Polymerization of metal-resin composite for restorative dental material

Abstract

Five kinds of metal particles, i.e., Ag, Zr, Cu, Mo and Zn were examined to establish if they could induce the polymerization of urethane dimethacrylate (UDMA) based monomer. Four different monomer compositions were used to combine with metal filler. As-received, Ag and Zr particles could not induce the polymerization of UDMA based monomer either containing coupling reagent (4-methacryloyloxyethyl trimellitate anhydride, 4-META) or radical initiator (benzoyl peroxide, BPO) or without containing of those components. Cu and Mo particles could induce the polymerization of UDMA based monomer even in the absence of 4-META, but they could not have the ability to do so in the absence of BPO. Zn particles could induce the polymerization of UDMA based monomer in the absence of BPO, but they could not have good ability in the absence of 4-META. From the above observation, molybdenum particles were chosen to study the details of the polymerization phenomena. Themixture of molybdenum particles moistened with a small amount of water and either bisphenol glycidyl methacrylate (Bis-GMA) based monomer or UDMA based monomer containing 4-META and BPO was investigated. The effects of monomer types and 4-META concentrations on the setting time and degree of conversion (DC) were studied. Molybdenum particles could induce the polymerization of both Bis-GMA based-monomer and UDMA based-monomer. A higher concentration of 4-META retarded the setting time but increased DC in both monomers. This molybdenum-resin composite had much higher DC than the previous metal-resin composites.