The effect of different aging protocols on the flexural strength and phase transformations of two monolithic zirconia ceramics

Introduction: The aim of the present study was to investigate how different aging protocols can affect the flexural strength and phase transformations of yttrium-stabilized zirconia ceramics (Y-TZP) for monolithic restorations. Materials and methods: Bar-shaped specimens from two zirconia ceramics bars were divided into three groups: a. no treatment (c), b. aging in an autoclave (a), and c. thermal cycling (t). The flexural strength was determined by the 3-point bending test and statistical analysis was performed to determine significant differences ( p< 0.05). Weibull statistics was used to analyze the dispersion of strength values while surface microstructural analysis was performed through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Results: Aging did not significantly affect the flexural strength but differences were recorded between the two groups, with group A presenting higher strength values and m-phase percentages. Conclusions: The observed differences between the two ceramics could be attributed to variations in composition and processing.

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Biaxial flexural strength and phase transformation characteristics of dental monolithic zirconia ceramics with different sintering durations: An in vitro study

Journal of Prosthetic Dentistry ◽

10.1016/j.prosdent.2021.04.003 ◽

2021 ◽

Author(s):

Rukiye Durkan ◽

Gonca Deste Gökay ◽

Hatice Şimşek ◽

Burak Yilmaz

Keyword(s):

Phase Transformation ◽

Flexural Strength ◽

In Vitro Study ◽

Vitro Study ◽

Zirconia Ceramics ◽

Biaxial Flexural Strength ◽

Monolithic Zirconia

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Evaluation of the flexural strength and surface roughness of dental material after immersion in coffee

Research Society and Development ◽

10.33448/rsd-v10i3.12486 ◽

2021 ◽

Vol 10 (3) ◽

pp. e30510312486

Author(s):

Patrícia Capellato ◽

Ana Paula Rosifini Alves Claro

Keyword(s):

Surface Roughness ◽

Flexural Strength ◽

Testing Machine ◽

Dental Material ◽

Bending Test ◽

Control Group ◽

Test Surface ◽

Physiological Serum ◽

Group A ◽

Group B

This study was done in order to evaluate the changes in flexural strength and surface roughness in dental material restorations after immersion in coffee. Bars specimens (2mm x 2mm x 25 mm) of Z100 3M/ESPE were made according to ISO 4049 using aluminum molds. After curing, the specimens were then randomly divided into five groups and conditioned at 37°C in physiological serum. In all groups, except control, samples were immersed in coffee for ten minutes daily. In group A, the samples were immersed in coffee. For group B, after to be immersed in coffee, samples were immersed in distilled water for one minute. For group C, samples were immersed in mouthwash for one minute. For group D, samples were brushing for ten minutes, with load of 250g and 4250 cycles after all treatments the samples were stored in physiological serum again. In control group, samples were only stored in physiological serum. The five groups were then divided into 2 subgroups according storage time, six and nine weeks, respectively. Flexural strength was determined using three point bending test in a universal testing machine. All the tests were carried out at a room temperature and samples were maintained in physiological serum during the test. Surface roughness measurements were made using a surface roughness tester. All data were analyzed using one-way analysis of variance (ANOVA) followed by Dunnet tests. The ANOVA indicated no difference in the means of surface roughness and significant was observed for flexural strength between control group and one group (coffee).

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Influence of grinding procedures on the flexural strength of zirconia ceramics

Brazilian Dental Journal ◽

10.1590/s0103-64402010000600008 ◽

2010 ◽

Vol 21 (6) ◽

pp. 528-532 ◽

Cited By ~ 17

Author(s):

Ufuk İşerı ◽

Zeynep Özkurt ◽

Ender Kazazoğlu ◽

Davut Küçükoğlu

Keyword(s):

