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Silva SEGD, Silva NRD, Santos JVDN, Moreira FGDG, Özcan M, Souza RODAE. Accuracy, adaptation and margin quality of monolithic zirconia crowns fabricated by 3D printing versus subtractive manufacturing technique: A systematic review and meta-analysis of in vitro studies. J Dent 2024; 147:105089. [PMID: 38772449 DOI: 10.1016/j.jdent.2024.105089] [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: 02/03/2024] [Revised: 04/28/2024] [Accepted: 05/18/2024] [Indexed: 05/23/2024] Open
Abstract
OBJECTIVE The purpose of this systematic review and meta-analysis was to evaluate the accuracy (trueness and precision), marginal and internal adaptation, and margin quality of zirconia crowns made by additive manufacturing compared to subtractive manufacturing technology. METHODS The investigation adhered to the PRISMA-ScR guidelines for systematic reviews and was registered at the Prospero database (n°CRD42023452927). Four electronic databases, including PubMed, Scopus, Embase, and Web of Science and manual search was conducted to find relevant studies published until September 2023. In vitro studies that assessed the trueness and precision, marginal and internal adaptation, and margin quality of printed crowns compared to milled ones were included. Studies on crowns over implants, pontics, temporary restorations, laminates, or exclusively experimental materials were excluded. RESULTS A total of 9 studies were included in the descriptive reporting and 7 for meta-analysis. The global meta-analysis of the trueness (P<0.74,I2=90 %) and the margin quality (P<0.61,I2=0 %) indicated no significant difference between the root mean square of printed and milled zirconia crowns. The subgroup analysis for the printing system showed a significant effect (P<0.01). The meta-analysis of the crown areas indicated no significant difference in most of the areas, except for the marginal (favoring milled crowns) and axial (favoring printed crowns) areas. For precision and adaptation, both methods showed a clinically acceptable level. CONCLUSIONS Additive manufacturing technology produces crowns with trueness and margin quality comparable to subtractive manufacturing. Both techniques have demonstrated the ability to produce crowns with precision levels, internal discrepancy, and marginal fit within clinically acceptable limits. CLINICAL SIGNIFICANCE 3D printing emerges as a promising and potentially applicable alternative method for manufacturing zirconia crowns, as it shows trueness and margin quality comparable to restorations produced by the subtractive method.
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Affiliation(s)
- Sarah Emille Gomes da Silva
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP 59056-000, Brazil
| | - Nathalia Ramos da Silva
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP 59056-000, Brazil
| | - João Vitor do Nascimento Santos
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP 59056-000, Brazil
| | - Fernanda Gurgel de Gois Moreira
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP 59056-000, Brazil
| | - Mutlu Özcan
- University of Zurich, Clinic for Masticatory Disorders and Dental Biomaterials, Center for Dental Medicine, Zentrum für Zahnmedizin, Plattenstrasse, 11, 8032 Zurich, Switzerland
| | - Rodrigo Othávio de Assunção E Souza
- Federal University of Rio Grande do Norte (UFRN), Department of Dentistry, Av. Salgado Filho, 1787, Lagoa Nova, Natal, RN, CEP 59056-000, Brazil.
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Zhu H, Zhou Y, Jiang J, Wang Y, He F. Accuracy and margin quality of advanced 3D-printed monolithic zirconia crowns. J Prosthet Dent 2023:S0022-3913(23)00444-4. [PMID: 37591717 DOI: 10.1016/j.prosdent.2023.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 08/19/2023]
Abstract
STATEMENT OF PROBLEM Nanoparticle jetting (NPJ) is a novel ceramic 3D-printing technology with high printing accuracy. However, studies reporting the accuracy of zirconia crowns manufactured by NPJ and comparing them with conventional zirconia crowns are lacking. PURPOSE The purpose of this in vitro study was to evaluate and compare the trueness, crown fit, and margin quality of monolithic zirconia crowns manufactured by NPJ with those milled by a computer numerical control system. MATERIAL AND METHODS A gypsum left mandibular first molar was prepared and scanned with an intraoral scanner (TRIOS 4). Three types of monolithic crowns were manufactured through 3D printing and subtractive manufacturing (SM): NPJ (3D printing), VITA (milling), UPCERA (milling). The crowns were scanned, and the dimensional deviation (trueness) was evaluated and compared by using a software program. The triple scan method was used to measure crown fit and uniform index through precise alignment in the software program, and margin quality was also observed with an optical microscope. The data were analyzed with 1-way analysis of variance and the Tukey post hoc test (α=.05). RESULTS The NPJ group reported better trueness of all crown and axial surfaces compared with the other SM group (P<.001), but marginal trueness (P=.601), intaglio surface (P=.596), and occlusal surface (P=.641) were statistically similar compared with the Vita milled group. All 3 groups reported clinically acceptable crown fit and uniformity with statistically similar values (P>.05). The NPJ group had more crowns judged to have flawless margin quality compared with the milled groups. CONCLUSIONS All 3 manufacturing methods can fabricate zirconia crowns with a clinically acceptable crown fit. The NPJ system could be used to manufacture monolithic zirconia crowns with better margin quality and proximal surface trueness than milled crowns.
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Affiliation(s)
- Han Zhu
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Yi Zhou
- Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Jimin Jiang
- Department of Prosthodontics, Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Yujie Wang
- Department of Periodontics, Department of Prosthodontics, Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China
| | - Fuming He
- Department of Prosthodontics and Implantology, Department of Prosthodontics, Department of Periodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China.
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Piemjai M, Donpinprai C. Improving retention of dental veneers fabricated from an experimental enamel-based biopolymer compared with CAD/CAM hybrid materials. Heliyon 2023; 9:e16219. [PMID: 37215792 PMCID: PMC10199219 DOI: 10.1016/j.heliyon.2023.e16219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 05/06/2023] [Accepted: 05/10/2023] [Indexed: 05/24/2023] Open
Abstract
Objectives CAD/CAM hybrid materials have become increasingly utilized in restorative dentistry. However, their low tensile bond strength (TBS) may lead to the detachment of minimally invasive restorations. When prepared, an experimental enamel-based biopolymer prosthesis provided a honeycomb-like interfacial layer with luting adhesives leading to a higher TBS than Ni-Cr-Be based alloy, lithium disilicate-based ceramic, and cured-resin-composite. This study aimed to compare TBSs of dental veneers fabricated from experimental biopolymer and commercial hybrid materials bonded to enamel using two different luting adhesives. Methods Laminate veneers (4 × 4 mm) 1 mm thick were prepared from commercial CAD/CAM blocks: VITA ENAMIC, SHOFU Block HC, KATANA AVENCIA, and an experimental biopolymer. The flat bonding surface of the veneers was ground to 600-grit, followed by 50-μm alumina air-abrading for standardization. Each veneer was fixed on flat ground bovine enamel using either Super-Bond C&B or RelyX™ U200 resin (n = 10). The surface treatment and bonding procedures were treated as recommended by the manufacturers. All bonded specimens were stored in water at 37 °C for 24 h before tensile testing with a universal testing machine at a cross-headed speed of 1.0 mm/min. The fractured surface was examined with a stereomicroscope and scanning electron microscope. TBS data were statistically analyzed using two-way ANOVA and Tukey's HSD test (α = 0.05). Results Experimental biopolymer veneers demonstrated the highest mean TBS with cohesive failure in the luting agents. Adhesive failure at the veneer side interface was found in other groups. There was no significant difference between the two luting agents. Conclusion The results indicate that the experimental biopolymer veneer bonded to enamel provided the best retention. The TBS at the enamel-resin interface is higher than at the veneer-resin interface for all commercial CAD/CAM hybrid materials. Clinical significance An experimental enamel-based biopolymer veneer can provide better retention than CAD/CAM hybrid materials in clinical treatment.
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Velho HC, da Rosa LS, Dapieve KS, Borges ALS, Pereira GKR, Venturini AB, Valandro LF. How does the occlusal contact region influence the mechanical fatigue performance and fracture region of monolithic lithium disilicate ceramic crowns? J Mech Behav Biomed Mater 2023; 140:105746. [PMID: 36878081 DOI: 10.1016/j.jmbbm.2023.105746] [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: 01/23/2023] [Revised: 02/23/2023] [Accepted: 02/26/2023] [Indexed: 03/05/2023]
Abstract
OBJECTIVE To characterize the effect of the occlusal contact region on the mechanical fatigue performance and on the fracture region of monolithic lithium disilicate ceramic crowns. MATERIALS AND METHODS Monolithic lithium disilicate ceramic crowns were machined in a CAD/CAM system and adhesively luted onto glass-fiber reinforced epoxy resin preparations with resin cement. The crowns were divided into three groups (n = 16) according to load application region (cusp tip: restricted to cusp tips; cusp plane: restricted to cuspal inclined plane; or mixed: associating tip cusp and cuspal inclined plane). The specimens were submitted to a cyclic fatigue test (initial load: 200 N; step-size: 100 N; cycles/step: 20,000; loading frequency: 20 Hz; load applicator: 6 mm or 40 mm diameter stainless steel) until observing cracks (1st outcome) and fracture (2nd outcome). The data were analyzed by the Kaplan-Meier + Mantel-Cox post-hoc tests for both outcomes (cracks and fracture). Finite element analysis (FEA), occlusal contact region, contact radii measurements, and fractographic analyzes were performed. RESULTS The mixed group presented worse fatigue mechanical behavior (550 N / 85.000 cycles) compared to the cuspal inclined plane group (656 N / 111,250 cycles) (p < 0.05) for the first crack outcome, while the cusp tip group was similar to both groups (588 N / 97,500 cycles) (p > 0.05). The mixed group had the worst fatigue behavior (1413 N / 253,029 cycles) in relation to the other groups (Cusp tip: 1644 N / 293,312 cycles; Cuspal inclined plane: 1631 N / 295,174 cycles) considering the crown fracture outcome (p < 0.05). FEA showed higher tensile stress concentration areas just below the load application region. In addition, loading on the cuspal inclined plane induced a higher tensile stress concentration in the groove region. The most prevalent type of crown fracture was the wall fracture. Groove fracture was observed in 50% of the loading specimens exclusively on the cuspal inclined plane. CONCLUSION Load application on distinct occlusal contact regions affects the stress distribution pattern and consequently the mechanical fatigue performance and fracture region of the monolithic lithium disilicate ceramic crowns. A combination of loading at distinct regions is recommended to promote better evaluation of the fatigue behavior of a restored set.
