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Tomm AGF, Machado PS, Rosa LSD, Pereira GKR, Spazzin AO, Alessandretti R. Fatigue resistance of monolithic and multilayer zirconia crowns using veneer layering or CAD-on technique. Braz Dent J 2023; 34:150-159. [PMID: 38133089 PMCID: PMC10742353 DOI: 10.1590/0103-6440202305687] [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: 08/15/2023] [Accepted: 11/24/2023] [Indexed: 12/23/2023] Open
Abstract
This study aims to evaluate the fatigue resistance of monolithic zirconia (Yz) and multilayer ceramic structures using the CAD-on technique in different thicknesses. Fifty (N=50) standardized single crowns preparations were made in fiberglass-reinforced epoxy resin (NEMA grade G10), digitalized, and restorations were machined in CAD-CAM, composing 5 groups (n= 10): Control: 1.5 mm (milled zirconia framework + manual layered porcelain); Yz monolithic 1.5 mm; Yz monolithic 1.0 mm; CAD-on 1.5 mm; and CAD-on 1.0 mm (milled zirconia framework 0.5 mm thickness bonded by a low fuse ceramic to a milled lithium disilicate layer of 1.0 mm or 0.5 mm, respectively). The G10 bases were conditioned with 10% hydrofluoric acid; the crowns were air abraded with 110 μm alumina particles; and then luted onto each other with self-adhesive resin cement. A cyclic fatigue test was performed (initial load: 400N for 10,000 cycles, frequency of 20 Hz, step size of 200N) until failure, and the data was submitted to a survival statistical analysis. No failures were observed at Yz monolithic 1.5 mm. High and similar performance was observed for Cad-On groups and Yz monolithic 1.0 mm. The control group depicted the worst behavior. The Weibull modulus of CAD-on 1.5 mm was higher than the control while being similar to the other conditions. Both the monolithic systems and the CAD-on technique showed high and similar fatigue fracture behavior and survival rates, which were also higher than the control bilayer system. Both systems reduced the occurrence of delamination failures, making them suitable for clinical use.
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Affiliation(s)
| | - Pablo Soares Machado
- Post-Graduate Program in Oral Sciences, Center for Development of Advanced Materials, Division of Prosthodontics-Biomaterials, Federal University of Santa Maria (UFSM), Santa Maria, Brazil
| | - Lucas Saldanha da Rosa
- Post-Graduate Program in Oral Sciences, Center for Development of Advanced Materials, Division of Prosthodontics-Biomaterials, Federal University of Santa Maria (UFSM), Santa Maria, Brazil
| | - Gabriel Kalil Rocha Pereira
- Post-Graduate Program in Oral Sciences, Center for Development of Advanced Materials, Division of Prosthodontics-Biomaterials, Federal University of Santa Maria (UFSM), Santa Maria, Brazil
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Comparative Stress Evaluation between Bilayer, Monolithic and Cutback All-Ceramic Crown Designs: 3D Finite Element Study. PROSTHESIS 2021. [DOI: 10.3390/prosthesis3020017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Different all-ceramic crown designs are available to perform indirect restoration; however, the mechanical response of each model should still be elucidated. The study aims to evaluate the stress distribution in three different zirconia crown designs using finite element analysis. Different three-dimensional molar crowns were simulated: conventional bilayer zirconia covered with porcelain, a monolithic full-contour zirconia crown, and the cutback modified zirconia crown with porcelain veneered buccal face. The models were imported to the computer-aided engineering (CAE) software. Tetrahedral elements were used to form the mesh and the mechanical properties were assumed as isotropic, linear and homogeneous materials. The contacts were considered ideal. For the static structural mechanical analysis, 100 N occlusal load was applied and the bone tissue was fixed. Maximum principal stress showed that the stress pattern was different for the three crown designs, and the traditional bilayer model showed higher stress magnitude comparing to the other models. However, grayscale stress maps showed homogeneous stress distribution for all models. The all-ceramic crown designs affect the stress distribution, and the cutback porcelain-veneered zirconia crown can be a viable alternative to adequate function and esthetic when the monolithic zirconia crown cannot be indicated.
