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Fukushima KA, Alhotan A, Riman SG, Joshi G, Duan Y, Griggs JA, Cesar PF. Comparison of subcritical growth parameters of a Y-TZP obtained via cyclic or dynamic fatigue tests. Dent Mater 2024; 40:747-755. [PMID: 38418282 DOI: 10.1016/j.dental.2024.02.005] [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: 05/15/2023] [Revised: 01/30/2024] [Accepted: 02/09/2024] [Indexed: 03/01/2024]
Abstract
OBJECTIVE The objective of this study was to 1) compare the stress corrosion coefficient (n) of a Y-TZP obtained by two fatigue tests: cyclic and dynamic and 2) evaluate the effect of frequency in the characteristic lifetime and the existence of interaction between the cyclic fatigue and slow crack growth. METHODS A total of 145 Y-TZP specimens were produced in accordance with the manufacturer's instructions. These specimens, measuring 4.0 × 3.0 × 25.0 mm, were used for dynamic (n = 70) and cyclic fatigue tests (n = 75). The specimens were obtained from CAD/CAM blocks, sectioned, and sintered in a furnace at 1530 °C with a heating rate of 25 °C/min. They were tested in their "as-sintered" form without any additional surface treatment. The fatigue tests were conducted using a four-point bending to obtain the slow crack growth parameters (n). The cyclic fatigue test was also conducted in two frequencies (2 and 10 Hz), using stress levels between 350 and 600 MPa. Data from these tests were analyzed using ASTM C 1368-00 formulas and Weibull statistics. Scanning electron microscope (SEM) was used for fracture surface analysis to identify the origin of the fracture. Critical defect size was measured and used, along with flexural strength values, to estimate fracture toughness. Dynamic fatigue test data were used to obtain subcritical crack growth (SCG) parameters and perform Weibull statistical analysis. The cyclic fatigue data were used in the General Log-linear Model equation using the ALTA PRO software. Data were analyzed using one-way ANOVA followed by Tukey post-hoc tests and Student's t-test at a significance level of p ≤ 0.05. RESULTS In the dynamic fatigue test, the values obtained for σfo and n were 667 and 54, respectively. This parameter indicates how the strength of the material diminishes over time due to internal cracks. The Weibull parameters obtained from the same test results were m = 7.9, σ0 = 968, 9 and σ5% = 767, which indicates the reliability of the material. The Weibull parameters obtained by cyclic fatigue were statistically similar for the two frequencies used, the m* was 0.17 (2 Hz) and 0.21 (10 Hz); characteristic lifetimes (η) were 1.93 × 106 and 40,768, respectively. The n values obtained by cyclic fatigue were 48 and 40 at frequencies of 2 and 10 Hz, respectively. There was no effect of the frequency, the stress level or the interaction of the two in the Y-TZP lifetime, when analysed by General Log Linear Model. SIGNIFICANCE the n values obtained by cyclic and dynamic fatigue tests showed no statistically significant difference and the effect of frequency in the characteristic lifetime and the existence of interaction between the cyclic fatigue and subcritical growth were not observed in the tested specimens.
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Affiliation(s)
- Karen Akemi Fukushima
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227, Cidade Universitária, São Paulo, SP 05508-000, Brazil
| | - Abdulaziz Alhotan
- Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11454, Saudi Arabia
| | - Sahar Ganz Riman
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227, Cidade Universitária, São Paulo, SP 05508-000, Brazil
| | - Gaurav Joshi
- Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 North State Street, Room D528, Jackson, MS 39216-4505, USA
| | - Yuanyuan Duan
- Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 North State Street, Room D528, Jackson, MS 39216-4505, USA
| | - Jason A Griggs
- Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 North State Street, Room D528, Jackson, MS 39216-4505, USA
| | - Paulo Francisco Cesar
- Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227, Cidade Universitária, São Paulo, SP 05508-000, Brazil.
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Vasiliu RD, Uțu ID, Rusu L, Boloș A, Porojan L. Fractographic and Microhardness Evaluation of All-Ceramic Hot-Pressed and CAD/CAM Restorations after Hydrothermal Aging. MATERIALS (BASEL, SWITZERLAND) 2022; 15:3987. [PMID: 35683294 PMCID: PMC9182156 DOI: 10.3390/ma15113987] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/29/2022] [Accepted: 06/02/2022] [Indexed: 12/04/2022]
Abstract
All-ceramic dental restorations have great advantages, such as highly esthetical properties, a less complex fabrication, and a similar abrasion resistance to enamel. Despite these advantages, ceramic materials are more prone to fracture due to their brittle microstructure. The main aim of this in vitro study was to determine the difference in hot-pressed and milled glass-ceramic mechanical properties such as fracture resistance and microhardness (VHN). Four types of ceramics, two hot-pressed and two milled, feldspathic glass-ceramics and zirconia-reinforced glass-ceramics were selected in this study and tested using the static loading test and Vicker’s testing. Hydrothermal aging, consisting of different baths with temperatures between 5 degrees Celsius and 55 degrees Celsius, was chosen as the in vitro aging method. Statistical analyses are performed using SPSS Statistics software at a significance level of p < 0.05. Micro-hardness values decrease after hydrothermal aging. The static loading test reveals a significant difference between the feldspathic hot-pressed glass-ceramic, which fractures at lower forces, and milled zirconia-reinforced lithium silicate glass-ceramic, which fractures at greater forces (N). Fractographic analysis of the fractured fragments resulted in the static loading test revealing different surface features about the crack origins and propagations under a stereomicroscope.
