Publications by authors named "Marju Väkiparta"

2 Publications

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Residual monomers and degree of conversion of partially bioresorbable fiber-reinforced composite.

Acta Biomater 2006 Jan 10;2(1):29-37. Epub 2005 Oct 10.

Department of Prosthetic Dentistry and Biomaterials Science, Turku Biomaterials Centre, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4 B, 20520 Turku, Finland.

The aim of this study was to evaluate the total quantity of residual monomer (bis-phenyl glycidyl dimethacrylate, i.e. Bis-GMA, and triethylene glycol dimethacrylate, i.e. TEGDMA), residual monomer release into water and the degree of monomer conversion (DC%) of glass fiber-reinforced composites (FRC) with a partially bioresorbable polymer matrix. Another aim was to find out whether the curing mode affects the quantity of residual monomer and degree of conversion. Glass fibers were preimpregnated with a bioresorbable poly(hydroxyproline) amide and non-resorbable Bis-GMA-TEGDMA resin system. Specimens were immersed in water for 1, 3 or 7 days (37 degrees C) to determine the quantity of leached residual monomers, or in the solvent tetrahydrofuran for 3 days to determine the total quantity of residual monomers by high performance liquid chromatography. DC% was measured by Fourier transform infrared spectroscopy. The quantity of residual monomer of the specimens decreased when the specimens contained glass fibers, and/or poly(hydroxyproline) amide, and/or when it was post-cured. The majority of the residual monomers were leached out during the first 24 h of immersion in water. The DC% of the specimens increased when post-cured. Also glass fibers in the composite increased the DC% in contrast to Bis-GMA-TEGDMA resin only. In conclusion, use of poly(hydroxyproline) amide as a sizing of the glass fibers in FRC does not increase the quantity of residual monomers. These results suggest that this new kind of partially bioresorbable FRC has potential for biomedical applications.
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http://dx.doi.org/10.1016/j.actbio.2005.08.009DOI Listing
January 2006

Release of silica, calcium, phosphorus, and fluoride from glass ionomer cement containing bioactive glass.

J Biomater Appl 2004 Jul;19(1):5-20

Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, 20520, Finland.

The aim of this study was to examine the release of silica (Si), calcium (Ca), phosphorous (P), and fluoride (F) from conventional glass ionomer cement (GI) and resin-modified glass ionomer cement (LCGI), containing different quantities of bioactive glass (BAG). Further aim was to evaluate in vitro biomineralization of dentine. The release of Si increased with the increasing immersion time from the specimens containing BAG, whereas the amount of Ca and P decreased indicating in vitro bioactivity of the materials. LCGI with 30wt% of BAG showed highest bioactivity. It also showed CaP-like precipitation on both the surface of the test specimens and on the dentin discs immersed with the material. Within the limitations of this study, it can be concluded that a dental restorative material consisting of glass ionomer cements and BAG is bioactive and initiates biomineralization on dentin surface in vitro.
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http://dx.doi.org/10.1177/0085328204044538DOI Listing
July 2004