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Chen YC, Lin CL, Hou CH. Investigating inlay designs of class II cavity with deep margin elevation using finite element method. BMC Oral Health 2021; 21:264. [PMID: 33993877 PMCID: PMC8127254 DOI: 10.1186/s12903-021-01630-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/06/2021] [Indexed: 11/25/2022] Open
Abstract
Background This study evaluates the mechanical performance of deep margin elevation technique for carious cavities by considering the shape designs and material selections of inlay using a computational approach combined with the design of experiments method. The goal is to understand the effects of the design parameters on the deep margin elevation technique and provide design guidelines from the biomechanics perspective. Methods Seven geometric design parameters for defining an inlay’s shape of a premolar were specified, and the influence of cavity shape and material selection on the overall stress distribution was investigated via automated modelling. Material selection included composite resin, ceramic, and lithium disilicate. Finite element analysis was performed to evaluate the mechanical behavior of the tooth and inlay under a compressive load. Next, the analysis of variance was conducted to identify the parameters with a significant effect on the stress occurred in the materials. Finally, the response surface method was used to analyze the stress responses of the restored tooth with different design parameters. Results The restored tooth with a larger isthmus width demonstrated superior mechanical performance in all three types of inlay materials, while the influence of other design parameters varied with the inlay material selection. The height of the deep margin elevation layer insignificantly affected the mechanical performance of the restored tooth. Conclusions A proper geometric design of inlay enhances the mechanical performance of the restored tooth and could require less volume of the natural dentin to be excavated. Furthermore, under the loading conditions evaluated in this study, the deep margin elevation layer did not extensively affect the strength of the tooth structure. Supplementary Information The online version contains supplementary material available at 10.1186/s12903-021-01630-z.
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Affiliation(s)
- Yung-Chung Chen
- School of Dentistry and Institute of Oral Medicine, Medical College, National Cheng Kung University, Tainan, Taiwan, Republic of China.,Division of Prosthodontics, Department of Stomatology, National Cheng Kung University Hospital, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Chi-Lun Lin
- Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Republic of China.
| | - Chun-Hsien Hou
- Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Republic of China
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Schrader P, Kolling S, Schlenz MA, Wöstmann B, Schmidt A. Finite element simulation of fixed dental prostheses made from PMMA -Part II: Material modeling and nonlinear finite element analysis. Dent Mater J 2021; 40:894-902. [PMID: 33883350 DOI: 10.4012/dmj.2020-231] [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: 11/23/2022]
Abstract
Material characteristics can change significantly with increasing chewing velocity. As these in-vitro examinations are very time-consuming and cost-intensive, the application of finite element analysis (FEA) offers a suitable alternative for predicting the material behavior of complex specimen geometries under clinically relevant loads. Although FEA is applied within numerous dental investigations, there are only few studies available in which a nonlinear FEA is validated with real experiments. Therefore, the aim of the present study was to predict the mechanical behavior of a clinically close three-unit temporary bridge composed of polymethyl methacrylate (PMMA) in the left upper jaw with nonlinear FEA and to verify the prediction through validation experiments. In conclusion, simplifying assumptions of linear elastic material properties for polymeric materials should be avoided in FEA studies, because rate dependencies, stress relaxation and plastic flow are not considered. Additionally, precise preliminary investigations for material characterization are necessary.