Flexural Strength ◽

High Speed ◽

Testing Machine ◽

Fracture Load ◽

Bending Test ◽

Control Group ◽

Zirconia Ceramics ◽

Significance Level ◽

Universal Testing ◽

Short Time

The surface of zirconia may be damaged during grinding, influencing the mechanical properties of the material. The purpose of this study was to compare the flexural strength of zirconia after different grinding procedures. Twenty bar-type zirconia specimens (21 x 5 x 2 mm) were divided into 4 groups and ground using a high-speed handpiece or a low-speed straight handpiece until the bars were reduced 1 mm using two different grinding times: continuous grinding and short-time grinding (n=5). Control specimens (n=5) were analyzed without grinding. The flexural strengths of the bars were determined by using 3-point bending test in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture load (N) was recorded, and the data were analyzed statistically by the Kruskal Wallis test at a significance level of 0.05. In the test groups, high-speed handpiece grinding for a short time had produced the highest mean flexural strength (878.5 ± 194.8 MPa), while micromotor continuous grinding produced the lowest mean flexural strength (733.8 ± 94.2 MPa). The control group was the strongest group (928.4 ± 186.5 MPa). However, there was no statistically significant differences among the groups (p>0.05). Within the limitations of the study, there was no difference in flexural strength of zirconia specimens ground with different procedures.

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A comparative study of biaxial flexural strength and Vickers microhardness of different zirconia materials: Effect of glazing and thermal cycling

Brazilian Dental Science ◽

10.14295/bds.2015.v18i2.1109 ◽

2015 ◽

Vol 18 (2) ◽

pp. 19 ◽

Cited By ~ 4

Author(s):

Esra Salihoglu Yener ◽

Mutlu Ozcan ◽

Ender Kazazoglu

Keyword(s):

Flexural Strength ◽

Thermal Cycling ◽

Vickers Hardness ◽

Vickers Microhardness ◽

Testing Machine ◽

Clinical Importance ◽

Zirconia Ceramics ◽

Biaxial Flexural Strength ◽

Monolithic Zirconia ◽

One Way Anova

Objective:This study evaluated the effect of glazing and thermal cycling on biaxial flexural strength and Vickers hardness of different zirconia core materials. Material and Methods: Disc shaped zirconia specimens (15 mm x 1.15 mm) were fabricated out of three systems (ZirkonZahn, Cercon, Ceramill) according to each manufacturer`s instructions. The specimens of each system were randomly divided into initially 2 groups. While half of the specimens were glazed, the other half was left unglazed. Each group was further divided into 4 subgroups to be subjected to thermal cycling (0-control, 1000, 3000, 5000 cycles, 5-55 ºC). Biaxial flexural strength was tested in a universal testing machine (1 mm/min). Another set of unglazed zirconia specimens were made and tested for Vickers microhardness with and without thermocycling (0-control, 1000, 3000, 5000 cycles, 5-55 ºC). Data were statistically analyzed using one-way ANOVA, two-way ANOVA and Tukey’s test (p < 0.05). Results: In non-aged conditions (11034-1388 MPa), glazing significantly decreased the biaxial flexural strength of all zirconia ceramics (845.65-897.35 MPa) (p = 0.000). While in the non-glazed groups, all thermal cycling regimens significantly decreased the biaxial flexural strength (864-1156 MPa) (p=0.000), in glazed groups thermal cycling did not affect the results (829.4-854.9 MPa) (p = 0.405). Compared to the non-aged group (1414.1 VHN), thermal cycling decreased the Vickers hardness significantly only for Cercon (1365.9 VHN) (p = 0.005). Conclusion: Glazing decreased the biaxial flexural strength of the zirconia ceramics tested. Unglazed zirconia ceramics were weaker against thermal cycling compared to glazed ones. For monolithic zirconia restorations, this information may have clinical importance.Keywords:Biaxial flexural strength; Glazing; Thermal cycling; Vickers microhardness; Zirconia.

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Effects of Different Air Particle Abrasion Protocols on the Biaxial Flexural Strength and Fractography of High/Ultra-Translucent Zirconia

Materials ◽

10.3390/ma15010244 ◽

2021 ◽

Vol 15 (1) ◽

pp. 244

Author(s):

Reem AlMutairi ◽

Hend AlNahedh ◽

Ahmed Maawadh ◽

Ahmed Elhejazi

Keyword(s):

