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Vardhaman S, Borba M, Kaizer MR, Kim DK, Zhang Y. Optical and Mechanical Properties of the Multi-Transition Zones of a Translucent Zirconia. J ESTHET RESTOR DENT 2024. [PMID: 39325338 DOI: 10.1111/jerd.13319] [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] [Received: 04/22/2024] [Revised: 07/30/2024] [Accepted: 09/06/2024] [Indexed: 09/27/2024]
Abstract
OBJECTIVE To characterize the composition, flexure resistance, and optical properties of a multilayer translucent zirconia in relation to its multi-transition zones. MATERIALS AND METHODS A multilayer zirconia (5Y/4Y) and a conventional 3 mol% yttria partially stabilized zirconia (3Y) were investigated. Bar-shaped specimens were obtained from the enamel and dentin layers, and the vertical cross-section of 5Y/4Y (N = 10). A four-point flexural (σf) test was performed using a universal testing machine (1.0 mm/min). Plate-shaped specimens (N = 6) were also produced from the enamel, transition 1, transition 2, and dentin layers. Translucency parameters (TPab and TP00) were determined using a dental spectrophotometer (N = 6). X-ray fluorescence and X-ray diffraction techniques were used to analyze elemental (N = 2) and phase compositions (N = 2), respectively. Data were analyzed using analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS The yttrium content and σf varied between layers of 5Y/4Y. 3Y had the highest σf, followed by dentin. Enamel and cross-section showed lower and statically similar σf. 3Y and dentin groups had similar but statistically lower TPab and TP00 than the enamel. CONCLUSIONS Different layers of multilayered zirconia have distinct compositions, which affect their mechanical and optical properties. The weak enamel layer compromises the mechanical properties of cross-sectional specimens. CLINICAL SIGNIFICANCE The development of novel cubic-containing multilayer zirconia ceramics to produce monolithic restorations brings new challenges to dental clinicians and laboratory technicians. The CAD/CAM design of multilayered 5Y/4Y restorations should consider the esthetic and mechanical requirements of each clinical case, as different properties are found in the different layers of these materials.
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Affiliation(s)
- Sonaj Vardhaman
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- College of Dental Medicine, Columbia University, New York, New York, USA
| | - Marcia Borba
- University of Manchester, Manchester, UK
- University of Passo Fundo, Passo Fundo, Brazil
| | - Marina R Kaizer
- Centre for Rural Dentistry and Oral Health, Charles Sturt University, Orange, New South Wales, Australia
- Post-Graduate Program in Dentistry, Universidade Positivo, Curitiba, Paraná, Brazil
| | - Do Kyung Kim
- Department of Materials Science and Engineering, KAIST, Daejeon, South Korea
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Nakamura K, Shishido S, Inagaki R, Kanno T, Barkarmo S, Svanborg P, Örtengren U. Critical evaluations on the crystallographic properties of translucent dental zirconia ceramics stabilized with 3-6 mol% yttria. Dent Mater 2024; 40:1425-1451. [PMID: 38942711 DOI: 10.1016/j.dental.2024.06.027] [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: 03/07/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 06/30/2024]
Abstract
OBJECTIVES This study aimed to determine the crystalline phase composition of 3-6 mol% yttria-stabilized zirconia (3-6YSZ), specifically investigating the presence of tetragonal (t), cubic (c), and/or additional yttria-rich tetragonal (t') phase. METHODS Laboratory-fabricated specimens comprising 3-5YSZ, resembling translucent dental zirconia ceramics (TZ specimens), and a blend of 3YSZ and 8YSZ, representing a c-phase reference, were prepared. Additionally, 25 dental zirconia products stabilized with 3-6 mol% yttria were analyzed. Whole X-ray diffraction (XRD) patterns were obtained for Rietveld analysis, complemented by fine scanning in the 2θ region from 72º to 76º for qualitative phase analysis. Moreover, yttria concentrations in each specimen were determined using X-ray fluorescence (XRF) spectroscopy. RESULTS In the 2θ region from 72º to 76º, TZ and dental zirconia product specimens displayed four peaks attributed to t- and t'-phases, but the c-phase peak was absent. Rietveld analysis of the whole XRD patterns, utilizing a t-t' model, demonstrated the t-phase fraction ranging from 86 mass% in 3YSZ to 11 mass% in 6YSZ. Rietveld analysis appeared reliable, as the yttria contents calculated based on lattice parameters aligned well with those measured by XRF. This study established that dental 3-6YSZ consisted of yttria-lean t- and yttria-rich t'-phases. SIGNIFICANCE The present study enhances understanding of the crystalline structure of dental zirconia ceramics. Future crystallographic analyses of these ceramics should consider the presence of t- and t'-phases.
