Effects of Hydrothermal Treatment on the Phase Transformation, Surface Roughness, and Mechanical Properties of Monolithic Translucent Zirconia

2022 ◽  
Author(s):  
CY Zhang ◽  
C Agingu ◽  
H Yang ◽  
H Cheng ◽  
H Yu
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Hydrothermal Treatment ◽  
Cross Sections ◽  
Monoclinic Phase ◽  
Control Group ◽  
Hydrothermal Aging ◽  
Characteristic Strength

SUMMARY Objectives: This study aimed to investigate the effects of hydrothermal treatment on four types of monolithic, translucent, yttria-stabilized, tetragonal zirconia polycrystals (Y-TZPs). Methods and Materials: Two commercially available Y-TZP brands—SuperfectZir High Translucency (Aidite Technology Co, China) and Katana HT (Kuraray Noritake Dental, Japan) were assessed. For each brand of Y-TZP, materials of four coloring types, including noncolored (NC), colored by staining (CS), precolored (PC), and multilayered (ML) specimens were investigated after hydrothermal aging in an autoclave at 134°C/0.2 MPa for 0 (control group), 5, 10, and 20 hours. The tetragonal-to-monoclinic phase transformation, surface roughness, flexural strength, and structural reliability (Weibull analysis) were measured and statistically analyzed (α=0.05). The subsurface microstructure was analyzed with scanning electron microscopy. Results: The group ML exhibited the lowest flexural strength and Weibull characteristic strength among the four coloring types (p<0.05). Slight increases in the monoclinic phase volume, flexural strength, and Weibull characteristic strength were observed after hydrothermal aging (pall<0.05). Regardless of coloring type, no significant effects of aging on the Weibull modulus or surface roughness were found for the tested materials. Compared with the Katana HT cross-sections, the SuperfectZir High Translucency cross-sections exhibited a similar but thicker transformation zone. Conclusions: The coloring procedure and material type were found to affect the mechanical properties and aging resistance of translucent monolithic Y-TZP ceramics. Regardless of the aging time, the surface roughness of the tested Y-TZP ceramics remained unchanged.

scholarly journals Effect of different surface treatments on surface roughness, phase transformation, and biaxial flexural strength of dental zirconia

2021 ◽  
Vol 15 (3) ◽  
pp. 210-218
Author(s):  
Niknaz Yahyazadehfar ◽  
Maryam Azimi Zavaree ◽  
Sayed Shojaedin Shayegh ◽  
Mobin Yahyazadehfar ◽  
Tabassom Hooshmand ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Surface Treatment ◽  
Monoclinic Phase ◽  
Pearson Correlation ◽  
Surface Treatments ◽  
Post Hoc ◽  
And Control

Background. Interfacial failures at the cement‒restoration interface highlights the importance of effective surface treatment with no adverse effect on the zirconia’s mechanical properties. This study aimed to determine the effect of different surface treatments on dental graded zirconia’s surface roughness and certain mechanical properties. Methods. Forty sintered zirconia specimens were randomly divided into four groups (n=10): control (no surface treatment), sandblasting (SA), grinding with diamond bur (GB), and Er,Cr:YSGG laser (LS). Following surface treatment, the surface roughness and surface topography of the specimens were examined. X-ray diffraction (XRD) was conducted. In addition, the biaxial flexural strengths of specimens were evaluated. The data were analyzed using one-way analysis of variance (ANOVA) and post hoc Tukey tests; the Pearson correlation coefficient was calculated between either volumetric percentage of monoclinic phase or roughness and flexural strength of specimens (α=0.05). Results. The GB group exhibited significantly greater surface roughness compared to the other groups (P<0.005). The LS and control groups exhibited a significantly lower volumetric percentage of the monoclinic phase (P<0.001) than the GB and SA treatments. The SA group exhibited significantly higher flexural strength than the control (P=0.02) and GB groups (P<0.01). Furthermore, the Weibull analysis for the LS showed higher reliability for the flexural strength than other treatments. Conclusion. Er,Cr:YSGG laser treatment, with the lowest extent of phase transformation and reliable flexural strength, can be a promising choice for surface treatment of zirconia.

scholarly journals Effect of Different Coloring Procedures on the Aging Behavior of Dental Monolithic Zirconia

