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Liu X, Yao X, Zhang R, Sun L, Zhang Z, Zhao Y, Zhang T, Yan J, Zhang Y, Wu X, Li B. Recent advances in glass-ceramics: Performance and toughening mechanisms in restorative dentistry. J Biomed Mater Res B Appl Biomater 2024; 112:e35334. [PMID: 37776023 DOI: 10.1002/jbm.b.35334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/13/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023]
Abstract
The use of glass-ceramics in the medical field has grown significantly since the 1980s. With excellent aesthetic properties, semi-translucency, outstanding mechanical properties, corrosion resistance, wear resistance and great biocompatibility and workability glass-ceramics is one of the most commonly used materials in restorative dentistry and is widely used in veneers, inlays, onlays, all-ceramic crowns, and implant abutments. This review provides an overview of the research progress of glass-ceramics in restorative dentistry, focusing on the classification, performance requirements, toughening mechanisms and their association with clinical performance, as well as the manufacturing and fabrication of glass-ceramics in restorative dentistry. Finally, the developments and prospects of glass-ceramics in restorative dentistry are summarized and discussed.
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Affiliation(s)
- Xiaoming Liu
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Xuemin Yao
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Ran Zhang
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Lingxiang Sun
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Zheyuan Zhang
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Yifan Zhao
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Tong Zhang
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Jingyu Yan
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Yanjie Zhang
- Research Institute of Photonics, Dalian Polytechnic University, Dalian, Liaoning, China
| | - Xiuping Wu
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
| | - Bing Li
- Shanxi Medical University School and Hospital of Stomatology, Taiyuan, Shanxi, China
- Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, China
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Awad MM, Alhalabi F, Alanazi AA, Alanazi AA, Alshahrani GA, Fu C, Albaijan RS, Alkattan R, Fawzy AS. "No-Primer" Resin Cementation of Lithium Disilicate Ceramic: A Microtensile Bond Strength Evaluation. MATERIALS (BASEL, SWITZERLAND) 2023; 17:137. [PMID: 38203993 PMCID: PMC10779915 DOI: 10.3390/ma17010137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/18/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
OBJECTIVE The objective of this study was to evaluate the resin-ceramic adhesion of a long-carbon-chain silane (LCSI)-containing resin cement. METHODS Polished lithium disilicate ceramic discs were etched with hydrofluoric acid and randomly assigned into four groups; (PSAP), cemented using a silane-free resin cement with no prior priming; (PSAP-S), primed using a silane-containing primer before cementation using a silane-free resin cement; (PSAU), cemented using a LCSI-containing resin cement with no prior priming; (PSAU-S), primed as for the group (PSAP-S) and cemented using a LCSI-containing resin cement. The cemented blocks were sectioned into microbeams. The resin-ceramic microtensile bond strength (μTBS) was measured at 1 week and after thermocycling. The failure modes of the tested microbeams were evaluated. RESULTS The μTBS of the LCSI-containing and silane-free resin cements, either with or without a prior priming step, did not significantly differ. The adhesion of the LCSI-containing resin cement to lithium disilicate ceramic, either with or without a prior priming step, did not significantly deteriorate after artificial aging. CONCLUSIONS The long-carbon-chain silane (LCSI) monomer incorporated in the resin cement eliminated the need for a silane priming step of a hydrofluoric acid-etched lithium disilicate ceramic.
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Affiliation(s)
- Mohamed M. Awad
- UWA Dental School, University of Western Australia, 17 Monash Avenue, Nedlands, WA 6009, Australia; (C.F.) (A.S.F.)
| | - Feras Alhalabi
- Department of Conservative Dental Sciences, College of Dentistry, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
| | - Abdulaziz Abdullah Alanazi
- College of Dentistry, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia; (A.A.A.); (A.A.A.); (G.A.A.)
| | - Abdulaziz Ali Alanazi
- College of Dentistry, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia; (A.A.A.); (A.A.A.); (G.A.A.)
| | - Ghanem Abdullah Alshahrani
- College of Dentistry, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia; (A.A.A.); (A.A.A.); (G.A.A.)
