Polishing of ground y-tzp ceramic is mandatory for improving the mechanical behavior

Abstract 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.

Resumo Este estudo avaliou o efeito do envelhecimento através da degradação a baixas temperaturas (low temperaturare degradation - LTD) após a realização de tratamentos de superfície pós- sinterização (polimento, tratamento térmico e glaze) nas características superficiais (micromorfologia e rugosidade), e na estabilidade estrutural (transformação de fase e comportamento mecânico - resistência flexural e confiabilidade estrutural) de uma cerâmica de zircônia tetragonal policristalina estabilizada por ítria (Y-TZP) desgastada. Discos de cerâmica Y-TZP (VITA In-Ceram YZ) foram confeccionados (ISO:6872-2015; 15mm de diâmetro e 1,2 ± 0,2mm de espessura) e randomicamente divididos em 10 grupos de acordo com dois fatores: "envelhecimento" (com e sem) e "tratamento de superfície" (Ctrl - sem tratamento; Gr - desgaste com ponta diamantada grossa; Gr + HT - desgaste mais tratamento térmico; Gr + Pol - desgaste mais polimento; Gr + Gl - desgaste mais glazeamento). Foram realizadas as análises de rugosidade (n=30), flexão biaxial (n=30), transformação de fase (n=2) e topografia de superfície (n=2). O envelhecimento levou a um aumento intenso no conteúdo de fase monoclínica (m) em todas as condições testadas, sendo observada uma maior susceptibilidade de transformação de fase t-m nas amostras do grupo controle (Ctrl= 65.6%). Apesar de provocar elevada transformação de fase, o envelhecimento não apresentou efeitos negativos nos desfechos avaliados. Não houve redução significativa do módulo de Weibull após os tratamentos. Além disso, o tratamento térmico e o glaze após desgaste levaram a uma redução da resistência característica, enquanto que o grupo polimento apresentou o mais alto valor de resistência característica. O glaze e o tratamento térmico geraram o pior desempenho mecânico, portanto a realização do polimento após desgaste de uma cerâmica Y-TZP é obrigatória.

Effect of conventional and microwave glazing on surface roughness of metal ceramics: An atomic force microscopy analysis

This study investigated and compared the surface roughness achieved by glazing porcelain samples in a conventional and a microwave oven. Materials and Methods: Two commercial brands of metal ceramics were used, VITA VMK MASTER and IPS CLASSIC. Sixty samples were fabricated, 30 for each type of ceramic. The samples were sintered in the conventional oven and hand-polished to remove any irregularities. Samples (n = 10) from each type of ceramic were further divided into three groups as follows: hand-polished (Group A), conventional oven glazed (Group B), and microwave glazed (Group C). Each specimen was evaluated for surface roughness by atomic force microscope. Data were statistically analyzed using two-way analysis of variance (ANOVA) and Tukey's post hoc test (a = 0.05). Results: Two-way ANOVA indicated a highly significant difference in surface roughness based on the type of glazing (P < 0.001), there was a significant difference based on the metal ceramics (P = 0.002). There was also a significant interaction between the type of glazing and metal ceramics (P = 0.009). The images obtained from the atomic force microscope corroborated the measured values. Conclusions: All the results indicate that microwave glazing can be a feasible option for glazing porcelain specimens. It was concluded that surface topography is influenced by surface treatment and microwave glazed ceramic is superior to conventional oven glazed ceramic and hand-polishing showed greater surface roughness when compared to glazing. IPS CLASSIC ceramic showed relatively smooth surface when compared to VITA VMK MASTER irrespective of the surface treatment.

Fraudes em peixes na região central da cidade de Joinville, SC / Fish fraud in the central region of the city of Joinville, SC

