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Zhou T, Mirchandani B, Li XX, Mekcha P, Buranawat B. Quantitative parameters of digital occlusal analysis in dental implant supported restorative reconstruction recent 5 years: a systematic review. Acta Odontol Scand 2023; 81:1-17. [PMID: 35617455 DOI: 10.1080/00016357.2022.2077980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE The aims of this systematic review were to evaluate the clinical masticatory performance of implant-supported restorations, observe the occlusal force changes in the distribution of the implant restoration and reveal the positive and negative contributing factors of implant design and components based on the outcomes of digital occlusal measurement. MATERIAL AND METHODS An extensive search was conducted through PubMed and CENTRAL to identify clinical trials on implant-retained restorations using digital occlusal analysis methods. Two researchers assessed the identified studies and data extraction independently, and the data synthesis strategies without meta-analysis that summarizes the effect estimates were adopted. RESULTS The search screened 3821 titles and abstracts, then full-text analysis for 26 articles was performed, and 14 studies were included in the quantitative synthesis. Four of six studies for implant-retained overdenture showed statistically significant improved bite force when immediate loading (p = .00045, .00005, .00055, and .00005, respectively), and no statistically significant results in the other two studies (p = .225, .371, respectively.) However, the results of the favoured intervention were not statistically significant (p = .104, .166, respectively) in two studies of single posterior implant restorations. In all three studies, the bite force distributed on the implant prostheses of partially fixed implant-retained restoration increased statistically significantly (p = .013, .001, .05, respectively). CONCLUSIONS The edentulous restoration supported by implants seems to significantly improves bite force and chewing efficiency compared with conventional dentures. Regular quantitative occlusal measurement is recommended to avoid the possible risk of overload. Smaller implants size and relatively small and flexible attachment designs may be more conducive to the stability and retention of the restoration of atrophy of alveolar bone.
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Affiliation(s)
- Ting Zhou
- Department of Orthodontics, School of Stomatology, Kunming Medical University, Yunnan, PR China.,Department of Periodontics and Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
| | - Bharat Mirchandani
- Department of Periodontics and Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
| | - Xing-Xing Li
- Department of Prosthodontics, School of Stomatology, Kunming Medical University, Yunnan, PR China
| | - Pichaya Mekcha
- Department of Periodontics and Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
| | - Borvornwut Buranawat
- Department of Periodontics and Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
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Novel Dental Restorative Solutions for Natural Teeth and Implants. BIOENGINEERING (BASEL, SWITZERLAND) 2022; 9:bioengineering9120772. [PMID: 36550979 PMCID: PMC9774112 DOI: 10.3390/bioengineering9120772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022]
Abstract
The long-term survival of restorations in the oral cavity has always been one of the most significant challenges in modern dental practice [...].
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Singh RG, Lyons KM, Waddell JN, Li KC. Effect of thermocycling on the mechanical properties, inorganic particle release and low temperature degradation of glazed high translucent monolithic 3Y-TZP dental restorations. J Mech Behav Biomed Mater 2022; 136:105495. [PMID: 36208582 DOI: 10.1016/j.jmbbm.2022.105495] [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: 08/22/2022] [Revised: 09/27/2022] [Accepted: 09/27/2022] [Indexed: 11/24/2022]
Abstract
The influence of thermocycling on the surface deterioration of glazed monolithic high translucent 3Y-TZP dental restorations is still unclear. The purpose of this study therefore was to evaluate low temperature degradation (LTD), elemental release and surface degradation pattern after five years of simulated clinical time. A total of 123 specimens were prepared from second-generation high translucent 3Y-TZP as per ISO 6872:2015 standards (3 mm × 4 mm × 30 mm). They were classified as per glazing and thermocycling protocol; group CPT, DGT and IGT. Glaze materials were applied on one surface of the specimen and subjected to a thermocycling in artificial saliva, four-point bending test, inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Flexural strength, characteristic strength and Weibull modulus values were derived from four-point bending test. Descriptive fractographic analysis of surfaces was conducted to observe the surface degradation characteristics and point of failure. Control/no glaze with thermocycling (CPT = 621.5, 1σ = 117.0 MPa) presented higher flexural strength values compared to glaze I with thermocycling (442.4, 1σ = 45.4 MPa) and glaze II with thermocycling (534.3, 1σ = 46.3 MPa). Characteristic strength from Weibull analysis also observed higher values (669.2 MPa) for the control specimens. XRD analysis showed that monoclinic volume fraction (Vm = 11.0, 1σ = 0.7%) was highest in control specimens. Fractographic analysis suggested that there was no correlation between the point of failure initiation and mean flexural strength values. Glazing protected the high translucent 3Y-TZP surface against LTD during thermocycling but negatively impacted on the flexural strength.
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Affiliation(s)
- Raj Gaurav Singh
- Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, New Zealand.
| | - Karl Michael Lyons
- Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, New Zealand.
| | - John Neil Waddell
- Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, New Zealand.
| | - Kai Chun Li
- Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, New Zealand.
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Camargo B, Willems E, Jacobs W, Van Landuyt K, Peumans M, Zhang F, Vleugels J, Van Meerbeek B. 3D printing and milling accuracy influence full-contour zirconia crown adaptation. Dent Mater 2022; 38:1963-1976. [DOI: 10.1016/j.dental.2022.11.002] [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: 09/26/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022]
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Ranjzad H, Heidari B, Rad FO, Hendi A, Ghorbani Z. Evaluation of Effect of Zirconia Surface Treatment with CO 2 and Nd:YAG Lasers on Shear Bond Strength between Zirconia Frameworks and Porcelain Veneers. J Contemp Dent Pract 2022; 23:1026-1032. [PMID: 37073917 DOI: 10.5005/jp-journals-10024-3412] [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] [Indexed: 03/11/2023]
Abstract
AIM The purpose of this study was to evaluate the effect of zirconia surface treatment with CO2 and Nd:YAG laser on shear bond strength (SBS) between the zirconia framework and porcelain veneering. MATERIALS AND METHODS In this in vitro study, zirconia blocks were converted to 50 cubes and were divided randomly into 5 groups. After sintering (S), porcelain was applied in the control group. The surface treatment of the second to fifth groups included CO2 laser + (S), (S + CO2), Nd:YAG laser + (S), and (S + Nd), respectively. The SBS test was done, and data were analyzed by SPSS16 software. One sample was randomly chosen from each group and the type of failure was examined under scanning electron microscope (SEM). To compare the pairs of means, the least significant difference test was used and the determined significance level was 5% (p < 0.05). RESULTS The SBS of S + Nd group was significantly higher than the other ones, except for S + CO2 group. The least amount of SBS belonged to CO2 + S and the highest to S + Nd group. There were no significant differences between the other groups. CONCLUSION The bond strength of veneering porcelain to zirconia can be altered by surface treatments. It can also be affected by the type and sequence of laser and sintering application. The effect of Nd:YAG laser on the surface of zirconia, in order to create roughness to increase SBS, is better than that of CO2 laser. CLINICAL SIGNIFICANCE Surface treatment of zirconia by certain types of lasers reduces the chipping of the ceramic veneer and increases the success rate of all-ceramic restorations.
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Affiliation(s)
- Hadi Ranjzad
- Department of Prosthodontics, Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran
| | | | - Farzane Ostovar Rad
- Department of Maxillofacial Radiology, Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran
| | - Amirreza Hendi
- Department of Prosthodontics, Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran
| | - Zahra Ghorbani
- Department of Prosthodontics, Dental Sciences Research Center, School of Dentistry, Guilan University of Medical Sciences, Rasht, Iran, Phone: +0098 9120248577, +0098 1332119328; e-mail:
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LI Y, ZHAO J, SUN Z, LIN N, ZHENG Y. Three-dimensional fit of self-glazed zirconia monolithic crowns fabricated by wet deposition. Dent Mater J 2022; 41:363-367. [DOI: 10.4012/dmj.2021-236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yuan LI
- School/Hospital of Stomatology, Zhejiang Chinese Medical University
| | - Jing ZHAO
- Stomatology Hospital of Zhejiang Chinese Medical University
| | - Zhe SUN
- Stomatology Hospital of Zhejiang Chinese Medical University
| | - Nengjie LIN
- Stomatology Hospital of Zhejiang Chinese Medical University
| | - Yuanna ZHENG
- School/Hospital of Stomatology, Zhejiang Chinese Medical University
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Cho MH, Seol HJ. Effect of Cooling Rate during Glazing on the Mechanical and Optical Properties of Monolithic Zirconia with 3 mol% Yttria Content. MATERIALS (BASEL, SWITZERLAND) 2021; 14:7474. [PMID: 34885629 PMCID: PMC8658760 DOI: 10.3390/ma14237474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 11/17/2022]
Abstract
Glazing is the final heat treatment process in the manufacturing of a monolithic zirconia prosthesis. Herein, the effect of cooling rate during zirconia glazing was investigated. A 3 mol% yttria-stabilized tetragonal zirconia polycrystal was glazed at the general cooling rate suggested by the manufacturer, as well as at higher and lower cooling rates, and the differences in flexural strength, hardness, optical properties, and crystal structure were evaluated. A higher cooling rate did not affect the flexural strength, hardness, grain size, optical properties, or crystal structure; however, the Weibull modulus decreased by 1.3. A lower cooling rate did not affect the flexural strength, optical properties, or crystal structure; however, the Weibull characteristic strength increased by 26.7 MPa and the Weibull modulus increased by 0.9. The decrease in hardness and the increase in grain size were statistically significant; however, the numerical differences were negligible. This study revealed that a lower cooling rate provides more reliable flexural strength. Therefore, glazing can proceed at a general cooling rate, which takes 3-4 min; however, glazing at a lower cooling rate will provide a more consistent flexural strength if desired, despite being time-consuming.
