The effect of repeat processing on the color stability of lithium disilicate glass-ceramic

This study evaluated the effect of different surface treatments on the tensile bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. Fifty truncated cone-shape glass-ceramics were divided into five groups (n = 10): G1, control: 10% hydrofluoric acid (HF); G2, Nd:YAG laser + silane; G3, Sil + Nd:YAG laser; G4, graphite + Nd:YAG laser + Sil; and G5, graphite + Sil + Nd:YAG laser. Fifty human third-molars were cut to cylindrical shape and polished to standardize the bonding surfaces. The glass-ceramic specimens were bonded to dentin with a dual-cured resin cement and stored in distilled water for 24 h at 37ºC. Tensile testing was performed on a universal testing machine (10 Kgf load cell at 1 mm/min) until failure. The bond strength values (mean ± SD) in MPa were G1 (9.4 ± 2.3), G2 (9.7 ± 2.0), G3 (6.7 ± 1.9), G4 (4.6 ± 1.1), and G5 (1.2 ± 0.3). Nd:YAG laser and HF improve the bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. The application of a graphite layer prior to Nd:YAG laser irradiation negatively affects this bonding and presented inferior results.

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LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic

Brazilian Dental Journal ◽

10.1590/0103-6440201300367 ◽

2015 ◽

Vol 26 (6) ◽

pp. 648-653 ◽

Cited By ~ 3

Author(s):

Carolina Nemesio de Barros Pereira ◽

Cláudia Silami de Magalhães ◽

Bruno Daleprane ◽

Rogéli Tibúrcio Ribeiro da Cunha Peixoto ◽

Raquel da Conceição Ferreira ◽

...

Keyword(s):

Regression Model ◽

Glass Ceramic ◽

Light Transmission ◽

Light Attenuation ◽

Lithium Disilicate ◽

Strong Negative Correlation ◽

Halogen Light ◽

Significant Difference ◽

Cad Cam ◽

Ceramic Thickness

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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Lubricated Wear of Machinable Lithium Disilicate Glass Ceramic

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.739.18 ◽

2017 ◽

Vol 739 ◽

pp. 18-22

Author(s):

Laura Elbourne-Binns ◽

Juan Carlos Baena ◽

Ling Yin ◽

Zhong Xiao Peng

Keyword(s):

Surface Roughness ◽

Glass Ceramic ◽

Sliding Friction ◽

Surface Preparation ◽

Lithium Disilicate ◽

Wear Volume ◽

Oral Environment ◽

Dry Conditions ◽

Applied Forces ◽

Lubrication Conditions

An experimental investigation was performed to study the wear of a promising dental ceramic, i.e., machinable lithium disilicate glass ceramic, under lubrication conditions, in particular, to examine effects of the surface finish and applied load on wear. Our previous work has shown that a fine finish in a dry condition did not necessarily translate to the lowest wear volume due to changes in the dominant wear mechanisms. This study tested the ceramic specimens with four average surface roughness values of Sa = 143 nm, 217 nm, 353 nm, and 692 nm on a reciprocating sliding friction rig against alumina balls with two applied forces of 5 N and 25 N in a bath of distilled water. Comparing with the results obtained in the dry conditions, this study shows that surface roughness of approximately 200 nm may be suitable for surface preparation of crowns made from the material in the wet and dry wear conditions in the oral environment.

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