Needle-like apatite-leucite glass-ceramic as a base material for the veneering of metal restorations in dentistry

A needle-like apatite-leucite glass-ceramic was prepared in the SiO2-Al2O3- Na2O-K2O-P2O5-F system. Nucleation and crystallization processes were studi ed in bulk and powdered samples. The crystallization of leucite follows the mechanism of surface crystallization. After the precipitation of NaCaPO4 c rystals and another unknown crystal phase, the formation of needle-like apa tite is based on a volume nucleation and crystallization process. The mecha nism of the formation of needle-like apatite differs to those of apatite pr ecipitation in glass-ceramics. The morphology of needle-like apatite is com parable to that of apatite in natural teeth. The properties of the glass-ceramic, especially the good chemical durabilit y, the optical properties, as well as mechanical and thermal properties all ow glass-ceramic to be used as a main component in a bio-material for the v eneering of metal restorations in dentistry. (C) 2000 Kluwer Academic Publi shers.