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Affiliation(s)
- Mi-Hyang Cho
- Department of Dental Lab, Wonkwang Health Science University, Iksan-si 54538, Jeonbuk-do, Korea;
| | - Hyo-Joung Seol
- Department of Dental Materials, Dental and Life Science Institute, School of Dentistry, Pusan National University, Yangsan-si 50612, Gyeongsangnam-do, Korea
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Zhou T, Wongpairojpanich J, Sareethammanuwat M, Lilakhunakon C, Buranawat B. Digital occlusal analysis of pre and post single posterior implant restoration delivery: A pilot study. PLoS One 2021; 16:e0252191. [PMID: 34214089 PMCID: PMC8253389 DOI: 10.1371/journal.pone.0252191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 04/09/2021] [Indexed: 11/18/2022] Open
Abstract
Objectives The purposes of this study were to analyze the effects of single posterior implant restorations delivery on the redistribution of bite force and to evaluate the changes in occlusal force distribution of prostheses and potential influencing factors on occlusion variation at different stages. Materials and methods Thirty-two single posterior restorations in 30 participants (18 women and 12 men aged 27 to 75 years) were placed into either a unilateral single-tooth defect (n = 17) or on either side of a bilateral teeth defects (n = 15). The bite force (%) of the prostheses, teeth and segments at the maximum intercuspation position (MIP) was evaluated using a T-scan at 5 stages (pre-placement, immediately following placement, and 2 weeks, 3 months, and 6 months post-placement). Results The occlusal force of implant-supported prostheses was significantly (P = .000) lower than those of the control natural teeth at the baseline, then no significant difference was found with that of the mesial teeth at 3 months, and finally it was significantly (P = .000) lower than that of the distal teeth at 6 months; meanwhile, it significantly (P = .008) increased by a mean of 2.04 times from 2 weeks (3.39 ± 2.61%) to 3 months (6.90 ± 4.77%), whereas no significant difference (P = .900) was found from 3 months (6.90 ± 4.77%) to 6 months (7.31 ± 4.60%). In addition, the bite force of the posterior segment on the restored side of both unilateral and bilateral gaps was significantly (P = .013,.001) improved by 3.31% and 6.83%, respectively, although the discrepancy in bite force significantly (P = .039) increased from an initial 3.52% to 5.02% for subjects with bilateral defects, accompanying increases in the proportion (15.38%) of the level III bilateral bite force deviation (P >.05). Conclusions Bite force and masticatory ability can be improved with the immediate delivery of a single posterior implant restoration. The bite force distributed on the implant prosthesis inevitably increases after placement of implant prostheses, a routine follow-up and occlusal evaluation are strongly needed.
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Affiliation(s)
- Ting Zhou
- Department of Periodontics & Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
- Department of Orthodontics, School of Stomatology, Kunming Medical University, Yunnan, China
| | - Jirapa Wongpairojpanich
- Department of Periodontics & Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
| | - Maytha Sareethammanuwat
- Department of Periodontics & Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
| | - Charukrit Lilakhunakon
- Department of Periodontics & Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
| | - Borvornwut Buranawat
- Department of Periodontics & Implant Dentistry, Faculty of Dentistry, Thammasat University, Phatum Thani, Thailand
- * E-mail:
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Abdulsatar AM, Hussein BMA, Mahmood AM. Effects of Different Laser Treatments on Some Properties of the Zirconia-Porcelain Interface. J Lasers Med Sci 2021; 12:e2. [PMID: 34084728 DOI: 10.34172/jlms.2021.02] [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] [Indexed: 11/09/2022]
Abstract
Introduction: This study was performed to compare the effect of Fractional CO2 laser or Q switched Nd:YAG laser of surface treatment on the shear bond strength of zirconia-porcelain interface. Methods: Fractional CO2 laser at 30 W, 2 ms, time interval 1 ms, distance between spots 0.3 mm, and number of scans is (4) or Q switched Nd:YAG laser at 30 J/mm2 and 10 Hz were used to assess the shear bond strength of zirconia to porcelain. Pre-sintered zirconia specimens were divided into three groups (n = 10) according to the surface treatment technique used: (a) untreated (Control) group; (b) CO2 group; (c) Nd:YAG group. All samples were then sintered and veneered with porcelain according to the manufacturer's instructions. Surface morphology was examined using a light microscope, the surface roughness test was done by the atomic force microscope (AFM), and the shear bond strength (SBS) test was done by a universal testing machine. After debonding following shear bond test, zirconia surfaces were examined under a light microscope to determine their fracture mode. Results: The Results of this study showed that the lowest SBS was recorded in the control group, and the highest SBS recorded in the Fractional CO2 group, followed by the Q switched Nd:YAG laser group, as well as an increase in surface roughness and change in the morphology and mode of failure in the experimental groups. Conclusion: This study shows that Fractional CO2 laser and Q switched Nd:YAG laser treatments significantly increase the bond strength than untreated zirconia.
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Affiliation(s)
| | - Basima M A Hussein
- Institute of Laser for Postgraduate Studies, University of Baghdad, Baghdad, Iraq
| | - Ali M Mahmood
- Institute of Laser for Postgraduate Studies, University of Baghdad, Baghdad, Iraq
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Rizonaki M, Jacquet W, Bottenberg P, Depla L, Boone M, De Coster PJ. Evaluation of marginal and internal fit of lithium disilicate CAD-CAM crowns with different finish lines by using a micro-CT technique. J Prosthet Dent 2021; 127:890-898. [PMID: 33541816 DOI: 10.1016/j.prosdent.2020.11.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 01/08/2023]
Abstract
STATEMENT OF PROBLEM Whether the precision of fit of computer-aided design and computer-aided manufacturing (CAD-CAM) complete crowns is affected by the finish line configuration is unclear. PURPOSE The purpose of this in vitro study was to evaluate the marginal and internal fit of CAD-CAM ceramic crowns made from lithium disilicate based on 3 different finish lines (rounded shoulder, chamfer, feather-edge). MATERIALS AND METHODS Thirty anterior lithium disilicate complete crowns (n=10 per finish line group) were fabricated by following a completely digital workflow based on digital scans made with the TRIOS scanner. The crowns were adhesively cemented on duplicate dies of the respective prepared Typodont teeth, and the marginal gap, absolute marginal discrepancy, and internal gap were evaluated by using microcomputed tomography (μCT). A total of 66 values were obtained for each specimen from sagittal and transaxial sections, and a rendering software program was used to calculate the volume of the cement gap for each specimen by means of 3D region growing. Two-way ANOVA, Tukey post hoc tests with Bonferroni correction, and the Kruskal-Wallis test were used to compare the values between the experimental groups (α=.05). RESULTS Marginal gap and absolute marginal discrepancy values were statistically significantly different between groups. In ascending order, marginal gap values were 23 ±14 μm for rounded shoulder, 54 ±28 μm for chamfer, and 96 ±36 μm for feather-edge finish lines. Absolute marginal discrepancy values were 96 ±34 μm for rounded shoulder, 124 ±37 μm for chamfer, and 157 ±34 μm for feather-edge finish lines. Internal gap values were 111 ±14 μm for feather-edge, 136 ±22 μm for chamfer, and 168 ±25 μm for rounded shoulder finish lines. The differences in cement volume between groups were not statistically significant (P=.200). CONCLUSIONS All 3 finish lines produced marginal gaps within the range of clinically accep table values. Lithium disilicate CAD crowns with a rounded shoulder finish line had the best marginal fit but the poorest internal fit, and lithium disilicate CAD crowns with a feather-edge finish line had the best internal fit but the poorest marginal fit.
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Affiliation(s)
- Maria Rizonaki
- Postgraduate student, Postgraduate Reconstructive Dentistry, Department of Reconstructive Dentistry, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Wolfgang Jacquet
- Professor, Oral Health Research Group ORHE, Faculty of Medicine and Pharmacy, VUB Vrije Universiteit Brussel, Brussels, Belgium; Professor, Department of Special Needs in Oral Health, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Peter Bottenberg
- Professor, Department of Oral Health Sciences, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium; Professor, Department of Educational Sciences EDWE-LOCI, Faculty of Psychology and Educational Sciences, VUB Vrije Universiteit Brussel, Brussels, Belgium
| | - Lennert Depla
- Undergraduate student, Master of Science in Dentistry, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Matthieu Boone
- Professor, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Peter J De Coster
- Professor, Department of Reconstructive Dentistry, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
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Gaziano P, Lorenzi C, Bianchi D, Monaldo E, Dolci A, Vairo G. Mechanical performance of Anatomic-Functional-Geometry dental treatments: A computational study. Med Eng Phys 2020; 86:96-108. [PMID: 33261740 DOI: 10.1016/j.medengphy.2020.10.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 11/28/2022]
Abstract
In this paper the biomechanical response of a novel dental preparation technique, referred to as the Anatomic-Functional-Geometry treatment (AFG), is investigated through a 3D nonlinear finite-element modelling approach. A comparative investigation against a standard technique employed in dental clinical practice is carried out, by simulating typical experimental mechanical tests and physiological functional conditions. Failure mechanisms of treated tooth models are investigated through a progressive damage formulation implemented via a displacement-driven incremental approach. Computational results clearly show that AFG-treated teeth, as a consequence of a more conservative morphological preparation of the tooth, are characterized by more effective crown-dentin loading transfer mechanisms, higher fracture strength levels and more homogeneous stress patterns than the standard-treated ones, thereby opening towards widespread clinical application.
