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Zandinejad A, Zadeh RS, Khanlar LN, Barmak AB, Revilla-León M. Fracture resistance, marginal and internal adaptation of innovative 3D-printed graded structure crown using a 3D jet printing technology. J Prosthodont 2024; 33:684-690. [PMID: 39118597 DOI: 10.1111/jopr.13895] [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: 10/21/2023] [Accepted: 05/27/2024] [Indexed: 08/10/2024] Open
Abstract
PURPOSE This in vitro study aimed to create a graded structured dental crown using 3D printing technology and investigate the fracture resistance and the adaptation of this new design. MATERIALS AND METHODS A dental crown with a uniform thickness of 1.5 mm was designed, and the exported stereolithography file (STL) was used to manufacture 30 crowns in three groups (n = 10), solid (SC), bilayer (BL), and multilayer (ML) crowns using 3D jet printing technology. Marginal and internal gaps were measured using the silicone replica technique. Crowns were then luted to a resin die using a temporary luting agent and the fracture resistance was measured using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used to compare the fracture resistance and the adaptation of crowns at a significance level of 0.05. RESULTS Mean marginal and internal gap of the ML group were 80 and 82 mm, respectively; which were significantly (p < 0.05) smaller than BL (203 and 183 mm) and SC (318 and 221 mm) groups. The SC group showed the highest mean load at fracture (2330 N) which was significantly (p < 0.05) higher than the BL (1716 N) and ML (1516 N) groups. CONCLUSION 3D jet printing technology provides an opportunity to manufacture crowns in a graded structure with various mechanical properties. This study provided an example of graded structured crowns and presented their fracture resistance. SC group had the highest fracture resistance; however, ML had the best marginal and internal adaptation.
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Affiliation(s)
- Amirali Zandinejad
- Implant Dentistry Associates of Arlington, ClearChoice, Arlington, Texas, USA
- School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
| | - Ramtin Sadid Zadeh
- Department of Restorative Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Leila Nasiry Khanlar
- A.T. Still University-Missouri School of Dentistry & Oral Health, Kirksville, Missouri, USA
| | - Abdul Basir Barmak
- Clinical Research and Biostatistics, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
| | - Marta Revilla-León
- Director of Research and Digital Dentistry, Kois Center, Seattle, Washington, USA
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Fouquet V, Larsen N, Stchepinsky AC, Vennat E, Benoit A, Tapie L. A parametrical finite element analysis for functionally graded material overlay restoration. J Mech Behav Biomed Mater 2024; 152:106409. [PMID: 38277910 DOI: 10.1016/j.jmbbm.2024.106409] [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: 11/08/2023] [Revised: 01/13/2024] [Accepted: 01/15/2024] [Indexed: 01/28/2024]
Abstract
The main cause of failure in bonded ceramic restorations is material fracture due to excessive stress concentration at the base of the prosthesis. The design of restorative functionally graded materials (FGM) could represent a major advance in dissipating mechanical stresses during occlusal contacts. The aim of this paper is to carry out a complete factorial design of finite element analyses to optimize a multilayer FGM introduced at the bottom of an overlay prosthesis. The number and thickness of layers vary within a spectrum compatible with ceramic shaping processes whereas Young's moduli variations are set in the range of dental tissues. For a 1.5-mm thick prosthesis, the optimal FGM configuration appears to be a 5 layers of 0.2 mm thickness with a linear distribution of Young's modulus from 30 to 70 GPa. This configuration was implemented in a 3D model of a restored tooth with realistic geometry to validate the proof-of-concept.
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Affiliation(s)
- Vincent Fouquet
- Université Paris Cité, Université Sorbonne Paris Nord, URB2i, F-92120, Montrouge, France; Université Sorbonne Paris Nord, F-93430, Villetaneuse, France; AP-HP, Louis-Mourier Hospital, Oral Medecine Department, F-92700, Colombes, France
| | - Nicoline Larsen
- Université Paris Cité, Université Sorbonne Paris Nord, URB2i, F-92120, Montrouge, France
| | | | - Elsa Vennat
- Université Paris Cité, Université Sorbonne Paris Nord, URB2i, F-92120, Montrouge, France; Université Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS - Laboratoire de Mécanique Paris-Saclay, 91190, Gif sur Yvette, France
| | - Aurélie Benoit
- Université Paris Cité, Université Sorbonne Paris Nord, URB2i, F-92120, Montrouge, France.
| | - Laurent Tapie
- Université Paris Cité, Université Sorbonne Paris Nord, URB2i, F-92120, Montrouge, France; EPF Engineering School, F-94230, Cachan, France.