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Affiliation(s)
- Keisuke Nakamura
- Department of Advanced Free Radical Science, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan; Department of Cariology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, SE-405 30 Gothenburg, Sweden.
| | - Shunichi Shishido
- Department of Advanced Free Radical Science, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan
| | - Ryoichi Inagaki
- Department of Advanced Free Radical Science, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan
| | - Taro Kanno
- Department of Advanced Free Radical Science, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan
| | - Sargon Barkarmo
- Department of Prosthetic Dentistry/Dental Materials Science, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Per Svanborg
- Department of Prosthetic Dentistry/Dental Materials Science, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Ulf Örtengren
- Department of Cariology, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, SE-405 30 Gothenburg, Sweden; Department of Material Science and Technology, Faculty of Odontology, Malmö University, SE-206 05 Malmö, Sweden
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da Silva BCD, da Silva SEG, da Silva NR, de Moreira FGG, Souza KB, Zhang Y, de Souza ROA. Effect of different surface treatments and adhesive cementation on the surface topography and flexural strength of translucent and ultra-translucent monolithic zirconia. J Prosthodont 2024. [PMID: 39189693 DOI: 10.1111/jopr.13929] [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] [Received: 01/28/2024] [Accepted: 07/28/2024] [Indexed: 08/28/2024] Open
Abstract
PURPOSE To evaluate the effect of different surface treatments and adhesive cementation on the miniflexural strength (MFS) of monolithic zirconia. MATERIALS AND METHODS Two-hundred and forty (240) sintered bars of translucent zirconia (ZT) and ultra-translucent zirconia (ZUT) were obtained (8 mm ×2 mm ×1 mm). The bars were divided into 16 groups (n = 15) according to the factors "Zirconia" (ZT and ZUT), "Cementation" (Cem) and "surface treatment" (Ctrl:Control, Al:Aluminum oxide/Al2O3 50 µm, Si:Silica/SiO2 coated alumina particles oxide 30 µm, Gl:Glazing+hydrofluoric acid). Half of the bars received an adhesive layer application, followed by application of resin cement and light curing. The surface roughness was measured in non-cemented groups. All the bars were subjected to the MFS test (1.0 mm/min; 100 kgf). Scanning electron microscopy was used for qualitative analyses. MFS data (MPa) and roughness (µm) were statistically evaluated by three-way and two-way ANOVA respectively and Tukey's test (5%). RESULTS The surface treatment and the interaction were significant for roughness. Glazing promoted less roughness compared to silicatization. Regarding MFS, only the zirconia and surface treatment factors were significant. For ZT, the sandblasted groups had an increase in MFS and glazing reduced it. There was no difference between the groups without cementation for the ZUT; however, ZUT.Si/Cem, and ZUT.Al/Cem obtained superior MFS among the cemented groups. CONCLUSIONS Sandblasting increases the flexural strength for ZT, while glaze application tends to reduce it. Applying resin cement increases the flexural strength of ZUT when associated with sandblasting. Sandblasting protocols promote greater surface roughness.