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Affiliation(s)
- Helder Callegaro Velho
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Lucas Saldanha da Rosa
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Kiara Serafini Dapieve
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Alexandre Luiz Souto Borges
- Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, São Paulo, Brazil.
| | - Gabriel Kalil Rocha Pereira
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Andressa Borin Venturini
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
| | - Luiz Felipe Valandro
- MSciD and Ph.D. Post-Graduate Program in Oral Sciences, Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
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May MM, Machry RV, Fraga S, de Andrade GS, Bottino MA, Valandro LF, May LG. Resin cement coating reverts the machining damage on the flexural fatigue strength of lithium disilicate glass-ceramic. J Biomed Mater Res B Appl Biomater 2023; 111:971-980. [PMID: 36434818 DOI: 10.1002/jbm.b.35206] [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: 07/26/2022] [Revised: 10/31/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022]
Abstract
This study evaluated the effect of resin cement coating with high and low viscosities on the flexural fatigue strength of machined lithium disilicate glass-ceramic. Discs (IPS e.max CAD; Ivoclar Vivadent) were prepared and divided according to the surface condition (machining [M]-CEREC inLab; and polishing [P]-laboratory procedures), resin cement coating (with or without), and cement viscosity (high [H] and low [L]). The ceramic bonding surface was etched/primed by a one-step primer application followed by resin cement application (Variolink N base + high or low viscosity catalyst; Ivoclar Vivadent). Biaxial flexural fatigue strength was evaluated on a piston-on-three-ball set by the step-test method (n = 15) (initial stress: 60 MPa; incremental steps: 20 MPa; 10,000 cycles/step, at 20 Hz). Weibull statistics were used for fatigue data. Contact angle, topographic, and fractographic analysis were also performed. Machining produced statistically lower contact angle than polishing and a significant detrimental effect on the fatigue behavior (σ0 M = 247.2 [246.9-268.3]; σ0 P = 337.4 [297.8-382.4]). Machined groups followed by resin cement coating (σ0 MH = 297.9 [276.0-321.5]; σ0 Ml = 301.2 [277.1-327.4]) behaved similarly to the polished and coated groups (σ0 PH = 342.0 [308.9-378.5]; σ0 PL = 357.3 [324.7-393.1]), irrespective of the cement viscosity. Therefore, cement coating has able to revert the detrimental effects of the machining on the fatigue strength of lithium disilicate glass-ceramic. High and low viscosity cements behaved similarly in the improvement of CAD-CAM lithium disilicate fatigue strength.
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Affiliation(s)
- Michele Mirian May
- Post-Graduate Program in Dental Sciences, Prosthetic Dentistry Unit, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Brazil
| | - Renan Vaz Machry
- Post-Graduate Program in Dental Sciences, Prosthetic Dentistry Unit, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Brazil
| | - Sara Fraga
- Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Marco Antonio Bottino
- Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, Brazil
| | - Luiz Felipe Valandro
- Department of Restorative Dentistry, Federal University of Santa Maria, Santa Maria, Brazil
| | - Liliana Gressler May
- Department of Restorative Dentistry, Federal University of Santa Maria, Santa Maria, Brazil
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Lana TMDSD, Weber KR, Medeiros JA, Goedel F, Benetti P, Borba M. Fatigue-life and stress distribution of a glass-ceramic under different loading conditions. Braz Dent J 2023; 34:80-88. [PMID: 36888848 PMCID: PMC10027096 DOI: 10.1590/0103-6440202305129] [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: 07/04/2022] [Accepted: 11/17/2022] [Indexed: 03/08/2023] Open
Abstract
This study aimed to evaluate the effect of different loading conditions on the mechanical behavior and stress distribution of a leucite-reinforced glass-ceramic. Plate-shaped ceramic specimens were obtained from leucite-reinforced glass-ceramic (1.5 × 8.4 × 8.3 mm) and adhesively cemented to a dentin analog substrate. Monotonic and cyclic contact fatigue tests were performed to simulate sphere-to-flat contact, using a 6 mm diameter spherical piston; and flat-to-flat contact, using a 3 mm diameter flat piston. For the monotonic test (n=20), a gradual compressive load (0.5 mm/min) was applied to the specimen using a universal testing machine. Failure load data were analyzed with Weibull statistics. The cyclic contact fatigue test was performed using protocols (load and a number of cycles) defined by the boundary technique (n=30). Fatigue data were analyzed using an inverse power law relationship and Weibull-lifetime distribution. The stress distribution was investigated using Finite Element Analysis (FEA). The monotonic and the fatigue Weibull modulus were similar among the two contact conditions. In fatigue, the slow crack growth exponent was greater for sphere-to-flat contact, which indicates that the load level had a greater effect on the specimen's probability of failure. In conclusion, FEA showed different stress distribution for the tested loading conditions. The stress distribution and probability of fatigue failure of specimens tested in sphere-to-flat contact showed greater dependency to load level.
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Affiliation(s)
| | - Kátia Raquel Weber
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, Rio Grande do Sul, Brazil
| | - Juliana Arisi Medeiros
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, Rio Grande do Sul, Brazil
| | - Fábio Goedel
- Engineering School, University of Passo Fundo(UPF), Passo Fundo, Rio Grande do Sul, Brazil
| | - Paula Benetti
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, Rio Grande do Sul, Brazil
| | - Márcia Borba
- Graduate Program in Dentistry, Dental School, University of Passo Fundo(UPF), Passo Fundo, Rio Grande do Sul, Brazil
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Hassouneh L, Jum'ah A, Ferrari M, Wood DJ. A Micro-computed Tomography Analysis of Marginal and Internal Fit of Endocrowns Fabricated from Three CAD/CAM Materials. Oper Dent 2023; 48:79-89. [PMID: 36445975 DOI: 10.2341/21-105-l] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To assess the marginal and internal misfit of endocrowns fabricated from a resin matrix ceramic (CS), a partially crystallized (EMC), and a fully crystallized (ILS) lithium disilicate glass-ceramic. METHODS AND MATERIALS Thirty human premolar teeth restored with endocrowns were investigated. Three CAD/CAM materials were used (n=10 per group): CS, EMC, and ILS. Two-dimensional (2D) analysis of marginal and internal misfit was performed on micro-computed tomography scans before and after adhesive bonding. Further, three-dimensional (3D) analysis was performed to determine the total internal volume discrepancy. Surface roughness of the fitting surfaces of endocrowns was characterized using optical profilometry and scanning electron microscopy. RESULTS Adhesive bonding did not significantly affect marginal or internal misfit (p≥0.093). Differences in marginal misfit among the experimental groups were not statistically significant (p≥0.221). However, differences in 2D internal misfit were statistically significant; the CS group exhibited the largest internal misfit (p=0.001), while no significant difference was found between other groups (p=0.123). The largest discrepancies were observed at the pulpal floor and cervical region of all investigated specimens. No statistically significant difference was found in 3D misfit between ILS and EMC groups (p=0.711); however both exhibited statistically lower 3D misfit values compared to the CS group (p≤0.037). ILS endocrowns exhibited the smoothest and most homogenous fitting surface profile (p<0.001). However, there was no significant correlation between 2D internal misfit and the surface roughness (p≥0.082). CONCLUSIONS The choice of CAD/CAM material may influence the fitting accuracy of endocrowns. The investigated lithium disilicate glass-ceramics conferred superior internal fit for endocrowns compared to resin matrix ceramic.
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Affiliation(s)
- L Hassouneh
- Layla Hassouneh, PhD, MClinDent, BDS, University of Leeds, School of Dentistry, Division of Restorative Dentistry, Leeds, UK; and Department of Conservative Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan
| | - A Jum'ah
- *Ahmad Jum'ah, PhD, MRD(Pros.)RSCEd, RSCEd, JB, MSc, BDS, Department of Conservative Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan; and Faculty of Dentistry, Aqaba Medical Sciences University, Aqaba, Jordan
| | - M Ferrari
- Marco Ferrari, MD DDS, PhD, 1. University of Siena, Department of Medical Biotechnologies, Division of Fixed Prosthodontics, Siena, Italy 2. University of Leeds, School of Dentistry, Division of Restorative Dentistry, Leeds, UK
| | - D J Wood
- David J Wood, BSc, PhD, University of Leeds, School of Dentistry, Division of Oral Biology, Leeds, UK
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Zheng Z, Wang H, Mo J, Ling Z, Zeng Y, Zhang Y, Wang J, Yan W. Effect of virtual cement space and restorative materials on the adaptation of CAD-CAM endocrowns. BMC Oral Health 2022; 22:580. [PMID: 36494663 PMCID: PMC9733092 DOI: 10.1186/s12903-022-02598-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND This study aimed to evaluate the effect of virtual cement space and restorative materials on the fit of computer-aided design and computer-aided manufacturing (CAD-CAM) endocrowns. METHODS A mandibular first molar tooth model received a butt joint margin endocrown preparation with a 2-mm occlusal thickness. Then, using a 3D-printing system, 120 copies of this prepared die were printed and assigned equally to three groups with different cement space settings (30, 60, and 120 μm) during the chairside CAD design. In the milling process, CAD-based models with a particular space setting were subdivided into four groups (n = 10) and fabricated from different CAD-CAM materials: Vita Suprinity (VS), Celtra Duo (CD), Lava Ultimate (LU), and Grandio blocs (GR). Finally, the endocrowns were stabilized over their corresponding models with siloxane and subjected to micro-computed tomography to measure the fit. RESULTS The cement space that was predesigned at 30 μm generated the largest marginal discrepancy (from 144.68 ± 22.43 μm to 174.36 ± 22.78 μm), which was significantly different from those at 60 μm and 120 μm (p < 0.001). The combination of VS or CD with a pre-setting cement space of 60 μm and the combination of LU or GR with a cement space of 120 μm showed better agreement between the predesigned and actual measured marginal gap widths. For internal adaptation, only the cement space set to 30 μm exceeded the clinically acceptable threshold (200 μm). CONCLUSIONS The setting of the cement space and restorative material significantly affected the marginal adaptation of CAD-CAM endocrown restorations. Considering the discrepancy between design and reality, different virtual cement spaces should be applied to ceramic and resin composite materials.
