Characteristic Properties Of Multi-functional Vinyl Esters / PMMA Resins

Objective: This investigation seeks to evaluate the characteristic properties of our proposed novel powder-liquid type denture base material using the elastic paste prepared by the mixing of multi-functional vinyl esters (MFVE) liquid and poly(methyl methacrylate) (PMMA) powder. Method: The elastic paste was prepared by the mixing of PMMA powder (M.W.: 5 x 10⁵, Particle size: 40~80μm) and MFVE liquid (Divinyl sebacate, Divinyl adipate, Divinyl glutarate, Vinyl methacrylate: VMA) at the P/L ratio of 2.4(g/ml). The dough was then packed into Teflon mold (f10 x 2mm), and thermo-polymerized with a dry heat curing unit (ST-101B1, Espec; 65°C/60min + 100°C/90min). The prepared disks were immersed in dist. water at 37°C, and the change of knoophardness number (KHN) (FM-700, Future-Tech; Test load: 10g, Dwell time: 20sec) and observed water uptake (WU) were followed up for 1 year. Result: All the KHN of MFVE/PMMA resins were proportional to the chain length between polymerizable groups of MFVE, and the KHN increased as the chain length between polymerizable groups of MFVE shortened. After water-immersion for 1 year, the KHN (19.8±0.4) of VMA/PMMA resin was significantly superior to that (17.8±0.9) of commercial acrylic denture base resin (DBR) (ANOVA, Turkey’s, p<0.05). The saturated WU (SWU) of MFVE/PMMA resins excluding VMA/PMMA resin was proportional to the hydrophilic-lipophilic balance (HLB_G) of MFVE, the SWU decreased as the lipophilic property of MFVE increased. On the other hand, the SWU (1.48±0.08wt%) of VMA/PMMA resin was lower than expected based on the HLB_G of VMA, and was significantly lower than that (1.72±0.04wt%) of commercial DBR. These characteristic properties of VMA/PMMA resin were anticipated based on the extremely high density cross-linked network structure of poly-VMA. Conclusion: The VMA/PMMA resin demonstrated excellent potential as a powder-liquid type denture base material considering its water-durability and ability to resist scratching.