The influence of the negative ion powder on the properties of alginate impression materials.

This paper investigated the effects of different contents of negative ion powder on the antibacterial activity and mechanical properties of the alginate impression materials. The cytotoxicity of the negative ion powder was evaluated. The antibacterial rate was evaluated by the plate count method, and the mechanical properties, including the gelation time, elastic recovery, compressive strain and compressive strength were characterized by standards method. MTT assay was used to evaluate the cytotoxicity of the negative ion powder. When the content of negative ion powder was 1-2%, the antibacterial rate could be up to 90-100%. It had no significant effect on the mechanical properties of the alginate impression materials when the added content of negative ion powder was less than 2% (p>0.05). The results of the MTT assay indicated that the material is noncytotoxic. The optimal adding ratio of negative ion powder is 1-2%.