Microhardness and Biocompatibility of Silicon Nitride Ceramic Developed for Dental Applications

Abstract

Silicon nitride (Si 3 N 4 ) ceramic is an attractive material for dental applications, especially used as a dental core material, due to its unique properties including high fracture toughness, high strength, high wear resistance and non-cytotoxicity. In this study, the Si 3 N 4 ceramic was fabricated by a non-pressure sintering technique at a relatively low sintering temperature of 1650 ℃ in nitrogen atmosphere. Borosilicate glass and 5 wt% ZrO 2 -added borosilicate glass were used for coating on the Si 3 N 4 core surface because of their compatibility in thermal expansion, high chemical resistance and bio-inert. The specimens were then fired in electric tube furnace at 1100 ℃ . The Vickers microhardness of borosilicate glass and 5 wt% ZrO 2 -added borosilicate glass veneering materials were measured and compared with the commercial dental veneer porcelain as a control (VITA VMK 95). The cytotoxicity of the Si 3 N 4 ceramic and the veneering materials were tested by MTT assay, using human gingival fibroblasts (HGF) and periodontal ligament fibroblasts (HPDLF). The results indicate that the Si 3 N 4 ceramic and Si 3 N 4 ceramic veneered with borosilicate glass or 5 wt% ZrO 2 -added borosilicate glass veneering materials tested in this study are not toxic to oral tissue and can be used to produce dental prostheses.