White Silicon nitride (Si3N4) ceramic has unique characteristics. Because of its high fracture toughness, strength, and biocompatibility, it can therefore be used to fabricate dental restorations. The purpose of this study was to produce partially-sintered block of Si3N4 for fabrication of CAD/CAM dental restorations. The related properties of this novel Si3N4 were evaluated including sintered shrinkage, flexural strength and fracture toughness. Partially sintered Si3N4 ceramic blocks were prepared by heating at 1,400°C for 2 h under N2 gas. After full sintering at 1,650oC for 2 h, the linear shrinkage value was recorded at 19.88±0.56%. The flexural strength and fracture toughness were measured, the results were 891.21±37.25 MPa and 6.33±0.30 MPa•m1/2, respectively. These results showed that flexural strength and fracture toughness of Si3N4 were more than 800 MPa and 5 MPa•m1/2, the white Si3N4 developed in this study can be used to fabricate multi-unit dental restorations According to ISO 6872.
Keywords: CAD/CAM; Flexural strength; Fracture toughness; Linear shrinkage; Silicon nitride.