Abstract: Objective To study the effect of nano TiO2 on the masking ability of silicone rubber prosthesis after two different treatments to find the proper treatment suitable for the oral silicon rubber prosthesis masking agent and to offer theorial basis for clinical selection and colourity of prosthesis in maxillofacial region. Method Spectrophotometer was used to meter the color parameter L, a, b of TiO2 nano silicon rubber specimens treated in different ways respectively under black and white backgrounds (L=22.0，a=-1.0，b=-6.2)、white(L= 92.7，a=-0.9，b=-2.0). According to the formula ?E=[(?L )2 +(?a )2 +(?b )2 ]1/2 , the value of chromatism under black and white backgrounds was calculated, which showed the masking ability of the masking agent. Result There was no significant difference in the value of chromatism as the proportion fraction of nano TiO2 was small, but with the proportion fraction increasing, the value of chromatism of nano TiO2 with cladding silicone and aluminium was higher than that of the test pieces of the other treatment. Conclusion The dispersion property of nano TiO2 treated with silicone and aluminium is better than that treated with silane coupling agent. After two treatments, there is no obvious difference in the masking ability as the proportion fraction is small but with proportion fraction increasing, masking ability of nano TiO2 treated with silane coupling agent is much better.

Key words: masking material, nano-TiO2, masking ability