Process for producing a sintered lithium disilicate glass ceramic dental restoration and kit of parts

A process for producing a sintered lithium disilicate glass ceramic dental restoration out of a porous 3-dim article, the process comprising:

• providing a porous 3-dim article, the 3-dim article having the shape of a dental milling block, the porous 3-dim article having a density from 0.5 to 2 g/cm3,
• machining the porous 3-dim article to obtain a machined porous 3-dim article having the shape of a dental restoration with an outer and inner surface,
• optionally coloring the porous 3-dim article having the shape of a dental restoration,
• sintering the porous 3-dim article having the shape of a dental restoration with an outer and inner surface at reduced atmospheric pressure without supporting the inner surface of the porous 3-dim article having the shape of a dental restoration during sintering to obtain a sintered lithium disilicate ceramic dental restoration,
• the sintering being done under reduced atmospheric pressure conditions, the reduce atmospheric pressure conditions being first applied at a temperature above 600° C.,
• the sintered lithium disilicate glass ceramic dental restoration having a density from 2 to 3 g/cm3 and comprising:
• Si oxide calculated as SiO2:
• from 55 to 80 wt.-%;
• Li oxide calculated as Li2O:
• from 7 to 16 wt.-%;
• Al oxide calculated as Al2O3:
• from 1 to 5 wt.-%;
• and
• P oxide calculated as P2O5:
• from 1 to 5 wt.-%,
• wt.-% with respect to the weight of the dental restoration.