Comparison of Fracture Strength and Fracture Modes of Zirconia Dental Ceramics Manufactured by Four Different CAD/CAM Systems

2011 ◽  
Vol 492 ◽  
pp. 30-34
Author(s):  
Dan Wang ◽  
Yuan Zhi Xu ◽  
Cheng Lin Lu ◽  
Qi Xiang Yang ◽  
Dong Sheng Zhang ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Critical Load ◽  
Fracture Strength ◽  
Fracture Load ◽  
Image Correlation ◽  
Zirconia Ceramic ◽  
Dental Ceramics ◽  
High Fracture ◽  
Fracture Modes ◽  
Cad Cam

Four sorts of zirconia dental ceramic systems including Cercon smart, Lava, Porcera, and CEREC 3 were studied to analyze fracture mechanism of different CAD/CAM zirconia ceramic. In each system, 12 sectioned specimens were prepared, 6 specimens were taken as controlled group, 6 as experimental group. Quasi-statistic loading before and after cyclic loading was applied at the veneer surface of the specimen. Deformation and crack initiation were monitored with camera in order to carry out digital image correlation (DIC) analysis. The results showed that median cracks were observed under the yielding zone. Specimens fractured along the core/veneer interface with the crack growth. No cone crack was confirmed and fracture only existed in veneer layer. After cyclic loading there were no significant differences for the four ceramic systems in terms of the critical load, while significant differences existed in terms of the fracture load. Both critical load and fracture load were lowered after cyclic loading. After cycling loading, the 4 tested zirconia CAD/CAM ceramic possess high fracture strength to meet the requirement for oral functions. The fracture modes of the four zirconia ceramic systems indicate that the strength of the veneer should be enhanced.

scholarly journals Fracture Strength of Zirconia and Alumina Ceramic Crowns Supported by Implants

2015 ◽  
Vol 41 (S1) ◽  
pp. 352-359 ◽  
Author(s):  
Tonino Traini ◽  
Roberto Sorrentino ◽  
Enrico Gherlone ◽  
Federico Perfetti ◽  
Patrizio Bollero ◽  
...  
Keyword(s):  
Fracture Strength ◽  
Glass Ceramic ◽  
Ceramic Materials ◽  
Fracture Load ◽  
Fractographic Analysis ◽  
Core Material ◽  
Loading Test ◽  
Significant Difference ◽  
Cad Cam ◽  
Ceramic Crowns

Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns.

scholarly journals Evaluation of Marginal/Internal Fit and Fracture Load of Monolithic Zirconia and Zirconia Lithium Silicate (ZLS) CAD/CAM Crown Systems

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6346
Author(s):  
Haneen A. Sadeqi ◽  
Mirza Rustum Baig ◽  
Mohammad Al-Shammari
Keyword(s):  
Fracture Strength ◽  
Fatigue Loading ◽  
Fracture Load ◽  
Lithium Silicate ◽  
Cad Cam ◽  
Monolithic Zirconia ◽  
Axial Compressive Strength ◽  
The Individual ◽  
Internal Fit ◽  
Mechanical Aging