Joinville é a maior cidade do estado de Santa Catarina em termos populacionais e, estando próxima a uma região litorânea, o consumo de peixes pelos seus habitantes faz parte dos costumes locais, sejam eles frescos ou congelados. Dentre as variedades de espécies e produtos de peixes congelados, destaca-se o filé de pescada, pelo seu preço acessível e versatilidade no preparo. Na produção, é necessária a prática de glaciamento, que consiste em envolver o filé em uma camada de gelo limitada a 20% do seu peso total. Esse processo servirá para proteger o produto contra oxidação e rancificação, porém muitos produtores extrapolam o limite de 20% para aumentar os ganhos com o produto, o que caracteriza uma fraude. Diante disso, o objetivo deste trabalho foi mensurar o nível de glaciamento nos filés de pescada congelados, comercializados na região central da cidade de Joinville/SC. A metodologia utilizada foi a preconizada pelo Ministério da Agricultura, Pecuária e Abastecimento na Instrução Normativa nº 25, de 2 de junho de 2011, em 14 amostras triplicadas. Foram constatadas 5 fraudes nas 14 amostras, totalizando 35,72%. Juntamente a isso, observou- se que havia diferença entre o peso líquido anunciado e o peso real de pescado em 100% das amostras, o que é considerado uma fraude de rotulagem pela Agência Nacional de Vigilância Sanitária. Por meio dos resultados, pode-se observar a necessidade do aumento de medidas oficiais de controle pelos órgãos reguladores.(AU)

Joinville is the largest city in the state of Santa Catarina in population terms and, being close to a coastal region, the consumption of fish by its inhabitants is part of local customs, be they fresh or frozen. Among the varieties of frozen fish species and products, we highlight hake fillet, for its affordable price and versatility in preparation. In production, it is common practice to glaze, which involves wrapping the fillet in a layer of ice limited to 20% of its total weight. This process will protect the product against oxidation and rancification, but many producers extrapolate the 20% limit to increase product gains, which is a fraud. Therefore, the objective of this work is to measure the level of glaciation in frozen hake fillets marketed in the central region of the city of Joinville/SC. The methodology used was that recommended by the Ministério de Agricultura, Pecuária e Abastecimento in Normative Instruction nº. 25, dated June 2, 2011, in 14 triplicate samples. Four frauds were detected in the 14 samples, totaling 35,72%. Together with this, it was observed that there was a difference between the announced net weight and the actual weight of fish in 100% of the samples, which is considered a labeling fraud by Agência Nacional de Vigilância Sanitária. Through the results, it is possible to observe the need for an increase in official control measures by regulatory agencies.

Polishing performance of different polishing tools for CEREC Blocs ceramic / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to compare the polishing performance of five different glass-ceramic polishing tools on CEREC Blocs ceramic and provide evidence for clinical polishing tool selection.</p><p><b>METHODS</b>Sixty ceramic specimens were prepared and divided into six groups (n=10). These specimens received different surface treatments, including glazing (group G), polishing with Shofu polishing set, that is, Porcelain Adjustment Kit+CeraMaster (group SF), 3M Sof-LexTM Discs (group 3M), TobooM polishing set (group Tob), EVE DIAPRO system (group EVE), and Ivoclar Vivadent OptraFine® system (group Ivo). Polishing quality was measured with a profilometer, and we selected Ra and Rz values for statistical analysis. Qualitative surface evaluation was performed by a scanning electron microscope (SEM).</p><p><b>RESULTS</b>The mean Ra values of each group were as follows: G (0.069 µm±0.008 µm)<3M (0.073 µm±0.009 µm)<SF (0.223 µm±0.025 µm)<Ivo (0.229 µm±0.022 µm)<EVE (0.491 µm±0.093 µm)<Tob (0.763 µm±0.067 µm). No significant difference was observed between G and 3M groups (P>0.05), and SF and Ivo groups (P>0.05), but the remaining treatment groups were significantly different from each other (P<0.05). Statistical results of Rz values were the same as the Ra values, and visual analysis of the images obtained from SEM was consistent with the statistical results.</p><p><b>CONCLUSIONS</b>The polishing performance of different polishing tools for CEREC Blocs ceramic was different. Sof-LexTM Discs achieved the most remarkable performance, which was comparable to that of glazing. 
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Influence of Water Infiltration and Flexural Strength Change with Glazing Treatment of Dental Porcelain / 치위생과학회지