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Affiliation(s)
- Pierfrancesco Gaziano
- Department of Civil Engineering and Computer Science (DICII), University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
| | - Claudia Lorenzi
- Department of Chemical Science and Technologies, University of Rome "Tor Vergata", Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Daniele Bianchi
- Mines Saint-Étienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U 1059 Sainbiose, Centre CIS, Saint-Étienne F - 42023, France
| | - Elisabetta Monaldo
- Department of Engineering, Roma Tre University, Via Vito Volterra 62, 00146 Rome, Italy
| | - Alessandro Dolci
- Department of Clinical Science and Translational Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133 Rome, Italy
| | - Giuseppe Vairo
- Department of Civil Engineering and Computer Science (DICII), University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy
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Juntavee N, Juntavee A, Kornrum S. Influence of Margin Designs on Crack Initiation of High Translucency Monolithic Zirconia Crowns. J Prosthodont 2020; 30:490-499. [PMID: 33009879 DOI: 10.1111/jopr.13269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2020] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Zirconia crowns often crack at the margin. This study determined the loads and the times at which cracks are initiated in high-translucency monolithic zirconia crowns with different margin designs. MATERIALS AND METHODS A total of 90 crowns were fabricated from Zirconia blanks. The fabricated crowns had different margin thicknesses (light-chamfer, CL and heavy-chamfer, CH ) and collar heights (no-collar, NC ; low-collar, LC ; high-collar, HC ). They were grouped as CL NC , CL LC , CL HC , CH NC , CH LC , and CH HC (15 crowns/group). The crowns were seated on a metal model and loaded vertically through round end punch (Φ = 10 mm) at 0.2 mm/min crosshead speed until cracks began to be seen. Videos of the crack initiation were recorded at the rate of 50 frames/second. Load-initiated cracks and durability time were compared for significant differences using analysis of variance. RESULTS The mean ± standard deviation values of load (N) and time (s) taken to initiate cracks were 3190 ±775, 212 ±47 for CL NC ; 2754 ±1109, 180 ±42 for CL LC ; 2887±832, 191±27 for CL HC ; 4082 ±896, 241 ±36 for CH NC ; 4180 ±1029, 220 ±28 for CH LC ; 4119 ±1124, 222 ±39 for CH HC . This indicates that the thickness of the margin has a significant influence on load-withstanding crack initiation capacity and durability time (p < 0.05). No significant impact of collar height was observed on either load-withstanding capacity or durability time (p > 0.05). No interaction was observed among these factors. CONCLUSION Heavy chamfer margin provided a stronger zirconia crown than the light chamfer margin, but both of them were capable of withstanding crack-initiated load higher than the theoretical maximum masticatory force. The presence or absence of a collar did not have any impact on the crack initiation. Fabrication of zirconia crowns with either a heavy or light chamfer margin and with or without the presence of a collar should be generated by considering the relevant emergence profile.
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Affiliation(s)
- Niwut Juntavee
- Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Apa Juntavee
- Division of Pediatric Dentistry, Department of Preventive Dentistry, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Sasiprapa Kornrum
- Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
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Impact of Coping Veneering Techniques on the Survival of Implant-Supported Zirconia-Based-Crowns Cemented to Hybrid-Abutments: An-In-Vitro Study. Bioengineering (Basel) 2020; 7:bioengineering7040117. [PMID: 32992792 PMCID: PMC7712862 DOI: 10.3390/bioengineering7040117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/14/2020] [Accepted: 09/20/2020] [Indexed: 11/17/2022] Open
Abstract
The objective of this study is to investigate the influence of veneering technique (hand-layering vs. milling) on the fracture resistance of bi-layer implant-supported zirconia-based hybrid-abutment crowns. Mandibular molar copings were anatomically designed and milled. Copings were then veneered by hand-layering (HL) (n = 20) and milling using the Cad-On technique (LD) (n = 20). Crowns were cemented to zirconia hybrid-abutments. Ten samples of each group acted as a control while the remaining ten samples were subjected to fatigue in a chewing simulator. Crowns were loaded between 50 and 100 N for 1.2 million cycles under simultaneous temperature fluctuation between 5 and 55 °C. Crowns were then subjected to static load a to fracture test. Data were statistically analysed using the one-way ANOVA. Randomly selected crowns from each group were observed under scanning electron microscopy to view fractured surfaces. Study results indicate that during fatigue, LD crowns had a 100% survival rate; while HL crowns had a 50% failure rate. Fracture resistance of LD crowns was statistically significantly higher than that of HL crowns at the baseline and after fatigue (p ≤ 0.05). However, fatigue did not cause a statistically significant reduction in fracture resistance in both LD and HL groups (p > 0.05). Copings fractured in the LD crowns only and the fracture path was different in both LD and HL groups. According to the results, it was concluded that milled veneer implant-supported hybrid-abutment crowns exhibit significantly higher fracture resistance, and better withstand clinical masticatory loads in the posterior region compared to the hand-layered technique. Also, fatigue application and artificial aging caused no significant strength reduction in both techniques. Clinical significance: Different veneering techniques and materials (hand-layering or milling) act differently to clinical forces and environment and may be prone to early chipping during service. Therefore, practitioners are urged to consider the appropriate veneering protocol for posterior implant-supported hybrid-abutment restorations.
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Effect of Marginal Designs on Fracture Strength of High Translucency Monolithic Zirconia Crowns. Int J Dent 2020; 2020:8875609. [PMID: 32831840 PMCID: PMC7421695 DOI: 10.1155/2020/8875609] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/04/2020] [Accepted: 07/14/2020] [Indexed: 11/18/2022] Open
Abstract
Introduction Monolithic zirconia is able to achieve certain aesthetic, but its durability in resisting fracture has been questioned, as fractures often originate from margins of restoration. This study determined fracture resistance of highly translucent monolithic zirconia crowns with different margin designs in terms of marginal thickness and collar height. Materials and Methods Zirconia blanks (Ceramill® Zolid HT+) were selected for the fabrication of zirconia crowns according to different designs, including varying margin thicknesses (light chamfer, CL; heavy chamfer, CH) and collar heights (no collar, NC; low collar, LC; high collar, HC), which resulted in CLNC, CLLC, CLHC, CHNC, CHLC, and CHHC groups (15 crowns each). The crowns were seated on a metal die and loaded vertically through round end punch (θ = 10 mm), contacting with inclined planes of cusp in a testing machine with crosshead speed of 0.2 mm/min until fracture. Videos with a rate of 50 frames/second were used to record fracture. Fracture load (N) and durable period (s) were compared for significant differences using ANOVA and Bonferroni test (α = 0.05). Results The mean ± sd of fracture load (N) and durable time (s) were 3211 ± 778 and 212 ± 47 for CLNC; 3041 ± 1370 and 188 ± 53 for CLLC; 2913 ± 828 and 192 ± 27 for CLHC; 4226 ± 905 and 245 ± 35 for CHNC; 4486 ± 807 and 228 ± 29 for CHLC; and 4376 ± 1043 and 227 ± 37 for CHHC. This indicated that marginal thickness had a significant influence on load-bearing capacity and durable time (p < 0.05). No significant impact of collar height was shown, either on load-bearing capacity or durable time (p > 0.05). No interaction between two factors was presented (p > 0.05). Conclusions Heavy chamfer margin provided stronger zirconia crown than light chamfer, but both were capable of withstanding fracture load higher than maximum masticatory force. Neither presence nor absence of collar indicated any impact on strength. Fabrication of zirconia crowns with either heavy or light chamfer margin and either presence or absence of collar, with the consideration of emergence profile, should be considered.
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15
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Han T, Chen K, Cao R, Zheng T, Chen Z, Zhang X, Yan X. Influence of post-core material and cement peculiarities on stress of post-cores under ultrasonic vibration: a three-dimensional finite element analysis. Int Endod J 2020; 53:1696-1704. [PMID: 32781493 DOI: 10.1111/iej.13388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 11/30/2022]
Abstract
AIM To analyse the effect of post-core, and cement materials and thickness of the cement lute on the stress in post-core systems under ultrasonic vibration at different frequencies and amplitudes using three-dimensional finite element analysis. METHODOLOGY Eight three-dimensional finite element models of a maxillary central incisor with post-cores were established. Two post-core materials (Au and Ni-Cr alloys), two cements (glass ionomer (GI) and zinc phosphate (ZP)) and two cement layer thicknesses (50 and 150 μm) were considered. Vibration loads were applied near the neck on the buccal side of the core at frequencies of 10-40 kHz and amplitudes of 10-50 μm. The maximum shear stress of the cement layer and maximum principal stress of the roots and their distributions were investigated. RESULTS The stresses on cements and roots increased with an increase in the frequency and amplitude of the vibration load and elastic modulus of the cements, and decreased with increasing thickness of the cement layer and elastic modulus of the post-core. Maximum cement stress was observed on the contralateral upper part of the loading side, whereas the maximum root stress was found on the ferrule where the load was applied. CONCLUSIONS In this simulated model, the frequency and amplitude of ultrasound needed to remove a post-core were positively related to the elastic modulus of the post-core and thickness of the cement layer and negatively related to the elastic modulus of the cements.
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Affiliation(s)
- T Han
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - K Chen
- Department of Endodontics, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - R Cao
- School of Stomatology, China Medical University, Shenyang, China
| | - T Zheng
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - Z Chen
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - X Zhang
- Center of Implant Dentistry, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
| | - X Yan
- The VIP Department, School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, China
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16
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Fahmi M, Giordano R, Pober R. Effect of time period on biaxial strength for different
Y‐TZP
veneering porcelains. J ESTHET RESTOR DENT 2020; 32:505-511. [DOI: 10.1111/jerd.12607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 01/16/2020] [Accepted: 05/18/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Mohammed Fahmi
- Restorative Sciences & Biomaterials departmentFaculty of Dentistry, Taif University Taif Saudi Arabia
| | - Russell Giordano
- Restorative Sciences & Biomaterials departmentBoston University Henry M. Goldman School of Dental Medicine, Boston University Boston Massachusetts USA
| | - Richard Pober
- Restorative Sciences & Biomaterials departmentBoston University Henry M. Goldman School of Dental Medicine, Boston University Boston Massachusetts USA
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17
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Almarza R, Ghassemieh E, Shahrbaf S, Martin N. The effect of crown fabrication process on the fatigue life of the tooth-crown structure. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 109:110272. [PMID: 32228995 DOI: 10.1016/j.msec.2019.110272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 10/01/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To compare the fatigue strength of lithium disilicate ceramic crowns when cemented as a compound structure, as a function of the manufacturing process and the type of ceramic variation. METHOD A typodont maxillary first premolar was prepared for an all-ceramic crown in accordance with the manufacturer's guidelines for monolithic ceramic crowns (IPS e. max®; Ivoclar-Vivadent, Liechtenstein). 60 dies were duplicated in a polymer with a Young's Modulus closely matched to dentine (Alpha die, Schütz GmbH). Three different crown fabrication techniques were used (n = 20): (i) Manually applied wax spacer and pressed-crown; (ii) digitally scanned preparation, CAD-printed wax-pattern (D76PLUS, Solidscape Inc.) and pressed-crown; (iii) digitally scanned preparation and machined-crown (CEREC-inLab® v3.6 Sirona GmbH). Resin-based cement (Variolink-II®, Ivoclar-Vivadent, Liechtenstein) was employed with a standardised mechanised cementation technique to apply a controlled axial cementation pressure [Universal testing machine (Lloyd LRX®, Lloyd Materials Testing Inc)]. The samples were subjected to fatigue life testing with a cyclic impact load of 453 N for 1.25 × 106cycles at 37C⁰ and 1 Hz frequency until the point of fracture. RESULT There was a significant difference in the resistance to fatigue loading between the three groups. Weibull probability analysis and the α and β Weibull parameters indicate that the teeth restored with a 'Manually-applied wax spacer and pressed-crown' are best able to resist cyclic fatigue loading. They also have the most uniform interface geometry. CONCLUSION Teeth restored with IPS e. max® crowns constructed by manually applied wax spacer and pressing, have a more uniform interface and a greater structural integrity than wax CAD-printed patterns or CAD-CAM crowns.
