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Joseph Anthony Von Fraunhofer - One of the best experts on this subject based on the ideXlab platform.

  • Effect of light source and time on the polymerization of resin cement through ceramic veneers
    Journal of Prosthodontics, 2001
    Co-Authors: Flavio H. Rasetto, Carl F. Driscoll, Joseph Anthony Von Fraunhofer
    Abstract:

    Purpose: The purpose of this study was to evaluate the efficiency of 3 different light sources to polymerize a light curing resin cement beneath 3 types of porcelain veneer materials. Materials and Methods: A conventional halogen light, a plasma arc light, and a high intensity halogen light were used to polymerize resin cement (Variolink II; Ivoclar North America Inc, Amherst, NY) through disks of veneer materials. Equal diameter and thickness disks of feldspathic porcelain (Ceramco II; Ceramco Inc, Burlington, NJ), pressable ceramic (IPS Empress; Ivoclar North America Inc), and aluminous porcelain (Vitadur Alpha; Vident Inc, Brea, CA) were used as an interface between the curing light tips and the light polymerized resin cement. The resin cement/ veneer combinations were exposed to 4 different photopolymerization time protocols of 5 seconds, 10 seconds, 15 seconds, and 20 seconds for high intensity light units (Apollo 95E [Dental Medical Diagnostic Systems Inc, Westlake Village, CA] and Kreativ 2000 [Kreativ Inc, San Diego, CA]), and 20 seconds, 40 seconds, 60 seconds, and 80 seconds for conventional halogen light (Optilux; Demetron Research Inc, Danbury, CT). A Surface Hardness Test (Knoop indenter) was used to determine the level of photopolymerization of the resin through the ceramic materials with each of the light sources. The data were analyzed by one-way analysis of variance and a post-hoc Scheffe Test (p < .05). Results: The data indicates that the Variolink II Knoop Hardness Number values vary with the light source, the veneer material, and the polymerization time. For a given light and veneer material, Knoop Hardness Number increases with longer polymerization times. The Kreativ light showed statistically significant differences (p < .05) between all Test polymerization times. Use of this light required a polymerization time of greater than 20 seconds to reach maximum resin cement Hardness. For samples polymerized with the Apollo light, there were statistically significant (p < .05) differences in Surface Hardness between samples polymerized at all times, except for the 15-second and 20-second times. Samples polymerized with the halogen light showed no statistically significant (p < .05) differences in Hardness between polymerization times of 60 seconds and 80 seconds. Conclusions: High intensity curing lights achieve adequate polymerization of resin cements through veneers in a markedly shorter time period than the conventional halogen light. However, the data in this report indicate that a minimum exposure time of 15 seconds with the Kreativ light and 10 seconds with the Apollo 95E light should be used to polymerize the Variolink II resin, regardless of the composition of the veneer. Conventional halogen lights required a correspondingly greater polymerization time of 60 seconds. J Prosthodont 2001;10:133-139. Copyright © 2001 by The American College of Prosthodontists.

Amer A. Taqa - One of the best experts on this subject based on the ideXlab platform.

  • The Effect of pH on Fluoride Release of Glass Ionomer Based Restorative Materials
    International Journal of Dental Sciences and Research, 2016
    Co-Authors: Amer A. Taqa, Abdul-k. Abdal, Alaa I. Dawood
    Abstract:

    Three Glass-ionomer based restorative materials (Conventional Glass-ionomer cement, resin-modified Glass-ionomer cement and Compomer) were used. The number of the specimens for the fluoride measurement and Surface Hardness Test was 156 specimens. The specimens for each material were divided into four equal groups: the first group was dry stored, the second group was stored in solution pH7, the third group was stored in solution pH5 and the last group was stored in solution pH3. All the specimens were stored in an incubator at 37°C for seven days. Fluoride release after seven days was measured with fluoride ion selective electrode. The amount of fluoride released from the three materials were significantly higher in acidic solutions than in neutral solutions. The Compomer released the highest amount of fluoride into the three storage solutions, while the least fluoride release was from the resin-modified glass-ionomer.

