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 poly-merization 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 repro-ducible results for dental resins