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Gaithersburg, MD, United States

Marovic D.,University of Zagreb | Tarle Z.,University of Zagreb | Hiller K.A.,University of Regensburg | Muller R.,University of Regensburg | And 4 more authors.
Clinical Oral Investigations | Year: 2014

Objectives: Experimental composite resins with amorphous calcium phosphate (ACP) have the potential to regenerate demineralized tooth structures. The aim of the study was to investigate the effect of the addition of silanized silica nanofillers to the ACP-based composites on their mechanical properties and the kinetics of calcium and phosphate release. Materials and methods: The test materials comprised 5 wt% (5-ACP) or 10 wt% (10-ACP) of silanized silica admixed to the 40 wt% ACP and 50 or 55 wt% resin. The ACP control (0-ACP) contained 40 wt% ACP and 60 wt% resin. Additionally, composite material CeramX (Dentsply, Germany) was included as control. Three-point bending test was performed to calculate flexural strength and modulus of elasticity. Inductively coupled plasma atomic emission spectroscopy was used for measurement of ion release. The micromorphology of calcium phosphate depositions on composite samples has been qualitatively evaluated using a scanning electron microscope. The results were analyzed using Mann-Whitney and Wilcoxon rank sum tests (α < 0.05). Results: Ion release was enhanced by the silica fillers, when compared to the 0-ACP. Although not statistically significant, flexural strength of 10-ACP was improved by 46 % compared to 0-ACP. Flexural modulus of 5-ACP was significantly higher than 0-ACP. Conclusions: The admixture of silanized fillers seems to be a promising approach for the improvement of mechanical and remineralizing properties of ACP composite resins. Clinical relevance: ACP-based composite resins with modified composition could serve as an effective remineralizing aid as base materials in restorative dental medicine. © 2013 Springer-Verlag Berlin Heidelberg.

Ding Y.,U.S. National Institute of Standards and Technology | Sun J.,U.S. National Institute of Standards and Technology | Sun J.,Paffenbarger Research Center | Ro H.W.,U.S. National Institute of Standards and Technology | And 6 more authors.
Advanced Materials | Year: 2011

The initial stages of cell alignment in response to surface topography can be largely described in terms of the work of adhesion encountered by a classical liquid droplet during spreading on a rough surface. This is manifested through a striking correlation between degree of cell alignment and anisotropic wetting of water droplets on the same topographical surfaces. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antonucci J.M.,U.S. National Institute of Standards and Technology | Skrtic D.,Paffenbarger Research Center
Polymers | Year: 2010

For over a decade our group has been designing, preparing and evaluating bioactive, remineralizing composites based on amorphous calcium phosphate (ACP) fillers embedded in polymerized methacrylate resin matrices. In these studies a major focus has been on exploring structure-property relationships of the matrix phase of these composites on their anti-cariogenic potential. The main challenges were to gain a better understanding of polymer matrix/filler interfacial properties through controlling the surface properties of the fillers or through fine-tuning of the resin matrix. In this work, we describe the effect of chemical structure and composition of the resin matrices on some of the critical physicochemical properties of the copolymers and their ACP composites. Such structure-property studies are essential in formulating clinically effective products, and this knowledge base is likely to have strong impact on the future design of therapeutic materials, appropriate for mineral restoration in defective tooth structures. © 2010 by the authors.

Sun J.,Paffenbarger Research Center | Hunston D.,U.S. National Institute of Standards and Technology | Forster A.M.,U.S. National Institute of Standards and Technology
28th Annual Technical Conference of the American Society for Composites 2013, ASC 2013 | Year: 2013

Dental adhesives are key components of resilient dental restorations such as fillings and crowns. The performance demands for a good adhesive require curing under visible irradiation, forming a strong bond, and resistant to attack from biological contaminants. A strategy that has been shown to meet many of these requirements has been to combine traditional methacrylate based resins with TiO2 nanoparticles (TiO2 NP). TiO2 NPs have a higher modulus than the resin and are photoreactive under visible light irradiation. This paper will demonstrate the capability of TiO2 NPs to increase the surface mechanical properties of visible light cured composite dental resins. The key to the composite property improvements is the functionalization of the surface of nanoparticles with acrylic acid to improve dispersion and bond the particles to the photocrosslinked network. While the chemistry of the particles will be highlighted, the focus will be on the surface mechanical properties of the composites.

Zhang F.,U.S. National Institute of Standards and Technology | Zhang F.,Northern Illinois University | Allen A.J.,U.S. National Institute of Standards and Technology | Levine L.E.,U.S. National Institute of Standards and Technology | And 5 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2012

The local structural changes in amorphous calcium phosphate (ACP)-based dental composites were studied under isothermal conditions using both static, bulk measurement techniques and a recently developed methodology based on combined ultra-small angle X-ray scattering-X-ray photon correlation spectroscopy (USAXS-XPCS), which permits a dynamic approach. While results from conventional bulk measurements do not show clear signs of structural change, USAXS-XPCS results reveal unambiguous evidence for local structural variations on a similar time scale to that of water loss in the ACP fillers. A thermal-expansion-based simulation indicates that thermal behavior alone does not account for the observed dynamics. Together, these results suggest that changes in the water content of ACP affect the composite morphology due to changes in ACP structure that occur without an amorphous-to-crystalline conversion. It is also noted that biomedical materials research could benefit greatly from USAXS-XPCS, a dynamic approach. © 2012 WILEY PERIODICALS, INC.

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