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Affiliation(s)
- Ziting Zheng
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
| | - Hebi Wang
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China ,grid.411866.c0000 0000 8848 7685Department of Stomatology, The Third Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong People’s Republic of China
| | - Jiayao Mo
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
| | - Zhiting Ling
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
| | - Yuting Zeng
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
| | - Yuxin Zhang
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
| | - Jilei Wang
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
| | - Wenjuan Yan
- grid.416466.70000 0004 1757 959XDepartment of Stomatology, Nanfang Hospital, Southern Medical University, 1838 N Guangzhou RD, Guangzhou, Guangdong People’s Republic of China
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Zumstein K, Fiscalini L, Al-Haj Husain N, Evci E, Özcan M, Ioannidis A. Load-bearing capacity of pressable lithium disilicates applied as ultra-thin occlusal veneers on molars. J Mech Behav Biomed Mater 2022; 136:105520. [PMID: 36341889 DOI: 10.1016/j.jmbbm.2022.105520] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/04/2022] [Accepted: 10/07/2022] [Indexed: 11/06/2022]
Abstract
PURPOSE The aim was to investigate the load bearing capacity of different pressable lithium disilicates cemented as occlusal veneers on molars. MATERIALS AND METHODS One control group and six test groups were formed consisting of 20 specimens each (n = 20). The six test groups differed in the utilizing pressable lithium disilicate to fabricate occlusal veneers. As a control group, "group Lis", the lithium disilicate with the highest reported flexural strength was used (initial LiSi Press, GC Europe; Leuven, Belgium / flexural strength: 508 MPa). The test groups consisted of other pressable lithium disilicates with lower flexural strength values: "Ema" (IPS e.max press), "Vit" (VITA Ambria), "Liv" (Livento Press), "Amb" (Amber Press), "Mas" (Amber Press Master) and "Ros" (Rosetta SP)". After the preparation of 140 extracted human molars, which included the removal of the central enamel, the specimens were scanned using a desktop scanner. With the aid of a design software, the occlusal veneers were designed in a standardized thickness of 0.5 mm. To fabricate the restorations, all tested materials were processed using heat-pressing technique. All restorations were adhesively cemented. Afterwards, the specimens underwent cyclic fatigue during an aging procedure in a chewing simulator (1'200'000 chewing-cycles, 49 N force, 5-55°C temperature changes). Subsequently, the specimens were statically loaded and the load which was necessary to fracture the specimen (Fmax) were measured. Differences between the groups were compared applying the Kruskal-Wallis (KW) test and the Wilcoxon-Mann-Whitney-Test (WMW: p < 0.05). The two-parameter Weibull distribution values were calculated. RESULTS The fatigue resistance was 100% for the groups Lis, Vit, Liv, Amb, Mas and Ros, whereas the group Ema showed a fatigue resistance of 95%. The control group Lis showed median Fmax values of 2'328 N. The median Fmax values for the test groups ranged between 1'753 N (Vit) and 2'490 N (Ros). Statistically significant difference was observed among the groups Lis (control) and Vit (KW: p < 0.001). Weibull distribution presented the highest shape values for the group Ros (12.83) and the lowest values for the group Ema (4.71). CONCLUSION Regarding their load-bearing capacity different pressable lithium disilicates can be recommended to fabricate ultra-thin occlusal veneers on molars when restoring occlusal tooth wear.
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Affiliation(s)
- Katrin Zumstein
- University of Zurich, Center of Dental Medicine, Clinic of Reconstructive Dentistry, Zurich, Switzerland
| | - Lorenzo Fiscalini
- University of Zurich, Center of Dental Medicine, Clinic of Reconstructive Dentistry, Zurich, Switzerland
| | - Nadin Al-Haj Husain
- University of Zurich, Center of Dental Medicine, Clinic of Reconstructive Dentistry, Zurich, Switzerland; University of Bern, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, Bern, Switzerland
| | - Erkan Evci
- University of Zurich, Center of Dental Medicine, Clinic of Reconstructive Dentistry, Zurich, Switzerland
| | - Mutlu Özcan
- University of Zurich, Center of Dental Medicine, Clinic of Reconstructive Dentistry, Zurich, Switzerland
| | - Alexis Ioannidis
- University of Zurich, Center of Dental Medicine, Clinic of Reconstructive Dentistry, Zurich, Switzerland.
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Channarong W, Lohawiboonkij N, Jaleyasuthumkul P, Ketpan K, Duangrattanaprathip N, Wayakanon K. Fracture resistance of bonded ceramic overlay restorations prepared in various designs. Sci Rep 2022; 12:16599. [PMID: 36198863 PMCID: PMC9534891 DOI: 10.1038/s41598-022-21167-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/23/2022] [Indexed: 11/26/2022] Open
Abstract
This study investigates fracture resistance of adhesive ceramic overlays of various designs. Forty-eight upper premolar teeth were divided into eight groups. The variations were: shoulder margins on the buccal and lingual surfaces with axial wall heights of 1, 2, or 3 mm; one shoulder margin with axial wall height of 1, 2, or 3 mm on the lingual surface and one contrabevel margin on the buccal surface; contrabevel margins on the buccal and lingual surfaces; and a control of sound teeth. Overlays were designed and fabricated with CAD/CAM using zirconia-reinforced lithium disilicate ceramic and bonded with resin cement. Samples underwent thermocycling and dynamic fatigue equivalent to 6 months of use. Compressive loading was applied until fracture, and fracture mode was analyzed. Results showed no statistical difference in fracture resistance between designs, and the fracture pattern of most was involvement of pulp tissue and below the CEJ. Fracture resistance of the restored teeth was also not statistically different from the control. All control fractures were within the dentin and above the CEJ. Overlay restorations were therefore effective in strengthening damaged teeth and imparting fracture resistance equal to sound teeth, and axial wall heights and margin types did not influence this result.
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Affiliation(s)
| | | | | | - Kittipong Ketpan
- Department of Restorative Dentistry, Naresuan University, Phitsanulok, Thailand
| | | | - Kornchanok Wayakanon
- Department of Restorative Dentistry, Naresuan University, Phitsanulok, Thailand.
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11
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Kolay S, Singh A, Varghese A, Bhargava P. Mechanical properties and machinability of lithium silicate glass-ceramics with varying MgO content. J Mech Behav Biomed Mater 2022; 132:105296. [DOI: 10.1016/j.jmbbm.2022.105296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/19/2022] [Accepted: 05/23/2022] [Indexed: 10/18/2022]
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Comparison of Marginal and Internal Adaptation in Endocrowns Milled from Translucent Zirconia and Zirconium Lithium Silicate. Int J Dent 2021; 2021:1544067. [PMID: 34917150 PMCID: PMC8670910 DOI: 10.1155/2021/1544067] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/10/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022] Open
Abstract
Purpose This study aimed to compare marginal and internal adaptation in endocrowns made from translucent zirconia and zirconium lithium silicate using CAD-CAM technology. Materials and Methods Twenty-eight freshly extracted upper molars were mounted in acrylic resin and underwent root canal therapy and endocrown preparation up to 2 mm above the cementoenamel junction. Endocrowns were CAD-CAM milled from zirconium lithium silicate (ZLS) and translucent zirconia (Zr). Internal and marginal adaptation was assessed by the replica technique before cementation. Marginal adaptation was evaluated by a stereomicroscope (×32) before and after cementation and also after thermomechanical aging. Results The ZLS group showed significantly higher internal adaptation compared to the Zr group (P = 0.028), while the marginal adaptation differences, at different times with different methods, were not statistically significant (P > 0.05). Axiomarginal angle had the highest and axiopulpal angle showed the lowest adaptation in both groups. The cementation process and thermomechanical aging increased the marginal gap in both groups significantly (P < 0.001). The marginal gap assessed by the replica technique before cementation was 7.11 µm higher than direct view under a stereomicroscope with intraclass correlation coefficient of 0.797. Conclusion Zirconia seems to be an acceptable material for endocrown with comparable internal and marginal adaptation to ZLS. Cementation and thermomechanical aging had significantly negative effects on marginal gap. The marginal gap assessed by the replica technique was higher than direct view under the stereomicroscope technique.
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Prott LS, Spitznagel FA, Bonfante EA, Malassa MA, Gierthmuehlen PC. Monolithic zirconia crowns: effect of thickness reduction on fatigue behavior and failure load. J Adv Prosthodont 2021; 13:269-280. [PMID: 34777717 PMCID: PMC8558575 DOI: 10.4047/jap.2021.13.5.269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/30/2021] [Accepted: 09/14/2021] [Indexed: 11/23/2022] Open
Abstract
PURPOSE The objective of this study was to evaluate the effect of thickness reduction and fatigue on the failure load of monolithic zirconia crowns. MATERIALS AND METHODS 140 CAD-CAM fabricated crowns (3Y-TZP, inCorisTZI, Dentsply-Sirona) with different ceramic thicknesses (2.0, 1.5, 1.0, 0.8, 0.5 mm, respectively, named G2, G1.5, G1, G0.8, and G0.5) were investigated. Dies of a mandibular first molar were made of composite resin. The zirconia crowns were luted with a resin composite cement (RelyX Unicem 2 Automix, 3M ESPE). Half of the specimens (n = 14 per group) were mouth-motion-fatigued (1.2 million cycles, 1.6 Hz, 200 N/ 5 – 55℃, groups named G2-F, G1.5-F, G1-F, G0.8-F, and G0.5-F). Single-load to failure was performed using a universal testing-machine. Fracture modes were analyzed. Data were statistically analyzed using a Weibull 2-parameter distribution (90% CI) to determine the characteristic strength and Weibull modulus differences among the groups. RESULTS Three crowns (21%) of G0.8 and five crowns (36%) of G0.5 showed cracks after fatigue. Characteristic strength was the highest for G2, followed by G1.5. Intermediate values were observed for G1 and G1-F, followed by significantly lower values for G0.8, G0.8-F, and G0.5, and the lowest for G0.5-F. Weibull modulus was the lowest for G0.8, intermediate for G0.8-F and G0.5, and significantly higher for the remaining groups. Fatigue only affected G0.5-F. CONCLUSION Reduced crown thickness lead to reduced characteristic strength, even under failure loads that exceed physiological chewing forces. Fatigue significantly reduced the failure load of 0.5 mm monolithic 3Y-TZP crowns.
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Affiliation(s)
- Lea Sophia Prott
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
| | - Frank Akito Spitznagel
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
| | - Estevam Augusto Bonfante
- Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of Sao Paulo, Bauru, SP, Brazil
| | | | - Petra Christine Gierthmuehlen
- Department of Prosthodontics, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University, Düsseldorf, Germany
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Rodrigues CS, Dhital S, Kim J, May LG, Wolff MS, Zhang Y. Residual stresses explaining clinical fractures of bilayer zirconia and lithium disilicate crowns: A VFEM study. Dent Mater 2021; 37:1655-1666. [PMID: 34481666 DOI: 10.1016/j.dental.2021.08.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To understand the stress development in porcelain-veneered zirconia (PVZ) and porcelain-veneered lithium disilicate (PVLD) crowns with different veneer/core thickness ratios and cooling rates. To provide design guidelines for better performing bilayer restorations with the aid of Viscoelastic Finite Element Method (VFEM). METHODS The VFEM was validated by comparing the predicted residual stresses with experimental measurements. Then, the model was used to predict transient and residual stresses in the two bilayer systems. Models with two different veneer/core thickness ratios were prepared (2:1 and 1:1) and two cooling protocols were simulated (Fast: ∼300 °C/min, Slow: ∼30 °C/min) using the heat transfer module, followed by stress analysis in ABAQUS. The physical properties of zirconia, lithium disilicate, and the porcelains used for the simulations were determined as a function of temperature. RESULTS PVLD showed lower residual stresses than PVZ. The maximum tensile stresses in PVZ were observed in the cusp area, whereas those in PVLD were located in the central fossa. The 1:1 thickness ratio decreased stresses in both layers of PVZ. Slow cooling slightly decreased residual stresses in both systems. However, the cooling rate effect was more evident in transient stresses. SIGNIFICANCE Slow cooling is preferable for both systems. A thinner porcelain layer over zirconia lowers stresses throughout the restoration. The different stress distributions between PVZ and PVLD may affect their failure modes. Smaller mismatches in modulus, CTE, and specific heat between the constituents, and the use of low Tg porcelains can effectively reduce the deleterious transient and residual tensile stresses in bilayer restorations.
