Surface oxide favors adherence. The results of this study do not support the hypothesis that chromium oxide has a deleterious effect on adherence as measured by the torsion test. 2. Gritblasting the surface before porcelain application improves adherence. Smooth uncoated specimens where oxide was removed before enameling developed insufficient amounts of oxide for bonding. 3. The particular coating agent used on this study indirectly promotes adherence, since additional oxide forms during its application. Also, it may be directly involved by its influence on the residual stress distribution in the interface porcelain. 4. The more extensive the reaction zone at the interface, the further away the fracture surface is from the interface.