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Contreras LPC, Rodrigues CS, Zucuni CP, Valandro LF, Marocho SMS, de Melo RM. Fatigue behavior of multilayer ceramic structures in traditional and reverse layering designs. J Prosthodont 2024; 33:389-395. [PMID: 37201944 DOI: 10.1111/jopr.13705] [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: 01/13/2023] [Revised: 05/11/2023] [Accepted: 05/12/2023] [Indexed: 05/20/2023] Open
Abstract
PURPOSE This study evaluated the fatigue failure load (FFL) and the number of cycles for fatigue failure (CFF) of traditional (porcelain layer up) and reversed (zirconia layer up) designs of porcelain-veneered zirconia samples prepared with heat-pressing or file-splitting techniques. MATERIALS AND METHODS Zirconia discs were prepared and veneered with heat-pressed or machined feldspathic ceramic. The bilayer discs were bonded onto a dentin-analog according to the bilayer technique and sample design: traditional heat-pressing (T-HP), reversed heat-pressing (R-HP), traditional file-splitting with fusion ceramic (T-FC), reversed file-splitting with fusion ceramic R-FC), traditional file-splitting with resin cement (T-RC), and reversed file-splitting with resin cement (R-RC). The fatigue tests were performed using the stepwise approach at 20 Hz, 10,000 cycles/step, step-size of 200 N starting at 600 N, and proceeding until failure detection or up to 2600 N if enduring. The failure modes (from radial and/or cone cracks) were analyzed in a stereomicroscope. RESULTS The reversed design decreased the FFL and CFF of bilayers prepared with heat-pressing and file-splitting with fusion ceramic. The T-HP and T-FC reached the highest results, which were statistically similar between them. The bilayers prepared by the file-splitting with resin cement (T-RC and R-RC) were similar to the R-FC and R-HP groups regarding FFL and CFF. Almost all reverse layering samples failed by radial cracks. CONCLUSIONS The reverse layering design did not improve the fatigue behavior of porcelain veneered zirconia samples. The three bilayer techniques behaved similarly when used in the reversed design.
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Affiliation(s)
- Lisseth Patricia Claudio Contreras
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, São Paulo, Brazil
| | - Camila Silva Rodrigues
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, São Paulo, Brazil
- Graduate Program in Dentistry, Federal University of Pelotas (UFPel), Pelotas, Rio Grande do Sul, Brazil
| | - Camila Pauleski Zucuni
- Department of Restorative Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Luiz Felipe Valandro
- Department of Restorative Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | | | - Renata Marques de Melo
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, São Paulo, Brazil
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Schubert J, Kirkpatrick T, Roberts H. The effect of endodontic access preparation on the failure load resistance of a 3Y-TZP monolithic zirconia crown. AUST ENDOD J 2021; 48:138-143. [PMID: 34258848 DOI: 10.1111/aej.12544] [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: 03/19/2021] [Revised: 06/20/2021] [Accepted: 06/30/2021] [Indexed: 11/29/2022]
Abstract
The effect of endodontic access preparation on the failure load resistance of 3Y-TZP zirconia crowns was accomplished by preparing human molars and luting monolithic zirconia crowns with a self-adhesive resin cement. Besides the intact control, teeth received endodontic access preparations and then grouped (n = 12) into a positive control (no access repair), dentin core replacement only and complete access repair groups. Specimens were axially tested until failure with results of no significant difference between the failure load of intact controls and the complete access repair group. However, the positive control and dentin replacement only groups failed at significantly lower loads. Under the conditions of this study, there was no significant failure load difference between 3Y-TZP monolithic zirconia crowns with repaired endodontic access preparations to that evidenced by an unprepared control. Although this evidence is encouraging, caution is advised and definitive recommendations cannot be made until verified by clinical studies.