Standard Deviation ◽

Flexural Strength ◽

Control Sample ◽

Zirconia Ceramic ◽

Air Abrasion ◽

Zirconia Ceramics ◽

Biaxial Flexural Strength ◽

Monolithic Zirconia ◽

The Mean ◽

Post Hoc

In this study, the biaxial flexural strength (BFS) and fractography of high/ultra-translucent monolithic zirconia ceramics subjected to different mechanical surface pretreatments were evaluated. A total of 108 disc-shaped samples (12 mm diameter, 1.2 mm thickness) of three zirconia materials (5Y-ZP KATANA Zirconia UTML (ML), 3Y-TZP DD Bio ZX2 (DB), and 5Y-ZP DD cube X2 (DC)) were used. The BFS was investigated after subjecting the samples to surface treatment using air abrasion particles of two types (aluminum oxide or glass microbeads). The data were analyzed using two-way analysis of variance, followed by Scheffe’s post hoc test for multiple comparisons. The mean ± standard deviation BFS for DB was highest after treatment with 50 µm Al2O3 (1626.05 ± 31.9 MPa), with lower values being observed following treatment with 50 µm glass microbeads (1399.53 ± 24.2 MPa) and in the control sample (1198.51 ± 21.1 MPa). The mean ± standard deviation (SD) BFSs for DC and ML were the highest in the control groups. Surface air abrasion with 50 µm Al2O3 particles and 2 bar pressure is recommended for 3Y-TZP translucent zirconia, while no abrasion of 5Y-ZP translucent zirconia ceramic.

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Flexural Properties of Renewable Coir Fiber Reinforced Magnesium Phosphate Cement, Considering Fiber Length

Materials ◽

10.3390/ma13173692 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3692 ◽

Cited By ~ 1

Author(s):

Liwen Zhang ◽

Zuqian Jiang ◽

Hui Wu ◽

Wenhua Zhang ◽

Yushan Lai ◽

...

Keyword(s):

Flexural Strength ◽

Waste Treatment ◽

Bending Test ◽

Magnesium Phosphate ◽

Flexural Properties ◽

Coir Fiber ◽

X Ray Diffraction ◽

Flexural Toughness ◽

Three Point Bending ◽

Curing Age

Coir fiber (CF), a renewable natural plant fiber, is more competitive in improving poor toughness and crack resistance of magnesium phosphate cement (MPC) than artificial fibers, due to its slight energy consumptions and low costs in production and waste treatment. In this paper, a typical three-point bending test was carried out to study the effects of CF length on MPC flexural properties. A total of forty-two cuboid specimens were employed to investigate the flexural strength, load-deflection behavior, and flexural toughness of MPC, with CF lengths varying from 0 to 30 mm at the curing age of 7 days and 28 days. Results showed that, at both two curing ages, MPC flexural strength first increased with CF length increasing, and then deceased when CF length exceeded the threshold. However, with the increase of CF length, MPC flexural toughness increased continuously, while MPC elastic modulus displayed a decreasing trend. Additionally, Modern micro testing techniques, such as scanning electron microscope (SEM) and X-ray diffraction (XRD), were also used to study the microstructure and phase compositions of specimens for further explaining the themicroscopic mechanism.

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Effect of Repeated Preheating Cycles on Flexural Strength of Resin Composites

Operative Dentistry ◽

10.2341/11-476-l ◽

2013 ◽

Vol 38 (1) ◽

pp. 33-38 ◽

Cited By ~ 4

Author(s):

M D'Amario ◽

S Pacioni ◽

M Capogreco ◽

R Gatto ◽

M Baldi

Keyword(s):

Flexural Strength ◽

Room Temperature ◽

Testing Machine ◽

Bending Test ◽

Resin Composites ◽

Control Groups ◽

Three Point Bending ◽

Universal Testing ◽

Group A ◽

Significant Factors

SUMMARY The aim of this study was to assess the flexural strengths of three resin composites prepared at room temperature or cured after 20 or 40 cycles of preheating to a temperature of 45°C. Three resin composites were evaluated: Enamel Plus HFO (Micerium) (HFO), Enamel Plus HRi (Micerium) (HRi), Opallis + (FGM) (OPA). One group of specimens for each composite was fabricated under ambient laboratory conditions, whereas in the other groups, the composites were cured after 20 or 40 preheating cycles to a temperature of 45°C in a preheating device. Ten specimens were prepared for each group. A three-point bending test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed with a two-way analysis of variance (ANOVA) test and a Games-Howell test (α = 0.05). The two-way ANOVA showed that both the material and the number of heating cycles were significant factors, able to influence the flexural strength values (p<0.05). However, there was not a statistically significant interaction (p>0.05). For all three composites flexural strengths were not affected after 20 preheating cycles in comparison with the control groups (0 preheating cycles) but were, however, significantly decreased when 40 prewarming cycles were conducted. The HRi and OPA groups had the highest flexural strengths, with no statistically significant differences among them. HFO presented significantly lower flexural strengths in comparison with HRi.

