R. Arlom*1, H. Kalbfleisch2, D. Buch2, R. Strietzel1(1Free University Berlin, 2Inter. working group f. biocomp. materials)
The covering of metal surfaces by ceramic before firing is often not satisfactory. In the present study this problem shall be solved by interducing glass or silicat layers respectively interducing ceramic layers with help from lasers.
With Rocatec and Silicoater MD glass respectively silicat layers were formed on the surface of a CoCr alloy (Dentaurum: Remanium 2000). Those surfaces were fused with ceramic (Vita: Omega). The time of the oxide firing was varified (without, for or after Rocatec, Silicoater MD). In an other series ceramic was connected with help of a laser on the metal surface. Afterwards the ceramic was fused as usual.
Bond strength was determined with the three point bending test (SCHWICKERATH - test). Additionally investigations with scanning electron and light microscopy were undertaken. Surfaces conditioned with Rocatec reveal more constant and slightly higher values for bonding strength then those conditioned with Silicoater MD and unconditioned surfaces. The surfaces with lasered ceramic prevent peeling of the ceramic. Only Cracks can be observed. On the other hand this procedure is costly and lengthy. Parameters for the laser must be carefully adjusted for each material and modellation otherwise distortions of the geometry result. Therefore it is not recommended as a routine method. Because of the glass layer formed through the Rocatec procedure the wash firing is supported sufficiently. Morphologic investigation reveal that better retention and adhesion is achieved.
Long term investigations and optimized parameters for the laser are necessary to value the influence of alas or ceramic layers on the bond strength of ceramic fused to metal.