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Affiliation(s)
| | | | - Howard Roberts
- University of Kentucky College of Dentistry, Lexington, Kentucky, USA
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Fouquet V, Tapie L, Attal JP, Benoit A. Design optimization of a functionally graded overlay using FEA. Comput Methods Biomech Biomed Engin 2020. [DOI: 10.1080/10255842.2020.1812858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- V. Fouquet
- Université de Paris, URB2I, UR 4462, Montrouge, France
| | - L. Tapie
- Université Sorbonne Paris Nord, URB2I, UR 4462, Bobigny, France
| | - J. P. Attal
- Université de Paris, URB2I, UR 4462, Montrouge, France
| | - A. Benoit
- Université de Paris, URB2I, UR 4462, Montrouge, France
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Thompson VP. The tooth: An analogue for biomimetic materials design and processing. Dent Mater 2020; 36:25-42. [DOI: 10.1016/j.dental.2019.08.106] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 08/21/2019] [Accepted: 08/28/2019] [Indexed: 01/05/2023]
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Roedel S, Mesquita-Guimarães J, Souza JCM, Silva FS, Fredel MC, Henriques B. Production and characterization of zirconia structures with a porous surface. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 101:264-273. [PMID: 31029319 DOI: 10.1016/j.msec.2019.03.087] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 02/07/2019] [Accepted: 03/24/2019] [Indexed: 12/21/2022]
Abstract
The aim of this study was to produce zirconia structures with a porous surface by the dip coating technique and assess the mechanical properties of the structures as well as the integrity of the porous layers. Surface porous layers with homogenous and graded porosity were produced over zirconia substrate discs using zirconia powders with different average sizes (d50 = 40 μm; d50 = 70 μm and d50 = 100 μm) and without pore forming fugitive phases. Specimens were inspected using Scanning Electron Microscopy. Bending strength of specimens was obtained from biaxial flexural tests (B3B). Porous layers were successfully produced on zirconia discs substrates and the bending strength of these specimens were ~35% lower than uncoated specimens. Delamination occurred especially in layers with higher thickness and made of bigger particles. Practical application examples were provided in this paper showing the versatility of these porous surfaces in the production of multifunctional surfaces for stronger interfaces.
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Affiliation(s)
- Stephanie Roedel
- Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC, Brazil.
| | | | - Júlio C M Souza
- CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal; School of Dentistry, Polythenic Institute of Healh Sciences of North (IUCS-CESPU), Gandra, Portugal
| | - Filipe S Silva
- CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
| | - Márcio C Fredel
- Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC, Brazil; School of Dentistry, Polythenic Institute of Healh Sciences of North (IUCS-CESPU), Gandra, Portugal
| | - Bruno Henriques
- Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC, Brazil; CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal; School of Dentistry (DODT), Post-Graduation Program in Dentistry (PPGO), Federal University of Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC, Brazil.
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Eldafrawy M, Nguyen J, Mainjot A, Sadoun M. A Functionally Graded PICN Material for Biomimetic CAD-CAM Blocks. J Dent Res 2018; 97:1324-1330. [DOI: 10.1177/0022034518785364] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The objective of this study was to introduce a functionally graded (FG) polymer-infiltrated ceramic network (PICN) block, characterized by a gradient of mechanical properties, as a biomimetic material for computer-aided design and manufacturing (CAD-CAM) prostheses. FG-PICN blocks were manufactured from a slurry of glass-ceramic powder, which was subsequently centrifuged and sintered. The ceramic network was infiltrated with urethane dimethacrylate and polymerized under high temperature-pressure. Blocks were sectioned into 9 layers, and each layer was subsequently cut into 3 samples. Samples were loaded into a 3-point bending device and tested for flexural strength, flexural load energy, and flexural modulus. The volume percentage of glass-ceramic, hardness, and brittleness index were also measured and scanning electron microscopy (SEM) observations were performed. Katana translucent zirconia (HT-ZIR) and e.max-CAD (EMX) were tested for comparison. Flexural strength, flexural load energy, and Weibull modulus of FG-PICN were shown to increase from the first (enamel-like zone) to the ninth layer (dentin-like zone), while, on the contrary, flexural modulus, hardness, brittleness index, and ceramic volume percentage decreased. SEM characterization highlighted a higher porosity in layer 9 than in layer 1. Flexural strength of the dentin-like zone (372.7 ± 27.8 MPa) was similar to EMX and lower than HT-ZIR. Flexural modulus was shown to vary from 41.9 ± 5.1 to 28.6 ± 2.0 GPa from surface to depth. Flexural load energy in the dentin-like zone (27.1 ± 4.9 mJ) was significantly superior to EMX and HT-ZIR. Hardness gradient was shown to be close to tooth tissues. This work introduces FG-PICN blocks, with a gradient of mechanical and optical properties through the entire thickness of the block designed to mimic dental tissues. FG-PICN demonstrated a favorable gradient of flexural strength, elastic modulus, and, most of all, flexural load energy and hardness compared to other CAD-CAM materials, which can promote the biomechanical behavior of single-unit restorations on teeth and implants.