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Affiliation(s)
- Roxana Diana Vasiliu
- Center for Advanced Technologies in Dental Prosthodontics, Department of Dental Prostheses Technology (Dental Technology), Faculty of Dental Medicine, “Victor Babeș” University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania;
| | - Ion-Dragoș Uțu
- Departament of Materials Engineering and Fabrication, University of Politehnică Timişoara, Bd. Mihai Viteazul nr.1, 300222 Timişoara, Romania;
| | - Lucian Rusu
- Department Mechanics and Vibrations, Faculty of Mechanical Engineering, Politehnica University, 1 Mihai Viteazu Street, 300222 Timisoara, Romania;
| | - Adrian Boloș
- Department of Oral Rehabilitation (Dental Technique), Faculty of Dental Medicine, “Victor Babeș” University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania;
| | - Liliana Porojan
- Center for Advanced Technologies in Dental Prosthodontics, Department of Dental Prostheses Technology (Dental Technology), Faculty of Dental Medicine, “Victor Babeș” University of Medicine and Pharmacy Timișoara, Eftimie Murgu Sq. No. 2, 300041 Timișoara, Romania;
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Abdulazeez MI, Majeed MA. Fracture Strength of Monolithic Zirconia Crowns with Modified Vertical Preparation: A Comparative In Vitro Study. Eur J Dent 2021; 16:209-214. [PMID: 34847612 PMCID: PMC8890931 DOI: 10.1055/s-0041-1735427] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Objective
The aim of this study was to evaluate the influence of different marginal designs (deep chamfer, vertical, and modified vertical with reverse shoulder) on the fracture strength and failure modes of monolithic zirconia crowns.
Materials and Methods
Thirty sound human maxillary first premolar teeth with comparable size were used in this study. The teeth were divided randomly into three groups according to the preparation design (
n
= 10): (1) group A: teeth prepared with a deep chamfer finish line; (2) group B: teeth prepared with vertical preparation; and (3) group C: teeth prepared with modified vertical preparation, where a reverse shoulder of 1 mm was placed on the buccal surface at the junction of middle and occlusal thirds. All samples were scanned by using an intraoral scanner (CEREC Omnicam, Sirona, Germany), and then the crowns were designed by using Sirona InLab 20.0 software and milled with a 5-axis machine. Each crown was then cemented on its respective tooth with self-adhesive resin cement by using a custom-made cementation device. A single load to failure test was used to assess the fracture load of each crown by using a computerized universal testing machine that automatically recorded the fracture load of each sample in Newton (N).
Statistical Analysis
The data were analyzed statistically by using one-way analysis of variance test and Bonferroni test at a level of significance of 0.05.
Results
The highest mean of fracture load was recorded by chamfer (2,969.8 N), which followed by modified vertical (2,899.3 N) and the lowest mean of fracture load was recorded by vertical (2,717.9 N). One-way ANOVA test revealed a significant difference among the three groups. Bonferroni test showed a significant difference between group A and group B, while a nonsignificant difference was revealed between group C with group A and group B.
Conclusion
Within the limitations of this in vitro study, the mean values of fracture strength of monolithic zirconia crowns of all groups were higher than the maximum occlusal forces in the premolar region. The modification of the vertical preparation with a reverse shoulder placed at the buccal surface improved the fracture strength up to the point that it was statistically nonsignificant with the chamfer group.
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Affiliation(s)
- Marwah Ismael Abdulazeez
- Department of Restorative and Esthetic Dentistry, College of Dentistry, Baghdad University, Baghdad, Iraq
| | - Manhal A Majeed
- Department of Restorative and Esthetic Dentistry, College of Dentistry, Baghdad University, Baghdad, Iraq
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Shelar P, Abdolvand H, Butler S. On the behaviour of zirconia-based dental materials: A review. J Mech Behav Biomed Mater 2021; 124:104861. [PMID: 34600431 DOI: 10.1016/j.jmbbm.2021.104861] [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: 08/10/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 11/28/2022]
Abstract
Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability. However, premature clinical failures of veneering porcelains raise a concern about their integrity. Extensive studies have been performed over a decade to resolve this issue, but it is challenging to reference all information effectively. A single source identifying the significance of potential parameters on material performance has not previously been available. An evidence-based meta-narrative review technique was used to review the characteristic parameters that can affect the overall behaviour of zirconia-based materials. Keywords were chosen to assess manuscripts based on scientific coherence with this paper's research objective. Online keyword searches were carried out on ScienceDirect, PubMed, and SAGE databases for relevant published manuscripts from year 1985-2020.261 out of 3170 identified manuscripts were included. A total of 10 parameters were identified and classified into the material, manufacturing, and geometric aspects. The effect of every parameter was reviewed on the performance of the material. A discrepancy in findings was observed and is attributed to the fact that there is no standard methodology. This review acts as a single source that summarizes various parameters' contribution to zirconia-based dental materials' performance. This review facilitates manufacturing improvements by accounting for every parameter's effect on overall performance.
