The Relationship between the Degree of Conversion in Dental Dimethacrylate Polymers Determined by Infrared Spectroscopy and Polymerization Shrinkage

In this work, the relationship between the degree of conversion (DC) in the Bis-GMA/TEGDMA polymer networks, determined by two methods—Fourier transform infrared spectroscopy (DCIR) and polymerization shrinkage (DCS)—was studied. The DCIR was calculated by using the internal standard method, whereas the DCS was calculated by measuring differences in the monomer and polymer densities, resulting in the polymerization shrinkage. Both methods revealed the same trend in the DC changes with alterations in the Bis-GMA/TEGDMA ratio. However, the DCS values were lower, in comparison to the DCIR values on average by 18%.