Because more than 200 million dental restorations are performed each year, the importance of using a restorative material that is safe as well as durable should not be underestimated. This research proposes two different ways of improving current composite dental restorative materials. The first method involves changing the functionality of the presently used monomer resins by incorporating different dimethacrylates as well as tri-, tetra-, and penta-methacrylates into the reaction mixture. In addition, copolymerizing multifunctional monomers with dimethacrylates of varying length and structure increases the double bond conversion while maintaining similar mechanical properties. The advantage of the increased double bond conversion is the significant reduction in the amount of unreacted monomer that may eventually leach out into the body. The second method for improvement of current dental resins involves the polymerization of liquid crystalline dimethacrylate monomers. These monomers tend to form crystalline regions within the liquid. The transition from the amorphous to the crystalline facilitates two significant benefits for dental restorative materials. First, a large amount of shrinkage, that would otherwise occur during the polymerization, occurs during the amorphous to crystalline transition. This volume change occurs before the material is placed in the dental cavity and lowers the polymerization volume shrinkage. Secondly, polymers from liquid crystalline materials will have lower thermal expansion coefficients (i.e. closer to that of human teeth). These techniques will each be attempted separately, and then they will be combined to determine the synergistic effects of these improvements. This research will lead to the development of novel dental restorative -materials which have improved durability, lower polymerization volume shrinkage, lower thermal expansion, and significantly reduced amounts of residual unreacted monomer.

R29DE010959

1995-09-15

2000-07-14