Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9561857 | Polymer Testing | 2005 | 5 Pages |
Abstract
The degree of conversion (DC) of a commercial photo-activated dental composite at different depths evaluated by a reliable method, Fourier transformation infrared spectroscopy (FT-IR), is reported. The polymerization reaction was carried out in cylindrical specimens with depth from 1 to 5Â mm using a halogen light curing unit (450Â nm, 21,200Â J/cm2). FT-IR spectra of the material before and after the cure reaction were taken and the ratio of heights between absorptions at 1637Â cmâ1 (variable) and 1610Â cmâ1 (reference) was used to determine DC. The DC showed a tendency to decrease with increasing depth, attaining values in the range of 40-50%. The low values of DC indicated that a large amount of residual monomer has remained. The factors that could contribute to decreasing of DC were the monomers viscosities and ratio, size of fillers and great difference in refractive indices of organic and inorganic constituents. Additionally, the composite formulation was investigated by commonly used techniques, such as, thermogravimetry (TGA), X-ray fluorescence (XRF), light scattering (LS) and proton-nuclear magnetic resonance (1H NMR). The composite is composed of: 78.6% inorganic fillers, 20.6% BisfenolA/dimethacrylate (BisGMA) and 0.8% triethyleneglycoldimethacrylate (TEGDMA) as monomers.
Related Topics
Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
Luis C. Mendes, Andrea D. Tedesco, Mauro S. Miranda,