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Affiliation(s)
- M. Eldafrawy
- Dental Biomaterials Research Unit (d-BRU), Institute of Dentistry, University of Liège (ULiège), Liège, Belgium
| | - J.F. Nguyen
- UFR d’Odontologie, Université Paris Diderot, Paris, France
- PSL Research University, Chimie ParisTech-CNRS, Institut de Recherche de Chimie Paris, Paris, France
| | - A.K. Mainjot
- Dental Biomaterials Research Unit (d-BRU), Institute of Dentistry, University of Liège (ULiège), Liège, Belgium
- Department of Fixed Prosthodontics, Institute of Dentistry, University of Liège Hospital (CHU), Liège, Belgium
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Segarra MS, Shimada Y, Sadr A, Sumi Y, Tagami J. Three-Dimensional Analysis of Enamel Crack Behavior Using Optical Coherence Tomography. J Dent Res 2016; 96:308-314. [PMID: 27872333 DOI: 10.1177/0022034516680156] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The aim of this study was to nondestructively analyze enamel crack behavior on different areas of teeth using 3D swept source-optical coherence tomography (SS-OCT). Ten freshly extracted human teeth of each type on each arch ( n = 80 teeth) were inspected for enamel crack patterns on functional, contact and nonfunctional, or noncontact areas using 3D SS-OCT. The predominant crack pattern for each location on each specimen was noted and analyzed. The OCT observations were validated by direct observations of sectioned specimens under confocal laser scanning microscopy (CLSM). Cracks appeared as bright lines with SS-OCT, with 3 crack patterns identified: Type I - superficial horizontal cracks; Type II - vertically (occluso-gingival) oriented cracks; and Type III - hybrid or complicated cracks, a combination of a Type I and Type III cracks, which may or may not be confluent with each other. Type II cracks were predominant on noncontacting surfaces of incisors and canines and nonfunctional cusps of posterior teeth. Type I and III cracks were predominant on the contacting surfaces of incisors, cusps of canines, and functional cusps of posterior teeth. Cracks originating from the dental-enamel junction and enamel tufts, crack deflections, and the initiation of new cracks within the enamel (internal cracks) were observed as bright areas. CLSM observations corroborated the SS-OCT findings. We found that crack pattern, tooth type, and the location of the crack on the tooth exhibited a strong correlation. We show that the use of 3D SS-OCT permits for the nondestructive 3D imaging and analysis of enamel crack behavior in whole human teeth in vitro. 3D SS-OCT possesses potential for use in clinical studies for the analysis of enamel crack behavior.
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Affiliation(s)
- M S Segarra
- 1 Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, Japan.,2 Section of Operative Dentistry, College of Dentistry, University of the Philippines, Manila, Philippines
| | - Y Shimada
- 1 Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, Japan
| | - A Sadr
- 1 Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, Japan.,3 Restorative Dentistry, University of Washington, Seattle, WA, USA
| | - Y Sumi
- 4 Advanced Medicine, National Center for Geriatrics and Gerontology, Obu, Japan
| | - J Tagami
- 1 Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, Japan
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Functionally graded materials for orthopedic applications – an update on design and manufacturing. Biotechnol Adv 2016; 34:504-531. [DOI: 10.1016/j.biotechadv.2015.12.013] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 12/23/2015] [Accepted: 12/23/2015] [Indexed: 12/26/2022]
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Madfa AA, Yue XG. Dental prostheses mimic the natural enamel behavior under functional loading: A review article. JAPANESE DENTAL SCIENCE REVIEW 2016; 52:2-13. [PMID: 28408950 PMCID: PMC5382785 DOI: 10.1016/j.jdsr.2015.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 05/18/2015] [Accepted: 07/23/2015] [Indexed: 11/30/2022] Open
Abstract
Alumina- and zirconia-based ceramic dental restorations are designed to repair functionality as well as esthetics of the failed teeth. However, these materials exhibited several performance deficiencies such as fracture, poor esthetic properties of ceramic cores (particularly zirconia cores), and difficulty in accomplishing a strong ceramic–resin-based cement bond. Therefore, improving the mechanical properties of these ceramic materials is of great interest in a wide range of disciplines. Consequently, spatial gradients in surface composition and structure can improve the mechanical integrity of ceramic dental restorations. Thus, this article reviews the current status of the functionally graded dental prostheses inspired by the dentino-enamel junction (DEJ) structures and the linear gradation in Young's modulus of the DEJ, as a new material design approach, to improve the performance compared to traditional dental prostheses. This is a remarkable example of nature's ability to engineer functionally graded dental prostheses. The current article opens a new avenue for recent researches aimed at the further development of new ceramic dental restorations for improving their clinical durability.
