The present invention provides a selective coating of an endodontic file, in which the distal end of the file is uncoated or alternatively leaving the outermost part of the blades of the distal end portion uncoated. The distribution of the nanoparticles is thus non uniform along the surface of the file leaving only a part of the file coated. In the present invention, the distal end of the device being subjected to the highest torque is either uncoated at all, or has a coated core and uncoated blades.