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Check Agingu ◽  
Neng-wu Jiang ◽  
Hui Cheng ◽  
Hao Yu
Keyword(s):  
Phase Transformation ◽  
Flexural Strength ◽  
Monoclinic Phase ◽  
Irregular Surface ◽  
Aging Behavior ◽  
Hydrothermal Aging ◽  
Transformation Zone ◽  
Aging Conditions ◽  
Monolithic Zirconia ◽  
Subsurface Microstructure

Objective. This study aimed to investigate the effect of different coloring procedures on the aging behavior of dental monolithic zirconia. Methods. Two types of translucent zirconia (SuperfectZir HTS, Aidite; Katana HT, Kuraray) were tested. Bar-shaped specimens with dimensions of 22 × 4 × 2 mm were prepared from uncolored and precolored blocks. Before being sintered, specimens made from uncolored blocks were colored by dipping them into a coloring liquid, whereas the precolored specimens were not treated. The specimens were then divided into 4 subgroups (n = 13) according to the aging conditions (no aging, 134°C/0.2 MPa for 5 h, 134°C/0.2 MPa for 10 h, and 134°C/0.2 MPa for 20 h). The flexural strength of the specimens was tested with the 4-point flexure. The crystalline phase composition of the specimens was analyzed by XRD. The subsurface microstructure of the fractured specimens was examined by using a SEM. The data were statistically analyzed using 3-way ANOVA and Tukey’s test (α = 0.05). Results. Significant differences were found in the flexural strength between the two zirconia materials tested (P<0.001). Aging and coloring procedures showed no significant effect on the flexural strength of the zirconia. Aging and coloring procedures significantly affected the t→m transformation of the zirconia. The monoclinic phase increased with the aging time. After aging, the precolored specimens showed a significantly higher t→m transformation than the specimens that were dipped in the coloring liquids. After aging for 20 h, the depth of the transformed zone with an irregular surface was approximately 6 µm for SuperfectZir HTS, whereas no detectable transformation zone was observed for Katana HT. Conclusion. Aging and coloring procedures had no significant effects on the flexural strength of the zirconia tested. The coloring procedure had a significant effect on the phase transformation of the zirconia subjected to hydrothermal aging.

scholarly journals Effect of Sintering Parameters on the Mechanical Properties of Monolithic Zirconia

2019 ◽  
Vol 13 (4) ◽  
pp. 247-252 ◽  
Author(s):  
Caner Öztürk ◽  
Gülşen Can
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Bending Test ◽  
Core Material ◽  
Control Groups ◽  
Critical Limit ◽  
Significance Level ◽  
Monolithic Zirconia

Background. Zirconia restorations with high mechanical properties are the current treatment options for fixed restorations with advantages of high biocompatibility and low pulp irritation. Although the effect of sintering time and temperature on the optical and mechanical properties of zirconia core material were investigated, the effect of these parameters on the translucent monolithic zirconia is still uncertain. This study aimed to evaluate the effect of the changes in sintering temperature and holding time on the mechanical and structural properties of monolithic zirconia. Methods. Totally, 340 self-colored (A2) zirconia specimens from two different monolithic zirconia groups (n=170) were prepared, measuring 15.5×12.5×1.2 mm. Then, 17 subgroups (n=10), including the control groups, were sintered according to sintering parameters. XRD analysis was used to determine phase transformations. The surface roughness of the specimens was evaluated using profilometry, and the flexural strength of the specimens was evaluated by the three-point bending test. The data were analyzed using three-way ANOVA and post hoc multiple comparison test with Bonferroni correction (a=0.05) at a significance level of 0.05. Independent-samples t-test was used to compare the subgroups between the control groups (P˂0.05). Results. No tetragonal-to-monoclinic phase transformation was observed in the groups. Changes in the sintering parameters did not significantly affect the surface roughness and flexural strength of monolithic zirconia. Surface roughness values for all the subgroups were above the clinically critical limit. Conclusion. According to the results of this study, changes in the sintering parameters did not affect the surface phase transformation, surface roughness, and flexural strength of monolithic zirconia.

scholarly journals Effect of Accelerated Aging on Some Mechanical Properties and Wear of Different Commercial Dental Resin Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2769
Author(s):  
Jonne Oja ◽  
Lippo Lassila ◽  
Pekka K. Vallittu ◽  
Sufyan Garoushi
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Accelerated Aging ◽  
Wear Depth ◽  
Resin Composites ◽  
Expiration Date ◽  
Dental Resin ◽  
Hydrothermal Aging ◽  
Dental Resin Composites