| | - Cheryl Fu
- UWA Dental School, University of Western Australia, 17 Monash Avenue, Nedlands, WA 6009, Australia; (C.F.) (A.S.F.)
| | - Refal Saad Albaijan
- Department of Prosthetic Dental Sciences, College of Dentistry, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia;
| | - Rana Alkattan
- Restorative and Prosthetic Dental Sciences, College of Dentistry, King Saud Bin Abdulaziz University for Health Sciences, Riyadh 11545, Saudi Arabia;
- King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs, Riyadh 11545, Saudi Arabia
| | - Amr S. Fawzy
- UWA Dental School, University of Western Australia, 17 Monash Avenue, Nedlands, WA 6009, Australia; (C.F.) (A.S.F.)
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Kraipok A, Mamanee T, Ruangsuriya J, Nawarat P, Leenakul W. Phase Formation, Mechanical Strength, and Bioactive Properties of Lithium Disilicate Glass-Ceramics with Different Al 2O 3 Contents. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8283. [PMID: 36499779 PMCID: PMC9738710 DOI: 10.3390/ma15238283] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Owing to its excellent mechanical properties and aesthetic tooth-like appearance, lithium disilicate glass-ceramic is more attractive as a crown for dental restorations. In this study, lithium disilicate glass-ceramics were prepared from SiO2-Li2O-K2O-P2O5-CeO2 glass systems with various Al2O3 contents. The mixed glass was then heat-treated at 600 °C and 800 °C for 2 h to form glass-ceramic samples. Phase formation, microstructure, mechanical properties and bioactivity were investigated. The phase formation analysis confirmed the presence of Li2Si2O5 in all the samples. The glass-ceramic sample with an Al2O3 content of 1 wt% showed rod-like Li2Si2O5 crystals that could contribute to the delay in crack propagation and demonstrated the highest mechanical properties. Surface treatment with hydrofluoric acid followed by a silane-coupling agent provided the highest micro-shear bond strength for all ceramic conditions, with no significant difference between ceramic samples. The biocompatibility tests of the material showed that Al2O3-added lithium disilicate glass-ceramic sample was bioactive, thus activating protein production and stimulating the alkaline phosphatase (ALP) activity of osteoblast-like cells.
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Affiliation(s)
- Arnon Kraipok
- Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand
- Graduate School, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Teerapong Mamanee
- Department of Restorative Dentistry and Periodontology, Faculty of Dentistry, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Jetsada Ruangsuriya
- Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Poomirat Nawarat
- Division of Industrial Materials Science, Faculty of Science and Technology, Rajamangala University of Technology Phra Nakhon, Bangkok 10800, Thailand
| | - Wilaiwan Leenakul
- Division of Industrial Materials Science, Faculty of Science and Technology, Rajamangala University of Technology Phra Nakhon, Bangkok 10800, Thailand
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Abstract
Resin-bonded ceramic restorations are common treatment options. Clinical longevity of resin-bonded ceramic restorations depends on the quality and durability of the resin-ceramic bond. The type and composition of the specific ceramic determines the selection of the most effective bonding protocol. Such protocol typically includes a surface pretreatment step followed by application of a priming agent. Understanding of fundamental ceramic properties and chemical compositions enables the clinician to make proper material selection decisions for clinically successful and long-lasting restorations. Based on research accrued over the past decades, this article reviews and discusses current resin-bonding protocols to most commonly used dental ceramics.
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Affiliation(s)
- Markus B Blatz
- Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, 240 South 40th Street, Philadelphia, PA 19104, USA.