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Affiliation(s)
- Prashant Shelar
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Hamidreza Abdolvand
- Department of Mechanical & Materials Engineering, Western University, London, Ontario, Canada
| | - Sheila Butler
- Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
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Alberto Jurado C, Kaleinikova Z, Tsujimoto A, Alberto Cortés Treviño D, Seghi RR, Lee DJ. Comparison of Fracture Resistance for Chairside CAD/CAM Lithium Disilicate Crowns and Overlays with Different Designs. J Prosthodont 2021; 31:341-347. [PMID: 34297866 DOI: 10.1111/jopr.13411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2021] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To determine the fracture resistance of chairside computer-aided design and computer-assisted manufacturing (CAD/CAM) lithium disilicate full coverage crowns and two different designs of overlay restorations for premolars. MATERIALS AND METHODS CAD/CAM lithium disilicate (IPS e.max CAD for CEREC/HT A1 C14, Ivoclar Vivadent) restorations (15 specimens/group) with 1.5 mm occlusal thickness and 1.0 mm chamfer were designed and fabricated with a chairside CAD/CAM system (CEREC, Dentsply Sirona). The restorations were prepared in three different designs: (1) full coverage crowns, (2) overlays with the margin located 2 mm above the gingiva, and (3) overlays with the margin located 4 mm above the gingiva. Restorations were cemented using conventional resin luting cement (Multilink, Ivoclar Vivadent) with primer system (Monobond Plus, Ivoclar Vivadent) to resin printed dies, load cycled (2,000,000 load cycles at 1 Hz with 275 N force), and then finally loaded with a steel indenter until failure. Scanning electron microscopy observations of fractured surfaces were also conducted. Group results were analyzed with one-way analysis of variance, and the medians were evaluated independently with Kruskal-Wallis. RESULTS The fracture force of CAD/CAM lithium disilicate restorations was significantly different (p < 0.001) depending on the design of the restoration. Full coverage crowns showed significantly higher force to fracture (1018.8 N) than both types of overlays (p = 0.002 for overlay 2.0 mm and p < 0.001 for overlay 4.0 mm above gingiva). Among the two overlays, the restoration with the margin located 2 mm above the gingiva showed significantly higher fracture force (813.8 N) than the overlay with margin at 4 mm above the gingiva (436.1 N; p < 0.001). The fracture appearance of the crowns was much more complex than that of the overlay restorations. CONCLUSIONS Full coverage chairside CAD/CAM lithium disilicate premolar crown showed higher fracture resistance than overlay restorations. Overlays with the margin located 2 mm above the margin demonstrated higher resistance than those with the margin located 4 mm above the gingiva.
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Affiliation(s)
- Carlos Alberto Jurado
- Woody L. Hunt School of Dental Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX
| | - Zinaida Kaleinikova
- Comprehensive Care Unit, A.T. Still University Arizona School of Dentistry & Oral Health, Mesa, AZ
| | - Akimasa Tsujimoto
- Department of Operative Dentistry, University of Iowa College of Dentistry, Iowa City, IA
| | | | - Robert R Seghi
- Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, OH
| | - Damian J Lee
- Advanced Prosthodontics Program, The Ohio State University College of Dentistry, Columbus, OH
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Alsubaiy EF, Chaturvedi S, Qutub OA, Mously HA, Zarbah MA, Haralur SB, Bhagat TV. Novel CAD-CAM zirconia coping design to enhance the aesthetics and strength for anterior PLZ crowns. Technol Health Care 2021; 29:1161-1171. [PMID: 33998567 DOI: 10.3233/thc-202782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The aesthetics and strength of anterior porcelain layered zirconia (PLZ) crowns are mainly affected by the zirconia (Zr) coping design. There is a need for a modified design to enhance aesthetics with strength. OBJECTIVES The purpose of this study was to compare the fracture resistance of anterior PLZ crowns having modified CAD-CAM Zr coping designs (in terms of thickness and marginal collar designs) with standard Zr copings. METHODS Fifty PLZ crowns were fabricated and divided into two groups: Gr 1: Standard Zr Coping (SZC) (control gr) with 0.5 mm thickness (Facial-F, Mesial-M, Distal-D, incisal-I, and Palatal-P) without a collar; Gr 2: Collar Zr Coping (CZC) (test gr) with 2.5 mm collar height on M, D, P and 0.2 mm F and variable facial wall thickness. Subgroups: Gr 2a: (CZC-0.5 mm) facial wall thickness 0.5 mm; Gr 2b: (CZC-0.4 mm) facial wall thickness 0.4 mm; Gr 2c: (CZC-0.3 mm) facial wall thickness 0.3 mm; Gr 2d: (CZC-0.2 mm) facial wall thickness 0.2 mm. The fracture load was determined and analysed using One-way ANOVA and Dunnet test. RESULTS The minimum fracture load was 927.36 ± 127.80 N observed for Gr 2c (CZC at 0.3 mm) while the maximum fracture load was 1373.61 ± 146.54 N observed for Gr 2a (CZC at 0.5 mm). A highly significant difference in mean fracture load among various Zr coping groups (p< 0.001) was determined. CONCLUSIONS Novel Zr coping design for anterior PLZ crowns can provide better aesthetics with strength. Reducing the thickness of Zr coping in the aesthetic zone to 0.2 mm and providing a modified collar design (2.5 mm collar height on M, D, P, and 0.2 mm F) would provide strength without jeopardizing aesthetics.
