An implant comprises or consists of titanium and has one or more surfaces which can be applied in or on a bone growth area. One or more of the said surfaces are arranged with a depot for bone-growth-initiating or bone-growth-stimulating substance, which depot is formed by a pore arrangement in a relatively thick oxide layer on the titanium. The substance is acted on, for a considerable period of time, by one or more release functions for the substance which permit a controlled or optimized release of substance to the surrounding tissue or bone growth area.