Novel Powder-liquid Type Low Water Absorption PMMA Based Resin

Objectives: This investigation seeks to evaluate the characteristic water absorption properties of a novel powder-liquid type denture base material using the elastic paste prepared by mixing poly(methyl methacrylate) (PMMA) powder and multi-functional monomer mixture (MFMM) liquid of vinyl methacrylate (VMA) with 1,4-pentadien-3-ol (14PD3OH).

Methods: The elastic paste was prepared by the mixing of PMMA powder (M.W.: 5 x 10⁵, particle size: 40~80mm) and VMA-14PD3OH liquid at the P/L ratio of 2.0(g/ml) and allowing MFMM to react physically with PMMA in a sealed jar until reaching a doughy consistency. The dough was packed into a 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 observed water uptake was monitored for 1 year. Each experiment included 10 determinations.

Results: The saturated water uptake (SWU) of PMMA/VMA-14PD3OH resin was dependent on the fraction of 14PD3OH. The SWU (1.0 ± 0.1mass%) of PMMA/VMA-14PD3OH (5~10vol%) resin was significantly lower than that (1.7 ± 0.1wt%) of commercial powder-liquid type acrylic resin for denture base (ANOVA, Tukey’s, p<0.05). The SWU of PMMA based resins was proportional to the hydrophilic-lipophilic balance (HLB_G) of monomer liquid. On the other hand, the SWU of PMMA/VMA-14PD3OH resin was significantly lower than that of HLB_G of VMA-14PD3OH. These characteristic water absorption properties of PMMA/VMA-14PD3OH resin were based on the semi-interpenetrating network structure of the polymer alloy that combines the poly(VMA-co-14PD3OH) of extremely high cross-link density with the PMMA as a liner polymer.

Conclusions: The SWU results demonstrate that the PMMA/VMA-14PD3OH resin has very promising potential as a novel powder-liquid type denture base material.