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Affiliation(s)
- Ebrahim Fihaid Alsubaiy
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Saurabh Chaturvedi
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Osama A Qutub
- Oral and Maxillofacial Prosthodontics Department, College of Dentistry, King Abdulaziz University, Saudi Arabia
| | - Hisham Abdullah Mously
- Oral and Maxillofacial Prosthodontics Department, College of Dentistry, King Abdulaziz University, Saudi Arabia
| | - Mohammad Abdullah Zarbah
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Satheesh B Haralur
- Department of Prosthetic Dentistry, College of Dentistry, King Khalid University, Abha, Saudi Arabia
| | - Tushar V Bhagat
- College of Dentistry, Prince Sattam bin Abdulaziz University, AlKharj, Saudi Arabia
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7
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Elashmawy Y, Elshahawy W, Seddik M, Aboushelib M. Influence of fatigue loading on fracture resistance of endodontically treated teeth restored with endocrowns. J Prosthodont Res 2020; 65:78-85. [PMID: 32938873 DOI: 10.2186/jpr.jpor_2019_485] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE This in vitro study aimed to evaluate the influence of fatigue loading on fracture resistance of endodontically treated molars restored with endocrowns using different machinable blocks. METHODS Endodontically treated mandibular first molars were prepared using a standardized method. Specimens were divided into 4 groups (n = 10).Anatomically shaped endocrowns groups were manufactured using VITA ENAMIC (VE) and KATANA Zirconia (KZ). Layered endocrowns groups were manufactured using IPS e.max CAD (EM) and BioHPP (BH). Half of the specimens of each group were subjected to fracture resistance test, while the other half were subjected to thermocycling and chewing simulation. After fatigue loading, specimens were loaded until failure. Specimens were examined using stereomicroscopy. Data were analyzed using ANOVA analysis of variance and Bonferroni post hoc test (α=0.05). RESULTS KZ group had the highest initial fracture resistance value (1810.20± 119.56 N) and BH had the lowest value (579.50± 76.15 N). The reduction of fracture resistance after fatigue loading was significant for KZ group (1588.30±216.25 N) and BH group (502.60±11.53 N) and non-significant to VE group (1101.70±77.05 N) and EM group (1112.10±74.12 N). Failure modes of KZ and EM groups showed high percentage of non-restorable fractures, while VE and BH groups showed high percentage of restorable fractures. CONCLUSIONS Within the limitations of this study, the following can be concluded: Poly infiltrated ceramics should be considered as a proper material to be used as an endocrown material because of its ability to be restorable if failure occurred.
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Affiliation(s)
- Yasmin Elashmawy
- Department of Fixed Prosthodontics, University of Tanta Faculty of dentistry, Tanta
| | - Waleed Elshahawy
- Department of Fixed Prosthodontics, University of Tanta Faculty of dentistry, Tanta
| | - Mohamed Seddik
- Department of Fixed Prosthodontics, University of Tanta Faculty of dentistry, Tanta
| | - Moustafa Aboushelib
- Department of Dental Materials, University of Alexandria Faculty of dentistry, Alexandria
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Saha MK, Bansal S, Pathak V, Bhardwaj S, Chauhan A, Nirwan AS. A comparative evaluation of fracture load of monolithic and bilayered zirconia crowns with and without a cervical collar: an in vitro study. Med Pharm Rep 2019; 92:172-177. [PMID: 31086846 PMCID: PMC6510367 DOI: 10.15386/mpr-985] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 04/11/2018] [Accepted: 04/25/2018] [Indexed: 11/23/2022] Open
Abstract
Introduction The use of zirconia based all-ceramic restorations are preferred nowadays owing to superior biologic and esthetic properties. However, these restorations have also reported higher incidences of fracture and chipping. The clinical success may be enhanced by optimizing the core design, through the introduction of monolithic zirconia, or the layered crowns can be strengthened by adding the cervical collar to them. Objective This study was performed with the objective to compare and evaluate the fracture load of monolithic and bilayered zirconia crowns with and without a cervical collar. Methods A prospective observational study was carried out to compare 45 fabricated zirconia crowns of three different designs on a customized metal mould. The samples were oriented on the metal mould and subjected to confocal microscope for the evaluation of marginal integrity followed by cementing the crown on the metal mould and subjecting it to the universal testing machine for the analysis for the flexural strength. Data were analyzed using one way Anova and t- test for inter and intra groups. The significance level was set at P ≤ 0.05. Results The monolith zirconia crowns and layered zirconia crowns with cervical collar reported more flexural strength. Conclusion The amount of force required to fracture the zirconia crowns was higher in the case of monolith zirconia crown and layered zirconia crown with cervical collar as compared to the layered zirconia crown without cervical collar.
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Affiliation(s)
- Mainak Kanti Saha
- Department of Prosthodontics, Rau College of Dental Sciences, Indore, India
| | - Surbhi Bansal
- Department of Prosthodontics, Rau College of Dental Sciences, Indore, India
| | - Vandana Pathak
- Department of Prosthodontics, Rau College of Dental Sciences, Indore, India
| | - Shivani Bhardwaj
- Department of Prosthodontics, Rau College of Dental Sciences, Indore, India
| | - Astha Chauhan
- Department of Public Health Dentistry, Index Institute of Dental Sciences, Indore, India
| | - Amit Singh Nirwan
- Department of Oral Surgery, Rau College of Dental Sciences, Indore, India
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Sorrentino R, Navarra CO, Di Lenarda R, Breschi L, Zarone F, Cadenaro M, Spagnuolo G. Effects of Finish Line Design and Fatigue Cyclic Loading on Phase Transformation of Zirconia Dental Ceramics: A Qualitative Micro-Raman Spectroscopic Analysis. MATERIALS 2019; 12:ma12060863. [PMID: 30875849 PMCID: PMC6470560 DOI: 10.3390/ma12060863] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/28/2019] [Accepted: 03/12/2019] [Indexed: 11/16/2022]
Abstract
Objectives: Stresses produced during the fabrication of copings and by chewing activity can induce a tetragonal-to-monoclinic (t–m) transformation of zirconia. As a consequence, in the m-phase, the material is not able to hinder possible cracks by the favorable mechanism known as “transformation toughening”. This study aimed at evaluating if different marginal preparations of zirconia copings can cause a premature phase transformation immediately after manufacturing milling and after chewing simulation. Methods: Ninety copings using three commercial zirconia ceramics (Nobel Procera Zirconia, Nobel Biocare Management AG; Lava Classic, 3M ESPE; Lava Plus, 3M ESPE) were prepared with deep-chamfer, slight-chamfer, or feather-edge finish lines (n = 10). Specimens were tested in a chewing simulator (CS-4.4, SD Mechatronik) under cyclic occlusal loads simulating one year of clinical service. Raman spectra were acquired and analyzed for each specimen along the finish lines and at the top of each coping before and after chewing simulation, respectively. Results: Raman analysis did not show any t–m transformation both before and after chewing simulation, as the typical monoclinic bands at 181 cm−1 and 192 cm−1 were not detected in any of the tested specimens. Conclusions: After a one-year simulation of chewing activity, irrespective of preparation geometry, zirconia copings did not show any sign of t–m transformation, either in the load application areas or at the margins. Consequently, manufacturing milling even in thin thickness did not cause any structural modification of zirconia ceramics “as received by manufacturers” both before and after chewing simulation.
