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

2015 ◽  
Vol 26 (6) ◽  
pp. 648-653 ◽  
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.

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

2019 ◽  
Vol 45 (4) ◽  
pp. 442-452 ◽  
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&lt;0.001; partial eta squared, ηP2=0.953), T (p&lt;0.001; ηP2=0.951), A (p&lt;0.001; ηP2=0.925), and O (p&lt;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.

Influence of Ceramic Thickness and Ceramic Materials on Fracture Resistance of Posterior Partial Coverage Restorations

2015 ◽  
Vol 40 (2) ◽  
pp. 211-217 ◽  
Author(s):  
EM Bakeman ◽  
N Rego ◽  
Y Chaiyabutr ◽  
JC Kois
Keyword(s):  
Glass Ceramic ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Tooth Structure ◽  
Partial Coverage ◽  
Significant Difference ◽  
Ceramic Thickness ◽  
Ceramic Restorations

SUMMARY This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (p&lt;0.001); however, the thickness of ceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (p&lt;0.05). There was no significant difference in fracture resistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

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

2019 ◽  
Vol 91 ◽  
pp. 326-334 ◽  
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

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

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 381 ◽  
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.

scholarly journals Effects of substrate, ceramic thickness, translucency, and cement shade on the color of CAD/CAM lithium‐disilicate crowns

2019 ◽  
Vol 31 (5) ◽  
pp. 457-464 ◽  
Author(s):  
Alexandra Czigola ◽  
Emese Abram ◽  
Zoltan I. Kovacs ◽  
Krisztina Marton ◽  
Peter Hermann ◽  
...  
Keyword(s):  
Lithium Disilicate ◽  
Cad Cam ◽  
Ceramic Thickness

Masking Colored Substrates Using Monolithic and Bilayer CAD-CAM Ceramic Structures

2017 ◽  
Vol 42 (4) ◽  
pp. 387-395 ◽  
Author(s):  
GR Basso ◽  
AB Kodama ◽  
AH Pimentel ◽  
MR Kaizer ◽  
A Della Bona ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Pearson Correlation ◽  
Lithium Disilicate ◽  
Color Difference ◽  
Color Variation ◽  
Color Coordinates ◽  
Cad Cam ◽  
Ceramic Thickness ◽  
Monolithic Structures ◽  
Monolithic Structure

SUMMARY Objective: To evaluate the masking ability and translucency of monolithic and bilayer CAD-CAM ceramic structures. Methods: Discs of high translucency (HT) and low translucency (LT) lithium disilicate–based ceramic (IPS e.max CAD) with different thicknesses (0.7, 1, 1.5, and 2 mm) were evaluated as a monolithic structure or combined (bilayer) with a 0.5-mm-thick zirconia framework (IPS e.max ZirCAD). The masking ability and translucency were calculated based on CIE L*a*b* color coordinates measured with a spectrophotometer (SP60, X-Rite). The translucency parameter (TP) was calculated using color coordinates measured over standard white-and-black backgrounds. The masking ability was calculated by CIEDE2000 color difference metric (ΔE00) for each specimen measured over a tooth-colored substrate (shade A2) compared to three darker backgrounds (shade C4 and two metal substrates). Confidence intervals (CI) for the means (95% CI) were calculated for TP and ΔE00. The Pearson correlation between ΔE00 and TP was investigated for monolithic and bilayer structures over all backgrounds. Results: The thinner the lithium disilicate layer, the greater the translucency and the higher the ΔE00 values. The effect of ceramic thickness on both translucency and masking ability was more pronounced for the monolithic structures. In addition, monolayers always presented a greater color variation than their bilayer counterparts. The metallic background produced greater ΔE00 than the C4-shaded substrate. Conclusion: Monolithic veneers were able to mask C4-shaded background but did not mask metallic backgrounds. Bilayer structures showed greater shade masking ability than monolithic structures.

scholarly journals Feldspathic and Lithium Disilicate Onlays with a 2-Year Follow-Up: Split-Mouth Randomized Clinical Trial