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Affiliation(s)
- Peer Schrader
- Institute of Mechanics and Materials, Technische Hochschule Mittelhessen
| | - Stefan Kolling
- Institute of Mechanics and Materials, Technische Hochschule Mittelhessen
| | | | - Bernd Wöstmann
- Department of Prosthodontics, Dental Clinic, Justus-Liebig-University
| | - Alexander Schmidt
- Department of Prosthodontics, Dental Clinic, Justus-Liebig-University
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Alves DM, Cadore-Rodrigues AC, Prochnow C, Burgo TADL, Spazzin AO, Bacchi A, Valandro LF, Rocha Pereira GK. Fatigue performance of adhesively luted glass or polycrystalline CAD-CAM monolithic crowns. J Prosthet Dent 2020; 126:119-127. [PMID: 32636073 DOI: 10.1016/j.prosdent.2020.03.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/23/2020] [Accepted: 03/23/2020] [Indexed: 11/17/2022]
Abstract
STATEMENT OF PROBLEM Data comparing the fatigue performance of adhesively luted glass or polycrystalline ceramic systems for computer-aided design and computer-aided manufacturing (CAD-CAM) are scarce. PURPOSE The purpose of this in vitro study was to evaluate and compare the fatigue performance of monolithic crowns manufactured from glass or polycrystalline CAD-CAM ceramic systems adhesively luted to a dentin analog. MATERIALS AND METHODS Fifty-four pairs of standardized preparations of dentin analog (NEMA Grade G10) and simplified ceramic crowns of 1.5-mm thickness were obtained with 3 ceramic materials: lithium disilicate (LD) glass-ceramic (IPS e.max CAD); zirconia-reinforced lithium silicate (ZLS) glass-ceramic (Vita Suprinity); and translucent yttrium fully stabilized polycrystalline zirconia (Trans YZ) (Prettau Anterior). The simplified crowns (n=15) were adhesively cemented onto the preparations and subjected to step-stress fatigue test (initial load of 400 N, 20 Hz, 10 000 cycles, followed by 100-N increment steps until failure). Collected data (fatigue failure load [FFL] and cycles for failure [CFF]) were submitted to survival analysis with the Kaplan-Meier and Mantel-Cox post hoc tests (α=.05) and to Weibull analysis (Weibull modulus and its respective 95% confidence interval). Failed crowns were submitted to fractography analysis. The surface characteristics of the internal surface (roughness, fractal dimension) of additional crowns were accessed, and the occlusal cement thickness obtained in each luted system was measured. RESULTS Trans YZ crowns presented the highest values of FFL, CFF, and survival rates, followed by ZLS and LD (mean FFL: 1740 N>1187 N>987 N; mean CFF: 149 000>92 613>73 667). Weibull modulus and cement thickness were similar for all tested materials. LD presented the roughest internal surface, followed by ZLS (mean Ra: 226 nm>169 nm>93 nm). The LD and ZLS internal surfaces also showed higher fractal dimension, pointing to a more complex surface topography (mean fractal dimension: 2.242=2.238>2.147). CONCLUSIONS CAD-CAM monolithic crowns of Trans YZ show the best fatigue performance. In addition, ZLS crowns also showed better performance than LD crowns.
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Affiliation(s)
- Daniela Meira Alves
- Post-Graduate Program in Dentistry, School of Dentistry, Meridional Faculty, IMED, Passo Fundo, Rio Grande do Sul, Brazil
| | - Ana Carolina Cadore-Rodrigues
- PhD student, MSciD and PhD Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Catina Prochnow
- MSciD and PhD Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Thiago Augusto de Lima Burgo
- Adjunct Professor, Department of Physics, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Aloísio Oro Spazzin
- Professor, Post-Graduate Program in Dentistry, School of Dentistry, Meridional Faculty, IMED, Passo Fundo, Rio Grande do Sul, Brazil
| | - Ataís Bacchi
- Professor, Post-Graduate Program in Dentistry, School of Dentistry, Meridional Faculty, IMED, Passo Fundo, Rio Grande do Sul, Brazil
| | - Luiz Felipe Valandro
- Professor, MSciD and PhD Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil
| | - Gabriel Kalil Rocha Pereira
- Adjunct Professor, MSciD and PhD Post-Graduate Program in Oral Science (Prosthodontics Units), Faculty of Dentistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil.