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Affiliation(s)
- R Almarza
- School of Dentistry of University of Sheffield, United Kingdom
| | - E Ghassemieh
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, United Kingdom.
| | - S Shahrbaf
- School of Dentistry of University of Sheffield, United Kingdom
| | - N Martin
- School of Dentistry of University of Sheffield, United Kingdom
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18
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Jang YS, Lim CH, Song UC, Noh HR, Joo KJ, Lee MH, Ahn SG, Bae TS. Debonding/crack initiation and flexural strengths of bilayered zirconia core and veneering ceramic composites. Dent Mater J 2020; 39:206-213. [PMID: 31694997 DOI: 10.4012/dmj.2018-321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The aim of this study was to evaluate the effects of the kinds of veneering ceramics and veneering methods on the debonding/crack initiation and 3-point flexural strengths in bilayered zirconia core and veneering ceramic composites. Zirconia block was used as core material, and Cerabien ZR and Lava Ceram for the layering technique and IPS e.max ZirPress and Amber LiSi-POZ for the heat pressing technique were used as veneering materials. Both debonding/crack initiation and 3-point flexural strengths of bilayered zirconia core and veneering ceramic composites as well as the bi-axial flexural strengths of veneering materials, were higher when using heat pressing technique than layering technique. It was identified that not only bonding strength between zirconia core and veneering materials but also the intrinsic strength of veneering ceramic should be high to prevent chipping of veneering material.
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Affiliation(s)
- Yong-Seok Jang
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 plus Program, School of Dentistry, Chonbuk National University
| | - Chung-Ha Lim
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 plus Program, School of Dentistry, Chonbuk National University
| | - Ung-Cheol Song
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 plus Program, School of Dentistry, Chonbuk National University
| | - Hyeong-Rok Noh
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 plus Program, School of Dentistry, Chonbuk National University
| | - Kyu-Ji Joo
- Department of Dental Technology, Gwangju Health College
| | - Min-Ho Lee
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 plus Program, School of Dentistry, Chonbuk National University
| | - Seung-Geun Ahn
- Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital.,Department of Prosthodontics, School of Dentistry, Chonbuk National University
| | - Tae-Sung Bae
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 plus Program, School of Dentistry, Chonbuk National University.,Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital
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19
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Saini H, Ackland DC, Gong L, Cheng, Röhrle O. Occlusal load modelling significantly impacts the predicted tooth stress response during biting: a simulation study. Comput Methods Biomech Biomed Engin 2020; 23:261-270. [PMID: 31965827 DOI: 10.1080/10255842.2020.1711886] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Computational models of the masticatory system can provide estimates of occlusal loading during (static) biting or (dynamic) chewing and therefore can be used to evaluate and optimize functional performance of prosthodontic devices and guide dental surgery planning. The modelling assumptions, however, need to be chosen carefully in order to obtain meaningful predictions. The objectives of this study were two-fold: (i) develop a computational model to calculate the stress response of the first molar during biting of a rubber sample and (ii) evaluate the influence of different occlusal load models on the stress response of dental structures. A three-dimensional finite element model was developed comprising the mandible, first molar, associated dental structures, and the articular fossa and discs. Simulations of a maximum force bite on a rubber sample were performed by applying muscle forces as boundary conditions on the mandible and computing the contact between the rubber and molars (GS case). The molar occlusal force was then modelled as a single point force (CF1 case), four point forces (CF2 case), and as a sphere compressing against the occlusal surface (SL case). The peak enamel stress for the GS case was 110 MPa and 677 MPa, 270 MPa and 305 MPa for the CF1, CF2 and SL cases, respectively. Peak dentin stress for the GS case was 44 MPa and 46 MPa, 50 MPa and 63 MPa for the CF1, CF2 and SL cases, respectively. Furthermore, the enamel stress distribution was also strongly correlated to the occlusal load model. The way in which occlusal load is modelled has a substantial influence on the stress response of enamel during biting, but has relatively little impact on the behavior of dentin. The use of point forces or sphere contact to model occlusal loading during mastication overestimates enamel stress magnitude and also influences enamel stress distribution.
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Affiliation(s)
- Harnoor Saini
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany
| | - David C Ackland
- Department of Biomedical Engineering, University of Melbourne, Victoria, Australia
| | - Lulu Gong
- School of Life Sciences and Technology, Tongji University, Shanghai, P.R. China
| | - Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Riddet Institute, Palmerston North, New Zealand
| | - Oliver Röhrle
- Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany.,Stuttgart Center of Simulation Science (SC SimTech), University of Stuttgart, Stuttgart, Germany.,Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA, Stuttgart, Germany
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20
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Tangsatchatham S, Juntavee N. Flexural strength of various types of computerized machinable ceramic veneered to yttria stabilized tetragonal zirconia polycrystalline ceramic upon different hybridized techniques. Clin Cosmet Investig Dent 2019; 11:61-71. [PMID: 31118822 PMCID: PMC6498980 DOI: 10.2147/ccide.s196297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/13/2019] [Indexed: 11/29/2022] Open
Abstract
Objective: This study determined biaxial flexural strength (BFS) of computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic veneered yttria-stabilized tetragonal zirconia poly-crystalline (Y-TZP) related with hybridization techniques and veneering materials. Material and methods: One hundred and twenty zirconia Y-TZP (0.8 mm thick and 12 mm in diameter) were prepared and randomly divided into eight groups, to be conjugated with different veneering ceramics: Vitabloc (Vm), e.max-CAD (Em), Vita-Suprinity (Vs) and Celtra-Duo (Cd), using different hybridized techniques, CAD-bonded (Cb) versus CAD-fused (Cf). BFS was determined using piston on three balls and analyzed for Weilbull reliability. An analysis of variance (ANOVA) and Bonferroni’s multiple comparisons were determined for significant differences. Microscopic structures were examined with scanning electron microscope (SEM), along with X-ray diffraction (XRD). Results: BFS (mean±sd; MPa), Weibull modulus (m), and characteristic strength (σo) of each group were 630.46±65.08, 10.72, and 659.47 for VmCb, 709.03±102.88, 7.67, and 753.03 for VmCf, 651.83±69.48, 9.47, and 685.82 for EmCb, 721.17±121.28, 5.99, and 777.04 for EmCf, 692.83±89.10, 8.56, and 731.87 for VsCb, 888.61±164.26, 5.80, and 959.08 for VsCf, 687.17±59.39, 12.85, and 713.95 for CdCb, and 953.12±134.30, 7.97, and 1010.65 for CdCf. The BFS of ceramic veneered zirconia were significantly affected by different veneering ceramics, hybridized techniques, and their interactions (p<0.05). Cd showed highest BFS, followed by Vs, Em and Vm respectively. Both Cd and Vs showed significant higher BFS than Em and VM (p<0.05). No significant difference of BFS between Cd and Vs and between Em and Vm were indicated (p>0.05). Cf technique showed significantly higher impact on BFS than Cb (p<0.05). Veneering zirconia with either Cd or Vs using Cf technique revealed significantly higher flexural strength than others combinations (p<0.05). Conclusions: Type of veneering ceramics and hybridization techniques affected BFS of ceramic veneered Y-TZP. Veneering zirconia with either Cd or Vs using Cf-process produced superior BFS.
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Affiliation(s)
- Siripim Tangsatchatham
- Division of Biomaterial and Prosthodontic Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Niwut Juntavee
- Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
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21
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Alammari MR, Abdelnabi MH, Swelem AA. Effect of total occlusal convergence on fit and fracture resistance of zirconia-reinforced lithium silicate crowns. Clin Cosmet Investig Dent 2018; 11:1-8. [PMID: 30643468 PMCID: PMC6318710 DOI: 10.2147/ccide.s193326] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Introduction Computer-aided design (CAD) and computer-aided manufacturing (CAM) monolithic crowns are gaining momentum. Limited evidence exists about the effect of tooth preparation total occlusal convergence (TOC) on marginal and internal gap distances in addition to load to fracture values. Aim The aim of this study was to evaluate, by microcomputed tomography (µCT), the influence of 12° and 20° TOC on marginal and internal adaptation of zirconia-reinforced lithium silicate (ZLS) crowns. Moreover, values of load to fracture with and without initial cyclic loading (CL) were compared. Material and methods Forty ZLS crowns were fabricated on dies with TOC of 12° and 20°, 20 crowns for each group. µCT was used to compare marginal and internal adaptation. Each specimen was measured at 140 points distributed on all tooth preparation surfaces for 2D gap distance assessment. 3D gap volume was also evaluated. Crowns were then cemented and divided into two subgroups; the first was stored in distilled water (no cyclic loading [NCL] subgroup), the second was subjected to CL (CL subgroup). Results Factorial repeated measures ANOVA followed by Bonferroni post hoc in addition to independent and dependent t-tests were used for statistical analysis. Marginal gap, absolute marginal discrepancy, and occlusal gap measurements showed significant differences between the measurement sites. Static load to fracture values showed significant differences between TOC groups for both NCL (P=0.011) and CL (P=0.025) subgroups. Conclusion An increase of TOC from 12° to 20° did not affect marginal and internal adaptation but resulted in higher values of load to fracture of ZLS crowns. CL simulating 1 year of service did not result in fatigue failure.
