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Irini D Sideridou - One of the best experts on this subject based on the ideXlab platform.
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dynamic mechanical thermal properties of the dental light cured nanohybrid composite kalore gc effect of various food oral simulating liquids
Dental Materials, 2015Co-Authors: Irini D Sideridou, Evangelia C Vouvoudi, Evanthia A AdamidouAbstract:Abstract Objective The aim of this work is the study of the dynamic mechanical thermal properties (viscoelastic properties) of a current dental commercial light-cured nanohybrid resin composite, Kalore, GC (GC Corporation, Tokyo, Japan) along with the study of the effect of some food/oral simulating liquids (FSLs) on these properties. Methods Dynamic mechanical thermal analysis (DMTA) tests were performed on a Diamond Dynamic Mechanical Thermal Analyzer in bending mode. A frequency of 1 Hz and a Temperature range of 25–185 °C were applied, while the heating rate of 2 °C/min was selected to cover Mouth Temperature and the material's likely Tg. The properties were determined after storage in air, distilled water, heptane, ethanol/water solution (75% v/v) or absolute ethanol at 37 °C for up to 1 h, 1, 7 or 30 days. Results Storage modulus, loss modulus and tangent delta (tanδ) were plotted against Temperature. The glass transition Temperatures are taken from the peak of the tangent tanδ versus Temperature curves. Moreover, some factors indicating the heterogeneity of the polymer matrix, such as the width (ΔT) at the half of tanδ peak and the “ζ” parameter were determined. All samples analyzed after storage for 1 h or 1 day in the aging media showed two Tg values. All samples analyzed after storage for 7 or 30 days in the ageing media showed a unique Tg value. Significance Storage of Kalore GC in dry air, water or heptane at 37 °C for 7 days caused post-curing reactions. Storage in air or water for 30 days did not seem to cause further effects. Storage in heptane for 30 days may cause plasticization and probably some degradation of the filler–silane bond and polymer matrix. Storage in ethanol/water solution (75% v/v) or ethanol for 7 days seems to cause post-curing reactions and degradation reactions of the matrix–filler bonds. Storage in ethanol for 30 days caused a strong change of the sample morphology and the DMTA results were not reliable.
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dynamic mechanical properties of dental nanofilled light cured resin composites effect of food simulating liquids
Journal of The Mechanical Behavior of Biomedical Materials, 2012Co-Authors: Evangelia C Vouvoudi, Irini D SideridouAbstract:Abstract This work is aimed at the study by dynamic mechanical analysis (DMA) of viscoelastic properties that is, the elastic modulus ( E ′ ), the loss modulus ( E ″ ), the loss tangent ( tan δ ) and the glass transition Temperature ( T g ) , of two current commercial light-cured resin composites, Filtek Supreme Body and Filtek Supreme Translucent, characterized as nanofilled. These composites show differences in the filler content and type. For DMA analysis the bar-shaped specimens were divided into groups of three samples each. The first group consisted of dry samples measured 1 h after light-curing (at room Temperature) during which they were placed in a desiccator at 37 °C. The other groups consisted of samples which had been stored in air, distilled water, artificial saliva SAGF or ethanol/water solution (75 v/v), at 37±1 °C for 1, 7, 30 or 90 days. DMA tests were performed on a Diamond Dynamic Mechanical Analyzer (Perkin–Elmer) in bending mode. A frequency of 1 Hz was applied and a Temperature range of 25–185 °C, while a heating rate of 2 °C/min were selected to cover Mouth Temperature and the materials’ likely T g . The studied dry composites showed comparable values for their properties in spite of their differences in the filler content and type. Storage of composites in air 37 °C for 1 day caused a significant post curing which was not continued during storage up to 90 days. Water and artificial saliva showed the same effect on composites. They caused both post curing and plasticization. Ethanol/water solution 75% v/v had a more strong effect than water and artificial saliva due to its organophilic nature. It caused post curing, plasticization and most probably degradation of the bond filler–silane coupling agent.
Khalid Ahmad Omar Arafa - One of the best experts on this subject based on the ideXlab platform.