The purpose of this study was to evaluate the influence of water infiltration and flexural strength changes in dental porcelain with glazing treatment. The block specimens were prepared as experimental materials, using feldspar type commercial dental porcelain; then, these were fired at 940oC for 1 minute. The fired specimens were polished with a dimension of 40×5.5×5 mm. The specimens were distributed to two experimental groups: with and without glazing treatment specimens (n=5), and they were immersed in a solution of pH 7 for 3, 7, and 20 days at 40℃ after fabrication. To evaluate the flexural strength changes with water infiltration treatment in specimens with and without glazing, the 3-point flexural test was performed, using a universal testing machine until failure occurred. Starting powder and fired specimens consisted of amorphous and leucite crystalline phase. The Vickers hardness of fired specimens was more than 1.6 times higher than that of the enamel of natural teeth. According to porosimeter results, the specimens without glazing treatment exhibited a porosity of about 14.7%, whereas the glazed specimens exhibited the lowest porosity at about 1.1%. The average flexural strength of glazed specimens was higher than the flexural strength of specimens without glazing treatment (p<0.05). The flexural strength of all specimens with and without glazing treatment deteriorated with accelerated aging in the solution. In addition, significant differences between these two treatment groups were observed in all of the specimens treated at various water infiltration periods (p<0.05). The exposure of internal pores and micro-cracks in the surface due to polishing of the fired specimens influenced mechanical behaviors. Especially, the flexural strength in specimens without glazing treatment has shown significant degradation with the infiltration of water. Therefore, this study suggests that glazing processes can improve mechanical properties of dental porcelain.

A comparative study on biaxial flexural strength and Vicker`smicrohardness of different zirconia materials: Effect of glazingand thermal cycling / Estudo comparativo da resistência à flexão biaxial e microdureza Vickers` em diferentes materiais à base de zircônia: Efeito doglazeamento e da ciclagem térmica

Objetivo: Este estudo avaliou o efeito do glazeamento e da ciclagem térmica na resistência à flexão biaxial e na dureza Vicker’s de diferentes materiais à base de zircônia. Material e Métodos: Espécimes de disco (15 mm x 1,15 mm) de zircônia foram confeccionados usando 3 sistemas (ZirkonZahn, Cercon, Ceramill) de acordo com a recomendação de cada fabricante. Os espécimes de cada sistema cerâmico foram randomicamente divididos em 2 grupos. Enquanto metade dos espécimes foram glazeados, a outra metade permaneceu não glazeado. Adicionalmente, cada grupo foi divido em 4 subgrupos submetidos a diferentes ciclagens térmicas (0-control, 1000, 3000, 5000 ciclos, 5-55 ºC). A resistência à flexão biaxial foi realizada em uma máquina de teste universal (1 mm/min). As amostras não glazeadas foram submetidas a microdureza Vicker’s antes e após a ciclagem térmica (0-control, 1000, 3000, 5000 cycles, 5-55 ºC). Os dados foram estatisticamente analisados usando ANOVA 1-fator, ANOVA 2-fatores e teste de Tukey’s (p < 0,05). Resultados: Nas amostras não cicladas (1104-1388 MPa), o glazeamento reduziu significativamente a resistência à flexão biaxial de todos os sistemas cerâmicos (845.65-897.35 MPa) (p = 0,000). Enquanto nos grupos não glazeados todas as modalidades de ciclagem térmica reduziram significantemente a resistência à flexão biaxial (864- 1156 MPa) (p = 0,000), nos grupos glazeados a ciclagem térmica não afetou os resultados (829.4- 854.9 MPa) (p = 0,405). Comparados aos grupos não envelhecidos (1414.1 VHN), a ciclagem térmica reduziu significantemente a dureza Vickers apenas para o Cercon (1365.9 VHN) (p = 0,005). Conclusão: O glazeamento reduz a resistência à flexão biaxial dos sistemas à base de zircônia testados. As amostras não glazeadas foram mais afetadas pela ciclagem que as amostras glazeadas. Estas informações podem ter relevância clínica na durabilidade de reconstruções em zircônia monolítica.

Objective: This study evaluated the effect of glazing and thermal cycling on biaxial flexural strength and Vickers hardness of different zirconia framework materials. Material and Methods: Disc shaped zirconia specimens (15 mm x 1.15 mm) were fabricated using three systems (ZirkonZahn, Cercon, Ceramill) according to each manufacturer`s instructions. The specimens of each system were randomly divided into 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). Unglazed zirconia specimens were subjected to Vickers microhardness with and without thermal cycling (0-control, 1000, 3000, 5000 cycles, 5-55 ºC). Data were statistically analyzed using one-way ANOVA, twoway ANOVA and Tukey’s test (p < 0.05). Results: In non-aged conditions (1104-1388 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 the long-term durability of monolithic zirconia reconstructions, this information may have clinical significance.