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Affiliation(s)
| | - Sarah Emille Gomes da Silva
- Department of Dentistry, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
| | - Nathália Ramos da Silva
- Department of Dentistry, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
| | | | - Karina Barbosa Souza
- Institute of Science and Technology, Paulista State University (UNESP), São José dos Campos, São Paulo, Brazil
| | - Yu Zhang
- Department of Preventive and Restorative, University of Pennsylvania, School of Dental Medicine, Philadelphia, USA
| | - Rodrigo Othávio Assunção de Souza
- Department of Dentistry, Adjunct Professor in Prosthodontics, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
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Akhlaghi O, Camposilvan E, Garnier V, Goharibajestani Z, Khabbaz S, Ow-Yang C, Jorand Y, Gremillard L, Chevalier J. Conventional sintering of nano-crystalline Yttria-Stabilized Zirconia enables high-strength, highly translucent and opalescent dental ceramics. Dent Mater 2024; 40:1031-1040. [PMID: 38755041 DOI: 10.1016/j.dental.2024.05.007] [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: 10/02/2023] [Revised: 04/30/2024] [Accepted: 05/03/2024] [Indexed: 05/18/2024]
Abstract
Development of restorative materials capable of mimicking optical and mechanical performance of natural teeth is a quest in aesthetic density. Yttria-Stabilized Zirconia (YSZ) ceramics represent one of the most popular choices for dental restorations, owing to their biocompatibility, white colour, and the possibility to use CAD-CAM technologies. In particular, YSZ doped with 3 mol. % yttria (3YSZ) is popular because it presents high strength. Nonetheless, the limited light transmission of commercially available high strength 3YSZ does not meet the requirements of highly aesthetic cases. On the other side, YSZ presenting a larger portion of yttria are more translucent but exhibit modest strength. Here, we report on fabrication of dense zirconia nanostructures in bulk form via conventional pressure-less sintering at temperatures down to 1100-1200 °C, achieving highly translucent and strong 3YSZ with significant opalescent behaviour. Both Hall-Petch and inverse Hall-Petch relationship were observed in 3YSZ samples with average grain size in the range of 250 nm and 55 nm, demonstrating the importance of grain size control to enhance both optical and mechanical properties of zirconia ceramics, simultaneously. Maximum biaxial strength of 1980 ± 260 MPa, in-line light transmission of 38% in the visible spectrum and opalescence approaching that of enamel were obtained at optimum grain size of 80 ± 5 nm. The notable optical properties are linked to the miniaturization of the residual pores and refinement of grain size towards the nanoscale while the superior mechanical strength is justified by the activation of different energy dissipation processes at nano and macroscale.
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Affiliation(s)
- Omid Akhlaghi
- INSA Lyon, Universite Claude Bernard Lyon 1, CNRS, MATEIS, UMR5510, 69621 Villeurbanne, France
| | | | - Vincent Garnier
- INSA Lyon, Universite Claude Bernard Lyon 1, CNRS, MATEIS, UMR5510, 69621 Villeurbanne, France.
| | | | - Sirous Khabbaz
- Materials Science & Nano-Engineering Program, Sabanci University, Tuzla, Istanbul 34956, Turkey
| | - Cleva Ow-Yang
- Materials Science & Nano-Engineering Program, Sabanci University, Tuzla, Istanbul 34956, Turkey; Nanotechnology Research and Application Center (SUNUM), Sabanci University, Tuzla, Istanbul 34956, Turkey
| | - Yves Jorand
- INSA Lyon, Universite Claude Bernard Lyon 1, CNRS, MATEIS, UMR5510, 69621 Villeurbanne, France
| | - Laurent Gremillard
- INSA Lyon, Universite Claude Bernard Lyon 1, CNRS, MATEIS, UMR5510, 69621 Villeurbanne, France
| | - Jérôme Chevalier
- INSA Lyon, Universite Claude Bernard Lyon 1, CNRS, MATEIS, UMR5510, 69621 Villeurbanne, France
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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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Chai H, Russ J, Vardhaman S, Lim C, Zhang Y. A Bilayer Method for Measuring Toughness and Strength of Dental Ceramics. J Dent Res 2024; 103:419-426. [PMID: 38410925 PMCID: PMC10966932 DOI: 10.1177/00220345231225445] [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] [Indexed: 02/28/2024] Open
Abstract
The ever-increasing usage of ceramic materials in restorative dentistry necessitates a simple and effective method to evaluate flexural strength σF and fracture toughness KC. We propose a novel method to determine these quantities using a bilayer specimen composed of a brittle plate adhesively bonded onto a transparent polycarbonate substrate. When this bilayer structure is placed under spherical indentation, tunneling radial cracks initiate and propagate in the lower surface of the brittle layer. The failure analysis is based on previous theoretical relationships, which correlate σF with the indentation force P and layer thickness d, and KC with P and mean length of radial cracks. This work examines the accuracy and limitations of this approach using a wide range of contemporary dental ceramic materials. The effect of layer thickness, indenter radius, load level, and length and number of radial cracks are carefully examined. The accuracy of the predicted σF and KC is similar to those obtained with other concurrent test methods, such as biaxial flexure and 3-point bending (σF), and bending specimens with crack-initiation flaws (KC). The benefits of the present approach include treatment for small and thin plates, elimination of the need to introduce a precrack, and avoidance of dealing with local material nonlinearity effects for the KC measurements. Finally, the bilayer configuration resembles occlusal loading of a ceramic restoration (brittle layer) bonded to a posterior tooth (compliant substrate).
