Factors affecting the quantity of remaining double bonds in restorative resin polymers.

The quantity of remaining unreacted double bonds may be a significant factor pertaining to the mechanical, physical and chemical properties of restorative resins. The said quantity was determined from the transmission IR-spectrum of the materials before and after polymerization. For proprietary resins the quantity of remaining double bonds was found to vary between 23 and 43%. For experimental, chemically cured resins the quantity in question was found to decrease with increasing resin content of amine and peroxide, and to increase with the content of inhibitor. The content of peroxide was the more influential of the three factors. For constant content of amine, peroxide, and inhibitor the number of remaining double bonds decreased with increasing content of diluting monomer in BISGMA-based monomer mixtures. The use of a trifunctional monomer as diluting monomer did not give rise to a higher degree of conversion of the double bonds in comparison to a bifunctional diluting monomer. The quantity of remaining double bonds of a light curing material was relatively small when compared to the quantity present in chemically cured materials of adequate setting time.