What is the Dynamic measurement of the displacement of bur head from its axis referred to?

Concentricity is a direct measurement of the symmetry of the bur head. It measures how closely a single circle can be passed through the tips of all the blades. It is an indication as to whether one blade is longer or shorter than the others. It is only a static measurement. Run-out, on the other hand, is a dynamic measurement of the maximum displacement of the bur head from it axis of rotation while the bur runs. The average clinically acceptable run-out is 0.023 mm.