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Affiliation(s)
- H. Chai
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - J. Russ
- School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - S. Vardhaman
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
- College of Dental Medicine, Columbia University, New York, NY, USA
| | - C.H. Lim
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
| | - Y. Zhang
- Department of Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA, USA
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Suliman S, Sulaiman TA, Deeb JG, Abdulmajeed A, Abdulmajeed A, Närhi T. Er:YAG laser debonding of zirconia and lithium disilicate restorations. J Prosthet Dent 2024; 131:253.e1-253.e6. [PMID: 37951718 DOI: 10.1016/j.prosdent.2023.10.016] [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: 06/07/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 11/14/2023]
Abstract
STATEMENT OF PROBLEM Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations of different formulations are being used increasingly in monolithic form for a range of clinical applications. Using rotary instruments to remove such restorations for any purpose is challenging, but they can be removed conservatively with erbium lasers. However, studies on how a laser penetrates different zirconias to break the cement bond between the tooth surface and the zirconia are lacking. PURPOSE The purpose of this in vitro study was to evaluate and compare the time required for an erbium-doped yttrium-aluminum-garnet (Er:YAG) laser to remove different types of zirconia and lithium disilicate crowns. MATERIAL AND METHODS Forty extracted premolar teeth were prepared, scanned, designed, and milled to fabricate 40 computer-aided design and computer-aided manufacturing (CAD-CAM) crowns, which were assigned to 4 groups (n=10): 3 mol% Y-TZP, 4 mol% Y-TZP, 5 mol% Y-TZP, and lithium disilicate as a control. All crowns were bonded to the teeth with a self-adhesive resin cement (Panavia SA Cement Universal). Each specimen was irradiated with an Er:YAG laser with the following parameters: 300 mJ, 15 Hz, 5.0 W, and a 50-microsecond pulse duration (supershort pulse mode). The irradiation time required for crowns to be retrieved successfully was recorded for each specimen. Data were statistically analyzed using analysis of variance and the Tukey honestly significant difference post hoc test (α=.05). The intaglio surfaces of the restorations were analyzed using scanning electron microscopy (SEM). RESULTS The mean ±standard deviation times in minutes needed for crown debonding were 12.46 ±4.17 for the 3 mol% Y-TZP group, 10.30 ±3.33 for the 4 mol% Y-TZP group, 4.03 ±1.62 for the 5 mol% Y-TZP group, and 2.08 ±0.92 for the lithium disilicate group. A statistically significant difference (P<.05) in the debonding time was found for all investigated groups, expect between the 3 mol% and 4 mol% Y-TZP groups and between the 5 mol% Y-TZP and lithium disilicate groups. SEM analysis of the ceramic surfaces showed no visual damage associated with Er:YAG laser irradiation. CONCLUSIONS Zirconia crown retrieval time with the Er:YAG laser was influenced by the yttria content of the zirconia, with decreasing retrieval time with increasing yttria content. Er:YAG laser debonding of zirconia crowns is a noninvasive, efficient, and rapid approach to the removal of crowns and could be applied in clinical practice.
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Affiliation(s)
- Sama Suliman
- Doctoral student, Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Turku, Turku, Finland; and Lecturer, Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Taiseer A Sulaiman
- Associate Professor, Division of Comprehensive Oral Health, Adams School of Dentistry, University of North Carolina at Chapel Hill, NC.
