THE EFFECT OF REPEATED HEAT-PRESSING ON THE BIAXIAL FLEXURAL STRENGTH AND SURFACE ROUGHNESS OF LITHIUM DISLILICATE GLASS-CERAMICS

2017 ◽  
Vol 63 (1) ◽  
pp. 833-840
Author(s):  
Amr EL-Etreby ◽  
Lomaya Ghanem
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Glass Ceramics ◽  
Biaxial Flexural Strength

scholarly journals Effect of the bur grit size on the flexural strength of a glass-ceramic

Cerâmica ◽  
2016 ◽  
Vol 62 (362) ◽  
pp. 121-127 ◽  
Author(s):  
P. P. Kist ◽  
I. L. Aurélio ◽  
M. Amaral ◽  
L. G. May
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Internal Surface ◽  
Grit Size ◽  
Diamond Grit ◽  
Cad Cam ◽  
Negative Effect ◽  
Ceramic Blocks

Abstract The purpose of the present study was to determine the biaxial flexural strength (BFS) of a CAD/CAM leucite reinforced glass-ceramic ground by diamond burs of different grit sizes and the influence of surface roughness on the BFS. For this, 104 plates were obtained from CAD/CAM ceramic blocks and divided into 4 groups (n = 26), according to bur grit size: extra-fine, fine, medium and coarse. Roughness parameters (Ra, RyMax) were measured, and plates were kept dry for 7 days. The flexural test was carried out and BFS was calculated. Ra, RyMax and BFS data were subjected to analysis of variance and post-hoc test. Weibull analysis was used to compare characteristic strength and Weibull modulus. Regression analysis was performed for BFS vs. Ra and RyMax. When burs with coarse grit were used, higher surface roughness values were found, causing a negative effect on the ceramic BFS (117 MPa for extra-fine, and 83 MPa for coarse). Correlation (r) between surface roughness and BFS was 0.78 for RyMax and 0.73 for Ra. Increases in diamond grit size have a significant negative effect on the BFS of leucite-reinforced glass-ceramics, suggesting that grinding of sintered glass-ceramic should be performed using burs with the finest grit possible in order to minimize internal surface flaws and maximize flexural strength.

Biaxial Flexural Strength and Microstructure Changes of Two Recycled Pressable Glass Ceramics

2004 ◽  
Vol 13 (3) ◽  
pp. 141-149 ◽  
Author(s):  
Mohammad Albakry ◽  
Massimiliano Guazzato ◽  
Michael Vincent Swain
Keyword(s):  
Flexural Strength ◽  
Glass Ceramics ◽  
Microstructure Changes ◽  
Biaxial Flexural Strength

scholarly journals Surface Topography, Gloss and Flexural Strength of Pressable Ceramic After Finishing-Polishing Protocols

2019 ◽  
Vol 30 (2) ◽  
pp. 164-170 ◽  
Author(s):  
Fernanda P. Silva ◽  
Ana L. R. Vilela ◽  
Matheus M. G. Almeida ◽  
André R. F. Oliveira ◽  
Luís H. A. Raposo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Glass Ceramic ◽  
Lower Surface ◽  
Good Alternative ◽  
Sem Analysis ◽  
Force Microscopy ◽  
Biaxial Flexural Strength ◽  
Surface Irregularities ◽  
Post Hoc

Abstract This study evaluated the effect of different finishing-polishing protocols on surface roughness, gloss, morphology and biaxial flexural strength of pressable fluorapatite glass ceramic. Thirty ceramic discs (12x1 mm) were produced and divided into five groups (n=6): CT: control (glaze); DA: fine grit diamond bur; DG: DA + new glaze layer; DP: DA + felt disk with fine grit diamond paste; DK: DA+ sequential polishing with silicon abrasive instruments, goat hair brush and cotton wheel. The specimens were analyzed for surface roughness (Ra) under profilometry and atomic force microscopy (AFM). Gloss was measured with spectrophotometry and micromorphology with scanning electron microscopy (SEM). Flexural strength was assessed by biaxial flexural strength test. Data were analyzed using one-way ANOVA and Tukey’s post hoc test (a=0.05). DK showed the lowest surface roughness values and DA presented the highest in the perfilometer analysis. No significant differences were observed in the AFM for the CT, DG and DK groups, which presented the lower surface roughness; DA and DP had the higher Ra values. The DA, DP and CT showed the lowest surface gloss values, and the reflectance was significantly different from those observed for DK and DG groups. SEM analysis revealed the smoothest surface for DK group, followed by DG and CT groups; DA and DP groups exhibited variable degrees of surface irregularities. No significant differences were observed among groups for the biaxial flexural strength. The polishing protocol used in DK group can be a good alternative for chairside finishing of adjusted pressable fluorapatite glass ceramic surfaces.

scholarly journals Effect of Acid Mixtures on Surface Properties and Biaxial Flexural Strength of As-Sintered and Air-Abraded Zirconia

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2359
Author(s):  
Jong-Eun Kim ◽  
Yong-Chan Kwon ◽  
Sunjai Kim ◽  
Young-Bum Park ◽  
June-Sung Shim ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Hydrofluoric Acid ◽  
Acid Treatment ◽  
Monoclinic Phase ◽  
Acid Mixture ◽  
Application Time ◽  
Air Abrasion ◽  
Strength Measurement ◽  
Biaxial Flexural Strength

The aim of this work was to evaluate the effects of application time of an acid mixture solution on the surface roughness, phase transformation, and biaxial flexural strength of 3Y-TZP after sintering or air abrasion. For the biaxial flexural strength measurement, 220 3Y-TZP disk-shaped specimens were prepared after as-sintering or air abrasion. The etching solution comprised a mixture of hydrofluoric acid, sulfuric acid, hydrogen peroxide, methyl alcohol, and purified water. The samples were divided into 11 subgroups according to the etching times (Control, 1, 2, 3, 5, 8, 10, 12, 15, 20, and 30 min). The results showed that acid treatment on both as-sintered and air-abraded 3Y-TZP surfaces increased the surface roughness. However, it had no significant effects on the monoclinic phase or flexural strength of as-sintered zirconia. The monoclinic phase and flexural strength of air-abraded zirconia increased sharply after air abrasion; however, they gradually decreased after acid treatment, to a similar level to the case of the untreated surface. Surface treatment with acid mixture increased the roughness, but the lack of increase of monoclinic phase is thought to be because the loose monoclinic particles remaining on the surface were removed through the etching process.

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