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Effect of Chemical Structure and Composition of the Resin Phase on Vinyl Conversion of Amorphous Calcium Phosphate-Filled Composites



Drago Skrtic, Joseph M. Antonucci


The objective of this study was to elucidate the effect of chemical structure and composition of the polymer matrix on the degree of vinyl conversion (DC) of copolymers (unfilled resins) and their amorphous calcium phosphate (ACP) composites attained upon photo-polymerization. The DC can also be an indirect measure of the probability of these polymeric materials to leach out into the oral environment un-reacted monomers which could adversely affect their biocompatibility. The following resin matrices were examined: 1) 2,2-bis[p-(2 -hydroxy-3 -methacryloxypropoxy)phenyl]propane (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (1:1 mass ratio; BT resin) combined with hydroxyethyl methacrylate (HEMA; BTH resin) and with HEMA and zirconyl dimethacrylate (BTHZ resin), 2) urethane dimethacrylate (UDMA)/HEMA resins, and 3) pyromellitic glycerol dimethacrylate (PMGDMA)/TEGDMA (PT resin).To make composite specimens, resins were mixed with a mass fraction of 40 % zirconia-hybridized ACP. Copolymers and their composites were evaluated by near infra-red spectroscopy for DC after 1 d and 28 d post-cure at 23 oC. Inclusion of HEMA into the BT and UDMA matrices yielded copolymers and composites with higher DCs. The significantly lower DCs of PT copolymers and their composites are attributed to the rigid aromatic core structure, tetra-vinyl functionality and very limited methacrylate side-chain flexibility of the surface-active PMGDMA monomer. Based on their relatively low DC data, PT composites are likely to have lower biocompatibility than the Bis-GMA and/or UDMA based composites.
Polymer International


amorphous calcium phosphate, composites, copolymers, degree of vinyl conversion


Skrtic, D. and Antonucci, J. (2008), Effect of Chemical Structure and Composition of the Resin Phase on Vinyl Conversion of Amorphous Calcium Phosphate-Filled Composites, Polymer International, [online], (Accessed July 13, 2024)


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Created August 18, 2008, Updated February 19, 2017