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 The Effect of Thermocycling and Surface Treatments on the Surface Roughness and Microhardness of Three Heat-Pressed Ceramics Systems

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 160 ◽  
Author(s):  
Roxana-Diana Vasiliu ◽  
Sorin-Daniel Porojan ◽  
Mihaela-Ionela Bîrdeanu ◽  
Ion-Dragoș Uțu ◽  
Liliana Porojan
Keyword(s):  
Surface Roughness ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
In Vitro Study ◽  
Surface Characteristics ◽  
Surface Treatments ◽  
Lithium Silicate ◽  
Before And After ◽  
Microhardness Tester

Dental ceramic restorations are widely used in restorative dentistry. However, these restorations can be affected once cemented in the oral cavity by several factors. How can conventional surface treatments, such as glazing and mechanical polishing, diminish the effects of aging? The purpose of this in vitro study was to evaluate the effect of thermocycling and conventional surface treatments on the surface roughness and microhardness of three types of glass-ceramics by using a profilometer, scanning electron microscopy (SEM), atomic force microscopy (AFM), and a microhardness tester. Three types of ceramic systems (zirconia reinforced lithium silicate glass-ceramic, lithium disilicate glass-ceramic, and feldspathic glass-ceramic) (n = 48) were prepared. The samples were subjected to thermocycling for 10,000 cycles. Surface roughness was evaluated numerically using a profilometer and visually by using SEM and AFM. Microhardness was performed using a microhardness tester. The data were interpreted using the ANOVA test, and the results were correlated using Pearson’s correlation formula (r). Significant differences were found before and after thermocycling for the Ra (p < 0.01) and Rz (p < 0.05) parameters. As well, differences between glazed and polished surfaces were significant before and after thermocycling for surface roughness and microhardness (p < 0.05). A correlation was made between average surface roughness and microhardness (r = −460) and for the maximum surface roughness and microhardness (r = −606). Aging increases the roughness and decreases in time the microhardness. The tested ceramic systems behaved differently to the aging and surface treatments. Surface treatments had a significant impact on the microhardness and surface characteristics. The glazed groups were reported with higher surface roughness and lower microhardness when compared to the polished groups before and after thermocycling. The measuring roughness techniques determine the scale-dependent values for the Ra (Sa) and Rz (Sq) parameters. Thermocycling almost doubled the surface roughness for all the tested samples. Microhardness decreased only for the Celtra glazed samples. Nano-roughness increased the values for Vita and slightly for Emax. Thermocycling had little effect on Emax ceramic and a more significant impact on Celtra Press ceramic.

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.

scholarly journals The Effect of Different Surface Treatments on the Micromorphology and the Roughness of Four Dental CAD/CAM Lithium Silicate-Based Glass-Ceramics

Ceramics ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 467-475
Author(s):  
Muna Bebsh ◽  
Asmaa Haimeur ◽  
Rodrigo França
Keyword(s):  
Surface Roughness ◽  
Hydrofluoric Acid ◽  
Glass Ceramics ◽  
Polycrystalline Diamond ◽  
Surface Treatments ◽  
Lithium Silicate ◽  
Sand Blasting ◽  
Force Microscopy ◽  
Significant Difference ◽  
Cad Cam

Objective: This study aimed to investigate and compare the effect of various surface treatments on the micromorphology and the roughness of four CAD/CAM lithium silicate-based glass-ceramics (LSGC). Method: Eighty specimens of four LDGC materials (IPS e. max® CAD (Ivoclar-Vivadent, Liechtenstein, Schaan), Vita Suprinity® (Vita Zahnfabrik, Bad Säckingen, Germany), Celtra Duo® (Dentsply, Hanau-Wolfgang, Germany) and n!ce (Straumann, Basel, Switzerland)) were used for this study. All specimens were highly polished with 400, 600, 1200 grit silicon carbide paper and then polished with 3 µm and 1 µm polycrystalline diamond suspension liquid with grinding devices. Each group of ceramic was assigned to one of the following three surface treatments (1) sand-blasting (SB) with 50 µm Al2O3 at 70 psi for 10s, (2) hydrofluoric acid etching (HF) with 5% hydrofluoric acid, according to the manufacturer instructions, (3) and a combination of sand-blasting and hydrofluoric acid (SB + HF). All specimens were cleaned with ethanol for 2 min and placed in an ultrasonic unit with distilled water for 15 min. The microstructure was analyzed by scanning electron microscopy (SEM). The surface roughness and topography were evaluated with atomic force microscopy in tapping mode (AFM). Statistical analysis was done using two-way ANOVA and Tukey tests (α = 5%). Results: All surface treatments had a significant effect on LDGC surface roughness compared to the untreated surface (p < 0.05). The sand-blasting treatment had a significantly higher mean surface roughness value for Vita Suprinity and Celtra Duo compared to other surface treatments (p < 0.05). However, there was no significant difference for surface roughness between sand-blasting and sand-blasting + etching for e.max CAD and n!ce. The hydrofluoric acid produced less surface roughness compared to other surface treatments but was able to change the surface structure. (5) Conclusions: The sand-blasting + etching treatment could be a sufficient method to produce surface roughness for all LSGC types.