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Affiliation(s)
- Roberto Sorrentino
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Division of Prosthodontics and Digital Dentistry, University of Naples "Federico II", via S. Pansini 5, 80131 Naples, Italy.
| | - Chiara Ottavia Navarra
- Department of Medical Sciences, University of Trieste, Piazza dell'Ospitale 1, 34129 Trieste, Italy.
| | - Roberto Di Lenarda
- Department of Medical Sciences, University of Trieste, Piazza dell'Ospitale 1, 34129 Trieste, Italy.
| | - Lorenzo Breschi
- Department of Biomedical Science and Neuromotor Sciences, DIBINEM, University of Bologna, Via San Vitale 59, 40123 Bologna, Italy.
| | - Fernando Zarone
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Division of Prosthodontics and Digital Dentistry, University of Naples "Federico II", via S. Pansini 5, 80131 Naples, Italy.
| | - Milena Cadenaro
- Department of Medical Sciences, University of Trieste, Piazza dell'Ospitale 1, 34129 Trieste, Italy.
| | - Gianrico Spagnuolo
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Division of Prosthodontics and Digital Dentistry, University of Naples "Federico II", via S. Pansini 5, 80131 Naples, Italy.
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10
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Kashkari A, Yilmaz B, Brantley WA, Schricker SR, Johnston WM. Fracture analysis of monolithic CAD‐CAM crowns. J ESTHET RESTOR DENT 2019; 31:346-352. [DOI: 10.1111/jerd.12462] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 01/19/2019] [Accepted: 02/13/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Afnan Kashkari
- Restorative and Esthetic DentistryJohns Hopkins Aramco Healthcare Dhahran Saudi Arabia
| | - Burak Yilmaz
- Division of Restorative and Prosthetic DentistryThe Ohio State University, College of Dentistry Columbus Ohio
| | - William A. Brantley
- College of Dentistry, Division of Restorative and Prosthetic DentistryThe Ohio State University Columbus Ohio
| | - Scott R. Schricker
- College of Dentistry, Division of Restorative and Prosthetic DentistryThe Ohio State University Columbus Ohio
| | - William M. Johnston
- College of Dentistry, Division of Restorative and Prosthetic DentistryThe Ohio State University Columbus Ohio
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11
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Abstract
Zirconia‐based restorations are showing an increase as the clinicians’ preferred choice at posterior sites because of the strength and esthetic properties of such restorations. However, all‐ceramic restorations fracture at higher rates than do metal‐based restorations. Margin design is one of several factors that can affect the fracture strength of all‐ceramic restorations. The aim of this study was to assess the effect of preparation and crown margin design on fracture resistance. Four groups of bilayer zirconia crowns (with 10 crowns in each group) were produced by hard‐ or soft‐machining technique, with the following four different margin designs: chamfer preparation (control); slice preparation; slice preparation with an additional cervical collar of 0.7 mm thickness; and reduced occlusal thickness (to 0.4 mm) on slice preparation with an additional cervical collar of 0.7 mm thickness. Additionally, 10 hard‐machined crowns with slice preparation were veneered and glazed with feldspathic porcelain. In total, 90 crowns were loaded centrally in the occlusal fossa until fracture. The load at fracture was higher than clinically relevant mastication loads for all preparation and margin designs. The crowns on a chamfer preparation fractured at higher loads compared with crowns on a slice preparation. An additional cervical collar increased load at fracture for hard‐machined crowns.
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Affiliation(s)
- Anneli Skjold
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Christian Schriwer
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Marit Øilo
- Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Bergen, Norway
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Miura S, Kasahara S, Yamauchi S, Egusa H. Effect of finish line design on stress distribution in bilayer and monolithic zirconia crowns: a three-dimensional finite element analysis study. Eur J Oral Sci 2018; 126:159-165. [DOI: 10.1111/eos.12402] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Shoko Miura
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
| | - Shin Kasahara
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
| | - Shinobu Yamauchi
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
| | - Hiroshi Egusa
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
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Cetik S, Bahrami B, Fossoyeux I, Atash R. Adaptation of zirconia crowns created by conventional versus optical impression: in vitro study. J Adv Prosthodont 2017; 9:208-216. [PMID: 28680553 PMCID: PMC5483408 DOI: 10.4047/jap.2017.9.3.208] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 02/12/2017] [Accepted: 04/24/2017] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The aim of this study was to compare the precision of optical impression (Trios, 3Shape) versus that of conventional impression (Imprint IV, 3M-ESPE) with three different margins (shoulder, chamfer, and knife-edge) on Frasaco teeth. MATERIALS AND METHODS The sample comprised of 60 zirconia half-crowns, divided into six groups according to the type of impression and margin. Scanning electron microscopy enabled us to analyze the gap between the zirconia crowns and the Frasaco teeth, using ImageJ software, based on eight reproducible and standardized measuring points. RESULTS No statistically significant difference was found between conventional impressions and optical impressions, except for two of the eight points. A statistically significant difference was observed between the three margin types; the chamfer and knife-edge finishing lines appeared to offer better adaptation results than the shoulder margin. CONCLUSION Zirconia crowns created from optical impression and those created from conventional impression present similar adaptation. While offering identical results, the former have many advantages. In view of our findings, we believe the chamfer margin should be favored.