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Affiliation(s)
- Manal Rahma Alammari
- Oral and Maxillofacial Prosthodontic Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia,
| | - Mohamed Hussein Abdelnabi
- Oral and Maxillofacial Prosthodontic Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia, .,Removable Prosthodontic Department, Faculty of Dentistry, Minia University, Minia, Egypt
| | - Amal Ali Swelem
- Oral and Maxillofacial Prosthodontic Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia, .,Removable Prosthodontic Department, Faculty of Dentistry, Cairo University, Giza, Egypt
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22
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Śmielak B, Klimek L, Świniarski J. The Use of the FEM to Identify the Optimal Groove Dimensions Ensuring the Least Stressed Connection between a Zirconia Coping and Veneering Ceramic. MATERIALS 2018; 11:ma11122360. [PMID: 30477158 PMCID: PMC6317009 DOI: 10.3390/ma11122360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/15/2018] [Accepted: 11/21/2018] [Indexed: 02/04/2023]
Abstract
Background: To examine the influence of coping notches with varying groove widths and depths on the quality of the connection with ceramic. Methods: Ten rectangular sintered zirconia (3Y-TZP) samples were etched with a neodymium-yag laser Nd:YAG. Then, a profilometer was used to test the depths and spacing of the grooves. A notch profile was used to design the shapes and spacing of the grooves based on a finite element method (FEM) simulating zirconia. The following situations were simulated: an increase in groove width from 100% to 180% and depth from 40% and 80%; and a 40% depth and width. Results: An increase of 10% in the baseline width caused an insignificant reduction of the strain in the connection. A further increase in this dimension led to a 50% increase in strain with a 40% increase in width. An increase in the groove depth by 40% reduced the strain level by 13%, while an increase in the groove depth by 80% reduced the strain level by 22%. Simultaneous deepening and widening of the groove by 40% had no significant impact on the strain level. Conclusion: Maintaining the width of the groove bottom while increasing the depth offers fewer advantages than deepening and narrowing the groove bottom.
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Affiliation(s)
- Beata Śmielak
- Department of Dental Prosthetics, Medical University of Lodz, ul. Pomorska 251, 92-213 Lodz, Poland.
| | - Leszek Klimek
- Department of Materials Research, Institute of Materials Science and Engineering, University of Technology, ul. Stefanowskiego 1/15, 90-924 Lodz, Poland.
| | - Jacek Świniarski
- Department of Strength of Materials, University of Technology, ul. Stefanowskiego 1/15, 90-924 Lodz, Poland.
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Abstract
This study aimed to compare the effects of two surface-coating methods on the shear bond strength (SBS) of veneering ceramics (VC) to zirconia. Eighty pre-sintered zirconia cubes were randomly assigned into four study groups: E60S, E60P, N60S, and N60P. The zirconia surface was coated with a mixture of two types of glaze and alumina (<60 μm) by airbrush spraying and fine- brush painting. Surface roughness (Ra), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and SBS measurements (both initial and artificial aged conditions, including one month of water storage) were performed. The Ra results revealed significant differences among all groups (p < 0.001). The N60P group exhibited higher values of Ra (5.717 ± 0.20 µm) and SBS before and after water storage with values of 37.22 ± 4.954 MPa and 34.42 ± 3.977 MPa, respectively. The fine-brush coatings showed significantly higher SBS than that of airbrush coatings, in both initial and artificial conditions. Both coating methods and various coating materials (p < 0.001) produced a significant influence on VC-zirconia SBS. A significant correlation between Ra and SBS (Spearman’s rho = 0.808; p < 0.001) was found. The novel coating by fine-brush painting is a promising surface treatment and an easy technique for obtaining a rougher surface, which subsequently improves the bond strength to VC.
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24
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Effect of preparation design for all-ceramic restoration on maxillary premolar: a 3D finite element study. J Prosthodont Res 2018; 62:436-442. [DOI: 10.1016/j.jpor.2018.04.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 02/18/2018] [Accepted: 04/09/2018] [Indexed: 11/21/2022]
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25
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Röhrle O, Saini H, Lee PVS, Ackland DC. A novel computational method to determine subject-specific bite force and occlusal loading during mastication. Comput Methods Biomech Biomed Engin 2018; 21:453-460. [PMID: 30010417 DOI: 10.1080/10255842.2018.1479744] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The evaluation of three-dimensional occlusal loading during biting and chewing may assist in development of new dental materials, in designing effective and long-lasting restorations such as crowns and bridges, and for evaluating functional performance of prosthodontic components such as dental and/or maxillofacial implants. At present, little is known about the dynamic force and pressure distributions at the occlusal surface during mastication, as these quantities cannot be measured directly. The aim of this study was to evaluate subject-specific occlusal loading forces during mastication using accurate jaw motion measurements. Motion data was obtained from experiments in which an individual performed maximal effort dynamic chewing cycles on a rubber sample with known mechanical properties. A finite element model simulation of one recorded chewing cycle was then performed to evaluate the deformation of the rubber. This was achieved by imposing the measured jaw motions on a three-dimensional geometric surface model of the subject's dental impressions. Based on the rubber's deformation and its material behaviour, the simulation was used to compute the resulting stresses within the rubber as well as the contact pressures and forces on the occlusal surfaces. An advantage of this novel modelling approach is that dynamic occlusal pressure maps and biting forces may be predicted with high accuracy and resolution at each time step throughout the chewing cycle. Depending on the motion capture technique and the speed of simulation, the methodology may be automated in such a way that it can be performed chair-side. The present study demonstrates a novel modelling methodology for evaluating dynamic occlusal loading during biting or chewing.
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Affiliation(s)
- Oliver Röhrle
- a Institute of Applied Mechanics (Civil Engineering) , University of Stuttgart , Stuttgart , Germany.,b Cluster of Excellence for Simulation Technology (SimTech) , Stuttgart , Germany.,c Biomechatronic Systems , Fraunhofer Institute for Manufacturing Engineering and Automation IPA , Stuttgart , Germany
| | - Harnoor Saini
- a Institute of Applied Mechanics (Civil Engineering) , University of Stuttgart , Stuttgart , Germany
| | - Peter V S Lee
- d Department of Biomedical Engineering , The University of Melbourne , Parkville , Australia
| | - David C Ackland
- d Department of Biomedical Engineering , The University of Melbourne , Parkville , Australia
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26
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Candido LM, Miotto LN, Fais LMG, Cesar PF, Pinelli LAP. Mechanical and Surface Properties of Monolithic Zirconia. Oper Dent 2018; 43:E119-E128. [DOI: 10.2341/17-019-l] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SUMMARY
Purpose:
This study compared monolithic zirconia with conventional ones based on mean roughness (Ra), Vickers hardness (VHN), topography, transmittance, grain size, flexural strength (FS), Weibull modulus, and fractographic behavior.
Methods and Materials:
One monolithic (Prettau Zircon [PR group]) and two conventional (ICE Zirkon Transluzent [IZ group] and BloomZir [BL group]) zirconias were used. Specimens were tested using a profilometer, a microhardness tester, a scanning electron microscope, a spectrophotometer, and a Universal Testing Machine (EMIC DL 2000). Ra, VHN, grain size, and transmittance were analyzed using the Kruskal-Wallis test associated with Dunn test (α=0.05). FS was analyzed using one-way analysis of variance with the Tukey honestly significant difference test (α=0.05).
Results:
Means and standard deviations of roughness, after sintering (Ra, in μm) and VHN, were, respectively, 0.11 ± 0.01, 1452.16 ± 79.49, for the PR group; 0.12 ± 0.02, 1466.72 ± 91.76, for the IZ group; and 0.21 ± 0.08, 1516.06 ± 104.02, for the BL group. BL was statistically rougher (p<0.01) than PR and IZ. Hardness was statistically similar (p=0.30) for all groups. Means and standard deviations of FS (in MPa) were 846.65 ± 81.97 for the PR group, 808.88 ± 117.99 for the IZ group, and 771.81 ± 114.43 for the BL group, with no statistical difference (p>0.05). Weibull moduli were 12.47 for the PR group, 7.24 for the IZ group, and 6.31 for the BL group, with no statistical differences. The PR and BL groups had higher transmittance values and grain sizes than the IZ group (p<0.05). Although the BL group had some fractures that originated in the center of the tensile surface, fractographic analyses showed the same fracture pattern.
Conclusions:
All tested zirconia showed similar VHN, and the monolithic zirconia had similar roughness compared to one of the conventional zirconias. In addition, the monolithic zirconia showed similar flexural strength and Weibull modulus compared to the others even though its mean grain size was larger. The total transmittance of monolithic zirconia was higher than only one of the conventional zirconias tested.
