Fatigue strength of yttria-stabilized zirconia polycrystals: Effects of grinding, polishing, glazing, and heat treatment

Zucuni, Camila Pauleski; Guilardi, Luís Felipe; Rippe, Marília Pivetta; Pereira, Gabriel Kalil Rocha; Valandro, Luiz Felipe

doi:10.1016/j.jmbbm.2017.06.016

Cited by 42 publications

(45 citation statements)

References 43 publications

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“…In this sense, smooth surfaces of ceramic restorations are mandatory in order to reduce the amount of plaque formation (21), secondary caries occurrence, besides a decreased wear of the antagonist tooth, improving the longevity of restorations (5). Thus, in addition to our findings, it becomes clear the necessity of executing a polishing protocol after the adjustment of Y-TZP restorations to provide a smoother and homogenous surface, enhancing its mechanical behavior, clinical performance and decreasing its susceptibility to aging (22).…”

Section: Discussionsupporting

confidence: 62%

Polishing of Ground Y-TZP Ceramic is Mandatory for Improving the Mechanical Behavior

et al. 2018

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It evaluated the effect of aging by Low Temperature Degradation (LTD), executed after post-processing surface treatments (polishing, heat treatment and glazing), on the surface characteristics (micromorphology and roughness) and on the structural stability (phase transformation and mechanical behavior-flexural strength and structural reliability) of a ground yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic. Discs of Y-TZP (VITA In-Ceram YZ) were manufactured (ISO:6872-2015; 15 mm in diameter and 1.2 ± 0.2 mm in thickness) and randomly assigned into 10 groups according two factors: "aging" in 2 levels (with or without) and "surface treatment" in 5 levels (Ctrl: as-sintered; Gr: grinding with coarse diamond bur; Gr + HT: grinding plus heat treatment; Gr + Pol: grinding plus polishing; Gr + Gl: grinding plus glazing). Roughness (n=30), biaxial flexural test (n=30), phase transformation (n=2), and surface topography (n=2) analyses were performed. Aging led to an intense increase in monoclinic (m) phase content for all the tested conditions, being the as-sintered samples (Ctrl= 65.6%) more susceptible to the t-m phase transformation. Despite of increasing the m-phase content, aging was not detrimental for characteristic strength (except to the grinding condition). There was no significant reduction in the Weibull modulus after surface treatments. Additionally, heat treatment and glazing after grinding led to a decrease in characteristic strength, while polishing presented the highest characteristic strength values. Thus, polishing is mandatory after grinding the Y-TZP ceramic, while performing glazing or heat-treatment alone after grinding lead to the worst mechanical performance.

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Section: Discussionsupporting

confidence: 62%

Polishing of Ground Y-TZP Ceramic is Mandatory for Improving the Mechanical Behavior

et al. 2018

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“…Kim et al showed that polishing decreased the L* value while increasing the b* value. Polishing is recommended to improve the surface characteristics of monolithic zirconia, while coarse burs should not be employed for grinding before polishing due to the increase of fracture risk . Diamond‐impregnated polishing systems are superior to silica carbide‐impregnated ones for grinding zirconia regarding polishing effects .…”