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Affiliation(s)
- Ahmed A. Madfa
- Department of Conservative Dentistry, Faculty of Dentistry, University of Thamar, Yemen
- Corresponding author at: Department of Conservative Dentistry, Faculty of Dentistry, University of Thamar, Dhamar, Yemen. Tel.: +967 6503255.
| | - Xiao-Guang Yue
- Department of Safety Science and Engineering, Wuhan University of Technology, China
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Liu R, Sun T, Zhang Y, Zhang Y, Jiang D, Shao L. The effect of graded glass–zirconia structure on the bond between core and veneer in layered zirconia restorations. J Mech Behav Biomed Mater 2015; 46:197-204. [DOI: 10.1016/j.jmbbm.2015.02.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/11/2015] [Accepted: 02/19/2015] [Indexed: 11/15/2022]
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Creep-assisted slow crack growth in bio-inspired dental multilayers. J Mech Behav Biomed Mater 2015; 46:41-8. [DOI: 10.1016/j.jmbbm.2015.01.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 01/22/2015] [Accepted: 01/26/2015] [Indexed: 11/23/2022]
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Ma L, Guess PC, Zhang Y. Load-bearing properties of minimal-invasive monolithic lithium disilicate and zirconia occlusal onlays: finite element and theoretical analyses. Dent Mater 2013; 29:742-51. [PMID: 23683531 PMCID: PMC3698988 DOI: 10.1016/j.dental.2013.04.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/06/2013] [Accepted: 04/09/2013] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The aim of this study was to test the hypothesis that monolithic lithium disilicate glass-ceramic occlusal onlay can exhibit a load-bearing capacity that approaches monolithic zirconia, due to a smaller elastic modulus mismatch between the lithium disilicate and its supporting tooth structure relative to zirconia. METHODS Ceramic occlusal onlays of various thicknesses cemented to either enamel or dentin were considered. Occlusal load was applied through an enamel-like deformable indenter or a control rigid indenter. Flexural tensile stress at the ceramic intaglio (cementation) surface-a cause for bulk fracture of occlusal onlays-was rigorously analyzed using finite element analysis and classical plate-on-foundation theory. RESULTS When bonded to enamel (supported by dentin), the load-bearing capacity of lithium disilicate can approach 75% of that of zirconia, despite the flexural strength of lithium disilicate (400MPa) being merely 40% of zirconia (1000MPa). When bonded to dentin (with the enamel completely removed), the load-bearing capacity of lithium disilicate is about 57% of zirconia, still significantly higher than the anticipated value based on its strength. Both ceramics show slightly higher load-bearing capacity when loaded with a deformable indenter (enamel, glass-ceramic, or porcelain) rather than a rigid indenter. SIGNIFICANCE When supported by enamel, the load-bearing property of minimally invasive lithium disilicate occlusal onlays (0.6-1.4mm thick) can exceed 70% of that of zirconia. Additionally, a relatively weak dependence of fracture load on restoration thickness indicates that a 1.2mm thin lithium disilicate onlay can be as fracture resistant as its 1.6mm counterpart.