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Affiliation(s)
- LM Candido
- Lucas Miguel Candido, PhD student, Department of Dental Materials and Prosthodontics, Araraquara Dental School, Universidade Estadual Paulista, Araraquara, Brazil
| | - LN Miotto
- Larissa Natiele Miotto, master degree, Department of Dental Materials and Prosthodontics, Araraquara Dental School, Universidade Estadual Paulista, Araraquara, Brazil
| | - LMG Fais
- Laiza Maria Grassi Fais, postdoctoral research, Department of Dental Materials and Prosthodontics, Araraquara Dental School, Universidade Estadual Paulista, Araraquara, Brazil
| | - PF Cesar
- Paulo Francisco Cesar, associate professor, Department of Biomaterials and Oral Biology, São Paulo Dental School, Universidade de São Paulo, São Paulo, Brazil
| | - LAP Pinelli
- Lígia Antunes Pereira Pinelli, associate professor, Department of Dental Materials and Prosthodontics, Araraquara Dental School, Universidade Estadual Paulista, Araraquara, Brazil
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Henriques B, Fabris D, Souza JCM, Silva FS, Carvalho Ó, Fredel MC, Mesquita-Guimarães J. Bond strength enhancement of zirconia-porcelain interfaces via Nd:YAG laser surface structuring. J Mech Behav Biomed Mater 2018. [PMID: 29524754 DOI: 10.1016/j.jmbbm.2018.02.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The aim of this study was to evaluate the effect of laser surface structuring on the bond strength of feldspar-based porcelain to zirconia, as compared to conventional sandblasting treatment. MATERIALS AND METHODS Thirty cylindrical zirconia substrates, previously sintered, were divided in three groups according to the type of surface conditioning: 1) sandblasting with 50 µm Al2O3; 2) laser structuring (Ø25 µm holes); and 3) laser structuring (Ø50 µm holes). Porcelain was injected onto the zirconia substrates. X-ray diffractometry (XRD) was used to evaluate the influence of the laser treatment on zirconia crystallographic phases. Shear bond strength test was performed. Micrographs using SEM were used to evaluate the zirconia surface after each surface treatment and to evaluate the fracture surface after the shear test. RESULTS The laser-structured groups presented the highest shear bond strength (65 ± 16 MPa and 65 ± 11 MPa, for the 25 µm and 50 µm holes, respectively). The sandblasting samples presented shear bond strength of 37 ± 16 MPa. XRD analysis showed that there was no phase transformation on the thermally affected surface due to laser action. Microcracks were created at some holes due to the high temperature gradient generated by laser. SIGNIFICANCE Laser structuring significantly increased (up to 75%) the shear bond strength of zirconia to veneering porcelain as compared to conventional sandblasting treatment. Therefore, laser structuring arises as a surface conditioning method for producing stronger and long lasting zirconia-porcelain interfaces.
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Affiliation(s)
- Bruno Henriques
- Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis, SC, Brazil; CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal; School of Dentistry (DODT), Postgraduate Program in Dentistry (PPGO), Federal University of Santa Catarina, Campus Trindade, 88040-900, Florianópolis, SC, Brazil.
| | - Douglas Fabris
- Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis, SC, Brazil
| | - Júlio C M Souza
- CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal; School of Dentistry (DODT), Postgraduate Program in Dentistry (PPGO), Federal University of Santa Catarina, Campus Trindade, 88040-900, Florianópolis, SC, Brazil
| | - Filipe S Silva
- CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
| | - Óscar Carvalho
- CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
| | - Márcio C Fredel
- Ceramic and Composite Materials Research Group (CERMAT), Federal University of Santa Catarina (UFSC), Campus Trindade, Florianópolis, SC, Brazil
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Jang YS, Noh HR, Lee MH, Lim MJ, Bae TS. Effect of Lithium Disilicate Reinforced Liner Treatment on Bond and Fracture Strengths of Bilayered Zirconia All-Ceramic Crown. MATERIALS 2018; 11:ma11010077. [PMID: 29303973 PMCID: PMC5793575 DOI: 10.3390/ma11010077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/22/2017] [Accepted: 01/03/2018] [Indexed: 11/23/2022]
Abstract
This study was performed to evaluate the effect of a lithium-disilicate spray-liner application on both the bond strength between zirconia cores and heat-pressed lithium-disilicate glass-ceramic veneers, and the fracture strength of all-ceramic zirconia crowns. A lithium-disilicate reinforced liner was applied on the surface of a zirconia core and lithium-disilicate glass-ceramic was veneered on zirconia through heat press forming. Microtensile and crown fracture tests were conducted in order to evaluate, respectively, the bonding strength between the zirconia cores and heat pressed lithium-disilicate glass-ceramic veneers, and the fracture strength of bilayered zirconia all-ceramic crowns. The role of lithium-disilicate spray-liner at the interface between zirconia and lithium-disilicate glass-ceramic veneers was investigated through surface and cross-sectional analyses. We confirmed that both the mean bonding strength between the zirconia ceramics and lithium-disilicate glass-ceramic veneers and the fracture strength of the liner-treated groups were significantly higher than those of the untreated groups, which resulted, on the one hand, from the chemical bonding at the interface of the zirconia and lithium-disilicate liner, and, on the other, from the existence of a microgap in the group not treated with liner.
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Affiliation(s)
- Yong-Seok Jang
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 Plus Program, School of Dentistry, Chonbuk National University, Jeonju 54896, Korea.
| | - Hyeong-Rok Noh
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 Plus Program, School of Dentistry, Chonbuk National University, Jeonju 54896, Korea.
| | - Min-Ho Lee
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 Plus Program, School of Dentistry, Chonbuk National University, Jeonju 54896, Korea.
| | - Myung-Jin Lim
- Department of Conservative Dentistry, School of Dentistry, Chonbuk National University, Jeonju 54896, Korea.
| | - Tae-Sung Bae
- Department of Dental Biomaterials, Institute of Biodegradable Materials, BK21 Plus Program, School of Dentistry, Chonbuk National University, Jeonju 54896, Korea.
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Figueiredo VMGD, Pereira SMB, Bressiani E, Valera MC, Bottino MA, Zhang Y, Melo RMD. Effects of porcelain thickness on the flexural strength and crack propagation in a bilayered zirconia system. J Appl Oral Sci 2017; 25:566-574. [PMID: 29069155 PMCID: PMC5806690 DOI: 10.1590/1678-7757-2015-0479] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 03/10/2017] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE This study evaluated the influence of porcelain (VM9, VITA Zahnfabrik, Germany) thickness on the flexural strength and crack propagation in bilayered zirconia systems (YZ, VITA Zahnfabrik, Germany). MATERIAL AND METHODS Thirty zirconia bars (20.0x4.0x1.0 mm) and six zirconia blocks (12.0x7.5x1.2 mm) were prepared and veneered with porcelain with different thickness: 1 mm, 2 mm, or 3 mm. The bars of each experimental group (n=10) were subjected to four-point flexural strength testing. In each ceramic block, a Vickers indentation was created under a load of 10 kgf for 10 seconds, for the propagation of cracks. RESULTS The results of flexural strength were evaluated by One-way ANOVA and Tukey's test, with a significance level of 5%. The factor "thickness of the porcelain" was statistically significant (p=0.001) and the l-mm group presented the highest values of flexural strength. The cracks were predominant among the bending specimens with 1 and 2 mm of porcelain, and catastrophic failures were found in 50% of 3-mm-thick porcelain. After the indentation of blocks, the most severe defects were observed in blocks with 3-mm-thick porcelain. CONCLUSION The smallest (1 mm) thickness of porcelain on the zirconia infrastructure presented higher values of flexural strength. Better resistance to defect propagation was observed near the porcelain/ zirconia interface for all groups. Higher flexural strength was found for a thinner porcelain layer in a bilayered zirconia system. The damage caused by a Vickers indentation near and far the interface with the zirconia shows that the stress profiles are different.
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Affiliation(s)
- Viviane Maria Gonçalves de Figueiredo
- Univ. Estadual Paulista, Instituto de Ciência e Tecnologia de São José dos Campos, Departamento de Materiais Odontológicos e Prótese, São Jose dos Campos, SP, Brasil
| | - Sarina Maciel Braga Pereira
- Univ. Estadual Paulista, Instituto de Ciência e Tecnologia de São José dos Campos, Departamento de Materiais Odontológicos e Prótese, São Jose dos Campos, SP, Brasil
| | - Eduardo Bressiani
- Univ. Estadual Paulista, Instituto de Ciência e Tecnologia de São José dos Campos, Departamento de Odontologia Restauradora, São Jose dos Campos, SP, Brasil
| | - Márcia Carneiro Valera
- Univ. Estadual Paulista, Instituto de Ciência e Tecnologia de São José dos Campos, Departamento de Odontologia Restauradora, São Jose dos Campos, SP, Brasil
| | - Marco Antônio Bottino
- Univ. Estadual Paulista, Instituto de Ciência e Tecnologia de São José dos Campos, Departamento de Materiais Odontológicos e Prótese, São Jose dos Campos, SP, Brasil
| | - Yu Zhang
- New York University, College of Dentistry, Biomaterials and Biomimetics, New York, USA
| | - Renata Marques de Melo
- Univ. Estadual Paulista, Instituto de Ciência e Tecnologia de São José dos Campos, Departamento de Materiais Odontológicos e Prótese, São Jose dos Campos, SP, Brasil
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Occlusal loading during biting from an experimental and simulation point of view. Dent Mater 2017; 34:58-68. [PMID: 29017762 DOI: 10.1016/j.dental.2017.09.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 09/15/2017] [Indexed: 11/20/2022]
Abstract
OBJECTIVES Occlusal loading during clenching and biting is achieved by the action of the masticatory system, and forms the basis for the evaluation of the functional performance of prosthodontic and maxillofacial components. This review provides an overview of (i) current bite force measurement techniques and their limitations and (ii) the use of computational modelling to predict bite force. A brief simulation study highlighting the challenges of current computational dental models is also presented. METHODS Appropriate studies were used to highlight the development and current bite force measurement methodologies and state-of-the-art simulation for computing bite forces using biomechanical models. RESULTS While a number of strategies have been developed to measure occlusal forces in three-dimensions, the use of strain-gauges, piezo-electric sensors and pressure sheets remain the most widespread. In addition to experimental-based measurement techniques, bite force may be also estimated using computational models of the masticatory system. Simulations of different bite force models clearly show that the use of three-dimensional force measurements enriches the evaluation of masticatory functional performance. SIGNIFICANCE Hence, combining computational modelling with three-dimensional force measurement techniques can significantly improve the evaluation of masticatory system and the functional performance of prosthodontic components.