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KURODA S, SHINYA A, GOMI H. Effect of frame design on the fracture strength of a zirconia crown and porcelain-faced crown. Dent Mater J 2019; 38:323-328. [DOI: 10.4012/dmj.2017-218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Soichi KURODA
- Department of Crown and Bridge, The Nippon Dental University, School of Life Dentistry at Tokyo
| | - Akikazu SHINYA
- Department of Crown and Bridge, The Nippon Dental University, School of Life Dentistry at Tokyo
- Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku
| | - Harunori GOMI
- Department of Crown and Bridge, The Nippon Dental University, School of Life Dentistry at Tokyo
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Thermal induced deflection of a porcelain-zirconia bilayer: Influence of cooling rate. Dent Mater 2019; 35:574-584. [PMID: 30738621 DOI: 10.1016/j.dental.2019.01.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 01/05/2019] [Accepted: 01/18/2019] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the thermal expansion of a porcelain (VM9) and tetragonal zirconia (Y-TZP) as well as the deflection upon re-heating and cooling of a bilayer fabricated from these two materials after slow and rapid cooling during initial fabrication. METHODS The coefficient of thermal expansion (CTE) of bulk porcelain and Y-TZP as well as bilayer beam deflection was measured with a novel non-contact optical dilatometer. The influence of cooling rate during initial fabrication of the porcelain-zirconia bilayer and the bulk porcelain during subsequent heating and cooling is investigated. Specimens were heated to 900°C in the dilatometer, well in excess of the glass transition temperature (Tg) and softening temperature (Ts) of the porcelain. RESULTS The thermal expansion of the porcelain above Tg exhibits a threefold increase in CTE over that observed below Tg. Observations of the bilayer deflection reflect the difference in the CTE of the component materials and enable Tg and Ts temperatures for the porcelain to be estimated. Initial cooling rate of the porcelain and porcelain-YTZP bilayer was found to have a profound influence on the subsequent response to slow reheating and cooling as well as the resultant residual deflection. SIGNIFICANCE The estimation of the residual stress and potential for chipping of porcelain-zirconia dental restorative systems should not be based solely on thermal expansion data measured below Tg.
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SIMÕES AC, MIRANDA JS, SOUZA RODAE, KIMPARA ET, LEITE FPP. Bond and topography evaluation of a Y-TZP ceramic with a superficial low-fusing porcelain glass layer after different hydrofluoric acid etching protocols. REVISTA DE ODONTOLOGIA DA UNESP 2018. [DOI: 10.1590/1807-2577.10118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Abstract Introduction Despite being one of the most studied ceramics today, zirconia still does not have a well-defined adhesion protocol. Objective Evaluate the influence of different etching times and hydrofluoric acid (HF) concentrations on the zirconia surface and bond strength between a vitrified Y-TZP ceramic and a resin cement. Materials and method The zirconia surface treatments were: sandblasting with silica-coated alumina (Co); glaze application + 5% HF etching for 5s (G5-5s), 10s (G5-10s) or 20s (G5-20s); glaze application + 10% HF etching for 5s (G10-5s), 10 (G10-10s) or 20s (G10-20s) . Then, cement cylinders (3.3 × 3.3 mm) were built up for shear bond test on all specimens. The specimens were subjected to 6000 thermal cycling before the test. Fractures were analyzed by stereomicroscope. Data were statistically analyzed by Kruskal-Wallis and Dunn statistical tests (5%). Extra samples of each group were made to obtain profilometry and scanning electron microscopy (SEM). Result Zirconia-cement bond strength was affected by the ceramic surface treatments (p = 0.001). G10-5s (2.71 MPa) recorded the highest bond strength values, followed by the Co (2.05 MPa) while G5 groups had the lowest bond value. Adhesive failure of the samples predominated. The image analysis revealed G5 groups seem to have a lower roughness when compared to groups treated by 10% HF. The creation of pores in the low-fusing porcelain glass layer surface occurred only when 10% HF was used. Conclusion The low-fusing porcelain glass layer application was able to overcome the sandblasting and obtain a greater adhesive bond to the resinous cement, however, only when 10% HF was used for an interval of 5 seconds.
