Marcos A. Vargas

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Bonding to tooth tissue can be achieved through an "etch&rinse," "self-etch" or "glass-ionomer" approach. In this paper, the basic bonding mechanism to enamel and dentin of these three approaches is demonstrated by means of ultramorphological and chemical characterization of tooth-biomaterial interfacial interactions. Furthermore, bond-strength testing and(More)
OBJECTIVES The objectives of this study were (1) to assess the bonding performance of a new auto-adhesive cement (RelyX Unicem, 3M ESPE) to enamel and dentin, using a standard micro-tensile bond strength (microTBS) test set-up, and (2) to evaluate the interaction of this material with dentin by means of high-resolution electron microscopy. METHODS The(More)
Fifteen strains of chlorophycean microalgae have been investigated with regard to their carotenoid profile. Lutein, beta-carotene and violaxanthin were present in virtually all of the strains, lutein, in general, being the most abundant carotenoid, whereas canthaxanthin and astaxanthin were found in some strains only. Chlorella fusca SAG 211-8b,(More)
The effect of dilution rate, mixing and daily solar cycles on lutein and biomass productivity of the green unicellular alga Muriellopsis sp. has been studied, throughout the year, in an outdoor tubular photobioreactor. Highest productivity values, for both lutein (about 180 mg m(-2) per day) and biomass (about 40 g (dry weight) m(-2) per day) were achieved(More)
BACKGROUND The authors compared the physical properties of three packable hybrid resin-based composites with those of a conventional hybrid and a microfill composite material advocated for use as posterior restorative materials. They evaluated diametral tensile strength, or DTS; compressive strength, or CS; flexural strength, or FS; and depth of cure, or(More)
STATEMENT OF PROBLEM All-ceramic restorations have been advocated for superior esthetics. Various materials have been used to improve ceramic core strength, but it is unclear whether they affect the opacity of all-ceramic systems. PURPOSE This study compared the translucency of 6 all-ceramic system core materials at clinically appropriate thicknesses. (More)
STATEMENT OF PROBLEM Provisional prostheses are subject to flexure under function. Selection of the appropriate material for their fabrication is difficult given the limited evidence-based information on the flexural strength of provisional resins. PURPOSE This study compared the flexural strength of 5 methacrylate-based resins and 8 bis-acryl resins used(More)
Considerable evidence indicates that corticotropin-releasing factor (CRF) is responsible for integrating not only the endocrine, but the autonomic and behavioral responses of an organism to stress. We have investigated the time course of action of the anxiolytic triazolobenzodiazepine, alprazolam, on the activity of the hypothalamic-pituitary-adrenal (HPA)(More)
The cyanobacterium (blue-green alga) Anabaena sp. ATCC 33047 produces an exopolysaccharide (EPS) during the stationary growth phase in batch culture. Chemical analysis of EPS revealed a heteropolysaccharidic nature, with xylose, glucose, galactose, and mannose the main neutral sugars found. The infrared (IR) spectrum of EPS showed absorption bands of(More)
UNLABELLED STATEMENT OF PROBLEM All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material. PURPOSE This study compared the translucency of 6 all-ceramic materials(More)