Section: Laboratory Proceduresmentioning

confidence: 99%

Color Aspect of Monolithic Zirconia Restorations: A Review of the Literature

Tabatabaian

2018

Journal of Prosthodontics

136

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Monolithic zirconia restoration is an acceptable treatment option in restorative dentistry and a developing trend in esthetic dentistry. Digital dentistry has simplified fabrication of monolithic zirconia restorations. Zirconia ceramic has introduced an opportunity to achieve both esthetic and mechanical requirements for restorations. This is rarely found for a ceramic in dentistry. Monolithic zirconia restorations represent an acceptable durability, comparable to metal-ceramic restorations, while they are superior to metal-ceramic restorations esthetically; however, difficulties to gain an optimal shade reproduction and a color match with monolithic zirconia restorations still remain. The color of these restorations may be influenced by manufacturing processes, laboratory procedures, and clinical factors. Manufacturing processes determine basic optical properties of zirconia ceramics. Different laboratory procedures may create optical changes in zirconia ceramics. Also clinical factors such as dental background, cement, and zirconia restoration features may affect the resulting color. This literature review aimed to discuss potent factors in the color of monolithic zirconia restorations. An electronic search of the PubMed/Google Scholar database was performed to find related English-language articles published between January 1, 2000, and October 31, 2017. The key terms of background, cement, ceramic, color, esthetics, shade, spectrophotometry, thickness, translucency, and zirconia were used both individually and simultaneously. Also, a manual search was conducted, and five classic articles of color science were added. Thus 192 articles were included. In the last decade, shade reproduction of monolithic zirconia restorations has been highly regarded; however, further improvements are required in the manufacturing process to produce tooth-like zirconia ceramics. An esthetic guideline named background-cement-ceramic color harmony was suggested in this study; however, more clinical practice guidelines should be established for monolithic zirconia restorations on esthetics, and therefore, more studies are required.

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“…Those treatments will influence the surface microstructure and roughness acting on the defects introduced by grinding and also on the m-phase content generated by t-m phase transformation and by that they may impact the materials aging susceptibility and fatigue behavior. A recent investigation by Zucuni and collaborators (26) shows that the polishing after grinding appears to play a relevant role for fatigue behavior improvements of polycrystalline zirconia material.…”

Section: Fatigue Strength Of Ground and Aged Y-tzpmentioning

confidence: 99%

Effect of Grinding and Multi-Stimuli Aging on the Fatigue Strength of a Y-TZP Ceramic

et al. 2018

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This study aimed to investigate the effect of grinding and multi-stimuli aging on the fatigue strength, surface topography and the phase transformation of Y-TZP ceramic. Discs were manufactured according to ISO-6872:2008 for biaxial flexure testing (diameter: 15 mm; thickness: 1.2 mm) and randomly assigned considering two factors "grinding" and "aging": C-control (as-sintered); CA-control + aging; G-ground; GA-ground + aging. Grinding was carried out with coarse diamond burs under water-cooling. Aging protocols consisted of: autoclave (134°C, 2 bars pressure, 20 hours), followed by storage for 365 days (samples were kept untouched at room temperature), and by mechanical cycling (10 6 cycles by 20 Hz under a load of 50% from the biaxial flexure monotonic tests). Flexural fatigue strengths (20,000 cycles; 6 Hz) were determined under sinusoidal cyclic loading using staircase approach. Additionally, surface topography analysis by FE-SEM and phase transformation analysis by X-ray Diffractometry were performed. Dixon and Mood methodology was used to analyze the fatigue strength data. Grinding promotes alterations of topographical pattern, while aging apparently did not alter it. Grinding triggered t-m phase transformation without impacting the fatigue strength of the Y-TZP ceramic; and aging promoted an intense t-m transformation that resulted in a toughening mechanism leading to higher fatigue strength for as-sintered condition, and a tendency of increase for ground condition (C < CA; G = GA). It concludes that grinding and aging procedures did not affect deleteriously the fatigue strength of the evaluated Y-TZP ceramic, although, it promotes surface topography alterations, except to aging, and t-m phase transformation. Effect of Grinding and Multi-S t i m u l i A g i n g o n t h e F a t i g u e S t r e n g t h o f a Y-T Z P C e r a m i c

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Fatigue strength of yttria-stabilized zirconia polycrystals: Effects of grinding, polishing, glazing, and heat treatment

Cited by 42 publications

References 43 publications

Polishing of Ground Y-TZP Ceramic is Mandatory for Improving the Mechanical Behavior

Polishing of Ground Y-TZP Ceramic is Mandatory for Improving the Mechanical Behavior

Color Aspect of Monolithic Zirconia Restorations: A Review of the Literature

Effect of Grinding and Multi-Stimuli Aging on the Fatigue Strength of a Y-TZP Ceramic

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