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Dal Piva AM, Tribst JP, Gondim LD, Ribeiro IL, Campos F, Arata A, Souza RO. Y-TZP surface behavior under two different milling systems and three different accelerated aging protocols. ACTA ACUST UNITED AC 2018; 67:237-245. [PMID: 30499286 DOI: 10.23736/s0026-4970.18.04138-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND To evaluate the influence of aging and milling system on zirconia surface roughness (SR) and phase transformation. METHODS Eighty crowns were divided in two groups according to yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic milling system (CAD-Neodent or MAD-Zirkonzahn). The crowns were submitted to different aging protocols (N.=10): 1) no aging; 2) autoclaving; 3) pH cycling; or 4) thermocycling. Next, the samples were submitted to an optical profilometry analysis to determine differences in the SR (µm). An X-ray diffraction analysis (XRD) was performed to quantify the percentage of monoclinic phase transformation. SR data was analyzed by two-way ANOVA (α=0.5%). RESULTS Aging protocol (P=0.42) and milling system (P=0.08) had no influence on the SR. However, the number of monoclinic phases was influenced by the autoclaving and pH cycling. CONCLUSIONS The surface roughness of zirconia-based crowns was not influenced by low temperature degradation or milling system. Regarding the phase transformation, autoclaving and pH-cycling aging presented a monoclinic phase increase when compared to the control group and thermocycled groups.
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Affiliation(s)
- Amanda M Dal Piva
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, Brazil -
| | - João Paulo Tribst
- Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, Brazil
| | - Laísa D Gondim
- Federal University of Paraíba (UFPB), João Pessoa, Brazil
| | - Isabella L Ribeiro
- Department of Social Odontology, Federal University of Paraíba (UFPB), João Pessoa, Brazil
| | - Fernanda Campos
- Department of Dentistry, Paraíba State University (UEPB), Araruna, Brazil
| | - Anelyse Arata
- Nuclear and Energy Research Institute, National Nuclear Energy Commission (IPEN-CNEN/SP), São Paulo, Brazil
| | - Rodrigo O Souza
- Division of Prosthodontics, Department of Restorative Dentistry, Federal University of Federal University of Rio Grande do Norte (UFRN), Natal, Brazil
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Aranda Yus E, Cantarell JMA, Miñarro Alonso A. Comparison of the marginal fit of milled yttrium stabilized zirconium dioxide crowns obtained by scanning silicone impressions and by scanning stone replicas. J Adv Prosthodont 2018; 10:236-244. [PMID: 29930794 PMCID: PMC6004355 DOI: 10.4047/jap.2018.10.3.236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 01/06/2018] [Accepted: 02/27/2018] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To determine the discrepancy in monolithic zirconium dioxide crowns made with computer-aided design and computer-aided manufacturing (CAD/CAM) systems by comparing scans of silicone impressions and of master casts. MATERIALS AND METHODS From a Cr-Co master die of a first upper left molar, 30 silicone impressions were taken. The 30 silicone impressions were scanned with the laboratory scanner, thus obtaining 30 milled monolithic yttrium stabilized zirconium dioxide (YSZD) crowns (the silicone group). They were poured and the working models were scanned, obtaining 30 milled monolithic yttrium stabilized zirconium dioxide (YSZD) crowns (the plaster group). Three predetermined points were analyzed in each side of the crown (Mesial, Distal ,Vestibular and Palatal), and the marginal fit was evaluated with SEM (×600). The response variable is the discrepancy from the master model. A repeated measures ANOVA with two within subject factors was performed to study significance of main factors and interaction. RESULTS Mean marginal discrepancy was 22.42±35.65 µm in the silicone group and 8.94±14.69 µm in the plaster group. The statistical analysis showed significant differences between the two groups and also among the four aspects. Interaction was also significant (P=.02). CONCLUSION The mean marginal fit values of the two groups were within the clinically acceptable values. Significant differences were found between the groups according to the aspects studied. Various factors influenced the accuracy of digitizing, such as the design, the geometry, and the preparation guidance, as well as the texture, roughness and the color of the scanned material.