The aim of current in vitro research was to determine the effect of hydrothermal accelerated aging on the mechanical properties and wear of different commercial dental resin composites (RCs). In addition, the effect of expiration date of the composite prior its use was also evaluated. Five commercially available RCs were studied: Conventional RCs (Filtek Supreme XTE, G-aenial Posterior, Denfil, and >3y expired Supreme XTE), bulk-fill RC (Filtek Bulk Fill), and short fiber-reinforced RC (everX Posterior). Three-point flexural test was used for determination of ultimate flexural strength (n = 8). A vickers indenter was used for testing surface microhardness. A wear test was conducted with 15,000 chewing cycles using a dual-axis chewing simulator. Wear pattern was analyzed by a three-dimensional (3D) noncontact optical profilometer. Degree of C=C bond conversion of monomers was determined by FTIR-spectrometry. The specimens were either dry stored for 48 h (37 °C) or boiled (100 °C) for 16 h before testing. Scanning electron microscopy (SEM) was used to evaluate the microstructure of each material. Data were analyzed using ANOVA (p = 0.05). Hydrothermal aging had no significant effects on the surface wear and microhardness of tested RCs (p > 0.05). While flexural strength significantly decreased after aging (p < 0.05), except for G-aenial Posterior, which showed no differences. The lowest average wear depth was found for Filtek Bulk Fill (29 µm) (p < 0.05), while everX Posterior and Denfil showed the highest wear depth values (40, 39 µm) in both conditions. Passing the expiration date for 40 months did not affect the flexural strength and wear of tested RC. SEM demonstrated a significant number of small pits on Denfil’s surface after aging. It was concluded that the effect of accelerated aging may have caused certain weakening of the RC of some brands, whereas no effect was found with one brand of RC. Thus, the accelerated aging appeared to be more dependent on material and tested material property.

Effects of Sintering Additives on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics by GPS

2010 ◽  
Vol 105-106 ◽  
pp. 27-30 ◽  
Author(s):  
Wei Ru Zhang ◽  
Feng Sun ◽  
Ting Yan Tian ◽  
Xiang Hong Teng ◽  
Min Chao Ru ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Additives ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics

Silicon nitride ceramics were prepared by gas pressure sintering (GPS) with different sintering additives, including La2O3, Sm2O3 and Al2O3. Effect of sintering additives on the phase-transformation, microstructure and mechanical properties of porous silicon nitride ceramics was investigated. The results show that the reaction of sintering additives each other and with SiO2 had key effects on the phase-transformation, grain growing and grain boundaries. With 9MPa N2 atmosphere pressure, holding 1h at 1850°C, adding 10wt% one of the La2O3, Sm2O3, Al2O3, porous silicon nitride was prepared and the relative density was 78%, 72%, 85% respectively. The flexural strength was less than 500MPa, and the fracture toughness was less than 4.8MPam1/2. Dropping compounds sintering additives, such as La2O3+Al2O3, Sm2O3+Al2O3 effectively improves the sintering and mechanical properties. The relative density was 99.2% and 98.7% with 10wt% compounds sintering additives. The grain ratio of length to diameter was up to 1:8. The flexural strength was more than 900MPa, and the fracture toughness was more than 8.9MPam1/2.

The Effect of the Electrical Discharge Machining Process on the Material Properties of Nonconductive Ceramics

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Nirdesh Ojha ◽  
Florian Zeller ◽  
Claas Mueller ◽  
Holger Reinecke
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Electrical Discharge ◽  
High Performance ◽  
Electrical Discharge Machining ◽  
Machining Process ◽  
Hardness Increase ◽  
Edm Process

Electrical discharge machining (EDM) is widely used to manufacture complex shaped dies, molds and critical parts in conductive materials. With the help of an assisting electrode (AE), EDM process can be used to machine nonconductive ceramics. This paper evaluates the mechanical properties of three high-performance nonconductive ceramics (ZrO2, Si3N4, and SiC) that have been machined with the EDM process using AE. Mechanical properties such as Vickers hardness (HV 0.3), surface roughness (Sq), and flexural strength of the machined and the nonmachined samples are compared. The EDM process causes decrease in Vickers hardness, increase in surface roughness, and decrease in flexural strength.