Fit accuracy and fracture strength of milled monolithic zirconia (Zi) and zirconia-reinforced lithium silicate (ZLS) crowns are important parameters determining the success of these restorations. This study aimed to evaluate and compare the marginal and internal fit of monolithic Zi and ZLS crowns, along with the fracture load, with and without mechanical aging. Thirty-two stone dies acquired from a customized master metal molar die were scanned, and ceramic crowns (16 Zi Ceramill Zolid HT+ and 16 ZLS Vita Suprinity) were designed and milled. Absolute marginal discrepancies (AMD), marginal gaps (MG), and internal gaps (IG) of the crowns, in relation to the master metal die, were evaluated using x-ray nanotomography (n = 16). Next, thirty-two metal dies were fabricated based on the master metal die, and crowns (16 Zi; 16 ZLS) cemented and divided into four groups of eight each; eight Zi with mechanical aging (MA), eight Zi without mechanical aging (WMA), eight ZLS (MA), and eight ZLS (WMA). Two groups of crowns (Zi-MA; ZLS-MA) were subjected to 500,000 mechanical cycles (200 ± 50 N, 10 Hz) followed by axial compressive strength testing of all crowns, until failure, and the values were recorded. Independent sample t tests (α = 0.05) revealed no significant differences between Zi and ZLS crowns (p > 0.05); for both internal and marginal gaps, however, there were significant differences in AMD (p < 0.005). Independent samples Mann–Whitney U and Kruskal–Wallis tests revealed significant differences between the two materials, Zi and ZLS, regardless of fatigue loading, and for the individual material groups based on aging (α = 0.05). Multiple comparisons using Bonferroni post-hoc analysis showed significant differences between Zi and ZLS material groups, with or without aging. Within the limitations of this study, the ZLS crown fit was found to be on par with Zi, except for the AMD parameter. As regards fracture resistance, both materials survived the normal range of masticatory forces, but the Zi crowns demonstrated greater resistance to fracture. The monolithic Zi and ZLS crowns seem suitable for clinical application, based on the fit and fracture strength values obtained.

scholarly journals Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

2013 ◽  
Vol 5 (2) ◽  
pp. 92 ◽  
Author(s):  
Taek-Ka Kwon ◽  
Hyun-Soon Pak ◽  
Jae-Ho Yang ◽  
Jung-Suk Han ◽  
Jai-Bong Lee ◽  
...  
Keyword(s):  
Fracture Strength ◽  
Zirconia Ceramic ◽  
Strength Analysis ◽  
Cad Cam ◽  
Ceramic Crowns

scholarly journals Fracture Load of Metal, Zirconia and Polyetheretherketone Posterior CAD-CAM Milled Fixed Partial Denture Frameworks

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 959
Author(s):  
Verónica Rodríguez ◽  
Celia Tobar ◽  
Carlos López-Suárez ◽  
Jesús Peláez ◽  
María J. Suárez
Keyword(s):  
Computer Aided Design ◽  
Testing Machine ◽  
Fracture Load ◽  
Fracture Pattern ◽  
Bending Test ◽  
Weibull Statistics ◽  
Promising Alternative ◽  
Computer Aided ◽  
Cad Cam ◽  
Group 2

The aim of this study was to investigate the load to fracture and fracture pattern of prosthetic frameworks for tooth-supported fixed partial dentures (FPDs) fabricated with different subtractive computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Thirty standardized specimens with two abutments were fabricated to receive three-unit posterior FDP frameworks with an intermediate pontic. Specimens were randomly divided into three groups (n = 10 each) according to the material: group 1 (MM)—milled metal; group 2 (L)—zirconia; and group 3 (P)—Polyetheretherketone (PEEK). The specimens were thermo-cycled and subjected to a three-point bending test until fracture using a universal testing machine (cross-head speed: 1 mm/min). Axial compressive loads were applied at the central fossa of the pontics. Data analysis was made using one-way analysis of variance, Tamhane post hoc test, and Weibull statistics (α = 0.05). Results: Significant differences were observed among the groups for the fracture load (p < 0.0001). MM frameworks showed the highest fracture load values. The PEEK group registered higher fracture load values than zirconia samples. The Weibull statistics corroborated these results. The fracture pattern was different among the groups. Conclusions: Milled metal provided the highest fracture load values, followed by PEEK, and zirconia. However, all tested groups demonstrated clinically acceptable fracture load values higher than 1000 N. PEEK might be considered a promising alternative for posterior FPDs.

scholarly journals Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3103
Author(s):  
Laurent Gremillard ◽  
Agnès Mattlet ◽  
Alexandre Mathevon ◽  
Damien Fabrègue ◽  
Bruno Zberg ◽  
...  
Keyword(s):  
Dental Implants ◽  
Fracture Load ◽  
Accelerated Ageing ◽  
Dental Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dental Restorations ◽  
Different Temperatures ◽  
Mechanical Performances ◽  
Kinetics Of

Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation.