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Affiliation(s)
- Estefanía Aranda Yus
- Department of Prosthodontics, Faculty of Dentistry, Medicine Doctorate and Translational Research, University of Barcelona, Spain
| | | | - Antonio Miñarro Alonso
- Department of Genetics, Microbiology and Stadistics, Faculty of Biology, University of Barcelona, Spain
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Chu J, Bennani V, Aarts JM, Chandler N, Lowe B. The effect of different geometric shapes and angles on the fracture strength of IPS e.max computer-aided designed ceramic onlays: An in vitro study. J Conserv Dent 2018; 21:210-215. [PMID: 29674827 PMCID: PMC5890415 DOI: 10.4103/jcd.jcd_242_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Statement of Problem: The current ceramic onlay preparation techniques for cuspal areas involve the reduction of cusps following the cuspal anatomy and the removal of all sharp angulations. However, there is little research literature studying the effect of occlusal preparation angles. Furthermore, there is no recent literature on the effect of angulations on IPS e.max computer-aided designed (CAD) (e.max) ceramic onlays. Purpose: The purpose of this study is to investigate the effect of geometric cuspal angulation and different internal preparation angles on the fracture strength of e.max CAD ceramic onlays. Materials and Methods: Sharp (33° and 22°) and round (33° and 22°) preparations were tested, each group having 10 specimens. e.max ceramic onlays were milled, sintered, glazed, and then bonded onto geometric tooth models. Fracture strength was measured at the initial fracture with a universal testing machine. The load was applied laterally to the central fossa (2-point contact) and vertically to the cusp peak (1-point contact). Results: A reduced cuspal angulation of 22° resulted in a stronger ceramic onlay than a 33° angulation when laterally loaded (P = 0.001). The presence of sharp angles weakened the ceramic significantly for both the 22° preparation (P = 0.0013) and 33° preparation (P = 0.0304). Conclusion: This in vitro study found that preparation angles of 22° resulted in superior fracture strength during central fossa loading and that rounding the preparation resulted in significantly higher fracture strength when a cusp peak load was applied. When the cusp tip loading is applied, the preparation angle does not appear to influence the fracture strength.
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Affiliation(s)
- Jonathan Chu
- Department of Oral Rehabilitation, University of Otago Faculty of Dentistry, Dunedin, New Zealand
| | - Vincent Bennani
- Department of Oral Rehabilitation, University of Otago Faculty of Dentistry, Dunedin, New Zealand
| | - John M Aarts
- Department of Oral Rehabilitation, University of Otago Faculty of Dentistry, Dunedin, New Zealand
| | - Nicholas Chandler
- Department of Oral Rehabilitation, University of Otago Faculty of Dentistry, Dunedin, New Zealand
| | - Bronwyn Lowe
- Department of Applied Sciences, University of Otago, Dunedin, New Zealand
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Miura S, Kasahara S, Yamauchi S, Egusa H. Effect of finish line design on stress distribution in bilayer and monolithic zirconia crowns: a three-dimensional finite element analysis study. Eur J Oral Sci 2018; 126:159-165. [DOI: 10.1111/eos.12402] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Shoko Miura
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
| | - Shin Kasahara
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
| | - Shinobu Yamauchi
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
| | - Hiroshi Egusa
- Division of Molecular and Regenerative Prosthodontics; Tohoku University Graduate School of Dentistry; Sendai Miyagi Japan
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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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Calha N, Messias A, Guerra F, Martinho B, Neto MA, Nicolau P. Effect of geometry on deformation of anterior implant-supported zirconia frameworks: An in vitro study using digital image correlation. J Prosthodont Res 2016; 61:139-148. [PMID: 27667555 DOI: 10.1016/j.jpor.2016.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 07/20/2016] [Accepted: 08/27/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE To evaluate the effect of geometry on the displacement and the strain distribution of anterior implant-supported zirconia frameworks under static load using the 3D digital image correlation method. METHODS Two groups (n=5) of 4-unit zirconia frameworks were produced by CAD/CAM for the implant-abutment assembly. Group 1 comprised five straight configuration frameworks and group 2 consisted of five curved configuration frameworks. Specimens were cemented and submitted to static load up to 200N. Displacements were captured with two high-speed photographic cameras and analyzed with video correlation system in three spacial axes U, V, W. Statistical analysis was made using the nonparametric Mann-Whitney test. RESULTS Up to 150N loads, the vertical displacements (V axis) were statistically higher for curved frameworks (-267.83±23.76μm), when compared to the straight frameworks (-120.73±36.17μm) (p=0.008), as well as anterior displacements in the W transformed axis (589.55±64.51μm vs 224.29±50.38μm for the curved and straight frameworks), respectively (p=0.008). The mean von Mises strains over the surface frameworks were statistically higher for the curved frameworks under any load. CONCLUSION Within the limitations of this in vitro study, it is possible to conclude that the geometric configuration influences the deformation of 4-unit anterior frameworks under static load. The higher strain distribution and micro-movements of the curved frameworks reflect less rigidity and increased risk of fractures associated to FPDs.