| | - Janina Golob Deeb
- Professor, Department of Periodontics, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia
| | - Awab Abdulmajeed
- Assistant Professor, Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia
| | - Aous Abdulmajeed
- Associate Professor, Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia
| | - Timo Närhi
- Professor, Department of Prosthetic Dentistry and Stomatognathic Physiology, Institute of Dentistry, University of Turku, Turku, Finland
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Sulaiman TA, Suliman AA, Abdulmajeed AA, Zhang Y. Zirconia restoration types, properties, tooth preparation design, and bonding. A narrative review. J ESTHET RESTOR DENT 2024; 36:78-84. [PMID: 37840220 PMCID: PMC10842315 DOI: 10.1111/jerd.13151] [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: 09/01/2023] [Revised: 10/01/2023] [Accepted: 10/03/2023] [Indexed: 10/17/2023]
Abstract
OBJECTIVE The purpose of this review was to provide dental professionals with information regarding the various types of zirconia restorations, their mechanical and optical properties, tooth preparation design, and bonding protocol in an effort to enhance the longevity and durability of zirconia restorations. OVERVIEW The yttria content of zirconia ceramics determines their classification. The mechanical and optical properties of each type are discussed, with an emphasis on the effect of yttria concentration on the properties of zirconia. The processing and sintering methods are also discussed as they have a direct impact on the properties of zirconia. The design of tooth preparation, specifically occlusal reduction, varies depending on the type of zirconia used in each case. Finally, a protocol for zirconia restoration bonding is described to ensure optimal bonding to the tooth structure. CONCLUSION Not all zirconia restorations are the same. The selection of zirconia type based on yttria concentration, processing and sintering methods, tooth preparation design, and adherence to the bonding protocol are all critical to the success and longevity of zirconia restorations. CLINICAL SIGNIFICANCE Zirconia restorations are the most commonly used indirect restorative material. The selection of the most appropriate zirconia type based on its yttria content, which determines its strength and translucency, is critical to the success and the longevity of the restoration. Tooth preparation design also influences the strength and translucency of the zirconia. Air-borne particle abrasion, followed by a ceramic primer and resin cement, can ensure a durable bond to the tooth structure.
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Affiliation(s)
- Taiseer A Sulaiman
- Division of Comprehensive Oral Health, University of North Carolina, Adams School of Dentistry, Chapel Hill, North Carolina, USA
| | - Abdulhaq A Suliman
- Department of Clinical Sciences, College of Dentistry, Ajman University, Ajman, UAE
| | - Aous A Abdulmajeed
- Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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10
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Giugliano TS, Zhang Y, Janal MN, Lim CH, Smith RM, Choi M. In vitro comparison of physical characteristics of milled versus printed zirconia discs. J Prosthodont 2023:10.1111/jopr.13778. [PMID: 37776103 PMCID: PMC10980599 DOI: 10.1111/jopr.13778] [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] [Received: 04/28/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 10/01/2023] Open
Abstract
PURPOSE The purpose of this study was to compare the dimensional accuracy, translucency, and biaxial flexural strength of milled zirconia (MZ) versus 3D-printed zirconia (PZ) discs. MATERIALS & METHODS A circular disc measuring 14.0 mm in diameter and 1.20 mm in thickness was designed using computer-aided design (CAD) software. The resulting standard tessellation language (STL) file was used both as a control and to fabricate 36 zirconia (3Y-TZP) disc specimens (n = 36): 18 were milled (group MZ) and 18 were 3D-printed (group PZ). The diameter and thickness of each disc were measured using a digital caliper. Translucency was evaluated using a calibrated dental colorimeter. The flexural strength was determined using the piston-on-three-ball biaxial flexure test. All measurements were done by one blinded examiner. The statistical significance level was set to α = 0.05. RESULTS The MZ discs had significantly more accurate dimensions than the PZ discs in both diameter and thickness when compared to the control CAD software-designed disc. The MZ discs exhibited significantly higher translucency (translucency parameter (TP) = 16.95 ±0.36 vs. 9.24 ±1.98) and biaxial flexural strength (996.16 ±137.37 MPa vs. 845.75 ±266.16 MPa) than the PZ discs. Finally, MZ possessed a significantly higher Weibull modulus relative to PZ. CONCLUSIONS The results showed that the milled specimens achieved better dimensional accuracy and were more translucent, stronger, and less prone to failure than printed specimens.