scholarly journals Surface Characterization and Optical Properties of Reinforced Dental Glass-Ceramics Related to Artificial Aging

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3407
Author(s):  
Liliana Porojan ◽  
Roxana-Diana Vasiliu ◽  
Mihaela-Ionela Bîrdeanu ◽  
Sorin-Daniel Porojan
Keyword(s):  
Optical Properties ◽  
Thermal Cycling ◽  
Glass Ceramic ◽  
Artificial Aging ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Dental Restoration ◽  
Lithium Silicate ◽  
Glass Ceramic Materials ◽  
Silicate Ceramic

The development of various dental glass-ceramic materials and the evolution of novel processing technologies lead to an essential change in the clinical and technical workflow. The long-term success of a dental restoration treatment is defined by its durability, which is directly influenced by the oral environment. This study’s purpose was to evaluate the artificial aging behavior of nanostructured, respective microstructured ceramics related to surface topography, roughness, and optical properties. Six monolithic restoration materials were selected: milled lithium disilicate glass-ceramic (LDS-M) MT (medium translucency), hot-pressed lithium disilicate glass-ceramic (LDS-P) MT and HT (high translucency), milled zirconia-reinforced lithium silicate ceramic (ZLS-M) MT and hot-pressed zirconia-reinforced lithium silicate ceramic (ZLS-P) MT and HT, resulting n = 96 surfaces. All the samples were artificially aged by thermal cycling, and all investigations were made before and after thermal cycling. In terms of optical properties, differences recorded between ZLS and LDS ceramics are not significant. Thermal cycling increases the translucency of ZLS and LDS glass-ceramic materials significantly, with the most harmful effect on the pressed and polished samples. Micro- and nano roughness are significantly influenced by in vitro aging and a negative correlation was recorded. Glazed samples are characterized by significant rougher surfaces for all types of materials. On nanolevel, ZLS materials are significantly smoothed by thermal cycling.

scholarly journals Innovative directions of development of ceramic materials for dentistry

2021 ◽  
pp. 19-25
Author(s):  
O.V. Savvova ◽  
G.K. Voronov ◽  
O.I. Fesenko ◽  
Yu.O. Smirnova ◽  
E. Bairamov
Keyword(s):  
High Temperature ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Oxide Glass ◽  
Lithium Silicate ◽  
Silicate System ◽  
Advantages And Disadvantages ◽  
Glass Ceramic Materials

The need to improve the level of dental health of the population of Ukraine was identified. The prospects for the use of ceramic prostheses to provide quality medical care in dentistry have been established. An analytical review of various types of ceramic and glass-ceramic materials used as dental prostheses for tooth replacement: porcelain, alumina, zirconium oxide, glass-ceramics based on leucite and lithium disilicate and mica with the addition of fluorides. Peculiarities of the structure and operational properties of ceramic and glass-ceramic materials for dentistry have been identified, their advantages and disadvantages have been established. The effectiveness of the use of glass-ceramic materials based on lithium disilicate for dental prosthetics is substantiated. The basic lithium silicate system was selected and glasses for obtaining glass-ceramic crowns based on lithium disilicate by the method of high-temperature pressing and calcium phosphate-silicate system for obtaining glass-ceramic coatings were synthesized. The methodological approach to the development of glass-ceramic prostheses based on lithium disilicate is determined. The limits of the compositions of oxide components are determined and raw materials for the synthesis of the glass matrix are selected. The technological parameters of melting (T = 1350 – 1400ºС) and heat treatment with simultaneous formation of products (stage of nucleation T = 600 – 650ºС, τ = 30 – 60 min; stages of formation T = 900ºС, τ ≈ 20 min) are selected. The composition of fluoroapatite glass-ceramic coating for glazing of glass-ceramics and the mode of its firing (T = 800 – 850ºС, τ ≈ 1,0 – 1,5 min) were determined. The serviceability of the developed glass-ceramic samples DL st.glass, which were obtained by the technology of high-temperature pressing, are determined. The comparative analysis of glass-ceramic prostheses for dentistry allowed to establish that the operational properties of the developed glass-ceramic prostheses according to ISO 6872:2015 are at the level of world analogues. This will allow them to successfully compete in the Ukrainian market with well-known foreign counterparts and help ensure the social priorities of the state in the field of health care.

