The bur includes a shaft (22) to which a bur head (32) is attached. The bur head includes a plurality of flutes (46). Each flute at least has a rake surface (45) and a cam surface (60). The rake surface extends radially outwardly from the longitudinal axis of the head. The rake surface defines a flute cutting edge (38). The associated cam surface curves away from the rake surface. One or more ribs (70) extend radially outwardly from the cam surface.