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Affiliation(s)
- Sibel Cetik
- Department of Stomatology and Dentistry, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Babak Bahrami
- Laboratory of Physiology and Pharmaceutics, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
| | - InÈs Fossoyeux
- Department of Stomatology and Dentistry, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Ramin Atash
- Department of Stomatology and Dentistry, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
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Aboushelib MN, Shawky R. Osteogenesis ability of CAD/CAM porous zirconia scaffolds enriched with nano-hydroxyapatite particles. Int J Implant Dent 2017; 3:21. [PMID: 28527036 PMCID: PMC5438327 DOI: 10.1186/s40729-017-0082-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 05/08/2017] [Indexed: 11/19/2022] Open
Abstract
Background The aim of this study was to evaluate osteogenesis ability of CAD/CAM porous zirconia scaffolds enriched with hydroxy apatite used to augment large boney defects in a dog model. Methods Surgical defects were made bilaterally on the lower jaw of 12 Beagle dogs. Cone beam CT images were used to create three dimensional images of the healed defects. Porous zirconia scaffolds were fabricated by milling custom made CAD/CAM blocks into the desired shape. After sintering, the pores of half of the scaffolds were filled with a nano-hydroxy apatite (HA) powder while the other half served as control. The scaffolds were inserted bilaterally in the healed mandibular jaw defects and were secured in position by resorbable fixation screws. After a healing time of 6 weeks, bone-scaffold interface was subjected to histomorphometric analysis to detect the amount of new bone formation. Stained histological sections were analyzed using a computer software (n=12, α=0.05). Mercury porosimetery was used to measure pore sizes, chemical composition was analyzed using energy dispersive x-ray analysis (EDX), and the crystal structure was identified using x-ray diffraction micro-analysis (XRD). Results HA enriched zirconia scaffolds revealed significantly higher volume of new bone formation (33% ± 14) compared to the controls (21% ± 11). New bone deposition started by coating the pore cavity walls and proceeded by filling the entire pore volume. Bone in-growth started from the surface of the scaffold and propagated towards the scaffold core. Islands of entrapped hydroxy apatite particles were observed in mineralized bone matrix. Conclusions Within the limitations of this study, hydroxy apatite enhanced osteogenesis ability of porous zirconia scaffolds.
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Affiliation(s)
- Moustafa N Aboushelib
- Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Champollion st, Azarita, Alexandria, Egypt.
| | - Rehab Shawky
- Oral Surgery Department, Faculty of Dentistry, Alexandria University, Alexandria, Egypt
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Elshiyab SH, Nawafleh N, George R. Survival and testing parameters of zirconia-based crowns under cyclic loading in an aqueous environment: A systematic review. ACTA ACUST UNITED AC 2017; 8. [DOI: 10.1111/jicd.12261] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 01/07/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Shareen Hayel Elshiyab
- School of Dentistry and Oral Health; Griffith University; Gold Coast Qld Australia
- Faculty of Applied Medical Sciences; Jordan University of Science and Technology; Irbid Jordan
| | - Noor Nawafleh
- School of Dentistry and Oral Health; Griffith University; Gold Coast Qld Australia
- Faculty of Applied Medical Sciences; Jordan University of Science and Technology; Irbid Jordan
| | - Roy George
- School of Dentistry and Oral Health; Griffith University; Gold Coast Qld Australia
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16
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Özcan M, Jonasch M. Effect of Cyclic Fatigue Tests on Aging and Their Translational Implications for Survival of All-Ceramic Tooth-Borne Single Crowns and Fixed Dental Prostheses. J Prosthodont 2016; 27:364-375. [DOI: 10.1111/jopr.12566] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2016] [Indexed: 11/29/2022] Open
Affiliation(s)
- Mutlu Özcan
- Dental Materials Unit, Center for Dental and Oral Medicine; Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, University of Zürich; Zurich Switzerland
| | - Moritz Jonasch
- Dental Materials Unit, Center for Dental and Oral Medicine; Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, University of Zürich; Zurich Switzerland
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Mokhtarpour H, Eftekhar Ashtiani R, Mahshid M, Tabatabaian F, Alikhasi M. Effect of screw access hole preparation on fracture load of implant-supported zirconia-based crowns: an in vitro study. J Dent Res Dent Clin Dent Prospects 2016; 10:181-8. [PMID: 27651885 PMCID: PMC5025220 DOI: 10.15171/joddd.2016.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 07/19/2016] [Indexed: 11/30/2022] Open
Abstract
Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a universal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05). Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001). The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44). Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns decreased the fracture load.