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Affiliation(s)
| | | | - Yu Zhang
- Department of Biomaterials and Biomimetics New York University College of Dentistry 345 East 24 Street, New York, NY 10010, USA
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Du J, Niu X, Rahbar N, Soboyejo W. Bio-inspired dental multilayers: effects of layer architecture on the contact-induced deformation. Acta Biomater 2013; 9:5273-9. [PMID: 22940125 DOI: 10.1016/j.actbio.2012.08.034] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 10/28/2022]
Abstract
The ceramic crown structures under occlusal contact are idealized as flat multilayered structures that are deformed under Hertzian contact loading. Those multilayers consist of a crown-like ceramic top layer, an adhesive layer and the dentin-like substrate. Bio-inspired design of the adhesive layer proposed functionally graded multilayers (FGM) that mimic the dentin-enamel junction in natural teeth. This paper examines the effects of FGM layer architecture on the contact-induced deformation of bio-inspired dental multilayers. Finite element modeling was used to explore the effects of thickness and architecture on the contact-induced stresses that are induced in bio-inspired dental multilayers. A layered nanocomposite structure was then fabricated by the sequential rolling of micro-scale nanocomposite materials with local moduli that increase from the side near the soft dentin-like polymer composite foundation to the side near the top ceramic layer. The loading rate dependence of the critical failure loads is shown to be well predicted by a slow crack growth model, which integrates the actual mechanical properties that are obtained from nanoindentation experiments.
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Libanori R, Erb RM, Reiser A, Le Ferrand H, Süess MJ, Spolenak R, Studart AR. Stretchable heterogeneous composites with extreme mechanical gradients. Nat Commun 2012; 3:1265. [DOI: 10.1038/ncomms2281] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 11/12/2012] [Indexed: 01/22/2023] Open
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Experimental evaluation of the bond strength between a CoCrMo dental alloy and porcelain through a composite metal–ceramic graded transition interlayer. J Mech Behav Biomed Mater 2012; 13:206-14. [DOI: 10.1016/j.jmbbm.2012.04.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/17/2012] [Accepted: 04/23/2012] [Indexed: 11/18/2022]
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Henriques B, Gonçalves S, Soares D, Silva F. Shear bond strength comparison between conventional porcelain fused to metal and new functionally graded dental restorations after thermal–mechanical cycling. J Mech Behav Biomed Mater 2012; 13:194-205. [DOI: 10.1016/j.jmbbm.2012.06.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 06/04/2012] [Accepted: 06/07/2012] [Indexed: 11/27/2022]
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Dorthé E, Zhang Y. Load-bearing increase in alumina evoked by introduction of a functional glass gradient. JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 2012; 32:1213-1220. [PMID: 22639492 PMCID: PMC3358778 DOI: 10.1016/j.jeurceramsoc.2011.11.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Alumina is the most commonly used ceramic in orthopedics due mainly to its wear resistance and chemical inertness. However, alumina has relatively low load-bearing capacity compared to other advanced ceramics, such as zirconia. We hypothesized that grading the elastic modulus at the surfaces may substantially increase the load-bearing capacity of alumina. In this study, graded structures were fabricated by infiltrating glass into dense alumina plates, resulting in a diminished modulus at the surface layers. The plates were then bonded to polycarbonate substrates and subjected to flexural loading with various loading rates spanning five orders of magnitude (dynamic fatigue) in water. Infiltrated specimens showed an increase in flexural load over homogenous controls for all loading rates, despite the graded alumina exhibiting greater load rate dependence than their homogenous counterparts. Our results indicate that controlled elastic gradients at the surface could be highly beneficial in improving the load-bearing capacity of alumina ceramics.
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Affiliation(s)
| | - Yu Zhang
- Corresponding author Yu Zhang, Ph.D (Last name: Zhang) Associate Professor New York University College of Dentistry Department of Biomaterials & Biomimetics Arnold and Marie Schwartz Hall of Dental Sciences 345 East 24th Street, Rm 813C New York, 10010 NY, USA TEL: 212-998-9637 (OFFICE) FAX: 212-995-4244
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Constantino PJ, Lee JJW, Gerbig Y, Hartstone-Rose A, Talebi M, Lawn BR, Lucas PW. The role of tooth enamel mechanical properties in primate dietary adaptation. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 148:171-7. [DOI: 10.1002/ajpa.21576] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Zhang Y, Sun MJ, Zhang D. Designing functionally graded materials with superior load-bearing properties. Acta Biomater 2012; 8:1101-8. [PMID: 22178651 DOI: 10.1016/j.actbio.2011.11.033] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 11/22/2011] [Accepted: 11/29/2011] [Indexed: 11/15/2022]
Abstract
Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidelines for designing FGMs with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (E(b)/E(s)) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15<n<0.5), coupled with a relatively small modulus ratio (3<E(b)/E(s)<6), is most desirable for reducing the maximum stress and transferring it into the interior, while keeping the surface stress low. Experimentally, we demonstrate that elastically graded materials with various n values and E(b)/E(s) ratios can be fabricated by infiltrating alumina and zirconia with a low-modulus glass. Flexural tests show that graded alumina and zirconia with suitable values of these parameters exhibit superior load-bearing capacity, 20-50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications.
