A method for restoring a blade or vane platform of a gas turbine assembly configured for a power plant by: providing a blade or a vane having a platform with an edge deterioration zone; removing the deterioration zone by electro discharging machining technology; and rebuilding a removed zone by additive manufacturing technology. The removing can be performed to create a recessed plane along a platform edge, the recessed plane being connected to a platform plane by an enter inclined plane and an exit inclined plane arranged opposed along the platform edge.