New perspectives for recycling dental zirconia waste resulting from CAD/CAM manufacturing process

Gouveia, Paula F.; Schabbach, Luciana Maccarini; Souza, Júlio C. M.; Henriques, Bruno; Labrincha, J.A.; Silva, Filipe; Fredel, Márcio C.; Mesquita‐Guimarães, J.

doi:10.1016/j.jclepro.2017.03.117

Cited by 42 publications

(29 citation statements)

References 50 publications

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“…The majority of dental zirconia manufacturers are supplied by Tosoh Corp., which provide powders composed of 40 nm primary particles (which match the microstructural units seen in Fig. 2b) mixed with 3 wt.% binders, resulting in a unimodal particle size distribution of spherical powder aggregates of 20 -200 µm in size (d50 ~ 50 µm, [30]), e.g. in their 3 mol.% Y2O3 powder TZ3YBE.…”

Section: The White-bodiesmentioning

confidence: 99%

A Revised Relationship Between Fracture Toughness and Y2O3 Content in Modern Dental Zirconias

Belli

Hurle²,

Schürrlein³

et al. 2021

Preprint

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The relationship between fracture toughness and Yttria content in modern zirconia ceramics was revised. For that purpose, we evaluated here 10 modern Y2O3-stabilized zirconia (YSZ) materials currently used in biomedical applications, namely prosthetic and implant dentistry. The most relevant range between 2-5 mol% Y2O3 was addressed by selecting from conventional opaque 3 mol% YSZ up to more translucent compositions (4-5 mol% YSZs). A technical 2YSZ was used to extend the range of our evaluation. The bulk mol% Y2O3 concentration was measured by X-Ray Fluorescence Spectroscopy. Phase quantification by Rietveld refinement are supplied by considering only two tetragonal phases or an additional improbable cubic phase. A first-account of the fracture toughness (KIc) of the partly-sintered materials is given, which amounted to 0.4 – 0.7 MPaÖm. In the fully-densified state, an inverse power-law behavior was obtained between KIc and bulk mol% Y2O3 content, whether using only our measurements or including literature data, challenging some established relationships.

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Section: The White-bodiesmentioning

confidence: 99%

A Revised Relationship Between Fracture Toughness and Y2O3 Content in Modern Dental Zirconias

Belli

Hurle²,

Schürrlein³

et al. 2021

Preprint

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show abstract

“…This would explain the shift of 4 PB specimens toward higher strength values. The majority of dental zirconia manufacturers are supplied by Tosoh Corp., which provide powders composed of 40 nm primary particles (which match the microstructural units seen in the magnification of Figure 4B) mixed with 3 wt% binders, resulting in a Gaussian unimodal particle size distribution 27,28 of spherical powder aggregates of 20-200 µm in size (d 50 ~ 50 µm, as measured by Faust Gouveia et al 27 ), for example, in their 3 mol% Y 2 O 3 powder TZ3YBE. The size of the defects seen in Figure 4A,B fall within a reasonable size scale, which could result from the vertex junctions arising from the pressing of granulates of such sizes.…”

Section: Resultsmentioning

confidence: 99%

The breakdown of the Weibull behavior in dental zirconias

Belli

Lohbauer

2021

J Am Ceram Soc

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A long-standing regular in the circles of controversy is the debate on the appropriateness of the common practice of treating datasets of strength measurements of brittle materials using Weibull statistics, or if they rather belong to the enclave of other probability distributions. We do not intend to take a slide into that mathematical rabbit hole, here. There have been enough strides on that terrain with valuable insights, 1-5 exposing for one, that small sample sizes, despite in compliance with standard recommendations, cannot offer the means for distinguishing between similar distributions (e.g., Gaussian, Weibull, log-normal). 6 For such experimental practices confined within single specimen sizes, distributions of a set of strength values will almost invariably appear to be of the Weibull type. 7 That alone is no definite testament of a Weibull material, that is, that its strength distribution is determined by an inherent distribution of flaw sizes of monotonically decreasing density, 8 while obeying the original assumption of the weakest link hypothesis. 9,10

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“…Similar to all CAD/CAM milling processes, dental zirconia milling dust (~30%) and block residuals (~80%) as wastes have been reported [18] that incur significant economic and environmental losses [19]. Therefore, an appropriate reuse of such zirconia wastes would certainly increase its eco-friendliness and cost efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, an appropriate reuse of such zirconia wastes would certainly increase its eco-friendliness and cost efficiency. Gouveia et al [19] attempted to recycle dental zirconia, but the recycled product can only be used in the jewelry industry. Therefore, in this study, we aim to seek an easy and clean method to recycle dental CAD/CAM zirconia green blank wastes that can be reused effectively for dental prostheses.…”

Section: Introductionmentioning

confidence: 99%

A simple solution to recycle and reuse dental CAD/CAM zirconia block from its waste residuals

et al. 2021

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Purpose: To seek a simple solution that can recycle and regenerate dental CAD/CAM zirconia green blanks from its waste residuals. Methods: Waste residuals (3M® Lava™ Plus HT) were pulverized after dry milling and cutting, and subsequently sieved before pickling in a 0.5 M nitric acid. These powders were then dry-pressed and pre-sintered into blocks at seven different temperatures in the range 800−1100 °C. New zirconia blocks flagged with the same batch numbers were used as control. These blocks were cut into bars before subjected them to manufacturerrecommended sintering at 1450 °C. Crystalline phases (by XRD), elemental compositions (by EDX), surface morphologies (by SEM), machinability, linear shrinkage rate, relative density, and Knoop microhardness were evaluated before and after sintering, and four-point flexural strengths were also evaluated for the sintered zirconia bars. Results: Only tetragonal phases were found in both pre-and fully-sintered recycled zirconia blocks. SEM results showed that pre-sintered samples at 950 °C had smooth and flat surfaces with evenly distributed particles. Recycled and control zirconia blocks had similar elemental compositions. Results from machined surface, linear shrinkage rate, relative density, and Knoop microhardness established that 950 °C and 1000 °C were suitable pre-sintering temperatures for recycling zirconia. Pre-sintered recycled zirconia had no significant differences in flexural strengths, however, samples pre-sintered at 1000 °C exhibited the closest value (897 MPa) compared to that of the control (904 MPa). Conclusions: Dental CAD/CAM zirconia can be recycled and reused from its waste residuals by adopting a simple method that requires a presintering at 950 or 1000 °C.

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New perspectives for recycling dental zirconia waste resulting from CAD/CAM manufacturing process

Cited by 42 publications

References 50 publications

A Revised Relationship Between Fracture Toughness and Y2O3 Content in Modern Dental Zirconias

A Revised Relationship Between Fracture Toughness and Y2O3 Content in Modern Dental Zirconias

The breakdown of the Weibull behavior in dental zirconias

A simple solution to recycle and reuse dental CAD/CAM zirconia block from its waste residuals

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