Zirconia based materials have been widely used in construction of dental prosthesis
because of their mechanical and aesthetical properties and a lot of money have been
invested in their development, but no one of the producers considered the aging of
zirconia. In this job have been demonstrated, with Raman spectroscopy, the low
temperature degradation of zirconia and has been investigated the residual stress in
zirconia-alumina composites at room temperature and in open-air after 8 years of
aging, then have been investigated the phase trasformation of tetragonal zirconia into
monocline form of pure zirconia and alumina-zirconia composites tested in water
with a thermal fatigue cycle between 5°C and 55°C. A partial solution of the problem
is proposed. Atomic Force Microsopy and Near-field Scanning Optical Microscopy
techniques have been tested as method of investigation and validation of the results.