| | - Julian Conejo
- Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, 240 South 40th Street, Philadelphia, PA 19104, USA
| | - Amirah Alammar
- Sijam Medical Center, Northern Ring Road, Alghadeer District, Riyadh, Saudi Arabia
| | - Jose Ayub
- Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, 240 South 40th Street, Philadelphia, PA 19104, USA
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Wear behavior and abrasiveness of monolithic CAD/CAM ceramics after simulated mastication. Clin Oral Investig 2022; 26:6593-6605. [PMID: 35819543 PMCID: PMC9643261 DOI: 10.1007/s00784-022-04611-w] [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: 03/22/2022] [Accepted: 06/28/2022] [Indexed: 11/30/2022]
Abstract
Objectives To evaluate the wear resistance and abrasiveness of monolithic CAD/CAM ceramics. Materials and methods Rectangular-shaped specimens (12 mm × 6.5 mm × 1.5 mm) were sectioned from the following CAD/CAM blocks (n = 10); partially crystallized lithium disilicate (PLD), experimental fully crystallized lithium disilicate (FLD), zirconia-reinforced lithium silicate (ZLS), super-translucent monolithic zirconia (SMZ), and ultra-translucent monolithic zirconia (UMZ). Silicon carbide papers were used to mechanically flatten and polish the surfaces. PLD specimens were subjected to a combined crystallization/glazing firing cycle. Ceramic specimens were mounted to the wear device and tested for 200,000 cycles against human premolars at 20 N force and 2 mm sliding distance. Artificial saliva was used as a lubricant. The teeth were scanned using micro-CT before and after the wear test and the generated models were overlapped to determine the volumetric tooth loss. Before and after the test, specimens’ weights and surface roughness (Ra) values were measured, and the differences were calculated. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were utilized for microstructural and chemical analysis. Statistical analysis was performed using one-way ANOVA or an equivalent test for non-parametric results. Significance level was set at P ≤ 0.05. Results The type of ceramic material affected the ceramic and antagonist wear rates (P < 0.001). PLD and ZLS had the highest ceramic and antagonist wear, whereas UMZ and SMZ demonstrated the lowest wear values. The FLD group showed comparable antagonist wear and significantly less ceramic wear than PLD and ZLS. Conclusions Monolithic zirconia demonstrated the best wear resistance and least abrasiveness to the antagonist. The experimental lithium disilicate was more wear-resistant than other glass–ceramic groups. Clinical relevance Monolithic zirconia is wear-resistant and gentle on the antagonist. In contrast, glass–ceramics are more abrasive to enamel. Supplementary Information The online version contains supplementary material available at 10.1007/s00784-022-04611-w.
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Barlaz Us S, Ataol AS, Ergun G. Impact of different fixed dental prostheses on radiation dose in helical tomotherapy as measured with metal oxide semiconductor field-effect transistor dosimetry. Oral Surg Oral Med Oral Pathol Oral Radiol 2022; 133:716-724. [PMID: 35248513 DOI: 10.1016/j.oooo.2022.01.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 01/03/2022] [Accepted: 01/08/2022] [Indexed: 11/27/2022]
Abstract
OBJECTIVE This ex vivo study evaluated the effects of different fixed dental prostheses and protective materials on scattered radiation during radiation therapy (RT). STUDY DESIGN Natural teeth (group NT) and 4 types of prostheses (group BL: bilayer lithium disilicate glass-ceramic; group MZ: monolithic zirconia ceramic; group BZ: bilayer zirconia-based all ceramic; and group BM: bilayer metal-ceramic restorations) were examined in maxillary and mandibular arch phantoms. All groups were divided into 3 subgroups: (1) without protective material over the prostheses; (2) protected with a soft acrylic night guard; and (3) protected with polyvinylsiloxane putty. All groups were irradiated with helical RT at 2 Gy and 6 MV photon energy. Doses were measured internally and externally 3 times on each phantom. Results were significant at P < .05. RESULTS No statistically significant differences in doses were found between groups NT and BL in either phantom, but these groups were different from the others. The differences between groups BZ and MZ were insignificant. Doses in group BM were significantly larger than all other groups. No significant differences existed between doses with and without protective material. CONCLUSIONS Doses increased significantly due to scattered radiation from the prostheses with increasing material density. Protective materials had no significant effect on dose.
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Affiliation(s)
- Songul Barlaz Us
- Faculty of Medicine, Department of Radiation Oncology, Mersin University, Mersin, Turkey.
| | | | - Gulfem Ergun
- Faculty of Dentistry, Department of Prosthodontics, Gazi University, Ankara, Turkey.