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Affiliation(s)
- Hadi Mokhtarpour
- Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Sari University of Medical Sciences, Sari, Iran
| | - Reza Eftekhar Ashtiani
- Assistant Professor, Department of Dental Technology, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Minoo Mahshid
- Professor, Department of Prosthodontics, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Farhad Tabatabaian
- Assistant Professor, Department of Prosthodontics, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Marzieh Alikhasi
- Associate Professor, Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
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18
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19
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Øilo M, Kvam K, Gjerdet NR. Load at fracture of monolithic and bilayered zirconia crowns with and without a cervical zirconia collar. J Prosthet Dent 2016; 115:630-6. [DOI: 10.1016/j.prosdent.2015.11.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 11/02/2015] [Accepted: 11/05/2015] [Indexed: 11/26/2022]
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20
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Partiyan A, Osman E, Rayyan MM, Aboushelib M, Ibrahim A, Jimbo R. Fracture resistance of three-unit zirconia fixed partial denture with modified framework. Odontology 2016; 105:62-67. [PMID: 27083582 DOI: 10.1007/s10266-016-0242-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 01/31/2016] [Indexed: 11/29/2022]
Abstract
Obtaining ideal prosthetic framework design is at times hindered by anatomical limitations in the posterior region that might increase the risk for zirconia restoration fracture. Modification such as increasing the bulk thickness especially in the connector region could result in strengthening the zirconia framework. Three-unit zirconia fixed partial dentures replacing mandibular molars were fabricated using the following two techniques: CAD/CAM technology and manual copy milling. Modified framework with unveneered full thickness connectors were designed and fabricated with the aforementioned methods. Conventional frameworks (0.5 mm thick with rounded 3 mm connectors) served as control (N = 20). After cementation on epoxy dies, the frameworks were loaded to fracture in a universal testing machine. Fractured surfaces were prepared for examination using scanning electron microscopy. Statistical analysis revealed significant differences in fracture resistance between conventional and modified framework design for both fabrication techniques tested. SEM examination indicated that critical crack originated at the tensile surface of the connectors for conventional frameworks. The critical crack for modified frameworks occurred on the axial wall of the abutments. The modification of the zirconia framework design presented significant improvement of the fracture resistance compared to the conventional design.
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Affiliation(s)
- Arthur Partiyan
- Department of Oral Rehabilitation Sciences, Faculty of Dentistry, Beirut Arab University, Beirut, Lebanon
| | - Essam Osman
- Department of Oral Rehabilitation Sciences, Faculty of Dentistry, Beirut Arab University, Beirut, Lebanon
| | - Mohammad M Rayyan
- Department of Oral Rehabilitation Sciences, Faculty of Dentistry, Beirut Arab University, Beirut, Lebanon.,Department of Fixed Prosthodontics, Faculty of Dentistry, Misr University for Science and Technology, 6th of October City, Egypt
| | - Moustafa Aboushelib
- Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Alexandria, Egypt
| | - Ahmed Ibrahim
- Public Health Service (Folktandvården), Gefle County, Sweden
| | - Ryo Jimbo
- Department of Oral and Maxillofacial Surgery and Oral Medicine, Malmö University, Malmö, Sweden.
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21
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Øilo M, Quinn GD. Fracture origins in twenty-two dental alumina crowns. J Mech Behav Biomed Mater 2016; 53:93-103. [DOI: 10.1016/j.jmbbm.2015.08.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/29/2015] [Accepted: 08/04/2015] [Indexed: 11/15/2022]
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Duzyol M, Sagsoz O, Polat Sagsoz N, Akgul N, Yildiz M. The Effect of Surface Treatments on the Bond Strength Between CAD/CAM Blocks and Composite Resin. J Prosthodont 2015. [DOI: 10.1111/jopr.12322] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Mustafa Duzyol
- Department of Restorative Dentistry; Ataturk University; Erzurum Turkey
| | - Omer Sagsoz
- Department of Restorative Dentistry; Ataturk University; Erzurum Turkey
| | | | - Nilgun Akgul
- Department of Restorative Dentistry; Ataturk University; Erzurum Turkey
| | - Mehmet Yildiz
- Department of Restorative Dentistry; Ataturk University; Erzurum Turkey
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23
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Cortellini D, Canale A, Souza RO, Campos F, Lima JC, Özcan M. Durability and Weibull Characteristics of Lithium Disilicate Crowns Bonded on Abutments with Knife-Edge and Large Chamfer Finish Lines after Cyclic Loading. J Prosthodont 2014; 24:615-9. [DOI: 10.1111/jopr.12237] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2014] [Indexed: 11/26/2022] Open
Affiliation(s)
| | | | - Rodrigo O.A. Souza
- Department of Dentistry, Division of Prosthodontics; Federal University of Rio Grande do Norte; Natal, RN Brazil
| | - Fernanda Campos
- São Jose dos Campos Dental School, Department of Prosthodontics and Dental Materials; São Paulo State University; São José dos Campos Brazil
| | - Julia C. Lima
- São Jose dos Campos Dental School, Department of Prosthodontics and Dental Materials; São Paulo State University; São José dos Campos Brazil
| | - Mutlu Özcan
- Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science; University of Zurich; Zurich Switzerland
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Euán R, Figueras-Álvarez O, Cabratosa-Termes J, Oliver-Parra R. Marginal adaptation of zirconium dioxide copings: Influence of the CAD/CAM system and the finish line design. J Prosthet Dent 2014; 112:155-62. [DOI: 10.1016/j.prosdent.2013.10.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 10/03/2013] [Accepted: 10/16/2013] [Indexed: 11/29/2022]
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Oilo M, Hardang AD, Ulsund AH, Gjerdet NR. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function. Eur J Oral Sci 2014; 122:238-44. [PMID: 24698173 PMCID: PMC4199274 DOI: 10.1111/eos.12127] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2014] [Indexed: 11/28/2022]
Abstract
Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation.