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Influence of Aging on Biaxial Flexural Strength and Hardness of Translucent 3Y-TZP

Materials ◽

10.3390/ma13010027 ◽

2019 ◽

Vol 13 (1) ◽

pp. 27 ◽

Cited By ~ 1

Author(s):

Nawal M. Moqbel ◽

Majed Al-Akhali ◽

Sebastian Wille ◽

Matthias Kern

Keyword(s):

Flexural Strength ◽

Surface Treatment ◽

Laser Scanning ◽

Monoclinic Phase ◽

X Ray Diffraction ◽

Air Abrasion ◽

Aged Group ◽

Alumina Particles ◽

Biaxial Flexural Strength ◽

Group A

The purpose of this research was to evaluate the influence of aging and surface treatment on surface roughness, biaxial flexural strength (BFS), and Vickers hardness (VHN) of translucent dental zirconia. Half of 80 disc-shaped zirconia specimens (1.2 mm thickness and 12 mm diameter) were aged (group A) in an autoclave for 20 h (134 °C and 0.2 MPa) and the other half were not aged (group N). Specimens were subjected to: no surface treatment (SIN), particle air-abrasion with 50 µm alumina particles at 1 bar (0.1 MPa) and 2.5 bar (0.25 MPa), or polishing down to 1 µm (POL). Specimens were analyzed using X-ray diffraction, laser scanning microscope, BFS, and VHN tests. Three groups (N-SIN, N-POL, and A-POL) showed almost no monoclinic phase. While other groups showed monoclinic phase ratios ranging from 7.5 vol. % ± 2.4 vol. % (N-0.1 MPa) to 41.5 vol. % ± 0.3 vol. % (A-0.1 MPa). Aging and particle air-abrasion increased significantly the BFS, ranging from 720 ± 37 MPa (N-SIN) to 1153 ± 92 MPa (N-0.1 MPa). The hardness was not influenced significantly by aging. A certain amount of monoclinic phase at the surface strengthens the high translucent dental zirconia, while hardness and roughness are not influenced. The pressure of particle air-abrasion showed no influence on the evaluated properties.

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Flexural Strength of Different Monolithic Computer-Assisted Design and Computer-Assisted Manufacturing Ceramic Materials upon Different Thermal Tempering Processes

European Journal of Dentistry ◽

10.1055/s-0040-1713957 ◽

2020 ◽

Vol 14 (04) ◽

pp. 566-574

Author(s):

Niwut Juntavee ◽

Pithiwat Uasuwan

Keyword(s):

