ; n = 10) was obtained through two different devices (three-point-bending and ball-in-hole device) and fatigue flexural strength (fσ; n = 15; initial load: 10 N; step-size: 5 N; 10,000 cycles/step) was assessed using a ball-in-hole device under cyclic load application. Vickers hardness test (n = 5), fracture toughness test (n = 10), and additional analyzes (Finite Element Analysis - FEA, Energy-dispersive X-ray spectroscopy - EDS and Scanning Electron Microscopy - SEM) were also performed. No differences were found between the different devices in the monotonic flexural strength test, and FEA showed similar tensile stress distribution for the two devices. 4-YSZ showed higher values of flexural strength under monotonic and cyclic load application modes (sσ = 1114.73 MPa; fσ = 798.84 MPa), and fracture toughness (KIC = 3.90 MPa√m). 4/5-YSZ had an intermediate sσ; however, fσ was similar to 5-YSZ (404.00-429.36 MPa) and KIC similar to 4-YSZ (KIC = 3.66 MPa√m). No statistical differences were found for hardness and Weibull modulus for fatigue flexural strength data. The amount of yttria in the layer compositions increased from 4-YSZ to 5-YSZ, and larger zirconia crystals were observed in the topographic images of 5-YSZ. Failures in the flexural strength and toughness tests started from the face subjected to tensile stress. Different layers of the multi-layered zirconia blank presented distinct mechanical properties. 4-YSZ (cervical layer) presented the highest flexural strength under monotonic and cyclic loads (fatigue), and higher fracture toughness even similar to the transition layer (4/5-YSZ). Hardness was similar between the layers. The ball-in-hole device performed similarly to the three-point bending device and can be used as an alternative to the traditional method.
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Affiliation(s)
- Renan Vaz Machry
- MSciD-PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, 1000 Roraima Av., Santa Maria, Rio Grande do Sul, Brazil.
| | - Kiara Serafini Dapieve
- MSciD-PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, 1000 Roraima Av., Santa Maria, Rio Grande do Sul, Brazil.
| | - Ana Carolina Cadore-Rodrigues
- MSciD-PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, 1000 Roraima Av., Santa Maria, Rio Grande do Sul, Brazil.
| | - Arie Werner
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, Noord-Holland, Netherlands.
| | - Niek de Jager
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, Noord-Holland, Netherlands.
| | - Gabriel Kalil Rocha Pereira
- MSciD-PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, 1000 Roraima Av., Santa Maria, Rio Grande do Sul, Brazil.
| | - Luiz Felipe Valandro
- MSciD-PhD Post-Graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, 1000 Roraima Av., Santa Maria, Rio Grande do Sul, Brazil.
| | - Cornelis Johannes Kleverlaan
- Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, Noord-Holland, Netherlands.
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Fracture Load and Fracture Patterns of Monolithic Three-Unit Anterior Fixed Dental Prostheses after In Vitro Artificial Aging-A Comparison between Color-Gradient and Strength-Gradient Multilayer Zirconia Materials with Varying Yttria Content. J Clin Med 2022; 11:jcm11174982. [PMID: 36078912 PMCID: PMC9457031 DOI: 10.3390/jcm11174982] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/18/2022] [Accepted: 08/19/2022] [Indexed: 12/02/2022] Open
Abstract
(1) Background: Due to advantages such as avoidance of chipping, pulp-friendly tooth preparation and cost reduction, zirconia is increasingly being used monolithically without veneering. Nevertheless, to enable good aesthetics, various multilayer systems have been developed. The aim of this study was to investigate the impact of different zirconia multilayer strategies and yttria levels on fracture load, fracture pattern, stress distribution and surface roughness. (2) Methods: Monolithic three-unit anterior FDPs were made from three different color-gradient zirconia multilayer materials with different yttria levels corresponding to varying strength and degrees of translucency grades (Katana HTML, STML, UTML, Kuraray) and one strength-gradient zirconia multilayer material (Katana YML, Kuraray) and artificially aged in a chewing simulator (1.2 × 106 load cycles, 50 N, 2 × 3000 thermocycles, 5−55 °C). Analyses of fracture load, fracture pattern, fracture surfaces, stress distribution and roughness were performed after the fracture load test. Shapiro−Wilk, Kruskal−Wallis, Mann−Whitney U-tests and one-way ANOVA were used (p < 0.05). (3) Results: Fracture loads of the high strength color-gradient material HTML and the strength-gradient material YML were comparable after 5 years of aging (p = 0.645). Increasing yttria levels resulted in a decrease in fracture resistance of 42−57% (p < 0.05). Surface roughness of different zirconia generations is comparable after polishing and aging. (4) Conclusions: Color-gradient multilayer zirconia materials and new strength-gradient zirconia materials with similar yttria levels in the basal layers show comparable mechanical properties and are suitable for anterior FDPs.