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Affiliation(s)
- Camila S Rodrigues
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, 777 Eng. Francisco José Longo Av, 12245-000, São José dos Campos, SP, Brazil
| | - Sukirti Dhital
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd., U-3037, Storrs, CT 06269, USA
| | - Jeongho Kim
- Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Rd., U-3037, Storrs, CT 06269, USA
| | - Liliana Gressler May
- Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, 1000 Roraima Av., T Street, Building 26F, 97105-900, Santa Maria, RS, Brazil
| | - Mark S Wolff
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA 19104, USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA 19104, USA.
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15
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Ioannidis A, Park JM, Hüsler J, Bomze D, Mühlemann S, Özcan M. An in vitro comparison of the marginal and internal adaptation of ultrathin occlusal veneers made of 3D-printed zirconia, milled zirconia, and heat-pressed lithium disilicate. J Prosthet Dent 2021; 128:709-715. [PMID: 33741143 DOI: 10.1016/j.prosdent.2020.09.053] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 09/11/2020] [Accepted: 09/11/2020] [Indexed: 10/21/2022]
Abstract
STATEMENT OF PROBLEM Whether additively produced zirconia could overcome problems with conventional computer-aided design and computer-aided manufacture (CAD-CAM) such as milling inaccuracies and provide accurate occlusal veneers is unclear. PURPOSE The purpose of this in vitro study was to compare the marginal and internal fit of 3D-printed zirconia occlusal veneers with CAD-CAM-fabricated zirconia or heat-pressed lithium disilicate ceramic (LS2) restorations on molars. MATERIAL AND METHODS The occlusal enamel in 60 extracted human molars was removed, with the preparation extending into dentin. Occlusal veneers at a thickness of 0.5 mm were designed and manufactured according to their group allocation: 3DP, 3D-printed zirconia; CAM, milled zirconia; and HPR, heat-pressed LS2. The prepared teeth and restorations were scanned and superimposed, and the marginal and internal adaptation were measured 2- and 3-dimensionally; the production accuracy (trueness) was also measured. The comparisons of the group medians were performed with nonparametric methods and a pairwise group comparison (α=.05). RESULTS Three-dimensionally printed zirconia revealed median outcomes of 95 μm (margin), 252 μm (cusp), 305 μm (fossa), and 184 μm (3D internal adaptation). CAM showed median values of 65 μm (margin), 128 μm (cusp), 203 μm (fossa), and 120 μm (3D internal adaptation). The respective values for the group HPR were 118 μm (margin), 251 μm (cusp), 409 μm (fossa), and 180 μm (3D internal adaptation). Significant differences (P<.001) between CAM and 3DP (cusp, fossa, 3D internal adaptation) and between CAM and HPR (all regions) were found, with the former group showing higher accuracies. The trueness showed median discrepancies of 26 μm (3DP), 13 μm (CAM), and 29 μm (HPR) with significant differences (P<.001) for the comparisons 3DP-CAM and CAM-HPR. CONCLUSIONS Three-dimensionally printed zirconia occlusal veneers produced by means of lithography-based ceramic manufacturing exhibit a marginal adaptation (95 μm) and a production accuracy (26 μm) similar to those of conventional methods.
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Affiliation(s)
- Alexis Ioannidis
- Senior Teaching and Research Assistant, Clinic of Reconstructive Dentistry, Center of Dental, University of Zurich, Zurich, Switzerland.
| | - Ji-Man Park
- Associate Professor, Department of Prosthodontics, Yonsei University, Seoul, Republic of Korea
| | - Jürg Hüsler
- Professor, Institute of Mathematical Statistics and Actuarial Science (IMSV), University of Bern, Bern, Switzerland
| | - Daniel Bomze
- Head of Business Unit Medical, Lithoz GmbH, Vienna, Austria
| | - Sven Mühlemann
- Senior Teaching and Research Assistant, Clinic of Reconstructive Dentistry, Center of Dental, University of Zurich, Zurich, Switzerland
| | - Mutlu Özcan
- Head, Division of Dental Biomaterials, Clinic of Reconstructive Dentistry, Center of Dental, University of Zurich, Zurich, Switzerland
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Alao AR, Stoll R, Zhang Y, Yin L. Influence of CAD/CAM milling, sintering and surface treatments on the fatigue behavior of lithium disilicate glass ceramic. J Mech Behav Biomed Mater 2021; 113:104133. [PMID: 33049621 PMCID: PMC7797189 DOI: 10.1016/j.jmbbm.2020.104133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/01/2020] [Accepted: 10/04/2020] [Indexed: 11/30/2022]
Abstract
This paper reports on the process-fatigue relation of lithium disilicate glass ceramic (LDGC) using low-cycle, high-load Hertzian indentations with a rigid indenter to simulate teeth grinding/clenching of LDGC restorations with different surface asperities obtained in CAD/CAM milling, sintering, polishing and glazing. The maximum contact stresses were evaluated as functions of the number of load cycles and surface treatments using the Hertzian model. Indentation-induced surface damage was viewed using scanning electron microscopy (SEM) to understand the relationships among microstructures, surface asperities, crack morphology and propagation. Different processes and surface treatments significantly affected the maximum contact stresses of indented LDGC surfaces (ANOVA, p < 0.05), which were all significantly reduced with the number of cycles (ANOVA, p < 0.05). Quasi-plastic deformation was dominant in single-cycle indentation of all processed and treated surfaces. In higher cycle indentations, inner cone cracks were formed on all surfaces; median and transverse cracks were formed on the roughest surfaces processed by CAD/CAM milling and sintering. Ring cracks, fretting, pulverization, micro-bridges, surface smearing and wedging, and edge chippings were also propagated on all surfaces. The process-fatigue relation provides an understanding of the mechanical functions of surface asperities produced in different processes and treatments. It indicates that the mechanically assisted growth of surface asperities with different roughness strongly affected the indentation-induced surface damage. Finally, the smoothest surfaces produced by CAD/CAM milling, polishing and sintering sustained the highest contact stresses and the least fatigue damage at higher cycles, ensuring their superior fatigue performance compared to other processed LDGC surfaces.
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Affiliation(s)
- Abdur-Rasheed Alao
- Mechanical Engineering Programme Area, Faculty of Engineering, Universiti Teknologi Brunei, Gadong, BE1410, Brunei Darussalam.
| | - Richard Stoll
- Restorative Dentistry, College of Medicine and Dentistry, James Cook University, Cairns, QLD, 4870, Australia
| | - Yu Zhang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ling Yin
- School of Mechanical Engineering, The University of Adelaide, Adelaide, SA, 5005, Australia.
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Shahmoradi M, Wan B, Zhang Z, Wilson T, Swain M, Li Q. Monolithic crowns fracture analysis: The effect of material properties, cusp angle and crown thickness. Dent Mater 2020; 36:1038-1051. [DOI: 10.1016/j.dental.2020.04.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 04/18/2020] [Accepted: 04/30/2020] [Indexed: 11/29/2022]
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Chen SE, Park AC, Wang J, Knoernschild KL, Campbell S, Yang B. Fracture Resistance of Various Thickness e.max CAD Lithium Disilicate Crowns Cemented on Different Supporting Substrates: An In Vitro Study. J Prosthodont 2019; 28:997-1004. [PMID: 31469479 DOI: 10.1111/jopr.13108] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2019] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To investigate the influence of abutment material properties on the fracture resistance and failure mode of lithium disilicate (IPS e.max) CAD/CAM (computer-aided design/manufacturing) crowns on traditionally and minimally prepared simulated tooth substrates. MATERIALS AND METHODS Thirty lithium disilicate (IPS e.max) CAD/CAM crowns were divided into three groups (n = 10): TD: traditional thickness crowns cemented on Paradigm MZ100 abutments; MD: minimal thickness crowns cemented on Paradigm MZ100 abutments; ME: minimal thickness crowns cemented on e.max abutments. The 3Shape system was used to scan, design and mill all abutments and crowns with a die space set to 40 µm. Traditional thickness crowns were designed based on manufacturer guidelines with 1.5 mm occlusal thickness and 1.0 mm margins. Minimal thickness crowns were designed with 0.7 mm occlusal thickness and 0.5 mm margins. MZ100 composite and e.max abutments were selected to simulate dentin and enamel substrates, respectively, based on their elastic-modulus. Variolink Esthetic was used to cement all samples following manufacturer's instructions. A universal testing machine was used to load all specimens to fracture with a 3 mm radius stainless steel hemispherical tip at a crosshead speed 0.5 mm/minute along the longitudinal axis of the abutment with a 1 mm thermoplastic film placed between the loading tip and crown surface. Data was analyzed using ANOVA and Bonferroni post hoc assessment. Fractographic analysis was performed with scanning electron microscopy (SEM). RESULTS The mean fracture load (standard deviation) was 1499 (241) N for TD; 1228 (287) N for MD; and 1377 (96) N for ME. Statistically significant difference between groups did not exist (p = 0.157, F = 1.995). In groups TD and MD with low e-modulus abutments, the dispersion of a probability distribution (coefficient of variation: CV) was statistically higher than that of group ME with high e-modulus abutments. SEM illustrated larger micro-fracture dimensions in Group MD than Group ME. CONCLUSION Minimal thickness e.max crowns did not demonstrate statistical difference in fracture resistance from traditional thickness crowns. Fracture mechanisms of minimal thickness e.max crowns may be affected by the e-modulus of the substrate. Minimal thickness e.max crowns may be a viable restorative option when supported by high e-modulus materials.
