Sorption of water, ethanol or ethanol/water solutions by light-cured dental dimethacrylate resins

ObjectivesThis work is concerned with the study of the sorption and desorption process of water, ethanol or ethanol/water solution 50% (v/v) or 75% (v/v) by the dental resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D3MA.MethodsA thin resin disc is placed in a bath of time to obtain the sorption curve mt = f(t). Then the liquid is desorbed until a constant mass for the disc is reached and the desorption curve is recorded. These experimental curves help in the determination of the sorbed/desorbed liquid amount at equilibrium, the percentage of the extracted mass of unreacted monomer known as “solubility”, and the sorption/desorption diffusion coefficient which expresses correspondingly the rate of the liquid sorption/desorption.ResultsThe highest liquid uptake by dental resins was 13.3 wt% ethanol for Bis-GMA-resin, 12.0 wt% ethanol for UDMA-resin, 10.10 wt% ethanol/water solution for TEGDMA-resin, 7.34 wt% ethanol for D3MA-resin and 6.61 wt% ethanol for Bis-EMA-resin. The diffusion coefficient for all resins was higher in water than in ethanol/water solution or ethanol. Bis-GMA-resin showed the highest diffusion coefficient (11.01 × 10−8 cm2 s−1) followed by Bis-EMA-resin (7.43 × 10−8 cm2 s−1), UDMA-resin (6.88 × 10−8 cm2 s−1), D3MA-resin (6.22 × 10−8 cm2 s−1) and finally by TEGDMA-resin (1.52 × 10−8 cm2 s−1).SignificanceAll studied dental resins, except TEGDMA-resin, absorbed higher amount of pure ethanol than water or ethanol water solution. TEGDMA-resin absorbed higher amount of ethanol/water solution (50/50 or 75/25 (v/v)) than water or ethanol. For all studied dental resins the diffusion coefficient was higher in water than in ethanol/water solution or ethanol.