Flexural Strength ◽

Tetragonal Zirconia ◽

Ceramic Materials ◽

Bending Test ◽

Lithium Silicate ◽

Computer Assisted ◽

Three Point Bending ◽

Significant Difference ◽

Monolithic Zirconia ◽

Thermal Tempering

Abstract Objective Strength of ceramics related with sintering procedure. This study investigated the influence of different tempering processes on flexural strength of three monolithic ceramic materials. Materials and Methods Specimens were prepared in bar-shape (width × length × thickness = 4 × 14 × 1.2 mm) from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP, inCoris TZI [I]), zirconia-reinforced lithium silicate (ZLS, Vita Suprinity [V]), and lithium disilicate (LS2, IPS e.max CAD [E]), and sintered with different tempering processes: slow (S), normal (N), and fast (F) cooling procedure (n = 15/group). Flexural strength (σ) was determined using three-point bending test apparatus at 1 mm/min crosshead speed. Statistical Analysis The analysis of variance and Bonferroni’s multiple comparisons were determined for significant difference (α = 0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristics strength (σo). Microstructures were evaluated with scanning electron microscope and X-ray diffraction. Results The mean ± standard deviation (MPa) of σ, m, and σo were: 1,183.98 ± 204.26, 6.23, 1,271.80 for IS; 1,084.43 ± 204.79, 5.76, 1,170.08 for IN; 777.19 ± 99.77, 8.78, 819.96 for IF; 267.15 ± 32.71, 9.11, 281.48 for VS; 218.43 ± 38.46, 6.40, 234.23 for VN; 252.67 ± 37.58, 7.20, 269.23 for VF; 392.09 ± 37.91, 11.37, 409.23 for ES; 378.88 ± 55.38, 7.45, 403.11 for EN, and 390.94 ± 25.34, 16.00, 403.51 for EF. Thermal tempering significantly affected flexural strength of Y-TZP (p < 0.05), but not either ZLS or LS2 (p > 0.05). Y-TZP indicated significantly higher flexural strength upon slow tempering than others. Conclusion Enhancing flexural strength of Y-TZP can be achieved through slow tempering process and was suggested as a process for monolithic zirconia. Strengthening of ZLS and LS2 cannot be accomplished through tempering; thus, either S-, N-, or F- tempering procedure can be performed. Nevertheless, to minimize sintering time, rapid thermal tempering is more preferable for both ZLS and LS2.

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Biaxial Flexural Strength of Different Monolithic Zirconia upon Post-Sintering Processes

European Journal of Dentistry ◽

10.1055/s-0041-1735937 ◽

2022 ◽

Author(s):

Niwut Juntavee ◽

Apa Juntavee ◽

Thipradi Phattharasophachai

Keyword(s):

Flexural Strength ◽

Testing Machine ◽

Sintering Process ◽

X Ray Diffraction ◽

Heat Treated ◽

Biaxial Flexural Strength ◽

Monolithic Zirconia ◽

Treatment Procedures ◽

Post Hoc ◽

Sintering Processes

Abstract Objective Different post-sintering processes are expected to be a reason for alteration in the strength of zirconia. This study evaluated the effect of post-sintering processes on the flexural strength of different types of monolithic zirconia. Materials and Methods A total of 120 classical- (Cz) and high-translucent (Hz) monolithic zirconia discs (1.2 mm thickness and 14 mm in Ø) were prepared, sintered, and randomly divided into four groups to be surface-treated with (1) as-glazed (AG); (2) finished and polished (FP); (3) finished, polished, and overglazed (FPOG); and (4) finished, polished, and heat-treated (FPHT) technique (n = 15). Biaxial flexural strength (σ) was determined on a piston-on-three ball in a universal testing machine at a speed of 0.5 mm/min. Statistical Analysis Analysis of variance, and post hoc Bonferroni multiple comparisons were determined for significant differences (α = 0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristic strength (σ0). The microstructures were examined with a scanning electron microscope and X-ray diffraction. Results The mean ± standard deviation value of σ (MPa), m, and σ0 were 1,626.43 ± 184.38, 9.51, and 1,709.79 for CzAG; 1,734.98 ± 136.15, 12.83, and 1,799.17 for CzFP; 1,636.92 ± 130.11, 14.66, and 1,697.63 for CzFPOG; and 1,590.78 ± 161.74, 10.13, and 1,663.82 for CzFPHT; 643.30 ± 118.59, 5.59, and 695.55 for HzAG; 671.52 ± 96.77, 3.28, and 782.61 for HzFP; 556.33 ± 122.85, 4.76, and 607.01 for HzFPOG; and 598.36 ± 57.96, 11.22, and 624.89 for HzFPHT. The σ was significantly affected by the post-sintering process and type of zirconia (p < 0.05), but not by their interactions (p > 0.05). The Cz indicated a significantly higher σ than Hz. The FP process significantly enhanced σ more than other treatment procedures. Conclusion Post-sintering processes enabled an alteration in σ of zirconia. FP enhanced σ, while FPOG and FPHT resulted in a reduction of σ. Glazing tends to induce defects at the glazing interface, while heat treatment induces a phase change to tetragonal, both resulted in reducing σ. Finishing and polishing for both Cz and Hz monolithic zirconia is recommended, while overglazed or heat-treated is not suggested.

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