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Affiliation(s)
- Thomas S. Giugliano
- Department of Prosthodontics, New York University College of Dentistry, New York, NY
| | - Yu Zhang
- Laboratories for Microstructure Physics & Mechanics of Materials, Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA
| | - Malvin N. Janal
- Department of Epidemiology & Health Promotion, New York University College of Dentistry, New York, NY
| | - 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
| | - Ruby M. Smith
- Post-Graduate Student, Department of Prosthodontics, New York University College of Dentistry, New York, NY
| | - Mijin Choi
- Department of Prosthodontics, New York University College of Dentistry, New York, NY
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11
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Alshahrani AM, Lim CH, Kim J, Zhang Y. Transient thermal stresses developed during speed sintering of 3 mol% yttria-stabilized tetragonal zirconia polycrystals. Dent Mater 2023; 39:522-528. [PMID: 37045719 PMCID: PMC10168597 DOI: 10.1016/j.dental.2023.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 04/05/2023] [Indexed: 04/14/2023]
Abstract
OBJECTIVES To investigate transient thermal stresses that developed in 3Y-TZP green compacts during speed sintering. METHODS A total of 312 disc-shaped green compacts (Ø17.1 ×1, 1.5, 2, 2.5, 3 mm) were cold-isostatically pressed from 3Y-TZP powder (Zpex, Tosoh Corp.) for speed sintering studies as well as compositional analysis and biaxial flexural strength measurements (both at room temperature and following heating at 90 °C/min to 500 °C). Flexural strength was determined using the piston-on-3-ball method. Phase assemblies were analyzed using the X-ray diffraction method. Effects of heating/cooling rates on transient stresses were investigated by conducting definitive sintering studies to determine the threshold for fracture. Finite element analysis (FEA) was used to validate the experimental findings using measured thermomechanical properties. RESULTS The bulk and relative density of the green compact were 2.95 ± 0.03 g/cm3 and 48.52% ± 0.45%. The flexural strength was drastically decreased from 10.3 ± 0.4 MPa to 1.09 ± 0.07 MPa following heating at 90 °C/min to 500 °C. The monoclinic and tetragonal contents were 54.9% and 45.1%, respectively. The threshold for fracture was located at 500 °C during the first heating stage with a 90 °C/min heating rate in specimens of 2.5 mm thickness or greater. No fractures occurred in the second heating stage and cooling phase. The FEA estimated that the principal transient tensile stress was ∼1.14 MPa at 500 °C during the heating phase, which exceeded the corresponding flexural strength (1.09 ± 0.07 MPa). SIGNIFICANCE Advanced FEA methods are an accurate and efficient tool to analyze the history of transient stresses during sintering of ceramic dental restorations.
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Affiliation(s)
- Abdulaziz M Alshahrani
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Restorative Dental Sciences, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Chek Hai Lim
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd, U-3037, Storrs, CT 06269, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Abstract
The purpose of this article is to review current understanding of lithia-based glass-ceramics and to identify future research needs for this class of dental materials in relation to novel compositions and fabrication methods. With rapid advances in material development and digital technology, time efficiency of dental workflow and fit accuracy of ceramic restorations are ever improving. Lithia-based glass-ceramics are at the forefront of this advance-new variants with more efficient fabrication routes are continually being introduced into the marketplace. Base glass composition, crystallization heat treatment, nucleant and coloration additives, and property gradation are some pertinent variables. The trend in fabrication is to move from CAD/CAM grinding of partially crystallized glass-ceramics to fully crystallized materials, thereby circumventing the need for postmachining firing altogether. In these endeavors, a better understanding of mechanical properties and evolving shaping technologies, such as ductile grinding, is paramount. Additive manufacturing and 3-dimensional printing methodologies offer a promising alternative to current CAD/CAM subtractive manufacturing routes. Challenges to the implementation of new technologies in efficient development and production of high-quality dental glass-ceramic prostheses are addressed.
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Affiliation(s)
- Y. Zhang
- Department of Preventive and
Restorative Sciences, School of Dental Medicine, University of Pennsylvania,
Philadelphia, PA, USA
| | - S. Vardhaman
- Department of Preventive and
Restorative Sciences, School of Dental Medicine, University of Pennsylvania,
Philadelphia, PA, USA
| | - C.S. Rodrigues
- Department of Dental Materials and
Prosthodontics, Institute of Science and Technology, São Paulo State University, São
José dos Campos, Brazil
| | - B.R. Lawn
- Material Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, MD, USA
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13
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Jung JM, Kim GN, Koh YH, Kim HE. Manufacturing and Characterization of Dental Crowns Made of 5-mol% Yttria Stabilized Zirconia by Digital Light Processing. MATERIALS (BASEL, SWITZERLAND) 2023; 16:1447. [PMID: 36837076 PMCID: PMC9963883 DOI: 10.3390/ma16041447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/05/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
We herein report manufacturing of dental crowns made of 5-mol% yttria partially stabilized zirconia (5Y-PSZ) with desired mechanical properties, optical translucency and dimensional accuracy using digital light processing (DLP). To this end, all processing parameters were carefully controlled and optimized. First, 5Y-PSZ particles with a bimodal distribution were prepared via calcination of as-received granules and subsequent ball-milling and then used to formulate 5Y-PSZ suspensions with a high solid loading of 50 vol% required for high densification after sintering. Dispersant content was also optimized. To provide high dimensional accuracy, initial dimensions of dental crowns for 3D printing were precisely determined by considering increase and decrease in dimensions during photopolymerization and sintering, respectively. Photopolymerization time was also optimized for a given layer thickness of 50 μm to ensure good bonding between layers. A multi-step debinding schedule with a slow heating rate was employed to avoid formation of any defects. After sintering at 1500 °C for 2 h, 5Y-PSZ could be almost fully densified without noticeable defects within layers and at interfaces between layers. They had high relative densities (99.03 ± 0.39%) with a high cubic phase content (59.1%). These characteristics allowed for achievement of reasonably high mechanical properties (flexural strength = 625.4 ± 75.5 MPa and Weibull modulus = 7.9) and % transmittance (31.4 ± 0.7%). In addition, 5Y-PSZ dental crowns showed excellent dimensional accuracy (root mean square (RMS) for marginal discrepancy = 44.4 ± 10.8 μm and RMS for internal gap = 22.8 ± 1.6 μm) evaluated by the 3D scanning technique.