  • An Autoclave Effect on the Powder of Poly Methylmethacrylate
    International Journal of Dental Sciences and Research, 2014
    Co-Authors: Manar.n.y. Nazhat, Tariq.y.q. Basshi, Amer A. Taqa
    Abstract:

    Background: Although most of the physical and mechanical properties of denture base resin polymerized by the conventional heat polymerization have been studied, the effect of autoclave processing on these properties has not been fully determined. The effect of autoclave on acrylic powder has not studied before. Materials and methods: Vertex was the heat – cured acrylic denture base material included in this study. A total of 90 specimens were prepared, the specimens were grouped into three control groups of Vertex acrylic resin which(group A) as curing by conventional water- bath technique (74oC for 90 minutes, then boil for 30 minutes, (group B) which curing by water- bath (100°C for 30 minutes), and (group C)which curing by autoclave (120 °C under 1.4 bar for 45 minutes). The other three groups of Vertex acrylic resin after treatment of powder by autoclave in 132 °C for 4 hours, and then grouped into (A1,B1 andC1) which curing as previously. To study the effect of treatment of powder of acrylic resin byautoclave and the effect of autoclave processing. Three Tests were conducted Surface roughness (profilometer Tester), transverse strength (Instron universal Testing machine), and Surface Hardness (Shore D). The results were analyzed to Descriptive Statistics and ANOVA Test. Results: There were no significant differences in Surface roughness in all studying groups. There was a highly significant difference in transverse strength Test results between studying groups. There was a significant difference in Surface Hardness Test results between studying groups. Conclusions: The treatment of powder of acrylic resin by autoclave had no significant differences in Surface roughness, but had a highly significant Difference in transverse strength in all Test results, and a significant difference in Hardness Surface Test in group B1. The autoclave processing technique might also be a good alternative to the conventional water- bath processing technique.

Flavio H. Rasetto - One of the best experts on this subject based on the ideXlab platform.

  • Effect of light source and time on the polymerization of resin cement through ceramic veneers
    Journal of Prosthodontics, 2001
    Co-Authors: Flavio H. Rasetto, Carl F. Driscoll, Joseph Anthony Von Fraunhofer
    Abstract:

    Purpose: The purpose of this study was to evaluate the efficiency of 3 different light sources to polymerize a light curing resin cement beneath 3 types of porcelain veneer materials. Materials and Methods: A conventional halogen light, a plasma arc light, and a high intensity halogen light were used to polymerize resin cement (Variolink II; Ivoclar North America Inc, Amherst, NY) through disks of veneer materials. Equal diameter and thickness disks of feldspathic porcelain (Ceramco II; Ceramco Inc, Burlington, NJ), pressable ceramic (IPS Empress; Ivoclar North America Inc), and aluminous porcelain (Vitadur Alpha; Vident Inc, Brea, CA) were used as an interface between the curing light tips and the light polymerized resin cement. The resin cement/ veneer combinations were exposed to 4 different photopolymerization time protocols of 5 seconds, 10 seconds, 15 seconds, and 20 seconds for high intensity light units (Apollo 95E [Dental Medical Diagnostic Systems Inc, Westlake Village, CA] and Kreativ 2000 [Kreativ Inc, San Diego, CA]), and 20 seconds, 40 seconds, 60 seconds, and 80 seconds for conventional halogen light (Optilux; Demetron Research Inc, Danbury, CT). A Surface Hardness Test (Knoop indenter) was used to determine the level of photopolymerization of the resin through the ceramic materials with each of the light sources. The data were analyzed by one-way analysis of variance and a post-hoc Scheffe Test (p < .05). Results: The data indicates that the Variolink II Knoop Hardness Number values vary with the light source, the veneer material, and the polymerization time. For a given light and veneer material, Knoop Hardness Number increases with longer polymerization times. The Kreativ light showed statistically significant differences (p < .05) between all Test polymerization times. Use of this light required a polymerization time of greater than 20 seconds to reach maximum resin cement Hardness. For samples polymerized with the Apollo light, there were statistically significant (p < .05) differences in Surface Hardness between samples polymerized at all times, except for the 15-second and 20-second times. Samples polymerized with the halogen light showed no statistically significant (p < .05) differences in Hardness between polymerization times of 60 seconds and 80 seconds. Conclusions: High intensity curing lights achieve adequate polymerization of resin cements through veneers in a markedly shorter time period than the conventional halogen light. However, the data in this report indicate that a minimum exposure time of 15 seconds with the Kreativ light and 10 seconds with the Apollo 95E light should be used to polymerize the Variolink II resin, regardless of the composition of the veneer. Conventional halogen lights required a correspondingly greater polymerization time of 60 seconds. J Prosthodont 2001;10:133-139. Copyright © 2001 by The American College of Prosthodontists.

