Characterization of thermally oxidized carbon fibre surfaces by ESCA, wetting techniques and scanning probe microscopy, and the interaction with polyethylmethacrylate. Development of a biocompatible composite material

Residual monomers released from glass-fibre-reinforced composite photopolymerised in contact with bone and blood

PURPOSE

The aim of this study was to determine the quantity of residual monomers of glass fibre-reinforced composite released into water from the composite that had been photopolymerized in contact with bone and blood.

MATERIALS AND METHODS

E-glass fibre reinforced composite (FRC) made of E-glass fibre veil and the bis-GMA-TEGDMA-PMMA resin system was used in the study. In the first group, pieces of non-polymerised FRC were photopolymerised (40 s) in air which influenced the oxygen inhibited resin layer (positive control). In the second group, the FRC was polymerized between two glass plates allowing both surfaces to be well polymerized (negative control). In the test groups, the FRC was polymerized in contact with bone or in contact with blood. FRC specimens from all four groups were incubated in three milliliters of deionised water at 37 degrees C for three days. At the end of the incubation period, the residual monomers were extracted from the water with dichloromethane, and the residual monomers of TEGDMA and bis-GMA quantitatively analysed by HPLC. The degree of monomer conversion was measured by FTIR from the surface of the test specimen. Differences between the groups were analysed using one-way ANOVA (p < 0.05).

RESULTS

The total quantity of residual monomers released from FRC polymerized in contact with bone was lower (0.55 wt%) than in the positive control group (0.97 wt%) (p = 0.021), and only slightly exceeded that of the negative control group (0.42 wt%) (p = 0.717). The total quantity of monomers released from FRC polymerized in contact with blood was at the level of the negative control group. The main residual monomer released was TEGDMA. The surfaces of the positive and negative controls showed a clear difference between the degree of monomer conversion, 34.0 and 62.8%, respectively, when analysed with FTIR (p < 0.001).

CONCLUSION

The surface of the bone or contact with blood did not significantly inhibit the photoinitiated free radical polymerisation of the dimethacrylate monomer system of the FRC.

Tissue engineering scaffolds using superstructures

Here, scaffolds as cell and tissue carriers are approached from an engineering point of view, emphasizing material superstructuring in the design of supports. Superstructure engineering provides optimal spatial and nutritional conditions for cell maintenance by the arrangement of structural elements (e.g. pores or fibres) so as to vary the order of cell to cell contact. This approach is illustrated in the design of several scaffolds: knitted fabrics as three-dimensional superstructures for optimized osteosynthesis implants, a new injectable open porous implant system, an angiopolar non-degradable ceramic cell carrier, and an injectable or microsurgically implantable entangled carrier system. The implications for tissue engineering are discussed.