Purpose: The purpose of this study was to investigate the combined effects of fiber loading and pigmentation on the color differences and flexural properties of glass fiber-reinforced thermoplastics (GFRTPs), for use in non-metal clasp dentures (NMCDs).
Methods: The GFRTPs consisted mainly of E-glass fibers, a polypropylene matrix, and a coloring pigment: the GFRTPs with various fiber loadings (0, 10, and 20mass%) and pigmentations (0, 1, 2, and 4mass%) were fabricated by using an injection molding. The color differences of GFRTPs were measured based on the Commission Internationale de l'Eclairage (CIE) Lab color system, by comparing with a commercially available NMCD. The flexural properties of GFRTPs were evaluated by using a three-point bending test, according to International Standards Organization (ISO) specification number 20795-1.
Results: The visible colors of GFRTPs with pigment contents of 2mass% were acceptable for gingival color, and the glass fibers harmonized well with the resins. The ΔE* values of the GFRTPs with pigment contents of 2mass% obtained by using the CIE Lab system were lowest at all fiber loadings. For GFRTPs with fiber contents of 10 and 20mass% at 2mass% pigment content, these GFRTPs surpassed the ISO 20795-1 specification regarding flexural strength (> 60MPa) and modulus (> 1.5GPa).
Conclusions: A combination of the results of color difference evaluation and mechanical examination indicates that the GFRTPs with fiber contents of 10 or 20mass%, and with pigment contents of 2mass% have acceptable esthetic appearance and sufficient rigidity for NMCDs.
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http://dx.doi.org/10.1016/j.jpor.2018.01.002 | DOI Listing |
J Mol Model
January 2025
Escuela Superior de Física y Matemáticas, IPN S/N, Edificio 9 de la Unidad Profesional "Adolfo López Mateos", Col. Lindavista, Alc. Gustavo A. Madero, 07738, Mexico City, Mexico.
Context: "Nanostructure of graphene-reinforced with polymethyl methacrylate" (PMMA-G), and vice versa, is investigated using its molecular structure, in the present work. The PMMA-G nanostructure was constructed by bonding PMMA with graphene nanosheet in a sense to get three different configurations. Each configuration consisted of polymeric structures with three degrees of polymerization (such as monomers, dimers, and trimers polymers, respectively).
View Article and Find Full Text PDFJ Esthet Restor Dent
January 2025
Department of Dental Materials and Prosthodontics, Sao Paulo State University (UNESP), School of Dentistry, Araçatuba, São Paulo, Brazil.
Objective: To evaluate the influence of in situ acid erosion on the structural and optical properties of nanoparticulate bisacrylic resin with different surface treatments, evaluating surface roughness (Ra), knoop microhardness (KHN), color change (ΔE, ΔL, ΔC, ΔH), contrast (CR) and translucency (TP).
Methods: Eighty specimens were made (n = 10 per group) and the following surface treatments were applied: U-unpolished; A-polishing with Astropol rubber tips (Ivoclar); S-Biscover LV surface sealant (Bisco) and S-Palaseal surface sealant (kulzer). For the in situ experiment, 10 volunteers wore an intraoral appliance containing eight specimens (two specimens per experimental group), with only one specimen from each experimental group being subjected to the acid process.
Anal Methods
November 2017
Centre de Recherche sur la Conservation (CRC), MNHN, Sorbonne-Universités CNRS, MCC, USR 3224, CP21, 36 rue Geoffroy Saint Hilaire, 75005 Paris, France.
Reflectance spectral imaging is a powerful tool for the non-invasive study of cultural heritage objects. Particular visible to short wave infrared (400-2500 nm) spectral features are linked to compositional information. Spectral images can hence be used to generate useful chemical maps.
View Article and Find Full Text PDFBMC Ecol Evol
January 2025
National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bellary Road, Bengaluru, 560065, India.
Background: Trait variation is shaped by functional roles of traits and the strength and direction of selection acting on the traits. We hypothesized that in butterflies, sexually selected colouration is more variable owing to condition-dependent nature and directional selection on sexual ornaments, whereas naturally selected colouration may be less variable because of stabilising selection. We measured reflectance spectra, and extracted colour parameters, to compare the amount of variation in sexually versus naturally selected colour patches across wing surfaces and sexes of 20 butterfly species across 4 families (Nymphalidae, Papilionidae, Pieridae, Lycaenidae).
View Article and Find Full Text PDFBMC Pregnancy Childbirth
January 2025
Oregon Health & Science University-Portland State University School of Public Health, Portland, OR, USA.
Background: Understanding the risks and effects of gestational weight gain (GWG) is a prominent area of perinatal research but approaches for quantifying GWG are evolving and remain underdeveloped, especially in clinical settings for underserved demographic subgroups. To fill this gap, we demonstrated and compared six GWG metrics across pre-pregnancy BMI classifications: total GWG, trimester-specific linear rate of GWG, adherence to total and trimester-specific recommendations, area under the curve, and GWG for gestational age z-scores.
Methods: We used clinical data on 44,801 pregnant people from community-based health care organizations with extensive longitudinal measures and substantial representation of understudied subgroups.
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