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A Comparative Evaluation of the Radiopacity of Contemporary Restorative CAD/CAM Blocks Using Digital Radiography Based on the Impact of Material Composition. Int J Biomater 2022; 2022:4131176. [PMID: 35237329 PMCID: PMC8885173 DOI: 10.1155/2022/4131176] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/08/2022] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Purpose The main purpose of this study was to assess the radiopacity of contemporary restorative computer-aided design (CAD)/computer-aided manufacturing (CAM) materials and the impact of material composition as measured by energy-dispersive X-ray spectrophotometry (EDX) on radiopacity. Materials and Methods Ten specimens of six CAD/CAM materials with 1 mm thickness were produced and then digitally radiographed with an aluminum (Al) step-wedge (SW) and 1 mm thick tooth slice. The specimen mean gray values (MGVs) were recorded in pixels and compared to an Al-SW, dentin, and enamel of equal thickness. For the elementary analysis of the composition of the materials, EDX was performed. Results The recorded MGVs ranged between 21.20 ± 4.94 and 238.5 ± 13.61 pixels. Materials were sorted according to the MGVs descendingly, Prettau, Vita Suprinity, Vita Enamic, Shofu, Pekkton, and BioHPP. Prettau and Vita Suprinity had significantly higher MGV than dentin and 1 mm thick Al. In comparison, Vita Enamic had a slightly higher value than dentin and 1 mm thick Al. Although Pekkton and BioHPP had MGV significantly lower than dentin and 1 mm thick Al, Shofu had a significantly lower value than dentin and nonsignificantly lower than 1 mm thick Al (p < 0.05). According to EDX analysis, the examined materials contained several components in varying quantities of radiopacity. Conclusions The radiopacity of only three studied materials exceeded the International Organization for Standardization's minimum standards (ISO).
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Blatz MB, Hariton‐Gross K, Anadioti E, Mante F, Zhang Y, Saleh N. Prospective 5-year clinical evaluation of posterior zirconia fixed dental prostheses veneered with milled lithium disilicate (CADon). J ESTHET RESTOR DENT 2022; 34:136-144. [PMID: 35083844 PMCID: PMC9934977 DOI: 10.1111/jerd.12877] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Bi-layer zirconia-based posterior fixed dental prostheses (FDPs) have reportedly a high incidence of veneering ceramic fractures. The CADon technique employs zirconia frameworks veneered with milled lithium disilicate glass-ceramic to overcome these shortcomings but long-term clinical studies are missing. This study evaluated the clinical efficacy of posterior 3-unit CADOn FDPs over a 5-year period. MATERIALS AND METHODS A total of 25 patients, 16 male and 9 female with a mean age of 55.6 years, received a total of 25 posterior three-unit CADOn FDPs. Patients were recalled for baseline and for follow-up visits at 6, 12, 24, and 60 months. Parameters evaluated were fracture, marginal adaptation, marginal discoloration, wear, polish, color match, surface staining, and retention of these restorations as well as secondary caries of the abutment teeth. RESULTS A total of 21 FDPs evaluated at 60-months revealed a 100% survival rate. All evaluated clinical parameters were satisfactory (alpha or bravo) and there was no statistically significant difference at different time points, except for surface staining, which was also worse at 60 months compared to baseline (p ≤ 0.001). CONCLUSIONS CADOn three-unit posterior FDPs demonstrate excellent fracture resistance after 5 years of clinical function. All evaluated clinical parameters were satisfactory, except for surface stain, which also increased over time. CLINICAL SIGNIFICANCE Conventionally veneered bi-layer zirconia-based posterior FDPs have limited clinical success. Based on this study, alternative methods such as zirconia frameworks veneered with milled lithium disilicate glass-ceramic provide a viable alternative with excellent long-term clinical outcomes.
