Principles and phenomena of bioengineering with glass-ceramics for dental restoration

The main aim of this paper is to demonstrate the processes of bioengineering by controlled microstructure formation, property control and special processing. Based on the mechanisms of nucleation and crystallization, the authors deduced directions to develop of leucite-based, lithium disilicate and leucite-apatite glass-ceramics. Thus, leucite glass-ceramics were developed by surface nucleation and crystallization. Viscous flow pressing and CAD/CAM are the preferred methods of processing single units for dental restoration. Lithium disilicate glass-ceramics were developed by heterogeneous nucleation and crystallization. The microstructure resulted in a flexural strength of approximately 400MPa of the material. The glass-ceramic is translucent and processing by pressing of CAD/CAM in a two step process is possible. Veneered with an apatite containing glass-ceramic, the material is used as three-unit dental bridge. Fundamental research showed improvement of flexural strength. Leucite and apatite were precipitated according to a two-fold nucleation and crystallization mechanism. The final result is a material characterized by translucency and a high C.T.E., that allows veneering of metal frameworks for dental restoration. (c) 2006 Elsevier Ltd. All rights reserved.