Competing fracture modes in brittle materials subject to concentrated cyclic loading in liquid environments: Bilayer structures

2005 ◽  
Vol 20 (10) ◽  
pp. 2792-2800 ◽  
Author(s):  
Sanjit Bhowmick ◽  
Yu Zhang ◽  
Brian R. Lawn
Keyword(s):  
Cyclic Loading ◽  
Driving Forces ◽  
Plate Thickness ◽  
Brittle Materials ◽  
Illustrative Case ◽  
Initial Growth ◽  
Tensile Stresses ◽  
Fracture Modes ◽  
Plate Flexure ◽  
Radial Cracks

A preceding study of the competition between fracture modes in monolithic brittle materials in cyclic loading with curved indenters in liquid environments is here extended to brittle layers on compliant substrates. The fracture modes include outer and inner cone cracks and radial cracks that initiate from the near-contact zone and penetrate downward. Outer cone cracks are driven by stresses from superposed Hertzian and plate flexure fields; inner cone cracks also grow within these fields but are augmented by mechanical driving forces from hydraulic pumping into the crack fissures. Radial cracks are augmented by mechanical driving forces from developing quasiplasticity zones beneath the indenter. Basically, the crack-growth rates are governed by a crack velocity relation. However, the hydraulic and quasiplastic mechanical forces can cumulate in intensity with each cycle, strongly enhancing fatigue. Plate flexure generates compressive stresses at the top surface of the brittle layer, somewhat inhibiting the initiation, and tensile stresses at the lower surface, strongly enhancing the far-field propagation. The tensile stresses promote instability in the crack propagation, resulting in through-thickness penetration (failure). Experiments on a model bilayer system consisting of glass plates bonded to thick polycarbonate bases are presented as an illustrative case study. In situ observations of the crack evolution from initial growth to failure reveal that each fracture mode can dominate under certain test conditions, depending on plate thickness, maximum load, and sphere radius. Implications concerning the failure of practical layer systems, notably dental crowns, are discussed.

The Effect of Thickness on the Fracture Strength and Failure Modes of Zirconia Crowns

2016 ◽  
Vol 697 ◽  
pp. 629-632
Author(s):  
Li Xian Zhang ◽  
Rui Li ◽  
Yu Niu ◽  
Yu Xiao Liu
Keyword(s):  
Fracture Strength ◽  
Failure Modes ◽  
Statistical Significance ◽  
Dental Practice ◽  
Significant Difference ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Different Thickness

To explore the effect of thickness on the fracture strength and failure modes of zirconia crowns, four crown models with different thickness (1.2 mm, 1.0 mm, 0.8 mm, 0.6 mm) with the same shape were designed by Dental Designer software in CAD/CAM system. They were manufactured to 40 zirconia crowns by CAM carving machine. The fracture strength and the failure modes of each crown was measured, while porcelain fused to metal (PFM) crowns as control. The average fracture strength of different zirconia crowns were recorded as below: 1308.38 ± 111.38 N (Group 0.6 mm), 1841.60 ± 68.21 N (Group 0.8 mm), 2429.88 ± 315.03 N (Group 1.0 mm), 3068.31 ± 233.88 N (Group 1.2 mm). There was no significant difference between Group 1.0 mm and Group 1.2 mm (P > 0.05), and statistical significance was obtained among every other two groups (P < 0.05). The failure modes of different thickness zirconium crowns are similar. There are more broken pieces from thicker crowns compared to thinner ones. It is concluded that the thickness can influence the fracture strength of zirconia crown. With the increase of the thickness, the fracture strength of the zirconium crowns also increases. We recommend zirconia crowns thicker than or at least 1.0 mm in dental practice.

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