Fracture-free surfaces of CAD/CAM lithium metasilicate glass-ceramic using micro-slurry jet erosion

The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, p<0.001) between ceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

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

Cerâmica ◽

10.1590/0366-69132016623621988 ◽

2016 ◽

Vol 62 (362) ◽

pp. 121-127 ◽

Cited By ~ 1

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.

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Coloration of mica glass-ceramic for use in dental CAD/CAM system

Materials Letters ◽

10.1016/s0167-577x(02)00804-2 ◽

2002 ◽

Vol 57 (2) ◽

pp. 425-428 ◽

Cited By ~ 3

Author(s):

Ying Sun ◽

Zhongyi Wang ◽

Jiemo Tian ◽

Xiaogang Cao

Keyword(s):

Glass Ceramic ◽

Cad Cam

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A Comparative Study of Light Transmission by Various Dental Restorative Materials and the Tooth Structure

Operative Dentistry ◽

10.2341/19-037-l ◽

2019 ◽

Vol 45 (4) ◽

pp. 442-452 ◽

Cited By ~ 3

Author(s):

N Ilie ◽

G Furtos

Keyword(s):

Optical Properties ◽

Glass Ceramic ◽

Light Transmission ◽

Lithium Disilicate ◽

Lithium Silicate ◽

Restorative Process ◽

Tooth Structure ◽

Computer Aided ◽

Restorative Materials ◽

Cad Cam

Clinical Relevance Light transmission through dental materials and tooth structure has direct clinical implication on such factors as selecting an appropriate curing technique during a restorative process. SUMMARY Introduction: This study aims to quantify and compare the amount of light that passes through seven different types of direct and indirect restorative materials comprising light-cured resin based composites (regular and bulk-fill), computer-aided design/computer-aided manufacturing (CAD/CAM) restoratives such as resin based composites, poly(methyl methacrylate) (PMMA) resin, leucite glass-ceramic, lithium silicate glass-ceramic, feldspar ceramic, and the natural tooth structure. Methods and Materials: Individual sets (n=6) of plane-parallel test specimens (2 mm) of 32 restorative materials belonging to the aforementioned seven material types and the tooth structure were prepared. Within the analyzed materials, one leucite glass-ceramic and one lithium disilicate glass-ceramic were considered in two different translucencies. In addition, two light-cured resin composites, one CAD/CAM resin composite, and one lithium disilicate glass-ceramic were considered in two different shades. Optical properties (transmittance, T; absorbance, A; and opacity, O) of each material were calculated from the relationship between incident and transmitted irradiance [I(d)] using a violet-blue light-curing unit. Incident and transmitted irradiance were assessed in real time on a spectrophotometer. A multivariate analysis (general linear model) assessed the effects of various parameters on the optical properties. Results: A very strong influence of the parameter material was identified on I(d) (p<0.001; partial eta squared, ηP2=0.953), T (p<0.001; ηP2=0.951), A (p<0.001; ηP2=0.925), and O (p<0.001; ηP2=0.886), while the effect of the parameter material type was not significant (p=0.079, p=0.05, p=0.05, and p=0.051, respectively). Light attenuation differed significantly by material within each shade category and by shade category within the analyzed material. Conclusions: Attenuation of light through restorative materials and tooth structure is high (59.9% to 94.9%); thus, deficits in polymerization are difficult to compensate for by additional light exposure at the end of the restorative process.

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Sequential usage of diamond bur for CAD/CAM milling: Effect on the roughness, topography and fatigue strength of lithium disilicate glass ceramic

Journal of the Mechanical Behavior of Biomedical Materials ◽

10.1016/j.jmbbm.2018.12.037 ◽

2019 ◽

Vol 91 ◽

pp. 326-334 ◽

Cited By ~ 7

Author(s):

Camila Ferreira Leite Madruga ◽

Mírian Galvão Bueno ◽

Amanda Maria de Oliveira Dal Piva ◽

Catina Prochnow ◽

Gabriel Kalil Rocha Pereira ◽

...

Keyword(s):

Fatigue Strength ◽

Glass Ceramic ◽

Lithium Disilicate ◽

Diamond Bur ◽

Cad Cam

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Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

Materials ◽

10.3390/ma13020381 ◽

2020 ◽

Vol 13 (2) ◽

pp. 381 ◽

Cited By ~ 6

Author(s):

Roxana-Diana Vasiliu ◽

Sorin Daniel Porojan ◽

Mihaela Ionela Bîrdeanu ◽

Liliana Porojan

Keyword(s):

Surface Roughness ◽

Optical Properties ◽

Glass Ceramic ◽

Glass Ceramics ◽

Lithium Disilicate ◽

Ceramic Materials ◽

Surface Treatments ◽

Lithium Silicate ◽

Before And After ◽

Cad Cam

Dental ceramic restorations are widely spread nowadays due to their aesthetics and biocompatibility. In time, the colour and structure of these ceramic materials can be altered by aging processes. How does artificial aging affect the optical and surface roughness of ceramics? This study aims to assess the effect of thermocycling, surface treatments and microstructure upon translucency, opalescence and surface roughness on CAD-CAM and heat-pressed glass-ceramic. Forty-eight samples (1.5 mm thickness) were fabricated from six types of A2 MT ceramic: heat-pressed and milled glass-ceramic (feldspathic, lithium disilicate and zirconia reinforced lithium silicate). The samples were obtained respecting the manufacturer’s instructions. The resulted surfaces (n = 96) were half glazed and half polished. The samples were subjected to thermocycling (10,000 cycles) and roughness values (Ra and Rz), colour coordinates (L*, a*, b*) and microstructural analyses were assessed before and after thermocycling. Translucency (TP) and opalescence (OP) were calculated. Values were statistically analysed using ANOVA test (one way). TP and OP values were significantly different between heat-pressed and milled ceramics before and also after thermocycling (p < 0.001). Surface treatments (glazing and polishing) had a significant effect on TP and OP and surface roughness (p < 0.05). The heat-pressed and milled zirconia reinforced lithium silicate glass-ceramic experienced a loss in TP and OP. Ra and Rz increased for the glazed samples, TP and OP decreased for all the samples after thermocycling. Microstructural analyse revealed that glazed surfaces were more affected by the thermocycling and especially for the zirconia reinforced lithium silicate ceramic. Optical properties and surface roughness of the chosen ceramic materials were affected by thermocycling, surface treatments and microstructural differences. The least affected of the ceramics was the lithium disilicate ceramic heat-pressed polished and glazed.

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