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Affiliation(s)
- Sara Elizabeth Chen
- University of Illinois at Chicago - Restorative Dentistry, Chicago, IL, United States
| | | | - Jingxu Wang
- Department of Stomatology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Kent L Knoernschild
- University of Illinois at Chicago - Restorative Dentistry, Chicago, IL, United States
| | - Stephen Campbell
- University of Illinois at Chicago - Restorative Dentistry, Chicago, IL, United States
| | - Bin Yang
- University of Illinois at Chicago - Restorative Dentistry, Chicago, IL, United States
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Luciano M, Francesca Z, Michela S, Tommaso M, Massimo A. Lithium disilicate posterior overlays: clinical and biomechanical features. Clin Oral Investig 2019; 24:841-848. [DOI: 10.1007/s00784-019-02972-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 06/06/2019] [Indexed: 10/26/2022]
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20
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El Ghoul WA, Özcan M, Ounsi H, Tohme H, Salameh Z. Effect of different CAD-CAM materials on the marginal and internal adaptation of endocrown restorations: An in vitro study. J Prosthet Dent 2019; 123:128-134. [PMID: 31027958 DOI: 10.1016/j.prosdent.2018.10.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 10/12/2018] [Accepted: 10/12/2018] [Indexed: 11/19/2022]
Abstract
STATEMENT OF PROBLEM Recent resin-based and ceramic-based computer-aided design and computer-aided manufacturing (CAD-CAM) materials have been used to restore endodontically treated teeth. Adaptation of the restoration is important for clinical success, but studies evaluating the effect of these materials on the adaptation of endocrowns are lacking. PURPOSE The purpose of this in vitro study was to evaluate the effect of resin-based and ceramic-based materials on the marginal and internal adaptation of endocrowns. MATERIAL AND METHODS Forty mandibular molars were divided into 4 groups (n=10); each group was restored with a different CAD-CAM material: group C: hybrid nanoceramic (Cerasmart; GC Corp), group T: fiber-composite material (Trilor; Bioloren Srl), group E: lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar Vivadent AG), and group V: zirconia-reinforced lithium silicate glass-ceramic (Vita Suprinity; VITA Zahnfabrik GmbH). A digital scan was made with an intraoral digital scanner (TRIOS 3; 3Shape A/S), and endocrowns were milled with a 5-axis milling machine (Coritec 250i; imes-icore GmbH). The replica technique and a stereomicroscope (×70) were used to measure the marginal and internal adaptation of the endocrowns at 32 points. All data were statistically analyzed using 1-way ANOVA and the Tukey honestly significant difference test (α=.05). RESULTS Statistical tests showed significant differences among the tested groups (P<.001). The resin-based groups displayed larger discrepancies than the ceramic-based groups. The resin-based groups showed a mean marginal gap larger than the mean internal gap C (P=.009), T (P<.001), whereas the ceramic-based groups showed similar gaps, V (P=.396), E (P=.936). The largest gap was observed at the pulpal floor (P<.001). CONCLUSIONS All materials had clinically acceptable internal and marginal gaps (≤150 μm), except for the marginal gap of the Trilor group.
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Affiliation(s)
- Wiam A El Ghoul
- Chief of clinical services, Department of Prosthodontics, School of Dentistry, Lebanese University, Beirut, Lebanon.
| | - Mutlu Özcan
- Professor, Department of Dental Materials, School of Dentistry, University of Zurich, Zurich, Switzerland
| | - Hani Ounsi
- Professor, Department of Endodontics, School of Dentistry, Lebanese University, Beirut, Lebanon
| | - Hani Tohme
- Department of Prosthodontics, School of Dentistry, Saint Joseph University, Beirut, Lebanon
| | - Ziad Salameh
- Professor, Department of Research, Department of Prosthodontics, School of Dentistry, Lebanese University, Beirut, Lebanon
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Maeder M, Pasic P, Ender A, Özcan M, Benic GI, Ioannidis A. Load-bearing capacities of ultra-thin occlusal veneers bonded to dentin. J Mech Behav Biomed Mater 2019; 95:165-171. [PMID: 31009900 DOI: 10.1016/j.jmbbm.2019.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 10/27/2022]
Abstract
OBJECTIVES To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybrid materials bonded to dentin does differ from those of porcelain-fused-to metal or lithium disilicate glass ceramic crowns. MATERIAL AND METHODS In 80 human molars, occlusal tooth substance was removed so that the defects extended into dentin, simulating defects caused by attrition/erosion. Restorations at a standardized thickness of either 0.5 mm or 1.0 mm were digitally designed. For both thicknesses, 4 test groups (n = 10 per group) were defined, each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava Ultimate). Consecutively, the specimens were thermo-mechanically aged and then loaded until fracture. The load-bearing capacities (Fmax) between the groups were statistically compared using the Kruskal-Wallis test (p < 0.05) and pairwise group comparison applying the Dunn's method. In addition, the results were compared to those of conventional lithium-disilicate ceramic crowns ("CLD") and to porcelain-fused to metal crowns ("PFM"). RESULTS The median Finitial values for the 0.5 mm thin restorations were 1'350 N for 0.5-ZIR, 850 N for 0.5-LDC, 1'100 N for 0.5-HYC and 1'950 N for 0.5-COC. With CLD as the control, a significant difference was found between the groups 0.5-COC and 0.5-LDC (KW: p = 0.0124). With PFM as the control, the comparisons between PFM and 0.5-LDC as well as between 0.5-COC and 0.5-LDC were significant (KW: p = 0.0026). Median Fmax values of 2'493 N in the group 0.5-ZIR, 1'165 in the group 0.5-LDC, 2'275 N in the group 0.5-HYC and 2'265 N in the group 0.5-COC were found. The medians of the Finitial values for the 1.0 thick restorations amounted of 2'100 N in 1.0-ZIR, 1'750 N in 1.0-LDC, 2'000 N in 1.0-HYC and 2'300 N in 1.0-COC. Testing the multiple comparisons with Dunn's method no significant differences were found (p > 0.05). The median Fmax values of the 1.0 mm thick restorations were: 2'489 N in the group 1.0-ZIR, 1'864 N in the group 1.0-LDC, 2'485 N in the group 1.0-HYC and 2'479 N in the group 1.0-COC. With CLD as the control group, a significant difference between zirconia and lithium-disilicate was found for the 0.5 (p = 0.0017) and 1.0 mm (p = 0.0320) thick specimens. Comparing the 0.5 mm thick specimens with CLD as the control, a significant difference was found between 0.5-HYC and 0.5-LDC (p = 0.0017). With PFM as the control, the comparison of lithium disilicate and zirconia was statistically significant for both thicknesses (p = 0.0009 for the 0.5 mm thick specimens; p = 0.0074 for the 1.0 mm thick specimens). In addition, with PFM as control group, significant differences were seen between 0.5-LDC and all other groups with restorations in 0.5 mm thickness (p = 0.0017). CONCLUSIONS Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic, hybrid materials or polymeric materials can be applied to correct occlusal tooth wear with exposed dentin and thus replace conventional crown restorations in cases of normally expected intraoral bite forces.
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Affiliation(s)
- Mila Maeder
- Doctoral Student at the Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Switzerland
| | - Pavla Pasic
- Doctoral Student at the Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Switzerland
| | - Adreas Ender
- Clinic of Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, Switzerland
| | - Mutlu Özcan
- Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Switzerland
| | - Goran I Benic
- Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Switzerland
| | - Alexis Ioannidis
- Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Switzerland.
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Baldissara P, Monaco C, Onofri E, Fonseca RG, Ciocca L. Fatigue resistance of monolithic lithium disilicate occlusal veneers: a pilot study. Odontology 2019; 107:482-490. [PMID: 30840218 DOI: 10.1007/s10266-019-00417-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/20/2019] [Indexed: 10/27/2022]
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23
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Bearing capacity of ceramic crowns before and after cyclic loading: An in vitro study. J Mech Behav Biomed Mater 2018; 87:197-204. [DOI: 10.1016/j.jmbbm.2018.07.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 07/18/2018] [Accepted: 07/24/2018] [Indexed: 11/21/2022]
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Yan J, Kaizer MR, Zhang Y. Load-bearing capacity of lithium disilicate and ultra-translucent zirconias. J Mech Behav Biomed Mater 2018; 88:170-175. [PMID: 30173069 DOI: 10.1016/j.jmbbm.2018.08.023] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/10/2018] [Accepted: 08/19/2018] [Indexed: 10/28/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the load-bearing capacity of monolithic lithium disilicate (LiDi - IPS e.max CAD) and novel ultra-translucent zirconia restorative systems of various compositions: 5Y-PSZ (5 mol% yttria-partially-stabilized zirconia) and 4Y-PSZ (4 mol% yttria-partially-stabilized zirconia); relative to a 3Y-TZP (3 mol% yttria-stabilized zirconia) control. MATERIALS AND METHODS Experiments were carried out with 10 disc specimens (Ø12 ×1 mm) per ceramic material. The zirconia intaglio surface (as machined) was sandblasted (50 µm Al2O3 at 2 bar), while LiDi was etched with 5% HF for 20 s. The ceramic discs were then adhesively bonded onto a dentin-like substrate (G10, a high-pressure fiberglass material) using Multilink Automix cement and Monobond Plus primer, producing a ceramic/cement/dentin-like substrate trilayer structure. The bonded specimens were stored in water for 3 days at 37 °C prior to a Hertzian indentation flexural radial fracture test. The plate-on-foundation theory was used to validate the load-bearing capacity of the trilayer systems based on the flexural tensile stress at the ceramic intaglio (cementation) surface-a cause for bulk fracture of ceramic onlays. RESULTS The experiment data showed that, when bonded to and supported by a dentin-like substrate, the load-bearing capacity of LiDi (872 N) is superior to the 5Y-PSZ (715 N) and can even reach that of 4Y-PSZ (864 N), while 3Y-TZP still holds the highest load-bearing capacity (1195 N). Theoretical analyses agree with experimental observations. The translucency of 5Y-PSZ approaches that of LiDi, which are superior to both 4Y-PSZ and 3Y-TZP. CONCLUSIONS When adhesively bonded to and supported by dentin, lithium disilicate exhibits similar load-bearing properties to 4Y-PSZ but much better than 5Y-PSZ.
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Affiliation(s)
- Jing Yan
- Department of Biomateirals & Biomimetics, New York University College of Dentistry, New York, NY 10010, United States
| | - Marina R Kaizer
- Department of Biomateirals & Biomimetics, New York University College of Dentistry, New York, NY 10010, United States
| | - Yu Zhang
- Department of Biomateirals & Biomimetics, New York University College of Dentistry, New York, NY 10010, United States.
