Abstract: To apply a silicon oxide adhesion-promoting layer to a metal prosthesis part or frame, for subsequent application of a dental plastic thereon, the prosthesis is subjected to flame hydrolysis derived from a flame hydrolysis burner (11) which has a silicon compound in vapor or gas form applied thereto in addition to a carbon-containing combustion gas, such as propane and air, the prosthesis part or frame being passed through the flame from the burner in the forward third thereof, the burner flame cone having, in operation, a length (L) of between 15 to 20 cm, a gas stream speed of about 1 m/sec., and wherein the length (L) of the cone exceeds the spacing distance (D) of the farthest part of the prosthesis from the mouth of the burner by only up to about 25%. For fine adjustment of the cone, a tinting substance can be added to the flame.