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


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).


CONCLUSIONS
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.
Tuusa
Sari M-R
SM
Department of Prosthetic Dentistry & Biomaterials Research, Institute of Dentistry, University of Turku, Turku, Finland. sari.tuusa@utu.fi
Puska
Mervi A
MA
Lassila
Lippo V J
LV
Vallittu
Pekka K
PK
D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001769:Blood; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D004058:Diffusion; D005147:Facial Bones / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry* / Q000528:radiation effects; D006801:Humans; D008027:Light; D008422:Materials Testing; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry* / Q000528:radiation effects; D013552:Swine
D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D005899:Glass Ionomer Cements; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C009753:fiberglass; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D019904:Polymethyl Methacrylate