Abstract: PURPOSE: To prepare a soft lining material with high elastic on the basis of excellent characteristics of Eucommia ulmoides gum, and explore its basic physical performance and cytotoxity. METHODS: Basic formula was used based on the existing formula of elastic Eucommia ulmoides gum and medical rubber, then hardness, tensile strength and elongation at break were investigated to determine the final formula of the material, named Eucommia ulmoides gum composite soft denture liner. L929 mouse fibroblasts cultured in vitro were used to detect the toxic effects of 50% of leaching solution released from three kinds of denture soft lining materials by MTT assay. Statistical analysis was performed using SPSS16.0 software package. RESULTS: The kinds and blending proportion of rubber matrix had significant impact on mechanical properties of Eucommia ulmoides gum composite soft denture liner, the addition of Eucommia ulmoides gum significantly increased the hardness, tensile strength and elongation at break of the butadiene rubber. MTT assay showed Eucommia ulmoides gum composite soft denture liner did not have cytotoxicity on L929 mouse fibroblasts. The toxicity levels of 5 groups of Eucommia ulmoides gum composite soft denture liner in the 2nd, 4th, 7th day were maintained in the first stage, only 70:30 group reached the second stage on the 7th day. The cell relative appreciation rate of Silagum and 5 groups of Eucommia ulmoides gum composite soft denture liner in 2nd, 4th, 7th day were significantly higher than that in the self-curing acrylic soft lining material (P<0.05). CONCLUSIONS: Eucommia ulmoides gum and butadiene rubber blend ratio of 70:30, adding appropriate amount of zinc oxide, magnesium, stearic acid, sublimed sulfur, CZ, antioxidants, can get optimum mechanical properties. Eucommia ulmoides gum composite soft denture liner has no effect on L929 fibroblasts proliferation, indicating good biocompatibility.

Key words: Eucommia ulmoides gum, Soft denture liner, Mechanical properties, Cytotoxicity