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Zaher AM, Hochstedler J, Rueggeberg FA, Kee EL. Shear bond strength of zirconia-based ceramics veneered with 2 different techniques. J Prosthet Dent 2017; 118:221-227. [DOI: 10.1016/j.prosdent.2016.11.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 11/22/2016] [Accepted: 11/28/2016] [Indexed: 10/20/2022]
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Abstract
AIM To evaluate the resistance to axial forces of screw-retained monolithic high translucency zirconia (mHTZr) crowns compared with high translucency zirconia + feldspathic ceramic (HTZrC) crowns, low translucency zirconia + feldspathic ceramic (LTZrC) crowns, and metal-ceramic (MC) crowns, and also to observe the different fracture patterns between all groups. METHODS Twenty-four crowns were fabricated (6 of each group) and loaded until failure, using a testing machine with a 5.0-kN load cell. RESULTS Mean fracture results varied between 1092.7 N (LTZrC group) and 3439.7 N (mHTZr group). No statistically significant differences were found between the HTZrC, LTZrC, and MC groups. However, statistically significant differences (P < 0.05) were found between mHTZr and the other 3 groups. In the MC group, only chipping of the ceramic veneering occurred. In the mHTZr group, when fracturing occurred, it was of the whole structure. Finally, the LTZrC and HTZrC groups suffered both chipping and core fractures. CONCLUSION High translucency monolithic zirconia implant-supported crowns proved to be the toughest group studied when an axial force was applied. Fracture patterns varied between different materials, chipping being the most common occurrence.
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Miura S, Kasahara S, Yamauchi S, Egusa H. Three-dimensional finite element analysis of zirconia all-ceramic cantilevered fixed partial dentures with different framework designs. Eur J Oral Sci 2017; 125:208-214. [PMID: 28303598 DOI: 10.1111/eos.12342] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2017] [Indexed: 11/28/2022]
Abstract
The purpose of this study were: to perform stress analyses using three-dimensional finite element analysis methods; to analyze the mechanical stress of different framework designs; and to investigate framework designs that will provide for the long-term stability of both cantilevered fixed partial dentures (FPDs) and abutment teeth. An analysis model was prepared for three units of cantilevered FPDs that assume a missing mandibular first molar. Four types of framework design (Design 1, basic type; Design 2, framework width expanded buccolingually by 2 mm; Design 3, framework height expanded by 0.5 mm to the occlusal surface side from the end abutment to the connector area; and Design 4, a combination of Designs 2 and 3) were created. Two types of framework material (yttrium-oxide partially stabilized zirconia and a high precious noble metal gold alloy) and two types of abutment material (dentin and brass) were used. In the framework designs, Design 1 exhibited the highest maximum principal stress value for both zirconia and gold alloy. In the abutment tooth, Design 3 exhibited the highest maximum principal stress value for all abutment teeth. In the present study, Design 4 (the design with expanded framework height and framework width) could contribute to preventing the concentration of stress and protecting abutment teeth.
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Affiliation(s)
- Shoko Miura
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Shin Kasahara
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Shinobu Yamauchi
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Hiroshi Egusa
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan
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Effect of cement space on stress distribution in Y-TZP based crowns. Dent Mater 2016; 33:144-151. [PMID: 27890357 DOI: 10.1016/j.dental.2016.11.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/09/2016] [Accepted: 11/10/2016] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the stress distribution in bi-layered Y-TZP based crowns, according to the occlusal internal spacing between coping and abutment. METHODS Twelve premolar shaped Y-TZP copings were made by a CAD/CAM system and seated on an abutment to evaluate the internal fit at the occlusal third using micro-CT images. Considering the fitting range obtained experimentally, two 3D finite element models, consisting on bone tissue, a titanium implant, a zirconia abutment, cement layer and a bi-layered Y-TZP ceramic crown were constructed based on the micro-CT images, one corresponding to the thinnest cement space and other representing the specimen with the thickest cement space obtained experimentally. A 250N axial load was applied at the center of the occlusal surface of the crown (≅0,8mm2 area) and the first principal stress distribution was plotted and analyzed. RESULTS The greatest maximum principal stress occurred within the veneer ceramic right below the site of loading. The thickest cement model showed higher stress concentration at the center of occlusal surface of veneer and the center of occlusal internal surface of coping. SIGNIFICANCE Knowledge of stress distribution in ceramic crowns with different cement thicknesses will help clinicians to properly adjust crown fit, in seeking to avoid porcelain fractures.
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Dogan S, Raigrodski AJ, Zhang H, Mancl LA. Prospective cohort clinical study assessing the 5-year survival and success of anterior maxillary zirconia-based crowns with customized zirconia copings. J Prosthet Dent 2016; 117:226-232. [PMID: 27765396 DOI: 10.1016/j.prosdent.2016.07.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/02/2016] [Accepted: 07/05/2016] [Indexed: 10/20/2022]
Abstract
STATEMENT OF PROBLEM Studies evaluating anterior zirconia-based crowns are limited. PURPOSE The purpose of this prospective cohort clinical study was to assess the efficacy of zirconia-based anterior maxillary crowns with 0.3-mm customized copings at the cervical third and anatomical design elsewhere for up to 5 years of service. MATERIAL AND METHODS Eighteen participants who required an anterior maxillary crown (n=20) and who had signed a consent form approved by the University of Washington Health Sciences Center Human Subjects Division were enrolled. All preparations were standardized and prepared with an occlusal reduction of 1.5 to 2 mm and an axial reduction of 1 to 1.5 mm with 10 degrees of convergence angle. All finish lines were located on the sound tooth structure. Zirconia copings (Lava; 3M ESPE) were custom designed and milled to a 0.3-mm thickness at the cervical third and with selective thickness elsewhere to support the veneering porcelain. All restorations were luted with self-etching self-adhesive composite resin cement. Recall appointments were at 2 weeks, 6 months, and 12 months, and annually thereafter for 5 years. Modified Ryge criteria were used to assess the clinical fracture measurements, esthetics, marginal discoloration, marginal adaptation, radiographic proximal recurrent caries, and periapical pathoses. Descriptive statistics and 95% confidence intervals were used to describe the number and rate of complications and self-reported satisfaction with the crowns. RESULTS Twenty crowns with a mean follow-up of 58.7 months were evaluated. All crowns were rated as Alfa for fracture measurements (smooth surface, no fracture/chipping). Twelve crowns were rated esthetically as Romeo (no mismatch in color and shade) and 8 as Sierra (mismatch in color and shade within normal range). Twelve crowns were rated as Alfa (no visible evidence of crevice) and 8 as Bravo (visible evidence of crevice, no penetration of explorer) for marginal integrity. Nineteen were rated as Alfa (no discoloration) and 1 as Bravo (superficial discoloration) for marginal discoloration. No proximal caries or periapical pathoses were detected in 5 years. Participants were highly satisfied with their crowns after 5 years (mean ±SD: 9.8 ±0.4 on 0 to 10 scale). CONCLUSIONS Zirconia-based anterior maxillary crowns with customized copings with 0.3-mm thickness at the cervical third and zirconia margins performed well after 5 years of service.
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Affiliation(s)
- Sami Dogan
- Assistant Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.
| | - Ariel J Raigrodski
- Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash
| | - Hai Zhang
- Associate Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash
| | - Lloyd A Mancl
- Research Associate Professor, Department of Dental Public Health Sciences, University of Washington, Seattle, Wash
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Yamamoto LT, Rodrigues VA, Dornelles LS, Bottino MA, Valandro LF, Melo RMD. Low-Fusing Porcelain Glaze Application on 3Y-TZP Surfaces can Enhance Zirconia-Porcelain Adhesion. Braz Dent J 2016; 27:543-547. [DOI: 10.1590/0103-6440201601014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/08/2016] [Indexed: 11/22/2022] Open
Abstract
Abstract The aim of this study was to assess whether surface treatment improves zirconia-porcelain adhesion. The 3Y-TZP blocks were cut into squares, then polished and sintered. The zirconia surface treatments were performed as follows: no treatment (C); tribochemical silica coating (TBS); glaze application + hydrofluoric acid etching (GA); glaze application + hydrofluoric acid etching + silanization (GAS); deposition of silica nanofilm (NF). After treatments, veneering porcelain cylinders (3.3 x 3.3 mm) were built up on all specimens and fired. Then the specimens were subjected to thermal cycling (6000 cycles), and subjected to shear test. Fractures were analyzed by stereomicroscopy and SEM. Data were statistically analyzed by 1-way ANOVA and Tukey's test (5%). Zirconia-porcelain bond strength was affected by the ceramic surface treatments (p=0.0001). GA (19.5±3 MPa) and GAS (16.2±4 MPa) recorded the highest bond strength values, while control group had the lowest bond value (10.1±4 MPa). Adhesive failure of the samples predominated. Therefore, glaze application as 3Y-TZP treatment before veneering porcelain stratification may enhance zirconia-porcelain adhesion.
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Al-Wahadni A, Shahin A, Kurtz KS. Veneered Zirconia-Based Restorations Fracture Resistance Analysis. J Prosthodont 2016; 27:651-658. [PMID: 27163490 DOI: 10.1111/jopr.12490] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2016] [Indexed: 11/27/2022] Open
Abstract
PURPOSE To examine the effects of the veneering technique on the fracture resistance of zirconia-based crowns. MATERIALS AND METHODS An artificial tooth was prepared with a 1.2 mm heavy chamfer finish line and 8° taper. The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and divided according to the veneering technique into three groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. The crowns were cemented onto the testing dies using glass ionomer cement. The specimens were thermocycled (3000 cycles, 5° to 55°) then statically loaded (3.7 mm ball, 0.5 mm/min crosshead speed) until failure. Failed crowns were inspected using a magnifier, and failure patterns were identified. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results. RESULTS Means and standard deviations of failure loads were 1200 ± 306 N for the LV group, 857 ± 188 N for the OV group, and 638 ± 194 N for the DV group. The differences in failure loads were statistically significant between all groups (p < 0.05). Failure mode was predominantly cohesive for LV and OV groups, whereas it was predominantly adhesive for the DV group. CONCLUSIONS The LV group was superior to other groups in terms of fracture resistance, while the DV group was inferior to the other groups in the same aspect.
