[Investigation of water sorption and solubility of three denture soft lining materials]

This assay was made to investigate the water sorption and solubility of autopolymerizing hydrogel, acrylic resin and silicone denture soft lining materials. The test discs with 50 mm in diameter and 1 mm in thickness were prepared according to powder and liquid ratio. The weight of sample was measured after 24 h drying (m1). The sample was put into artificial saliva and distilled water for 7 d and 28 d, the moisture weight was measured after soaking (m2). After drying again, the last data of weight (m3) was acquired till the constant mass was recorded. Finally the values of water sorption and water solubility were calculated respectively with statistical analysis. The results showed the means of percentage about absorption at 7 d and 28 d were 28.62% and 24.96% for hydrogel, 1.89% and 1.65% for acrylic resin, 0.25% and 0.29% for silicone in artificial saliva. The percentage solubility at two stages were 0.56% and 0.51% for hydrogel, 0.74% and 0.83% for acrylic resin, 0.10% and 0.12% for silicone. In distilled water, the means of percentage about absorption at 7 d and 28 d were 30.15% and 27.85% for hydrogel, 3.64% and 6.17% for acrylic resin, 0.83% and 0.98% for silicone. The percentage solubility at two stages were 0.79% and 1.16% for hydrogel, 0.86% and 1.01% for acrylic resin, 0.10% and 0.14% for silicone respectively. The conclusion is that the order of percentage about absorption for these three denture soft lining materials were hydrogel > acrylic resin > silicone. The percentage solubility of acrylic resin was higher than that of the other two materials because of the plasticizer existing in acrylic resin material. In some degree, the ionic component increased may affect water sorption and solubility. Further clinical demonstration is needed for this hydrogel with higher percentage absorption.