GC Initial LiSi Fluo-Dentin FD-91 Initial LiSi is a feldspar-based porcelain specially adapted to the material lithium disilicate. The porcelain is built on the same load as the other modules in the Initial concept and has been developed with a view to copying the light dynamics in the natural tooth. The material can be used for both layer and cutback technique, on pressed or milled skeletons and the material is stable, even after several burning cycles.