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Affiliation(s)
- Jae-Min Jung
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul 02841, Republic of Korea
- School of Biomedical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Gyu-Nam Kim
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul 02841, Republic of Korea
- School of Biomedical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Young-Hag Koh
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul 02841, Republic of Korea
- School of Biomedical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Hyoun-Ee Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
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14
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Yang SY, Koh YH, Kim HE. Digital Light Processing of Zirconia Suspensions Containing Photocurable Monomer/Camphor Vehicle for Dental Applications. MATERIALS (BASEL, SWITZERLAND) 2023; 16:402. [PMID: 36614741 PMCID: PMC9821819 DOI: 10.3390/ma16010402] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 12/24/2022] [Accepted: 12/28/2022] [Indexed: 05/27/2023]
Abstract
This study reports the utility of solid camphor as a novel diluent in photocurable hexanediol diacrylate (HDDA) monomer to manufacture 4 mol% yttria partially stabilized zirconia (4Y-PSZ) components for dental applications by digital light processing (DLP). The use of a 65 wt% HDDA-35 wt% camphor solution allowed 4Y-PSZ suspensions to have reasonably low viscosities (1399 ± 55.8 mPa·s at a shear rate of 75 s-1), measured by a cone/plate viscometer, at a high solid loading of 48 vol%, where 4Y-PSZ particles prepared by calcination of as-received 4Y-PSZ granules, followed by a ball-milling process, were used with assistance of a dispersant. These 4Y-PSZ suspensions could be successfully applied to our custom-made DLP machine for manufacturing 4Y-PSZ components. To this end, several processing parameters, including layer thickness of 4Y-PSZ suspension, UV illumination time for layer-by-layer photocuring process, and initial dimensions of 4Y-PSZ objects, were tightly controlled. As sintering temperature increased from 1300 °C to 1500 °C, relative density and grain size of 4Y-PSZ objects increased, and cubic phase content also increased. Thus, after sintering at the highest temperature of 1500 °C for 3 h, high mechanical properties (biaxial flexural strength = 911 ± 40.7 MPa, hardness = 1371 ± 14.4 Hv) and reasonably high optical transmittance (translucency parameter = 7.77 ± 0.32, contrast ratio = 0.809 ± 0.007), evaluated by a spectrophotometer, were obtained due to a high relative density (97.2 ± 1.38%), which would be useful for dental applications.