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Liu Y, Xu Y, Su B, Arola D, Zhang D. The effect of adhesive failure and defects on the stress distribution in all-ceramic crowns. J Dent 2018; 75:74-83. [PMID: 29857076 DOI: 10.1016/j.jdent.2018.05.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 04/09/2018] [Accepted: 05/27/2018] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVES To explore the effect of adhesive failure and defects between the crown and cement on the stress distribution within all-ceramic crowns and the corresponding risk of failure. METHODS An IPS e.max crown of lithium disilicate produced by CAD/CAM for a first mandibular molar was modeled using finite element analysis based on X-ray micro-CT scanned images. Predefined debonding states and interfacial defects between the crown and cement were simulated using the model. The first principal stress distribution of the crown and cement was analyzed under a vertical occlusal load of 600 N. A concept of failure risk was proposed to evaluate the crown. RESULTS Stress concentrations in the crown were identified on the occlusal surface surrounding the region of loading, beneath the area of loading and at the margin of the interior surface. Stress concentrations in the cement were also evident at the boundary of the debonded areas. The lower surface of the crown is safe to sustain the 600 N vertical load, but the top surface of the cement would undergo cohesive failure. According to the evaluation of failure risk of the crown, the conditions of highest risk corresponded to the conditions with highest percentage of cement damage. The risk of failure is not only associated with debonding between the crown and cement, but also associated with its distribution. CONCLUSIONS Debonding related defects and cementing defects are more deleterious to the interfacial stress than debonding itself. The axial wall plays a critical role in maintaining the principal tensile stress of the crown at an acceptable level.
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Affiliation(s)
- Yonggang Liu
- Shanghai Institute of Applied Mathematics and Mechanics, Shanghai, 200072, PR China
| | - Yuanzhi Xu
- The Tenth People's Hospital of Tongji University, Shanghai, 200072, PR China
| | - Bo Su
- Bristol Dental School, University of Bristol, Bristol, BS1 2LY, UK
| | - Dwayne Arola
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, 98195, USA; Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, 98195, USA; Department of Mechanics, Shanghai University, Shanghai, 200444, PR China
| | - Dongsheng Zhang
- Department of Mechanics, Shanghai University, Shanghai, 200444, PR China; Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, 200072, PR China.
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Abstract
A survey of the development of dental ceramics is presented to provide a better understanding of the rationale behind the development and clinical indications of each class of ceramic material. Knowledge of the composition, microstructure, and properties of a material is critical for selecting the right material for specific applications. The key to successful ceramic restorations rests on material selection, manufacturing technique, and restoration design, including the balancing of several factors such as residual stresses, tooth contact conditions, tooth size and shape, elastic modulus of the adhesives and tooth structure, and surface state.
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Affiliation(s)
- Yu Zhang
- Department of Biomaterials and Biomimetics, NYU College of Dentistry, 433 First Avenue, Room 810, New York, NY 10010, USA.
| | - J Robert Kelly
- Department of Biomedical Engineering, University of Connecticut Health Center, Mailstop 1615, 263 Farmington Avenue, Farmington, CT 06030-1615, USA
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Alao AR, Stoll R, Song XF, Abbott JR, Zhang Y, Abduo J, Yin L. Fracture, roughness and phase transformation in CAD/CAM milling and subsequent surface treatments of lithium metasilicate/disilicate glass-ceramics. J Mech Behav Biomed Mater 2017. [PMID: 28645068 DOI: 10.1016/j.jmbbm.2017.06.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This paper studied surface fracture, roughness and morphology, phase transformations, and material removal mechanisms of lithium metasilicate/disilicate glass ceramics (LMGC/LDGC) in CAD/CAM-milling and subsequent surface treatments. LMGC (IPS e.max CAD) blocks were milled using a chairside dental CAD/CAM milling unit and then treated in sintering, polishing and glazing processes. X-ray diffraction was performed on all processed surfaces. Scanning electron microscopy (SEM) was applied to analyse surface fracture and morphology. Surface roughness was quantitatively characterized by the arithmetic average surface roughness Ra and the maximum roughness Rz using desktop SEM-assisted morphology analytical software. The CAD/CAM milling induced extensive brittle cracks and crystal pulverization on LMGC surfaces, which indicate that the dominant removal mechanism was the fracture mode. Polishing and sintering of the milled LMGC lowered the surface roughness (ANOVA, p < 0.05), respectively, while sintering also fully transformed the weak LMGC to the strong LDGC. However, polishing and glazing of LDGC did not significantly improve the roughness (ANOVA, p > 0.05). In comparison of all applied fabrication process routes, it is found that CAD/CAM milling followed by polishing and sintering produced the smoothest surface with Ra = 0.12 ± 0.08µm and Rz = 0.89 ± 0.26µm. Thus, it is proposed as the optimized process route for LMGC/LDGC in dental restorations. This route enables to manufacture LMGC/LDGC restorations with cost effectiveness, time efficiency, and improved surface quality for better occlusal functions and reduced bacterial plaque accumulation.
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Affiliation(s)
- Abdur-Rasheed Alao
- Mechanical Engineering, College of Science and Engineering, James Cook University, Townsville QLD 4811, Australia
| | - Richard Stoll
- Restorative Dentistry, College of Medicine and Dentistry, James Cook University, Cairns QLD 4870, Australia
| | - Xiao-Fei Song
- Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education, School of Mechanical Engineering, Tianjin University, Tianjin 300072, China
| | - John R Abbott
- JCU Dental, James Cook University, Cairns QLD 4870, Australia
| | - Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
| | - Jaafar Abduo
- Melbourne Dental School, Melbourne University, 720 Swanston Street, Melbourne, Victoria 3010, Australia
| | - Ling Yin
- Mechanical Engineering, College of Science and Engineering, James Cook University, Townsville QLD 4811, Australia.
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28
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Reliability and mode of failure of bonded monolithic and multilayer ceramics. Dent Mater 2017; 33:191-197. [DOI: 10.1016/j.dental.2016.11.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 11/24/2016] [Accepted: 11/29/2016] [Indexed: 11/21/2022]
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Yu T, Wang F, Liu Y, Wu T, Deng Z, Chen J. Fracture behaviors of monolithic lithium disilicate ceramic crowns with different thicknesses. RSC Adv 2017. [DOI: 10.1039/c6ra28847b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The present in vitro study assessed the fracture resistance of monolithic ceramic crowns, made from two lithium disilicate glass ceramics with different thicknesses.
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Affiliation(s)
- Tao Yu
- State Key Laboratory of Military Stomatology
- National Clinical Research Center for Oral Diseases
- Shaanxi Key Laboratory of Stomatology
- Department of Prosthodontics
- School of Stomatology
| | - Fu Wang
- State Key Laboratory of Military Stomatology
- National Clinical Research Center for Oral Diseases
- Shaanxi Key Laboratory of Stomatology
- Department of Prosthodontics
- School of Stomatology
| | - Yan Liu
- State Key Laboratory of Military Stomatology
- National Clinical Research Center for Oral Diseases
- Shaanxi Key Laboratory of Stomatology
- Department of Prosthodontics
- School of Stomatology
| | - Tao Wu
- State Key Laboratory of Military Stomatology
- National Clinical Research Center for Oral Diseases
- Shaanxi Key Laboratory of Stomatology
- Department of Prosthodontics
- School of Stomatology
| | - Zaixi Deng
- State Key Laboratory of Military Stomatology
- National Clinical Research Center for Oral Diseases
- Shaanxi Key Laboratory of Stomatology
- Department of Prosthodontics
- School of Stomatology
| | - Jihua Chen
- State Key Laboratory of Military Stomatology
- National Clinical Research Center for Oral Diseases
- Shaanxi Key Laboratory of Stomatology
- Department of Prosthodontics
- School of Stomatology
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Gaintantzopoulou MD, El-Damanhoury HM. Effect of Preparation Depth on the Marginal and Internal Adaptation of Computer-aided Design/Computer-assisted Manufacture Endocrowns. Oper Dent 2016; 41:607-616. [DOI: 10.2341/15-146-l] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SUMMARY
The aim of the study was to evaluate the effect of preparation depth and intraradicular extension on the marginal and internal adaptation of computer-aided design/computer-assisted manufacture (CAD/CAM) endocrown restorations. Standardized preparations were made in resin endodontic tooth models (Nissin Dental), with an intracoronal preparation depth of 2 mm (group H2), with extra 1- (group H3) or 2-mm (group H4) intraradicular extensions in the root canals (n=12). Vita Enamic polymer-infiltrated ceramic-network material endocrowns were fabricated using the CEREC AC CAD/CAM system and were seated on the prepared teeth. Specimens were evaluated by microtomography. Horizontal and vertical tomographic sections were recorded and reconstructed by using the CTSkan software (TView v1.1, Skyscan).The surface/void volume (S/V) in the region of interest was calculated. Marginal gap (MG), absolute marginal discrepancy (MD), and internal marginal gap were measured at various measuring locations and calculated in microscale (μm). Marginal and internal discrepancy data (μm) were analyzed with nonparametric Kruskal-Wallis analysis of variance by ranks with Dunn's post hoc, whereas S/V data were analyzed by one-way analysis of variance and Bonferroni multiple comparisons (α=0.05). Significant differences were found in MG, MD, and internal gap width values between the groups, with H2 showing the lowest values from all groups. S/V calculations presented significant differences between H2 and the other two groups (H3 and H4) tested, with H2 again showing the lowest values. Increasing the intraradicular extension of endocrown restorations increased the marginal and internal gap of endocrown restorations.
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Affiliation(s)
- MD Gaintantzopoulou
- Marianna D Gaintantzopoulou, DDS, MSD, PhD, assistant professor, Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - HM El-Damanhoury
- Hatem M El-Damanhoury, BDS, MDS, PhD, assistant professor, Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates; and Department of Operative Dentistry, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
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31
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Uzgur R, Ercan E, Uzgur Z, Çolak H, Yalçın M, Özcan M. Cement Thickness of Inlay Restorations Made of Lithium Disilicate, Polymer-Infiltrated Ceramic and Nano-Ceramic CAD/CAM Materials Evaluated Using 3D X-Ray Micro-Computed Tomography. J Prosthodont 2016; 27:456-460. [DOI: 10.1111/jopr.12521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/30/2016] [Indexed: 11/27/2022] Open
Affiliation(s)
- Recep Uzgur
- Department of Prosthodontics; Faculty of Dentistry; Zirve University; Gaziantep Turkey
| | - Ertuğrul Ercan
- Department of Restorative Dentistry; Faculty of Dentistry; Kırıkkale University; Kırıkkale Turkey
| | - Zeynep Uzgur
- Department of Prosthodontics; Faculty of Dentistry; Zirve University; Gaziantep Turkey
| | - Hakan Çolak
- Department of Restorative Dentistry; Faculty of Dentistry; Zirve University; Gaziantep Turkey
| | - Muhammet Yalçın
- Department of Restorative Dentistry; Faculty of Dentistry, Inonu University; Malatya Turkey
| | - Mutlu Özcan
- University of Zurich, Dental Materials Unit; Center for Dental and Oral Medicine; Clinic for Fixed and Removable Prosthodontics and Dental Materials Science; Zurich Switzerland
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Shembish FA, Tong H, Kaizer M, Janal MN, Thompson VP, Opdam NJ, Zhang Y. Fatigue resistance of CAD/CAM resin composite molar crowns. Dent Mater 2016; 32:499-509. [PMID: 26777092 DOI: 10.1016/j.dental.2015.12.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 11/03/2015] [Accepted: 12/07/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. METHODS Fully anatomically shaped monolithic resin composite molar crowns (Lava Ultimate, n=24) and leucite reinforced glass-ceramic crowns (IPS Empress CAD, n=24) were fabricated using CAD/CAM systems. Crowns were cemented on aged dentin-like resin composite tooth replicas (Filtek Z100) with resin-based cements (RelyX Ultimate for Lava Ultimate or Multilink Automix for IPS Empress). Three step-stress profiles (aggressive, moderate and mild) were employed for the accelerated sliding-contact mouth-motion fatigue test. Twenty one crowns from each group were randomly distributed among these three profiles (1:2:4). Failure was designated as chip-off or bulk fracture. Optical and electron microscopes were used to examine the occlusal surface and subsurface damages, as well as the material microstructures. RESULTS The resin composite crowns showed only minor occlusal damage during mouth-motion step-stress fatigue loading up to 1700N. Cross-sectional views revealed contact-induced cone cracks in all specimens, and flexural radial cracks in 2 crowns. Both cone and radial cracks were relatively small compared to the crown thickness. Extending these cracks to the threshold for catastrophic failure would require much higher indentation loads or more loading cycles. In contrast, all of the glass-ceramic crowns fractured, starting at loads of approximately 450N. SIGNIFICANCE Monolithic CAD/CAM resin composite crowns endure, with only superficial damage, fatigue loads 3-4 times higher than those causing catastrophic failure in glass-ceramic CAD crowns.