Saeed Safa - One of the best experts on this subject based on the ideXlab platform.

  • Effect of incorporation of zinc oxide nanoparticles on mechanical properties of conventional glass ionomer cements.
    Journal of Conservative Dentistry, 2018
    Co-Authors: Narges Panahandeh, Hassan Torabzadeh, Mohammadamin Aghaee, Elham Hasani, Saeed Safa
    Abstract:

    Aim: The aim of this study is to investigate the physical properties of conventional and resin-modified glass ionomer cements (GICs) compared to GICs supplemented with zinc oxide (ZnO) nanofiller particles at 5% (w/w). Methods: In this in vitro study, ZnO nanoparticles of different morphologies (nanospherical, nanorod, and nanoflower) were incorporated to glass ionomer powder. The samples were subjected to the flexural strength (n = 20) and Surface Hardness Test (n = 12) using a universal Testing machine and a Vickers Hardness machine, respectively. Surface analysis and crystal structure of samples were performed with scanning electron microscope and X-radiation diffraction, respectively. The data were analyzed using one-way ANOVA, Shapiro–Wilk, and Tukey's Tests (P Results: Flexural strength of glass ionomer containing nanoparticles was not significantly different from the control group (P > 0.05). The Surface Hardness of the glass ionomer containing nanospherical or nanoflower ZnO was significantly lower than the control group (P Conclusions: Incorporation of nanospherical and nanoflower ZnO to glass ionomer decreased their Surface Hardness, without any changes on their flexural strength. Incorporation of nanorod ZnO particles caused no effect on the mechanical properties.

Sung Hwan Choi - One of the best experts on this subject based on the ideXlab platform.

  • Changes in tribological and antibacterial properties of poly(methyl methacrylate)-based 3D-printed intra-oral appliances by incorporating nanodiamonds
    Journal of the Mechanical Behavior of Biomedical Materials, 2020
    Co-Authors: Utkarsh Mangal, You Jin Min, Ji-young Seo, Dae-eun Kim, Jung-yul Cha, Kee-joon Lee, Jae-sung Kwon, Sung Hwan Choi
    Abstract:

    Abstract It is essential for 3D-printed intra-oral appliances to be able to withstand the mechanical and microbial insult existent in the harsh environment of the oral cavity. Poly(methyl methacrylate) (PMMA)-based appliances are widely used in dentistry. Hence, the present study aimed to evaluate the role of nanodiamonds (NDs) as fillers to enhance the resistance to friction and wear. Using a solution-based mixing technique, 0.1 wt% ND was incorporated into the PMMA, and specimens were 3D-printed for tribological and bacterial analysis. The control specimens without ND fillers were Tested against specimens with both amine-functionalized NDs (A-ND) and pure non-functionalized NDs (ND). The Surface Hardness Test revealed a statistically significant increase in the Vickers micro-Hardness (p