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Schönhoff LM, Lümkemann N, Buser R, Hampe R, Stawarczyk B. Fatigue resistance of monolithic strength-gradient zirconia materials. J Mech Behav Biomed Mater 2021; 119:104504. [PMID: 33845296 DOI: 10.1016/j.jmbbm.2021.104504] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/24/2021] [Accepted: 03/29/2021] [Indexed: 11/18/2022]
Abstract
PURPOSE Evaluation of the effect of three different dynamic fatigue protocols on the fracture resistance of two monolithic strength-gradient zirconia materials. MATERIALS AND METHODS A total of 240 specimens (3 × 4 × 45 mm) was milled from two different layers (incisal and middle) of two types of strength-gradient zirconia blanks (IPS e. max ZirCAD MT Multi A2 vs. IPS e. max ZirCAD Prime A2), resulting in 60 specimens per material and layer group (IPS e. max ZirCAD MT Multi A2: incisal (MI), middle (MM); IPS e. max ZirCAD Prime A2: incisal (PI), middle (PM)). Each group was divided into one static (n = 15) and three dynamic fatigue protocols (N = 45, n = 15): i. 50 N increase every 5000 cycles ii. Increase by 5% of static fracture load every 5000 cycles iii. 10 N increase every 1000 cycles until facture. All specimens were loaded until facture in CeraTest 2 k. Kaplan-Meier, Log-Rank and Chi-squared-test as well as Weibull statistics were performed. A fractographic analysis was performed. The specimens were classified according to the number of crack origins and evaluated using the Ciba-Geigy table. RESULTS With regard to the fracture load, in the static loading MI and PI showed a higher fracture load and in dynamic fatigue protocol 2 PI showed a lower fracture load. The number of cycles until fracture only differed within three groups: MM and MI survived a higher number of cycles in dynamic fatigue protocol 2; PI survived a higher number of cycles in dynamic fatigue protocol 2 than in protocol 1. Within dynamic fatigue protocols, PM resisted the highest number of cycles in protocol 1 and 3 and MI in protocol 2. Comparing groups, Weibull modulus differed only within the static loading, with PI showing lower values than MM and MI. Within the material groups, MI showed higher values in static loading than in dynamic fatigue protocol 1 and 2, and PI showed higher values in the dynamic fatigue protocol 3 than in static loading. With regard to fracture patterns, no differences were found between the groups. CONCLUSIONS Dynamic fatigue protocols provide clinically relevant information on the long-term stability and reliability of monolithic strength-gradient zirconia materials. However, no definitive instructions for dynamic testing can be provided from this investigation.
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Affiliation(s)
- Lisa Marie Schönhoff
- Dental Material Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Nina Lümkemann
- Dental Material Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Ramona Buser
- Dental Material Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany; Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
| | - Rüdiger Hampe
- Dental Material Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany
| | - Bogna Stawarczyk
- Dental Material Unit, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany.
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