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Affiliation(s)
- Fatma A Shembish
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 First Avenue, New York, NY 10010, USA
| | - Hui Tong
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 First Avenue, New York, NY 10010, USA; School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, PR China
| | - Marina Kaizer
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 First Avenue, New York, NY 10010, USA; Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil
| | - Malvin N Janal
- Department of Epidemiology and Health Promotion, New York University College of Dentistry, 380 Second Avenue Suite 301, New York, NY 10010, USA
| | - Van P Thompson
- Tissue Engineering and Biophotonics, King's College London Dental Institute, United Kingdom
| | - Niek J Opdam
- Radboud University Nijmegen Medical Centre, College of Dental Sciences, Preventive and Restorative Dentistry, Ph van Leydenlaan 25, PO Box 9101, 6500HB Nijmegen, The Netherlands
| | - Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, 433 First Avenue, New York, NY 10010, USA.
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Nawafleh N, Hatamleh M, Elshiyab S, Mack F. Lithium Disilicate Restorations Fatigue Testing Parameters: A Systematic Review. J Prosthodont 2015; 25:116-26. [PMID: 26505638 DOI: 10.1111/jopr.12376] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2015] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To review laboratory studies that investigated fatigue resistance of lithium disilicate (LD) crowns and fixed dental prostheses (FDPs) to elucidate study designs and testing parameters. METHODS An electronic search was performed in PubMed, Scopus, and Ovid to identify in vitro studies that investigated fatigue resistance of LD crowns and FDPs. The search included all studies published in English in peer-reviewed journals in the period from 1998 to June 2014. The search followed a specific strategy that included combination of the following keywords: lithium disilicate, e.max, empress, all-ceramic, all ceramic, glass ceramic, fatigue, cyclic loading, dynamic loading, chewing simulator, fracture resistance, thermocycling, laboratory simulation, aging, crown, FDPs, FPDs, fixed partial denture, fixed dental prosthesis, and bridge. Studies were selected if mechanical and thermal loading parameters were clearly identified. Search results with abstracts were transferred into Endnote reference system, and duplicates were deleted. The remaining studies were then reviewed at three levels (title, abstract, full text) to further refine the articles. RESULTS The initial search retrieved 1044 eligible studies. After deduplication, 864 records were examined by titles and then abstracts; 826 were excluded, and 38 were assessed by full-text reading. In total, 19 articles met inclusion criteria and were included in this study. CONCLUSION The studies reviewed showed a level of heterogeneity, as testing parameters were considered through different setups. The current study demonstrated that various setting of the testing parameters and having a lack of testing standardization has likely led to inconsistency in the reported results. The obvious heterogeneity in the setting of testing variables-especially the magnitude of load and number of cycles applied-made it impractical to run direct comparisons between the reviewed studies. Therefore, specific international standardization of fatigue testing of dental restorations is urgently needed to ensure the delivery of consistent, indicative, and comparable data.
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Affiliation(s)
- Noor Nawafleh
- School of Dentistry and Oral Health, Griffith University, Queensland, Australia
| | - Muhanad Hatamleh
- Cranio-Maxillofacial Prosthetics Unit, King's College Hospital NHS Foundation Trust, London, UK
| | - Shareen Elshiyab
- School of Dentistry and Oral Health, Griffith University, Queensland, Australia
| | - Florian Mack
- School of Dentistry and Oral Health, Griffith University, Queensland, Australia
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Srikanth R, Kosmac T, Della Bona A, Yin L, Zhang Y. Effects of cementation surface modifications on fracture resistance of zirconia. Dent Mater 2015; 31:435-42. [PMID: 25687628 DOI: 10.1016/j.dental.2015.01.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 11/15/2014] [Accepted: 01/20/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia. METHODS Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending. RESULTS Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength. SIGNIFICANCE While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia.
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Affiliation(s)
- Ramanathan Srikanth
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
| | - Tomaz Kosmac
- Engineering Ceramics Department, Jozef Stefan Institute, Jamova 39, SI 1000 Ljubljana, Slovenia
| | - Alvaro Della Bona
- Post-graduation Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil
| | - Ling Yin
- School of Engineering and Physical Sciences, James Cook University, Townsville, Qld 4811, Australia
| | - Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA.
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Guess PC, Schultheis S, Wolkewitz M, Zhang Y, Strub JR. Influence of preparation design and ceramic thicknesses on fracture resistance and failure modes of premolar partial coverage restorations. J Prosthet Dent 2014; 110:264-73. [PMID: 24079561 DOI: 10.1016/s0022-3913(13)60374-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
STATEMENT OF PROBLEM Preparation designs and ceramic thicknesses are key factors for the long-term success of minimally invasive premolar partial coverage restorations. However, only limited information is presently available on this topic. PURPOSE The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of ceramic premolar partial coverage restorations with different preparation designs and ceramic thicknesses. MATERIAL AND METHODS Caries-free human premolars (n=144) were divided into 9 groups. Palatal onlay preparation comprised reduction of the palatal cusp by 2 mm (Palatal Onlay Standard), 1 mm (Palatal-Onlay-Thin), or 0.5 mm (Palatal Onlay Ultrathin). Complete-coverage onlay preparation additionally included the buccal cusp (Occlusal Onlay Standard; Occlusal Onlay Thin; Occlusal Onlay Ultrathin). Labial surface preparations with chamfer reductions of 0.8 mm (Complete-Veneer-Standard), 0.6 mm (Complete-Veneer-Thin), and 0.4 mm (Complete Veneer Ultrathin) were implemented for complete veneer restorations. Restorations were fabricated from a pressable lithium disilicate ceramic (IPS-e.max-Press) and cemented adhesively (Syntac-Classic/Variolink-II). All specimens were subjected to cyclic mechanical loading (F=49 N, 1.2 million cycles) and simultaneous thermocycling (5°C to 55°C) in a mouth-motion simulator. After fatigue, restorations were exposed to single-load-to-failure. Two-way ANOVA was used to identify statistical differences. Pair-wise differences were calculated and P-values were adjusted by the Tukey-Kramer method (α=.05). RESULTS All specimens survived fatigue. Mean (SD) load to failure values (N) were as follows: 837 (320/Palatal-Onlay-Standard), 1055 (369/Palatal-Onlay-Thin), 1192 (342/Palatal-Onlay-Ultrathin), 963 (405/Occlusal-Onlay-Standard), 1108 (340/Occlusal-Onlay-Thin), 997 (331/Occlusal-Onlay-Ultrathin), 1361 (333/Complete-Veneer-Standard), 1087 (251/Complete-Veneer-Thin), 883 (311/Complete-Veneer-Ultrathin). Palatal-onlay restorations revealed a significantly higher fracture resistance with ultrathin thicknesses than with standard thicknesses (P=.015). Onlay restorations were not affected by thickness variations. Fracture loads of standard complete veneers were significantly higher than thin (P=.03) and ultrathin (P<.001) restorations. CONCLUSIONS In this in vitro study, the reduction of preparation depth to 1.00 and 0.5 mm did not impair fracture resistance of pressable lithium-disilicate ceramic onlay restorations but resulted in lower failure loads in complete veneer restorations on premolars.
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Affiliation(s)
- Petra C Guess
- Associate Professor, Department of Prosthodontics, School of Dentistry, Albert-Ludwigs-University Freiburg, Germany.
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Marginal and internal fit of heat pressed versus CAD/CAM fabricated all-ceramic onlays after exposure to thermo-mechanical fatigue. J Dent 2013; 42:199-209. [PMID: 24161516 DOI: 10.1016/j.jdent.2013.10.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 09/21/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVES The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after thermo-mechanical fatigue. MATERIALS AND METHODS Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups (n=24/group). All teeth received an onlay preparation with a mesio-occlusal-distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerising resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98 N, 1.2 million cycles; 5°C/55°C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200× magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements. RESULTS Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays. CONCLUSIONS Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique. CLINICAL RELEVANCE Clinical requirements of 100 μm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays. Superior internal fit was observed with the heat-press manufacturing method. The impact of present findings on the clinical long-term behaviour of differently fabricated all-ceramic onlays warrants further investigation.
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Zhang Y, Lee JJW, Srikanth R, Lawn BR. Edge chipping and flexural resistance of monolithic ceramics. Dent Mater 2013; 29:1201-8. [PMID: 24139756 DOI: 10.1016/j.dental.2013.09.004] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 05/20/2013] [Accepted: 09/10/2013] [Indexed: 12/29/2022]
Abstract
OBJECTIVE Test the hypothesis that monolithic ceramics can be developed with combined esthetics and superior fracture resistance to circumvent processing and performance drawbacks of traditional all-ceramic crowns and fixed-dental-prostheses consisting of a hard and strong core with an esthetic porcelain veneer. Specifically, to demonstrate that monolithic prostheses can be produced with a much reduced susceptibility to fracture. METHODS Protocols were applied for quantifying resistance to chipping as well as resistance to flexural failure in two classes of dental ceramic, microstructurally-modified zirconias and lithium disilicate glass-ceramics. A sharp indenter was used to induce chips near the edges of flat-layer specimens, and the results compared with predictions from a critical load equation. The critical loads required to produce cementation surface failure in monolithic specimens bonded to dentin were computed from established flexural strength relations and the predictions validated with experimental data. RESULTS Monolithic zirconias have superior chipping and flexural fracture resistance relative to their veneered counterparts. While they have superior esthetics, glass-ceramics exhibit lower strength but higher chip fracture resistance relative to porcelain-veneered zirconias. SIGNIFICANCE The study suggests a promising future for new and improved monolithic ceramic restorations, with combined durability and acceptable esthetics.
