Adhesive oxides
By adhesive oxides on the surface of dental alloys can silicon atoms of the ceramic via oxygen bridges connect with the metal. This makes it possible to veneer (clad) metal dental crowns with ceramic materials in the tooth color and to give the teeth a natural appearance. There is a boundary layer with mutual diffusion of the elements involved. The adhesive oxides form the most important basis for the adhesion and thus the manufacture of ceramic-veneered tooth crowns and bridges in dentistry .
Precious metal alloys
Alloys with a high gold content have to be added in small amounts of base components such as gallium (Ga), iron (Fe), indium (In), tin (Sn), iridium (Ir) or titanium (Ti) so that they can form oxides. These additives form oxides on the metal surface, to which a considerable share is attributed to the formation of the metal-ceramic adhesive bond. Adhesive oxides are produced by the oxide firing in alloys containing precious metals. The formation of the oxygen bridges between the aluminum or silicon atoms of the ceramic and the oxidized atoms in the metal surface creates the chemical bond between metal and ceramic.
Base metal alloys
Non-precious metal alloys do not require additional adhesive oxide formers ( tracers ), since a chemical bond takes place between the metal and the ceramic via the passivating chromium oxide layers. The boundary layer that creates the connection contains a diffusion zone of 2 μm in the case of cobalt - chromium alloys as adhesive oxide.
Binding effect of the adhesive oxides
The importance of the individual parameters of the metal-ceramic composite system is weighted as follows:
- Chemical forces: 50%
- Contraction Forces: 26%
- Mechanical retention forces: 22%
- Adhesive forces: 2%
literature
- Metals: Materials science with its chemical and physical principles . Verlag Neuer Merkur GmbH, 1999, ISBN 978-3-929360-44-8 , pp. 69–.
Individual evidence
- ↑ Doreen Pritzel, Influence of changed parameters when veneering non-precious metal alloys with ceramics on the adhesive bond , dissertation, 2012. Retrieved on November 18, 2016.
- ↑ gentleness J. Materials Science and Technology. In: Siebert GK ed. Dental alloys in dental prosthetics. Munich, Vienna: Carl Hanser Verlag, 1989: 23-111.
- ↑ K. Eichner, Metal-Ceramics in Dental Prosthetics. Munich-Vienna: Hanser, 1979. ISBN 3-446-12596-5 .