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Affiliation(s)
- Ahed Al-Wahadni
- Professor of Fixed Prosthodontics, Aesthetic Dentistry and Dental Implants, Faculty of Dentistry-Jordan University of Science and Technology, Irbid, Jordan
| | - Ahmad Shahin
- Private practice in prosthodontics, Amman, Jordan
| | - Kenneth S Kurtz
- Clinical Professor of Prosthodontics, Director-Division of Maxillofacial Prosthetics, Stony Brook University School of Dental Medicine, Stony Brook, NY
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Ha SR. Biomechanical three-dimensional finite element analysis of monolithic zirconia crown with different cement type. J Adv Prosthodont 2015; 7:475-83. [PMID: 26816578 PMCID: PMC4722152 DOI: 10.4047/jap.2015.7.6.475] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/26/2015] [Accepted: 12/07/2015] [Indexed: 11/26/2022] Open
Abstract
PURPOSE The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimensional finite element models. Four models were prepared according to different cement types (zinc phosphate, polycarboxylate, glass ionomer, and resin). A load of 700 N was applied vertically on the crowns (8 loading points). Maximum principal stress was determined. RESULTS Zinc phosphate cement had a greater stress concentration in the cement layer, while polycarboxylate cement had a greater stress concentration on the distal surface of the monolithic zirconia crown and abutment tooth. Resin cement and glass ionomer cement showed similar patterns, but resin cement showed a lower stress distribution on the lingual and mesial surface of the cement layer. CONCLUSION The test results indicate that the use of different luting agents that have various elastic moduli has an impact on the stress distribution of the monolithic zirconia crowns, cement layers, and abutment tooth. Resin cement is recommended for the luting agent of the monolithic zirconia crowns.
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Affiliation(s)
- Seung-Ryong Ha
- Department of Dentistry, Ajou University School of Medicine, Suwon, Republic of Korea
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Chantranikul N, Salimee P. Biaxial flexural strength of bilayered zirconia using various veneering ceramics. J Adv Prosthodont 2015; 7:358-67. [PMID: 26576251 PMCID: PMC4644776 DOI: 10.4047/jap.2015.7.5.358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 08/03/2015] [Accepted: 09/23/2015] [Indexed: 11/08/2022] Open
Abstract
PURPOSE The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (α=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. RESULTS It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. CONCLUSION From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength.
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Affiliation(s)
- Natravee Chantranikul
- Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Prarom Salimee
- Department of Prosthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
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Ramos GF, Monteiro EBC, Bottino M, Zhang Y, de Melo RM. Failure Probability of Three Designs of Zirconia Crowns. INT J PERIODONT REST 2015; 35:843-9. [PMID: 26509988 PMCID: PMC4671273 DOI: 10.11607/prd.2448] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study used a two-parameter Weibull analysis for evaluation of the lifespan of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. A sample of 60 first molars were selected and prepared for full-coverage crowns with three different designs (n = 20): traditional (crowns with zirconia framework covered with feldspathic porcelain), modified (crowns partially covered with veneering porcelain), and monolithic (full-contour zirconia crowns). All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100 N, 3 Hz) with a piston with a hemispherical tip (Ø = 6 mm) until the specimens failed or up to 2 × 10⁶ cycles. Every 500,000 cycles, the fatigue tests were interrupted and stereomicroscopy (10×) was used to inspect the specimens for damage. The authors performed Weibull analysis of interval data to calculate the number of failures in each interval. The types and numbers of failures according to the groups were: cracking (13 traditional, 6 modified) and chipping (4 traditional) of the feldspathic porcelain, followed by delamination (1 traditional) at the veneer/core interface and debonding (2 monolithic) at the cementation interface. Weibull parameters (β, scale; η, shape), with a two-sided confidence interval of 95%, were: traditional-1.25 and 0.9 × 10⁶ cycles; modified-0.58 and 11.7 × 10⁶ cycles; and monolithic-1.05 and 16.5 × 10⁶ cycles. Traditional crowns showed greater susceptibility to fatigue, the modified group presented higher propensity to early failures, and the monolithic group showed no susceptibility to fatigue. The modified and monolithic groups presented the highest number of crowns with no failures after the fatigue test. The three crown designs presented significantly different behaviors under fatigue. The modified and monolithic groups presented less probability of failure after 2 × 10⁶ cycles.
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Affiliation(s)
- G. Freitas Ramos
- Institute of Science and Technology, São Paulo State University (UNESP), Sao Jose dos Campos, Brazil
| | | | - M.A. Bottino
- Institute of Science and Technology, São Paulo State University (UNESP), Sao Jose dos Campos, Brazil
| | - Y. Zhang
- Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY 10010, USA
| | - R. Marques de Melo
- Institute of Science and Technology, São Paulo State University (UNESP), Sao Jose dos Campos, Brazil
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Murray CG. Advanced restorative dentistry - a problem for the elderly? An ethical dilemma. Aust Dent J 2015; 60 Suppl 1:106-13. [DOI: 10.1111/adj.12289] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- CG Murray
- Prosthodontic and Special Needs Dentistry; Private Practice; Melbourne Victoria Australia
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Effect of surface treatment and liner material on the adhesion between veneering ceramic and zirconia. J Mech Behav Biomed Mater 2014; 40:369-374. [DOI: 10.1016/j.jmbbm.2014.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 11/27/2022]
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The impact of luting agents and stiffness of implant-abutments on marginal adaptation, chipping, and fracture resistance of zirconia crowns. J Mech Behav Biomed Mater 2014; 39:279-91. [PMID: 25168974 DOI: 10.1016/j.jmbbm.2014.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 07/21/2014] [Indexed: 11/20/2022]
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45
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Kelly R, Fleming G, Hooi P, Palin W, Addison O. Biaxial flexure strength determination of endodontically accessed ceramic restorations. Dent Mater 2014; 30:902-9. [DOI: 10.1016/j.dental.2014.05.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 04/26/2014] [Accepted: 05/21/2014] [Indexed: 10/25/2022]
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46
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Anami LC, Lima JMDC, Corazza PH, Yamamoto ETC, Bottino MA, Borges ALS. Finite element analysis of the influence of geometry and design of zirconia crowns on stress distribution. J Prosthodont 2014; 24:146-51. [PMID: 24975118 DOI: 10.1111/jopr.12175] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2013] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To evaluate the influence of the geometry and design of prosthetic crown preparations on stress distribution in compression tests, using finite element analysis (FEA). MATERIALS AND METHODS Six combinations of 3D drawings of all-ceramic crowns (yttria-stabilized zirconia framework and porcelain veneer) were evaluated: F, flat preparation and simplified crown; FC, flat preparation and crown with contact point; FCM, flat preparation and modified crown; A, anatomical preparation and simplified anatomical crown framework; AC, anatomical preparation and crown with contact point; and ACM, anatomical preparation and modified crown. Bonded contact types at all interfaces with the mesh were assigned, and the material properties used were according to the literature. A 200 N vertical load was applied at the center of each model. The maximum principal stresses were quantitatively and qualitatively analyzed. RESULTS The highest values of tensile stress were observed at the interface between the ceramics in the region under the load application for the simplified models (F and A). Reductions in stress values were observed for the model with the anatomical preparation and modified infrastructure (ACM). The stress distribution in the flat models was similar to that of their respective anatomical models. CONCLUSIONS The modified design of the zirconia coping reduces the stress concentration at the interface with the veneer ceramic, and the simplified preparation can exert a stress distribution similar to that of the anatomical preparation at and near the load point, when load is applied to the center of the crown.
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Affiliation(s)
- Lilian Costa Anami
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, UNESP - Univ Estadual Paulista, São José dos Campos, Brazil
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Daou EE. The zirconia ceramic: strengths and weaknesses. Open Dent J 2014; 8:33-42. [PMID: 24851138 PMCID: PMC4026739 DOI: 10.2174/1874210601408010033] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/18/2013] [Accepted: 12/30/2013] [Indexed: 11/22/2022] Open
Abstract
Metal ceramic restorations were considered the gold standard as reliable materials. Increasing demand for esthetics
supported the commercialization of new metal free restorations. A growing demand is rising for zirconia prostheses.
Peer-reviewed articles published till July 2013 were identified through a Medline (Pubmed and Elsevier). Emphasizing
was made on zirconia properties and applications. Zirconia materials are able to withstand posterior physiologic loads.
Although zirconia cores are considered as reliable materials, these restorations are not problem free.
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Affiliation(s)
- Elie E Daou
- Department of Prosthodontics, Lebanese University, Beirut, Lebanon
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KIM KY, KWON TK, KANG TJ, YANG JH, LEE SJ, YEO IS. Digital veneering system enhances microtensile bond strength at zirconia coreveneer interface. Dent Mater J 2014; 33:792-8. [DOI: 10.4012/dmj.2014-168] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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49
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Hu J, Dai N, Bao Y, Gu W, Ma J, Zhang F. Effect of different coping designs on all-ceramic crown stress distribution: A finite element analysis. Dent Mater 2013; 29:e291-8. [DOI: 10.1016/j.dental.2013.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/09/2013] [Accepted: 09/02/2013] [Indexed: 10/26/2022]
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50
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Aktas G, Sahin E, Vallittu P, Ozcan M, Lassila L. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients. Int J Oral Sci 2013; 5:236-41. [PMID: 24158142 PMCID: PMC3967313 DOI: 10.1038/ijos.2013.66] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 11/19/2012] [Indexed: 11/09/2022] Open
Abstract
This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min(-1)). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)-(39.7±4.7) and (27.4±5.6)-(35.9±4.7) MPa with and without colouring, respectively) (P<0.001). While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering <1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.
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Affiliation(s)
- Guliz Aktas
- Department of Prosthodontics, Faculty of Dentistry, Hacettepe University, Ankara, Turkey
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