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Affiliation(s)
- Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA.
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Abstract
OBJECTIVES Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. DATA/SOURCES The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. CONCLUSIONS Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. CLINICAL SIGNIFICANCE Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy.
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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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Li Y, Chen J, Liu J, Zhang L, Wang W, Zhang S. Estimation of the reliability of all-ceramic crowns using finite element models and the stress-strength interference theory. Comput Biol Med 2013; 43:1214-20. [PMID: 23930816 DOI: 10.1016/j.compbiomed.2013.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 06/05/2013] [Accepted: 06/07/2013] [Indexed: 11/29/2022]
Abstract
The reliability of all-ceramic crowns is of concern to both patients and doctors. This study introduces a new methodology for quantifying the reliability of all-ceramic crowns based on the stress-strength interference theory and finite element models. The variables selected for the reliability analysis include the magnitude of the occlusal contact area, the occlusal load and the residual thermal stress. The calculated reliabilities of crowns under different loading conditions showed that too small occlusal contact areas or too great a difference of the thermal coefficient between veneer and core layer led to high failure possibilities. There results were consistent with many previous reports. Therefore, the methodology is shown to be a valuable method for analyzing the reliabilities of the restorations in the complicated oral environment.
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Affiliation(s)
- Yan Li
- Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, PR China
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Zhang Y. Overview: Damage resistance of graded ceramic restorative materials. JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 2012; 32:2623-2632. [PMID: 22778494 PMCID: PMC3390941 DOI: 10.1016/j.jeurceramsoc.2012.02.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Improving mechanical response of materials is of great interest in a wide range of disciplines, including biomechanics, tribology, geology, optoelectronics, and nanotechnology. It has been long recognized that spatial gradients in surface composition and structure can improve the mechanical integrity of a material. This review surveys recent results of sliding-contact, flexural, and fatigue tests on graded ceramic materials from our laboratories and elsewhere. Although our findings are examined in the context of possible applications for next-generation, graded all-ceramic dental restorations, implications of our studies have broad impact on biomedical, civil, structural, and an array of other engineering applications.
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Affiliation(s)
- Yu Zhang
- 345 East 24th Street, Room 813C, New York, NY 10010, USA, Tel.: +1 212 998 9637; Fax: +1 212 995 4244.
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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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Stappert CFJ, Baldassarri M, Zhang Y, Stappert D, Thompson VP. Contact fatigue response of porcelain-veneered alumina model systems. J Biomed Mater Res B Appl Biomater 2012; 100:508-15. [PMID: 22113973 DOI: 10.1002/jbm.b.31977] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 07/19/2011] [Accepted: 08/28/2011] [Indexed: 01/25/2023]
Abstract
Fatigue damage modes and reliability of hand-veneered (HV) and over-pressed (OP) aluminum-oxide layer structures were compared. Influence of luting cement thickness on mechanical performance was investigated. Sixty-four aluminum-oxide plates (10 × 10 × 0.5 mm) were veneered with hand built-up or pressed porcelain (0.7 mm) and adhesively luted (50- or 150-μm cement thickness) to water-aged composite resin blocks (12 × 12 × 4 mm). Single-load-to-failure and fatigue tests were performed with a spherical tungsten carbide indenter (d = 6.25 mm) applied in the center of the veneer layer. Specimens were inspected with polarized-reflected-light and scanning electron microscopy. Use-level probability Weibull curves were plotted with two-sided 90% confidence bounds, and reliability at 75,000 cycles and 250 N load was calculated. For all specimens but two OP with 50-μm cement thickness, failure was characterized by flexural radial cracks initiating at the bottom surface of the alumina core and propagating into the veneering porcelain before cone cracks could extend to the porcelain/alumina interface. HV specimens showed higher reliability compared to OP. Those with 50-μm cement thickness were more reliable relative to their 150-μm counterparts (HV_50 μm: 95% (0.99/0.67); HV_150 μm: 55% (0.92/0.01); OP_50 μm: 69% (0.84/0.48); OP_150 μm: 15% (0.53/0.004)). Similar failure modes were observed in HV and OP specimens. Radial cracks developing in the core and spreading into the veneer are suggested to cause bulk fracture, which is the characteristic failure mode for alumina core crowns. However, the highest resistance to fatigue loading was found for the HV specimens with thin cement thickness, while the lowest occurred for the OP with thick cement layer.
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Affiliation(s)
- Christian F J Stappert
- Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, New York; Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, New York; Department of Prosthodontics, Albert-Ludwigs-University, Freiburg, Germany.
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Silva NR, Sailer I, Zhang Y, Coelho PG, Guess PC, Zembic A, Kohal RJ. Performance of Zirconia for Dental Healthcare. MATERIALS 2010. [PMCID: PMC5513513 DOI: 10.3390/ma3020863] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The positive results of the performance of zirconia for orthopedics devices have led the dental community to explore possible esthetical and mechanical outcomes using this material. However, questions regarding long-term results have opened strong and controversial discussions regarding the utilization of zirconia as a substitute for alloys for restorations and implants. This narrative review presents the current knowledge on zirconia utilized for dental restorations, oral implant components, and zirconia oral implants, and also addresses laboratory tests and developments, clinical performance, and possible future trends of this material for dental healthcare.
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Affiliation(s)
- Nelson R.F.A. Silva
- New York University, 345 East 24 Street Room 804-S, New York, NY, 10010, USA; E-Mails: (Y.Z.); (P.G.C.)
- Author to whom correspondence should be addressed; E-Mails: or ; Tel.: + 1 212 998 9365; Fax: + 1 212 995 4244
| | - Irena Sailer
- University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland; E-Mails: (I.S.); (A.Z.)
| | - Yu Zhang
- New York University, 345 East 24 Street Room 804-S, New York, NY, 10010, USA; E-Mails: (Y.Z.); (P.G.C.)
| | - Paulo G. Coelho
- New York University, 345 East 24 Street Room 804-S, New York, NY, 10010, USA; E-Mails: (Y.Z.); (P.G.C.)
| | - Petra C. Guess
- University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany; E-Mails: (P.C.G.); (R.J.K.)
| | - Anja Zembic
- University of Zurich, Plattenstrasse 11, 8032 Zurich, Switzerland; E-Mails: (I.S.); (A.Z.)
| | - Ralf J. Kohal
- University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany; E-Mails: (P.C.G.); (R.J.K.)
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Kim JW, Thompson VP, Rekow ED, Jung YG, Zhang Y. Fracture Modes in Curved Brittle Layers Subject to Concentrated Cyclic Loading in Liquid Environments. JOURNAL OF MATERIALS RESEARCH 2009; 24:1075-1081. [PMID: 26028811 PMCID: PMC4445760 DOI: 10.1557/jmr.2009.0081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Damage response of brittle curved structures subject to cyclic Hertzian indentation was investigated. Specimens were fabricated by bisecting cylindrical quartz glass hollow tubes. The resulting hemi-cylindrical glass shells were bonded internally and at the edges to polymeric supporting structures and loaded axially in water on the outer circumference with a spherical tungsten carbide indenter. Critical loads and number of cycles to initiate and propagate near-contact cone cracks and far-field flexure radial cracks to failure were recorded. Flat quartz glass plates on polymer substrates were tested as a control group. Our findings showed that cone cracks form at lower loads, and can propagate through the quartz layer to the quartz/polymer interface at lower number of cycles, in the curved specimens relative to their flat counterparts. Flexural radial cracks require a higher load to initiate in the curved specimens relative to flat structures. These radial cracks can propagate rapidly to the margins, the flat edges of the bisecting plane, under cyclic loading at relatively low loads, owing to mechanical fatigue and a greater spatial range of tensile stresses in curved structures.
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Affiliation(s)
- Jae-Won Kim
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
| | - Van P. Thompson
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
| | - E. Dianne Rekow
- Basic Science Department, New York University College of Dentistry, New York, NY 10010, USA
| | - Yeon-Gil Jung
- School of Nano and Advanced Materials Engineering, Changwon National University, Changwon, Korea
| | - Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
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Zhang Y, Kim JW. Graded structures for damage resistant and aesthetic all-ceramic restorations. Dent Mater 2009; 25:781-90. [PMID: 19187955 DOI: 10.1016/j.dental.2009.01.002] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 12/22/2008] [Accepted: 01/02/2009] [Indexed: 10/21/2022]
Abstract
OBJECTIVES Clinical studies revealed several performance deficiencies with alumina- and zirconia-based all-ceramic restorations: fracture; poor aesthetic properties of ceramic cores (particularly zirconia cores); and difficulty in achieving a strong ceramic-resin-based cement bond. We aim to address these issues by developing a functionally graded glass/zirconia/glass (G/Z/G) structure with improved damage resistance, aesthetics, and cementation properties. METHODS Using a glass powder composition developed in our laboratory and a commercial fine zirconia powder, we have successfully fabricated functionally graded G/Z/G structures. The microstructures of G/Z/G were examined utilizing a scanning electron microscopy (SEM). The crystalline phases present in G/Z/G were identified by X-ray diffraction (XRD). Young's modulus and hardness of G/Z/G were derived from nanoindentations. Critical loads for cementation radial fracture in G/Z/G plates (20mmx20mm, 1.5 or 0.4mm thick) bonded to polycarbonate substrates were determined by loading with a spherical indenter. Parallel studies were conducted on homogeneous yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) controls. RESULTS The G/Z/G structure consists of an outer surface aesthetic glass layer, a graded glass-Y-TZP layer, and a dense Y-TZP interior. The Young's modulus and hardness increase from surface to interior following power-law relations. For G/Z/G plates of 1.5 and 0.4mm thick, critical loads for cementation radial fracture were 1990+/-107N (mean+/-S.D., n=6) and 227+/-20N (mean+/-S.D., n=6), respectively, which were approximately 30 and 50% higher than those for their monolithic Y-TZP counterparts (1388+/-90N for 1.5mm and 113+/-10N for 0.4mm thick; mean+/-S.D., n=6 for each thickness). A 1-sample t-test revealed significant difference (p<0.001) in critical loads for radial fracture of G/Z/G and homogeneous Y-TZP for both specimen thicknesses. SIGNIFICANCE Our results indicate that functionally graded G/Z/G structures exhibit improved damage resistance, aesthetics, and potentially cementation properties compared to homogeneous Y-TZP.
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Affiliation(s)
- Yu Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York University, New York 10010, USA.
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