Celtra Press. Developed to make a difference The new generation of high strength glass ceramics, ZLS, available in tooth-colored ingots optimized for the heat-pressing technique in your laboratory. The Celtra Press System is a multi-component system that also includes Celtra Press investment, Celtra Ceram veneering ceramics and accessories. ZLS is the only material option delivering the highest level of esthetics mimicking natural dentition. A smart, simplified system that improves your laboratory workflow and profitability.