scholarly journals Evaluation of Some Mechanical Properties of a Maxillofacial Silicon Elastomer Reinforced with Polyester Powder

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Yagthan Mohammed Haider ◽  
Zainab Salih Abdullah ◽  
Ghasak H. Jani ◽  
Norehan Mokhtar
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Hardness Test ◽  
Silicone Elastomer ◽  
Control Group ◽  
Silicone Elastomers ◽  
Tear Strength ◽  
To Come ◽  
Post Hoc

Maxillofacial silicone elastomers are used to replace and reconstruct missing facial parts for patients with trauma or a certain disease. Although commonly favorable silicone elastomers are not ideal in properties, many studies have been carried out to improve their mechanical properties and to come out with ideal maxillofacial prosthetic materials, so as to render patients with the best maxillofacial prostheses. The aim of the current study is to evaluate the effect of addition of different concentrations of polyester powder on hardness, tear strength, surface roughness, and tensile strength of maxillofacial A-2186 RTV silicone elastomers. Polyester powder was added to the silicone elastomer in the concentrations of 1%, 3% and 5% by using an electronic digital balance, compared with the control group of 0% polyester filler. The shore A hardness test was done according to ASTM D 2240 standards. The tear test was done according to ASTM D624 type C standards. The tensile test was done according to ISO specification number 37:2011. The surface roughness test was performed according to ISO 7619-1 2010 specifications. The data collected were then analyzed using one-way analysis of variance (ANOVA) and post hoc and Fisher’s LSD tests. All three groups showed a highly significant increase in tear strength, tensile strength, hardness, and roughness, compared to the control group. Reinforcement of A-2186 Platinum RTV Silicone Elastomer with 5% polyester significantly improved the mechanical properties tested in this study.

Si3N4/BN Composite Ceramics with Nd2O3-Al2O3-Y2O3 Ternary Additives by Pressureless Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 106-108
Author(s):  
Ping Liu ◽  
Yong Feng Li ◽  
Xiang Dong Wang ◽  
Hai Yun Jin ◽  
Guan Jun Qiao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Fracture Toughness Testing ◽  
Β Phase ◽  
Toughness Testing

Si3N4/BN composite ceramics with 25vol% h-BN were prepared by pressure-less sintering process with Nd2O3/Al2O3/Y2O3 as sintering additives. The effects of these ternary additives on the densification behaviors and mechanical properties were investigated. XRD and FESEM were used to investigate the α-β phase transformation and microstructure. The XRD results showed that α-Si3N4 has transformed to β-Si3N4 completely in all the samples during the pressureless sintering process. The line shrinkage increased with the Nd2O3 contents increasing, and the highest line shrinkage (7.75%) was observed when 4wt% Nd2O3 was added, then decreased. The same trends were observed in flexural strength and fracture toughness testing. The ternary additives of Y2O3-Al2O3-Nd2O3 could improve the density, strength and fracture toughness of the material effectively.

Influence of Low Temperature Aging on the Flexural Strength of Y-TZP Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1756-1760 ◽  
Author(s):  
Chen Wang ◽  
Li Min Dong ◽  
Yuan Fu Yi ◽  
Ning Wen ◽  
Qing Feng Zan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Low Temperature ◽  
Flexural Strength ◽  
Monoclinic Phase ◽  
Accelerated Aging ◽  
Strength Increase ◽  
Low Temperature Aging ◽  
Temperature Aging

Low temperature aging (LTD) is an important factor of Y-TZP ceramic as artificial joint femoral head and dental restorative materials in vivo for long-term application. In this paper, the accelerated aging experiments on Y-TZP ceramics were conducted. The t-m phase transition is occurring from the surface to the inside during low temperature aging of Y-TZP ceramics. As content of phase transformation increases, thickness of phase transformation layer increases. While the content of surface monoclinic phase is less, the volume expansion and surface stress caused by phase transformation can make cracks and holes shrink or even close, then the flexural strength increase. As a large number of surface monoclinic phase was generated, due to there are a lot of microscopic defects in the phase transition layer, crystals loose, strength of grain boundary lower than that of not aging area and phase transformation layers fracture in the intergranular mode, that damages the flexural strength. Therefore, the flexural strength increase firstly and then decrease with the increase of surface monoclinic content.

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