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Affiliation(s)
- Seo-Young Yang
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul 02841, Republic of Korea
| | - Young-Hag Koh
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul 02841, Republic of Korea
- School of Biomedical Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Hyoun-Ee Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
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15
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Alves LMM, Rodrigues CDS, Ramos NDC, Buizastrow J, Campos TMB, Bottino MA, Zhang Y, Melo RMD. Silica infiltration on translucent zirconia restorations: Effects on the antagonist wear and survivability. Dent Mater 2022; 38:2084-2095. [PMID: 36446649 PMCID: PMC9928576 DOI: 10.1016/j.dental.2022.11.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 09/23/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To assess potential antagonist wear and survival probability of silica-infiltrated zirconia compared to glass-graded, glazed, and polished zirconia. METHODS Table top restorations made of 3Y-TZP (3Y), 5Y-PSZ (5Y), and lithium disilicate (LD) were bonded onto epoxy resin preparations. Each zirconia was divided into five groups according to the surface treatment: polishing; glaze; polishing-glaze; glass infiltration; and silica infiltration. The LD restorations received a glaze layer. Specimens were subjected to sliding fatigue wear using a steatite antagonist (1.25 ×106 cycles, 200 N). The presence of cracks, fractures, and/or debonding was checked every one/third of the total number of cycles was completed. Roughness, microstructural, Scanning electron microscopy, wear and residual stress analyses were conducted. Kaplan-Meier, Mantel-Cox (log-rank) and ANOVA tests were performed for statistical analyses. RESULTS The survival probability was different among the groups. Silica infiltration and polishing-glaze led to lower volume loss than glaze and glass-infiltration. Difference was observed for roughness among the zirconia and surface treatment, while lithium disilicate presented similar roughness compared to both glazed zirconia. Scanning electron microscopy revealed the removal of the surface treatment after sliding fatigue wear in all groups. Compressive stress was detected on 3Y surfaces, while tensile stress was observed on 5Y. SIGNIFICANCE 3Y and 5Y zirconia behaved similarly regarding antagonist wear, presenting higher antagonist wear than the glass ceramic. Silica-infiltrated and polished-glazed zirconia produced lower antagonist volume loss than glazed and glass-infiltrated zirconia. Silica-infiltrated 3Y and lithium disilicate restorations were the only groups to show survival probabilities lower than 85%.
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Affiliation(s)
- Larissa Marcia Martins Alves
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Camila da Silva Rodrigues
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Nathalia de Carvalho Ramos
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil
| | - Jeff Buizastrow
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 1st Ave., New York, NY 10010, United States
| | - Tiago Moreira Bastos Campos
- Department of Physics, Aeronautics Technological Institute (ITA), Praça Marechal Eduardo Gomes, 50, 12228-900 São José dos Campos, SP, Brazil
| | - Marco Antonio Bottino
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, United States
| | - Renata Marques de Melo
- Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, Av. Eng. Francisco José Longo, 777, Jardim São Dimas, 12245-000 São José dos Campos, SP, Brazil.
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16
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Patil A, Jebaseelan D. 3-D Surface Morphological Characterization of CAD/CAM Milled Dental Zirconia: An In Vitro Study of the Effect of Post-Fabrication Processes. MATERIALS (BASEL, SWITZERLAND) 2022; 15:4685. [PMID: 35806812 PMCID: PMC9268120 DOI: 10.3390/ma15134685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/06/2022] [Accepted: 06/18/2022] [Indexed: 02/04/2023]
Abstract
Objective: To investigate the effect on zirconia surface of the post-fabrication surface treatments on the morphological characteristics and mechanical properties of CAD/CAM milled dental zirconia specimens as well as to identify the critical parameters in the measurement of oral retention under in vitro circumstances. Method: The zirconia specimens (N = 20, n = 4) were subjected to CAD/CAM milling and divided into five groups. The specifications were: Group G1—sintered; Group G2—sintered followed by a polishing process; Group G3—sintered followed by polishing and sandblasting with alumina particles Al2O3 (110 µm); Group G4—sintered followed by sandblasting; Group G5—sintered followed by sandblasting with polishing as the end process. All the groups were subjected to Fretting wear tests, 3-D surface roughness measurements, and Vickers’s Micro hardness tests. Investigation of the phase transformation using XRD, and surface feature examination using SEM were also carried out. Additionally, one-way ANOVA, Tukey, and Pearson correlations were statistically analysed. Results: The fabrication processes had a significant effect on the performance of zirconia specimens in all the groups (p > 0.05). Specimens that underwent polishing as the last process exhibited lower surface roughness. The monoclinic phase of zirconia was observed in all the specimens before and after wear except for those in the G2 and G5 groups, where polishing was the end process. In G5, the post-wear surface properties revealed lower surface roughness and hardness. Further, the SEM and 3-D topography show grooves as seen by the dale void volume (Vvv) values; shallow valley depth (Svk); micro craters; and wear track. Conclusion: Specimens in G5 that were subjected to multistep post-fabrication process, namely sandblasting followed by polishing, yielded better results when compared to those in the other groups (G1, G2, G3, and G4). G5 with an interlayer of alumina is recommended for clinical applications due to its enhanced surface properties, mechanical properties, and low wear.
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Affiliation(s)
| | - Davidson Jebaseelan
- School of Mechanical Engineering (SMEC), Vellore Institute of Technology, Chennai 600127, India;
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