of groove 5 is formed between the tooth wall 4 a and the groove 5 transition edge 4 b may have a sharpened edge grooves 5 and the adjoining tooth walls 4 a thus show an axial direction of the main course parallel to the axis so that the teeth 4 formed are located on the external diameter of shank 2 cutter 1 has a flat closure on the front side this flat closure brings about the formation of a sharp cutting edge of the teeth 4 at the front side distal end a as an alternative a bent closure may also be provided which will be explained in more detail below in fig5 and 5 a furthermore shank 2 of cutter 1 has a recessed colored ceramic ring 8 with a width of about 2 mm the cutters 1 in fig2 and 3 have not only a colored ceramic ring 8 but correspondingly two or three colored ceramic rings 8 it is thus possible to distinguish the different cutters by means of the number and color of the ceramic rings 8 furthermore shank 2 has an annular recess 9 whose center is located at a distance of 13 mm from a proximal end b located opposite the.