Characterization of Reinforced and Unreinforced Glass-Ceramic Veneers

2021 ◽  
Author(s):  
AR Oliveira ◽  
KS Jodha ◽  
SM Salazar Marocho ◽  
GA Galhano
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Glass Ceramic ◽  
Optical Microscope ◽  
Lithium Silicate ◽  
Atomic Force ◽  
Before And After ◽  
Cad Cam ◽  
Topographical Analysis ◽  
Post Hoc

SUMMARY This study aimed to characterize the surface topography, effect of polishing on surface roughness, residual stresses, and hardness in two glass-ceramic veneers. Fifty-two (52) upper incisors were collected, prepared, and scanned for ceramic veneers. Half of the teeth were restored with veneers made up of feldspathic ceramic (FE), and the other half with zirconia-reinforced lithium silicate ceramic (SZ). All the veneers were designed and milled using a CAD/CAM system and later cemented following the manufacturer’s guideline. An optical microscope analyzed the topography of the specimens before and after polishing. The surface roughness was measured using the roughness meter (n=12) and the topographical analysis was carried out using an atomic force microscope (n=6). The residual stresses and Vickers’ hardness were evaluated by the indentation method in a micro-hardness indenter (n=6). The surface roughness was analyzed using a three-way analysis of variance (ANOVA) followed by a post hoc Tukey test. The Student t-test was used to compare the residual stresses and hardness between the two ceramics. The topographical analysis revealed that both glass-ceramic veneers had similar percentages of specimens with cracks, before (34.6%) and after (42.3%) polishing. The surface roughness decreased after polishing (p&lt;0.001), and the polishing smoothed out the surface of the veneers. The zirconia-reinforced lithium silicate veneer had a lower roughness as compared to the feldspathic one after polishing, while the residual stresses (p=0.722) and hardness (p=0.782) were statistically similar for both ceramic veneers.

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.

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 Mechanical Wear and Surface Roughness of Glass and Hybrid Ceramics

2019 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Surface Roughness ◽  
Weight Loss ◽  
Wear Resistance ◽  
Glass Ceramic ◽  
High Surface ◽  
Lithium Disilicate ◽  
Mechanical Wear ◽  
Roughness Change ◽  
Before And After ◽  
Ceramic Blocks

Aim: The purpose of this invitro study was to evaluate wear resistance and surface roughness of two hybrid ceramics in comparison to lithium disilicate glass ceramic before and after mechanical abrasion. Materials and Methods: Thirty samples were divided according to material of construction into three groups, group (1): Lithium disilicate glass ceramic (IPS e.max, n=10), group (2): Resin nanoceramic (Lava Ultimate, n=10), group (3): Polymer infiltrated ceramic (Vita Enamic, n=10). All samples were fabricated out of CAD CAM ceramic blocks, weighed and evaluated for surface roughness before and after mechanical wear. Results: Resin nanoceramic (Lava ultimate), showed significantly low weight loss and surface roughness change after mechanical wear than IPS e.max. The polymer infiltrated ceramic (Vita Enamic) showed significantly high surface roughness than Resin nanoceramic (Lava ultimate), while IPS e.max showed the highest weight loss and surface roughness change. Conclusion: Resin nanoceramics revealed highest mechanical wear resistance contributed by terms of weight loss and surface roughness change, while Lithium disilicate glass ceramic showed the least wear resistance.

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