Effect of Artificial Saliva Storage on Microhardness and Fracture Toughness of a Hydrothermal Glass‐Ceramic

Fahmy, Nadia Z.; Guindy, Jylan El; Zamzam, M. A.

doi:10.1111/j.1532-849x.2009.00448.x

Cited by 20 publications

(20 citation statements)

References 46 publications

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“…Commercially available over-the-counter bleaching systems containing hydrogen peroxide in strip and paint on gel form did not have any effect on either the surface morphology or the surface roughness of porcelains, 36,37 whereas increased surface roughness 38,39 and decreased surface microhardness 11, 40 were evaluated with carbamide peroxidecontaining tray-based systems. Consistent with the previously mentioned literature, in the present study, the tray-based carbamide peroxide-containing bleaching system Opalescence PF significantly decreased the microhardness of leucite-reinforced glass ceramic, glass ceramic, and feldspathic porcelain with respect to before bleaching, whereas the hydrogen peroxide-containing over-the-counter bleaching agent Treswhite Supreme did not significantly affect their microhardness.…”

Section: Discussionmentioning

confidence: 99%

Effect of Bleaching on Microhardness of Esthetic Restorative Materials

Malkondu¹,

Yurdagüven²,

Say³

et al. 2011

Operative Dentistry

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High-concentration carbamide peroxide containing home bleaching may cause a varying influence on the microhardness of esthetic restorative materials. SUMMARYThis study evaluated the effect of a highconcentration carbamide peroxide-containing home bleaching system (Opalescence PF) and a hydrogen peroxide-containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucitereinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 lm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n¼10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test.Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p¼0.005), Empress Esthetic (p¼0.003), Empress 2 layering (p¼0.005), and Matchmaker-MC (p¼0.003), whereas a statistically significant

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Section: Discussionmentioning

confidence: 99%

Effect of Bleaching on Microhardness of Esthetic Restorative Materials

Malkondu¹,

Yurdagüven²,

Say³

et al. 2011

Operative Dentistry

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“…Vickers microhardness was evaluated (n=30) at disks with a load of 4,904 N applied for 20 seconds (HMV-2, Shimadzu Corp., Kyoto, Japan) 20 . Five randomly chosen sites per sample were evaluated and a mean value (VHN) was obtained.…”

Section: Microhardnessmentioning

confidence: 99%

“…Fracture toughness was evaluated (n=30) by the indentation method proposed by Anstis 22 , using a microhardness tester (HMV-2, Shimadzu Corp., Kyoto, Japan) 4,11,18,20 . A load of 19,6N was applied for 20 seconds.…”

Section: Fracture Toughnessmentioning

confidence: 99%

“…Three randomly sites per sample were evaluated. Crack length was measured from the center of indent and a mean value for cracks was used to calculate fracture toughness using the formula 20 , where K IC is fracture toughness (MPa/m), E is elastic modulus (GPa), P is the load applied (N), H is Vickers microhardness (GPa) and c is crack length(m):…”

Section: Fracture Toughnessmentioning

confidence: 99%

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Fracture toughness of three heat pressed ceramic systems

et al. 2018

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Aim: The aim of this study was to evaluate fracture toughness by indentation method of three dental ceramics processed by heat pressing. The ceramics evaluated were fluorapatite glass ceramic (ZIR), glass ceramic containing leucite (POM) and leucite-reinforced glass ceramic (EMP). Materials and methods: Ninety disks (13mm of diameter x 4mm of thickness) and nine rectangular specimens (25x4x2mm) were made to evaluate, respectively, microhardness/fracture toughness (n=30) and elastic modulus (n=3). Samples were obtained by pressing ceramic into refractory molds. After polishing, Vickers microhardness was evaluated under 4,904N load for 20s. Elastic modulus was measured by impulse excitation technique. Data from microhardness and elastic modulus were used to calculate fracture toughness, after measuring crack length under 19,6N load applied for 20s. Results were evaluated by ANOVA and Tukey´s test. Results: Microhardness (VHN) of POM (637.9±53.6) was statistically greater (p<0.05) than ZIR (593.0±14. The results suggest that fluorapatite glass ceramic (ZIR) and leucite-reinforced glass ceramic (EMP) processed by heat pressing presented greater fracture toughness, improving clinical prognosis of metal free restorations.

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“…However, there are still controversies about the effects of the surface treatments on the strength of the ceramic. Some studies have reported no difference in the flexural strength and the fracture resistance of glazed and polished ceramics 2,11,12) , while others have reported that polished porcelain has higher fracture resistance than glazed porcelain 3,13) . As an alternative to the glazing procedure, various chair-side polishing instruments have been evaluated, especially in terms of enamel wear of the opposing teeth 8,14,15) .…”

Section: Introductionmentioning

confidence: 99%

Performance of a novel polishing rubber wheel in improving surface roughness of feldspathic porcelain

et al. 2014

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Replacing glazing with polishing is still controversial in terms of the surface roughness of dental porcelains. This study investigated the polishing performance of a ceramic-polishing rubber wheel (CP-RW), which contains large uniform and rounded silicon carbide particles and small diamond particles, in improving the surface roughness of two feldspathic porcelains for sintering and CAD/ CAM milling. Using a confocal laser scanning microscopy, the changes in the surface roughness parameters were evaluated before and after polishing or glazing for three surface treatment groups: SofLex polishing, CP-RW polishing, and Glazing. Regardless of the parameters, all treatments reduced roughness values (repeated measures ANOVA, p<0.05). The roughness values obtained after CP-RW polishing were lower than those obtained after SofLex polishing and glazing (2-way ANOVA, p<0.05). Polishing both ceramics with CP-RW made the surfaces smooth with the lowest roughness values in all parameters. The effect was dependent on the materials used.

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Effect of Artificial Saliva Storage on Microhardness and Fracture Toughness of a Hydrothermal Glass‐Ceramic

Cited by 20 publications

References 46 publications

Effect of Bleaching on Microhardness of Esthetic Restorative Materials

Effect of Bleaching on Microhardness of Esthetic Restorative Materials

Fracture toughness of three heat pressed ceramic systems

Performance of a novel polishing rubber wheel in improving surface roughness of feldspathic porcelain

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