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effect of different denture base materials and changed Mouth Temperature on dimensional stability of complete dentures
International Journal of Dentistry, 2016Co-Authors: Khalid Ahmad Omar ArafaAbstract:Background. Type of materials used in fabrication of denture base has an effect on dimension during denture base material processing and other factors related to clinical use. Objective. The study aims were to assess the dimensional stability including thermal changes of three different denture base materials. Methods. Ninety patients were selected to construct complete dentures with different denture base materials. They were randomly divided into three groups: group 1, patients with cobalt chrome metallic base; group 2, patients with heat curing acrylic resin fabricated by injection moulding technique; and group 3, patients with denture bases fabricated by conventional heat curing acrylic resin. The dimensional changes were assessed using digital caliper. Results. After the twelfth month, injection moulding acrylic resin had significantly the highest dimensional change followed by the conventional heat curing acrylic resin. There were no significant differences in the dimensions between the three types of denture base materials at normal Mouth Temperature, while, after hot tea drinking at 45°C, the dimensional change was significantly the highest in cobalt chrome metallic denture base group. Conclusion. Cobalt chrome metallic denture base has stable dimension compared to denture bases fabricated of acrylic resin but it was more affected by altered Mouth Temperature. The study was registered in the International Standard Randomized Controlled Trials Number (ISRCTN) registry with study ID (ISRCTN94238244).
Evangelia C Vouvoudi - One of the best experts on this subject based on the ideXlab platform.
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dynamic mechanical thermal properties of the dental light cured nanohybrid composite kalore gc effect of various food oral simulating liquids
Dental Materials, 2015Co-Authors: Irini D Sideridou, Evangelia C Vouvoudi, Evanthia A AdamidouAbstract:Abstract Objective The aim of this work is the study of the dynamic mechanical thermal properties (viscoelastic properties) of a current dental commercial light-cured nanohybrid resin composite, Kalore, GC (GC Corporation, Tokyo, Japan) along with the study of the effect of some food/oral simulating liquids (FSLs) on these properties. Methods Dynamic mechanical thermal analysis (DMTA) tests were performed on a Diamond Dynamic Mechanical Thermal Analyzer in bending mode. A frequency of 1 Hz and a Temperature range of 25–185 °C were applied, while the heating rate of 2 °C/min was selected to cover Mouth Temperature and the material's likely Tg. The properties were determined after storage in air, distilled water, heptane, ethanol/water solution (75% v/v) or absolute ethanol at 37 °C for up to 1 h, 1, 7 or 30 days. Results Storage modulus, loss modulus and tangent delta (tanδ) were plotted against Temperature. The glass transition Temperatures are taken from the peak of the tangent tanδ versus Temperature curves. Moreover, some factors indicating the heterogeneity of the polymer matrix, such as the width (ΔT) at the half of tanδ peak and the “ζ” parameter were determined. All samples analyzed after storage for 1 h or 1 day in the aging media showed two Tg values. All samples analyzed after storage for 7 or 30 days in the ageing media showed a unique Tg value. Significance Storage of Kalore GC in dry air, water or heptane at 37 °C for 7 days caused post-curing reactions. Storage in air or water for 30 days did not seem to cause further effects. Storage in heptane for 30 days may cause plasticization and probably some degradation of the filler–silane bond and polymer matrix. Storage in ethanol/water solution (75% v/v) or ethanol for 7 days seems to cause post-curing reactions and degradation reactions of the matrix–filler bonds. Storage in ethanol for 30 days caused a strong change of the sample morphology and the DMTA results were not reliable.