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Affiliation(s)
- Markus B. Blatz
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Karina Hariton‐Gross
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Evanthia Anadioti
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Francis Mante
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Yu Zhang
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
| | - Najeed Saleh
- Department of Preventive and Restorative Sciences University of Pennsylvania School of Dental Medicine Philadelphia Pennsylvania USA
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Review on Polymer, Ceramic and Composite Materials for CAD/CAM Indirect Restorations in Dentistry-Application, Mechanical Characteristics and Comparison. MATERIALS 2021; 14:ma14071592. [PMID: 33805176 PMCID: PMC8037100 DOI: 10.3390/ma14071592] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/14/2021] [Accepted: 03/18/2021] [Indexed: 11/17/2022]
Abstract
The aim of this review article is to present various material groups, including ceramics, composites and hybrid materials, currently utilized in the field of CAD/CAM. The described technology is amongst the most important in modern prosthetics. Materials that are applicable in this technique are constantly tested, evaluated and improved. Nowadays, research on dental materials is carried out in order to meet the increasing demand on highly aesthetic and functional indirect restorations. Recent studies present the long-term clinical success of restorations made with the help of both ceramic and composite materials in the CAD/CAM method. However, new materials are developed and introduced that do not have long-term in vivo observations. We can outline a monolithic polymer-infiltrated ceramic network and zirconia teeth support that show promising results to date but require further assessment. The materials will be compared with regard to their mechanical and clinical properties, purpose, advantages and limitations.
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Abstract
This article describes and illustrates the current state of chairside computer-aided design computer-aided manufacturing technologies and materials. It provides a historical background and discusses the different components of the chairside digital workflow: intraoral scanners, design software, milling machines, and sinter furnaces. The material range available for chairside digital dentistry is broad and includes polymethyl methacrylates, composite resins, and a large variety of ceramics. Clinical applications and success rates of the different material groups are summarized and discussed based on the current scientific evidence.
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Affiliation(s)
- Markus B Blatz
- Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, 240 South 40th Street, Philadelphia, PA 19104, USA.
| | - Julian Conejo
- Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, 240 South 40th Street, Philadelphia, PA 19104, USA
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Influence of veneer pore defects on fracture behavior of bilayered lithium disilicate glass-ceramic crowns. Dent Mater 2019; 35:e83-e95. [PMID: 30745210 DOI: 10.1016/j.dental.2019.01.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 11/28/2018] [Accepted: 01/13/2019] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To identify the conditions under which fabrication pore defects within veneering porcelain in bilayered lithium disilicate glass-ceramic (LDG) crowns will influence and jeopardize the mechanical integrity of the structure. METHODS Thirty standardized molar crowns (IPS e.max Press) were fabricated and microCT scanned to 3D-analyze the size, morphology and distribution of pores in veneering porcelain, followed by in vitro fracture test and SEM fractographic observation. Finite element analysis (FEA) of the microCT reconstructed models was used to evaluate the stress state. RESULTS The volumes of pores in samples ranged from 3241μm3 to 1.29×109μm3 with the equivalent radius between 10μm to 680μm. Deviation of sphericity of pores ranged from 0.10 to 0.81 and the average of 99.97% pores was near 0.63. For the smaller pores their distribution tended to be uniform, while the larger pores were irregular with elongated ellipsoidal form and located at or near the veneer-core interface. During wedge loading blunt contact fracture testing 21 crowns failed from the fissure on the occlusal surface, of which 16 failed from surface or near surface pores, 2 from the midpoint of the oblique ridge, and 7 from larger interfacial pores. FEA analysis indicated that defects were detrimental to veneer integrity only in regions of tensile stress and where the pore radius associated with crack initiation ranged from 30 to 50μm. Pore morphology appeared to have only a minor effect on fracture. SIGNIFICANCE Within the limitation of the microCT resolution and FEA, it suggests that pores radius large than 30-50μm and located in the tensile stress area like grooves and fissures on the occlusal surface or near surface as well as cervical margins of veneering porcelain will jeopardize the bilayered structure and mechanical integrity of LDG.
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Al-Aali KA. Effect of phototherapy on shear bond strength of resin cements to zirconia ceramics: A systematic review and meta-analysis of in-vitro studies. Photodiagnosis Photodyn Ther 2018; 23:58-62. [DOI: 10.1016/j.pdpdt.2018.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/08/2018] [Accepted: 05/10/2018] [Indexed: 12/13/2022]
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