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Affiliation(s)
- Nuno Calha
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal
| | - Ana Messias
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal; Centre for Mechanical Engineering, University of Coimbra, Portugal.
| | - Fernando Guerra
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal; Centre for Mechanical Engineering, University of Coimbra, Portugal
| | - Beatriz Martinho
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal
| | | | - Pedro Nicolau
- Department of Dentistry, Faculty of Medicine, University of Coimbra, Portugal; Centre for Mechanical Engineering, University of Coimbra, Portugal
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Anami LC, Lima JMC, Valandro LF, Kleverlaan CJ, Feilzer AJ, Bottino MA. Fatigue Resistance of Y-TZP/Porcelain Crowns is Not Influenced by the Conditioning of the Intaglio Surface. Oper Dent 2015; 41:E1-12. [PMID: 26266655 DOI: 10.2341/14-166-l] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The objective of this study was to investigate the effects of treatments of the intaglio surface of Y-TZP frameworks and luting agents on the fatigue resistance of all-ceramic crowns. METHODS A research design was chosen that attempted to reduce the likelihood of Hertzian cracking and to increase the probability of fracture initiation at the intaglio surface of the framework. Ninety identical preparations were machined in a dentin-like epoxy composite. Each preparation was restored with a Y-TZP framework made by a CAD/CAM system and veneered using feldspathic ceramic. Prior to cementation the intaglio surface of the ceramic was treated using one of four treatments: 1) cleaning with isopropyl alcohol; 2) application of an overglaze; 3) sandblasting with 125 μm aluminum oxide powder; and 4) sandblasting with 30 μm silica powder (CJ). One of three luting cements were used: 1) zinc phosphate; 2) glass ionomer; and 3) adhesive resin cement (PN). All three cements were tested against frameworks that were alcohol cleaned. Only the PN cements were tested against frameworks that had been sandblasted or glazed. Altogether, six groups of 15 specimens each were tested. Fatigue resistance was evaluated using stepwise loads at 1.4 Hz until failure: 5000 cycles at maximum load of 200 N, followed by 10,000 cycles at maximum loads of 800, 1000, 1200, and 1400 N. The cement thickness and failure modes were analyzed using a stereomicroscope and scanning electron microscopy. The results were analyzed using the Kaplan-Meier and Mantel-Cox log rank tests (5%), a one-way analysis of variance, Tukey multiple comparison test, and Weibull nonparametric test. RESULTS The predominant failure mode was chipping of the veneer. The crowns cemented with the adhesive resin cement exhibited chipping failure at higher mean loads than did crowns cemented with cements that usually do not bond strongly with dentin. When the adhesive cement was used, glazing and sandblasting intaglio framework surface treatments exhibited lower mean loads at chipping than did crowns whose intaglio surface was only cleaned with alcohol. Weibull analysis indicated that all specimens had a high ratio of late-to-early failures. CONCLUSIONS The fatigue experiment produced a pattern of failures that is very similar to that observed in clinical trials of Y-TZP crowns that are veneered with feldspathic porcelain. Crowns cemented with an adhesive resin cement exhibited chipping at a significantly higher mean load than those cemented with luting cements that do not usually form strong bonds with dentin. When cemented with adhesive resin cement, glazing or sandblasting the intaglio surface of the framework significantly reduced the mean fatigue loads at which chipping of veneers occurred, as compared to crowns whose intaglio surface had only been cleaned with alcohol. For this cement glazing or sandblasting the intaglio surface of the crown is not recommended.
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