Fourier transform infrared analysis of degree of polymerization in unfilled resins--methods comparison

Two methods of transmission Fourier Transform Infrared analysis were compared to determine the degree of polymerization (DP) in unfilled Bis-GMA-based dental resins. Diluent concentration, curing mode, and activator type were investigated. DP ranged from 55-72% and was highest for the most diluted resins. The effects of polymerization activation mode and type were insignificant. DP was slightly enhanced in the bulk of the resin, as determined by a KBr-pellet technique, in comparison with results from a thin film method, but both techniques seem to provide useful and reproducible results for dental resins.