2021 ◽  
Vol 32 (2) ◽  
pp. 53-63
Author(s):  
Guilherme de Siqueira Ferreira Anzaloni Saavedra ◽  
João Paulo Mendes Tribst ◽  
Nathália de Carvalho Ramos ◽  
Renata Marques de Melo ◽  
Vinícius Anéas Rodrigues ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Significant Difference ◽  
Term Trial ◽  
Cad Cam ◽  
Age Range ◽  
Postoperative Sensitivity

Abstract The present study was a prospective, controlled, randomized, clinical short-term trial aiming to evaluate the clinical performance of adhesively luted, lithium disilicate and feldspathic glass-ceramics onlays over a period up to 2 years. A total of 11 patients (7 female, 4 male; age range: 18-60 years, mean age: 39 years) were selected for this study. Each patient received a maximum of two restorations per group in a split-mouth-design. LD: Eleven onlays, performed with lithium disilicate-based ceramic (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein), and FP: Eleven onlays, performed with feldspathic ceramic (Vita Mark II, Vita Zanhfabrik, Bad Säckingen). Recalls were performed at 2 weeks (baseline = R1), 1 year (R2) and 2 years (R3) after the cementation by three calibrated blinded independent investigators using mirrors, magnifying eyeglasses, probes and bitewing radiographs. The postoperative sensitivity, secondary caries, marginal integrity, marginal discoloration, color match, surface roughness, tooth integrity, and restoration integrity were evaluated. The Friedman test was used to determine if there was a statistically significant difference in time-to-time comparison of the parameters in the ceramics restorations. A total of 95.4% of the restorations were clinically acceptable at the 2-year recall, without a difference for any evaluation parameter for both ceramic materials. Based on the 2-year data, the CAD-CAM onlays manufactured with feldspathic and lithium-disilicate based ceramics showed similar clinical performance.

scholarly journals Effect of Thermo-Mechanical Aging and Repressing on Fracture Resistance of Lithium Disilicate Crowns

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Amr El-Etreby ◽  
Mahmoud Metwally ◽  
Gihan EL-Nagar
Keyword(s):  
Glass Ceramic ◽  
Fracture Resistance ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Mean Value ◽  
Resistance Testing ◽  
Novel Approach ◽  
Significant Difference ◽  
Keywords Fracture ◽  
Mechanical Aging

Objective: The recycling of heat pressed lithium disilicate glass-ceramic leftover material has been reported to be done by dental laboratories. The effect of this procedure on the fracture resistance of single crowns is unknown, especially when it is functioning inside the oral cavity with subsequent exposure to temperature changes and cycles of mastication. Material and Methods: A total of 28 lithium disilicate glass-ceramic crowns (IPS emax Press) were constructed and randomly assigned into two groups (n = 14); Group (P): Included crowns fabricated from new e.max ingots. Group (R): Included crowns fabricated from repressed e.max buttons. Specimens of each group were divided into two equal subgroups (n = 7) according to whether the aging of specimens will be performed or not before fracture resistance testing. Subgroup (N), samples were subjected to fracture resistance without thermo-mechanical aging, while subgroup (A), samples were subjected to thermo-cycling and cyclic loading before being subjected to fracture strength testing. Different methods; SEM, XRD, EDAX were used to characterize the properties of lithium disilicate glass-ceramics before and after repressing. Results: The highest statistically significant fracture resistance value was recorded for the subgroup (RN) repressed/non-aged, followed by the subgroup repressed/aged (RA), while the lowest statistically significant mean value was recorded for the subgroup pressed/aged (PA). There was no significant difference between pressed/non-aged (PN) and repressed/aged (RA) subgroups. Conclusion: Repressing of leftover buttons may increase the fracture resistance of IPS emax Press crowns. Thermo-mechanical aging may negatively affect the fracture resistance of IPS emax Press crowns, yet Repressing may decrease this effect. Clinical implications: This is a novel approach that targets a point of research that has not been investigated before. It elaborates how repressing may decrease the effect of aging and increase the fracture resistance of lithium disilicate crowns. Thus, recycling of lithium disilicate glass ceramics might decrease its failure and prolong their serviceability.   Keywords Fracture resistance; Heat pressed; Lithium disilicate; Recycling; Repressing; Thermo-mechanical aging.

Sign in / Sign up

Export Citation Format

Share Document