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Affiliation(s)
- Marit Oilo
- Department of Clinical Dentistry, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway
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Oilo M, Kvam K, Gjerdet NR. Simulation of clinical fractures for three different all-ceramic crowns. Eur J Oral Sci 2014; 122:245-50. [PMID: 24698209 PMCID: PMC4298035 DOI: 10.1111/eos.12128] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2014] [Indexed: 11/27/2022]
Abstract
Comparison of fracture strength and fracture modes of different all-ceramic crown systems is not straightforward. Established methods for reliable testing of all-ceramic crowns are not currently available. Published in-vitro tests rarely simulate clinical failure modes and are therefore unsuited to distinguish between the materials. The in-vivo trials usually lack assessment of failure modes. Fractographic analyses show that clinical crowns usually fail from cracks initiating in the cervical margins, whereas in-vitro specimens fail from contact damage at the occlusal loading point. The aim of this study was to compare three all-ceramic systems using a clinically relevant test method that is able to simulate clinical failure modes. Ten incisor crowns of three types of all-ceramic systems were exposed to soft loading until fracture. The initiation and propagation of cracks in these crowns were compared with those of a reference group of crowns that failed during clinical use. All crowns fractured in a manner similar to fracture of the clinical reference crowns. The zirconia crowns fractured at statistically significantly higher loads than alumina and glass-ceramic crowns. Fracture initiation was in the core material, cervically in the approximal areas.
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Affiliation(s)
- Marit Oilo
- Department of Clinical Dentistry - Biomaterials, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway
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Clinically relevant fracture testing of all-ceramic crowns. Dent Mater 2013; 29:815-23. [PMID: 23746750 DOI: 10.1016/j.dental.2013.04.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 04/23/2013] [Accepted: 04/25/2013] [Indexed: 11/20/2022]
Abstract
OBJECTIVES Fracture strength measured in vitro indicates that most all-ceramic crowns should be able to withstand mastication forces. Nevertheless, fractures are one of the major clinical problems with all-ceramic restorations. Furthermore, the fracture mode of all-ceramic crowns observed in clinical use differs from that found in conventional fracture strength tests. The aim of the present study was to develop and investigate a method that simulates clinical fracture behavior in vitro. METHODS 30 crowns with alumina cores were made to fit a cylindrical model with a molar-like preparation design. These crowns were randomly allocated to 3 tests groups (n=10). The crowns in group 1 were cemented to abutment models of epoxy and subsequently fractured by occlusal loading without contact damage. The crowns in group 2 were fractured by cementation with expanding cement. The crowns in group 3 were cemented on an abutment model of epoxy split almost in two and fractured by increasing the diameter of the model in the bucco-lingual direction. The fractured crowns were analyzed by fractographic methods and compared to a reference group of 10 crowns fractured in clinical use. RESULTS The fracture modes of all the in vitro crowns were similar to clinical fracture modes. The fracture modes in group 1 were most closely matched to the clinical fractures. These crowns also fractured at clinically relevant loads. CONCLUSION Laboratory tests that induce a distortion of the abutment model during occlusal loading without occlusal contact damage can simulate clinical fractures of all-ceramic crowns.
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Alhasanyah A, Vaidyanathan TK, Flinton RJ. Effect of core thickness differences on post-fatigue indentation fracture resistance of veneered zirconia crowns. J Prosthodont 2013; 22:383-90. [PMID: 23387466 DOI: 10.1111/jopr.12016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2012] [Indexed: 11/30/2022] Open
Abstract
PURPOSE Despite the excellent esthetics of veneered zirconia crowns, the incidence of chipping and fracture of veneer porcelain on zirconia crowns has been recognized to be higher than in metal ceramic crowns. The objective of this investigation was to study the effect of selected variations in core thickness on the post-fatigue fracture resistance of veneer porcelain on zirconia crowns. MATERIALS AND METHODS Zirconia crowns for veneering were prepared with three thickness designs of (a) uniform 0.6-mm thick core (group A), (b) extra-thick 1.7 mm occlusal core support (group B), and (c) uniform 1.2-mm thick core (group C). The copings were virtually designed and milled by the CAD/CAM technique. Metal ceramic copings (group D) with the same design as in group C were used as controls. A sample size of N = 20 was used for each group. The copings were veneered with compatible porcelain and fatigue tested under a sinusoidal loading regimen. Loading was done with a 200 N maximum force amplitude under Hertzian axial loading conditions at the center of the crowns using a spherical tungsten carbide indenter. After 100,000 fatigue cycles, the crowns were axially loaded to fracture and maximum load levels before fracture was recorded. One-way ANOVA (P < 0.05) and post hoc Tukey tests (α = 0.05) were used to determine significant differences between means. RESULTS The mean fracture failure load of group B was not significantly different from that of control group D. In contrast, the mean failure loads of groups A and C were significantly lower than that of control group D. Failure patterns also indicated distinct differences in failure mode distributions. The results suggest that proper occlusal core support improves veneer chipping fracture resistance in zirconia crowns. CONCLUSIONS Extra-thick occlusal core support for porcelain veneer may significantly reduce the veneer chipping and fracture of zirconia crowns. This is suggested as an important consideration in the design of copings for zirconia crowns.
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Affiliation(s)
- Abdulrahman Alhasanyah
- Department of Restorative Dentistry, NJ Dental School, University of Medicine and Dentistry of NJ, Newark, NJ 07103, USA
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