The effect of repeated firings on the color change of dental ceramics using different glazing methods

PURPOSE: Surface color is one of the main criteria to obtain an ideal esthetic. Many factors such as the type of the material, surface specifications, number of firings, firing temperature and thickness of the porcelain are all important to provide an unchanged surface color in dental ceramics. The aim of this study was to evaluate the color changes in dental ceramics according to the material type and glazing methods, during the multiple firings. MATERIALS AND METHODS: Three different types of dental ceramics (IPS Classical metal ceramic, Empress Esthetic and Empress 2 ceramics) were used in the study. Porcelains were evaluated under five main groups according to glaze and natural glaze methods. Color changes (DeltaE) and changes in color parameters (DeltaL, Deltaa, Deltab) were determined using colorimeter during the control, the first, third, fifth, and seventh firings. The statistical analysis of the results was performed using ANOVA and Tukey test. RESULTS: The color changes which occurred upon material-method-firing interaction were statistically significant (P<.05). DeltaE, DeltaL, Deltaa and Deltab values also demonstrated a negative trend. The MC-G group was less affected in terms of color changes compared to other groups. In all-ceramic specimens, the surface color was significantly affected by multiple firings. CONCLUSION: Firing detrimentally affected the structure of the porcelain surface and hence caused fading of the color and prominence of yellow and red characters. Compressible all-ceramics were remarkably affected by repeated firings due to their crystalline structure.

The effects of surface glazing materials on dental sealant surface hardness and roughness / 대한구강보건학회지

OBJECTIVES: To assess the effect of glazing materials with different sealants on sealant surface roughness and surface hardness. METHODS: Ultraseal XT(TM) sealant (group 1) and 3M Concise(TM) sealant (group 2) were applied on the buccal surfaces of 26 bicuspid teeth per group. The buccal surface of each tooth was then divided into two half surfaces for 52 halves per group. BisCover LV(TM) glaze was applied to one of the two buccal half surfaces of randomly selected 13 teeth per group. For the other remaining 13 teeth per group, we applied Fortify(TM) glaze to one of the two half surfaces. The remaining 26 buccal half surfaces per group covered with sealant only, did not receive any glaze. The surface roughness and hardness of each sample was measured, and the average value of the three measurements from the individual sample was calculated. The sample surfaces were also observed by scanning an electron microscopy. RESULTS: Two-way ANOVA with surface roughness and hardness as the individual dependent variables identified a statistically significant interaction between the sealants and glazing materials. BisCover LV lowered Ultraseal XT surface roughness and application of surface glazing materials on 3M Concise promoted the hardness. Micro-cracks were identified on the surface in no glaze compared to being less in any glaze. CONCLUSIONS: Surface glaze material could improve the surface roughness and hardness of the selected pit and fissure sealant material. Such a sealant-reinforcing procedure, involving surface glazing, may be clinically useful.

Effect on the Color Stability of Stained Porcelain due to Tooth Brushing / 대한치과보철학회지

This study is going to compare the degree of color change which occurs in the following two cases of the factors which cause the color change of extra-staining,one is during glazing by the dental technician,the other is tooth brush abrasion which makes the biggest influence on color change. To compare the degree of color change before and after glazing,a sample was made with vintage incisal porcelain No.59 OPAL(Shofu Inc,Japan),after that it was painted with three colors of porcelain stainers,then the degree of color was measured with a spectrophometer(Model Chromaview 300,Spectoron Tech Co.Korea)after it had been treated with firing only and glazing after firing. 40,000-cycle and 80,000-cycle of tooth brush abrasion test were carried out in order to simulate the brushing effect of 4 years and 8 years by using the abrasion tester.The colors were mesured before the test,and after the 40,000-cycle and 80,000-cycle operations and the surfaces were examined by SEM. The results of this study were as follows ; 1.The color change before and after glazing was not great enough to have a clinical significance but the orange color was changed more significantly statistically than the blue and light brown(P<0.05). 2.In the case of the color change of stained porcelain by tooth brushing,carrying out staining and glazing with two-times firings resulted in statically less color change than one firing only(P<0.05). 3.In the case of the difference in the stainer's color,the orange color which has higher chroma was statically more sensitive than the blue color(P<0.05). 4.In the case of the color change after the 80,000-cycle abrasion,all showed color change when there was one firing and the orange stainer showed some color change with clinical significance when firings were done two times.