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Affiliation(s)
- Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 345 East 24th Street, New York, NY 10010, USA.
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Ren L, Liu L, Bhowmick S, Gerbig YB, Janal MN, Thompson VP, Zhang Y. Improving fatigue damage resistance of alumina through surface grading. J Dent Res 2011; 90:1026-30. [PMID: 21555776 DOI: 10.1177/0022034511408427] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Porcelain-veneered alumina crown restorations often fail from bulk fracture resulting from radial cracks that initiate at the cementation surface with repeated flexure of the stiffer crown layers on the soft dentin support. We hypothesized that bulk fracture may be substantially mitigated by grading the elastic modulus at the crown surfaces. In this study, we fabricated graded structures by infiltrating glass into dense alumina plates, resulting in a diminished modulus at the surface layers. The plates were then bonded to polycarbonate substrates and subjected to fatigue loading in water. Tests were terminated when fracture occurred at the cementation tensile surface or at the fatigue endurance limit (1 million cycles). Infiltrated specimens showed a significant increase in fatigue fracture loads over non-infiltrated controls. Our results indicate that controlled elastic gradients at the surface could be highly beneficial in the design of fracture-resistant alumina crowns.
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Affiliation(s)
- L Ren
- Department of Chemical, Materials & Biomolecular Engineering, Center for Clean Energy Engineering, University of Connecticut, 191 Auditorium Road, Unit 3222, Storrs, CT 06269-3222, USA
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Abstract
One failure mode of all-ceramic restorations is radial cracking at the cementation surface, from occlusally induced flexure of the stiffer ceramic layer(s) on the softer dentin underlayer. We hypothesize that such failure may be substantially mitigated by an appropriate grading of elastic modulus through the ceramic thickness. In this study, we fabricated graded structures by infiltrating glass into zirconia plates, with resulting diminished modulus in the outer surfaces. The plates were then bonded to a polymeric base and subjected to flexure by contact loading until fracture. Comparison of infiltrated specimens with non-infiltrated controls showed a significant increase in the fracture loads, by a factor of nearly 2. Finite element analysis revealed the cause of increase in the load-bearing capacity to be diminished tensile stresses within the lower-modulus graded zone, corresponding to an increase in material strength. The results confirmed that suitably graded structures can be highly beneficial in the design of next-generation all-ceramic restorations.
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Affiliation(s)
- Y Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 345 East 24th Street, New York, NY 10010, USA.
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Niu X, Rahbar N, Farias S, Soboyejo W. Bio-inspired design of dental multilayers: experiments and model. J Mech Behav Biomed Mater 2008; 2:596-602. [PMID: 19716103 DOI: 10.1016/j.jmbbm.2008.10.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 09/29/2008] [Accepted: 10/13/2008] [Indexed: 11/17/2022]
Abstract
This paper combines experiments, simulations and analytical modeling that are inspired by the stress reductions associated with the functionally graded structures of the dentin-enamel-junctions (DEJs) in natural teeth. Unlike conventional crown structures in which ceramic crowns are bonded to the bottom layer with an adhesive layer, real teeth do not have a distinct "adhesive layer" between the enamel and the dentin layers. Instead, there is a graded transition from enamel to dentin within a approximately 10 to 100 microm thick regime that is called the Dentin Enamel Junction (DEJ). In this paper, a micro-scale, bio-inspired functionally graded structure is used to bond the top ceramic layer (zirconia) to a dentin-like ceramic-filled polymer substrate. The bio-inspired functionally graded material (FGM) is shown to exhibit higher critical loads over a wide range of loading rates. The measured critical loads are predicted using a rate dependent slow crack growth (RDEASCG) model. The implications of the results are then discussed for the design of bio-inspired dental multilayers.
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Affiliation(s)
- Xinrui Niu
- Princeton Institute for the Science and Technology of Materials (PRISM), Princeton University, Princeton, NJ 08544, United States
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Ihara H, Abe Y, Miyamoto A, Nishihara M, Takafuji M, Ono M, Okayasu S, Mashimo T. Chemistry in Mega-gravity: Preparation of Molecular-scaled Graded Materials from Radical Copolymerization. CHEM LETT 2008. [DOI: 10.1246/cl.2008.200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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