Differential Thermal Analyses (DTA), X-Ray Diffraction analyses (XRD) and Scanning Electron Microscopy (SEM) were used to study the effect of P₂O₅ addition on the crystallization properties of dental glass-ceramics in the Li₂O-SiO₂-Al₂O₃-K₂O-ZnO glass system. It was concluded that P₂O₅ was an effective nucleating agent for this glass system. The nucleation density of this glass system was too low to form tiny crystal after heat-treatment, when it contained no P₂O₅, and the major crystal phase was lithium silicate. Adding P₂O₅ resulted in major tiny crystal phase of lithium disilicate after heat-treatment. 4.5 wt% of P₂O₅ could give high content and prospecting SEM appearance of dental lithium disilicate glass-ceramic. 6.0 wt% of P₂O₅ opacified base glass.

Key words: P₂O₅, glass-ceramics, crystallization