Method for producing a dental prosthesis

A method for producing a dental prosthesis based on lithium silicate glass or lithium silicate glass-ceramic, comprising the steps of:

• (a) melting a powder mixture with the composition in wt-%
• SiO2
• 50-70%;
• Li2O
• 5-25%;
• Al2O3
• 0.1-20%;
• K2O
• 0.1-15%;
• CeO2
• 0.1-15%;
• B2O3
• 0-5%;
• P2O5
• 0-15%;
• Tb2O3
• 0-2%;
• ZrO2
• 0-15%;
• ZnO
• 0-4%;
• and
• at least one additive between 0.1 and 5 wt-%, the additive being selected from the group consisting of BaO, CaO, MgO, MnO, Er2O3, Gd2O3, Na2O, Pr2O3, Pr6O11, Sm2O3, TiO2, V2O5, and Y2O3,
• (b) producing spherical or lens-shaped glass particles solidified from the melt;
• (c) portioning the glass particles and filling them into a crucible;
• (d) melting the glass particles in the crucible and setting a viscosity v, wherein 4 dPa·s≤v≤80 dPa·s;
• (e) casting the thus produced melt into a negative mold which is enclosed by an embedding compound and corresponds to the dental prosthesis to be produced;
• (f) solidifying the melt in the negative mold;
• (g) crystallizing lithium metasilicate as main crystalline phase from the solidified melt by employing a first heat treatment at a temperature between 600° C. and 760° C. over a time between 20 min and 120 min, and
• (e) comprising the step of crystallizing lithium disilicate as main crystalline phase in a second heat treatment at a temperature between 760° C. and 860° C. over a time between 5 min and 60 min;
• wherein the first and second heat treatment of the solidified melt takes place either in the negative mold or after removal from the negative mold.