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dynamic mechanical properties of dental nanofilled light cured resin composites effect of food simulating liquids
Journal of The Mechanical Behavior of Biomedical Materials, 2012Co-Authors: Evangelia C Vouvoudi, Irini D SideridouAbstract:Abstract This work is aimed at the study by dynamic mechanical analysis (DMA) of viscoelastic properties that is, the elastic modulus ( E ′ ), the loss modulus ( E ″ ), the loss tangent ( tan δ ) and the glass transition Temperature ( T g ) , of two current commercial light-cured resin composites, Filtek Supreme Body and Filtek Supreme Translucent, characterized as nanofilled. These composites show differences in the filler content and type. For DMA analysis the bar-shaped specimens were divided into groups of three samples each. The first group consisted of dry samples measured 1 h after light-curing (at room Temperature) during which they were placed in a desiccator at 37 °C. The other groups consisted of samples which had been stored in air, distilled water, artificial saliva SAGF or ethanol/water solution (75 v/v), at 37±1 °C for 1, 7, 30 or 90 days. DMA tests were performed on a Diamond Dynamic Mechanical Analyzer (Perkin–Elmer) in bending mode. A frequency of 1 Hz was applied and a Temperature range of 25–185 °C, while a heating rate of 2 °C/min were selected to cover Mouth Temperature and the materials’ likely T g . The studied dry composites showed comparable values for their properties in spite of their differences in the filler content and type. Storage of composites in air 37 °C for 1 day caused a significant post curing which was not continued during storage up to 90 days. Water and artificial saliva showed the same effect on composites. They caused both post curing and plasticization. Ethanol/water solution 75% v/v had a more strong effect than water and artificial saliva due to its organophilic nature. It caused post curing, plasticization and most probably degradation of the bond filler–silane coupling agent.
M Braden - One of the best experts on this subject based on the ideXlab platform.
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viscoelastic properties of some soft lining materials ii ageing characteristics
Biomaterials, 1999Co-Authors: Kambiz Sabersheikh, R L Clarke, M BradenAbstract:Abstract A non-resonant forced vibration, dynamic mechanical analyser was employed to measure the viscoelastic characteristics of soft lining materials at 1 Hz, after storage in distilled water at Mouth Temperature for periods up to and including one year. The six commercial products included methacrylate, silicone, and phosphazine based polymers and the one experimental material was a methacrylate. Water sorption of the soft liners, recorded by change in sample mass, ranged from −4.39 to +48.57% and their solubilities from 0.13 to 13.58%, after one year. The heat-cured silicone was the most stable polymer in water in contrast to its autopolymerised counterpart. The excessive water uptake of this latter material resulted in a massive reduction in modulus. At the other extreme one methacrylate with a high plasticiser content hardened substantially after ageing (modulus changed from 5.87 to 72.3 MPa). Changes in loss tangent data were relatively small for all the polymers tested, even for materials with high water uptake. Reduced leaching and/or plasticiser content have led to a more stable generation of soft lining materials.
Mary J Frangou - One of the best experts on this subject based on the ideXlab platform.
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influence of curing method sealer and water storage on the hardness of a soft lining material over time
Journal of Prosthodontics, 2001Co-Authors: Gregory L Polyzois, Mary J FrangouAbstract:PURPOSE The purpose of this study was to determine the hardness of plasticized acrylic resin soft lining materials over time when curing procedures were modified and when surface sealers were either used or omitted. MATERIALS AND METHODS A chairside plasticized acrylic resin material and a heat processed plasticized resin material were made into disks 40 mm in diameter and 10 mm in thickness. Materials were cured by processing at an elevated Temperature or at Mouth Temperature. Five samples were used with each processing method. Half of all samples were treated with a surface sealer, whereas the other samples received no surface treatment. After processing, the samples were immersed in 37 degrees C water for a total time of 1 year. Specimens were tested to determine hardness on a monthly basis. Testing was accomplished using a Shore A durometer. RESULTS Hardness testing showed differences relative to material and to time after processing. The heat-processed plasticized resin material showed significantly higher Shore A hardness values than the chairside over the entire experimental period (p <.01). Increased hardness was seen for all materials over time, but this was more pronounced with plasticized acrylic resin in which the hardness increased from 28.4% to 115.8% depending on processing method and surface treatment. Surface treatment showed significant softening only when the samples were cured at simulated Mouth Temperature (p <.05). CONCLUSIONS Processing method and time after processing have an effect on surface hardness of the tested materials, but neither of these effects is as profound as the initial choice of material. J Prosthodont 2001;10:42-45.