[Material found on the cleaned diamond turbine drilling heads after injury cases].

Grinding of the hard tissues of the teeth with diamond points and airotor led to bullet-like flying off of part of the instrument. The causes were investigated: Unsatisfactory fixation in the turbine head, deficient material in the rotating instrument, unnecessary notches in the shaft resulting in reduction of diameter, and finally the so far uncorrected radial vibration of the rotating instrument. All of these causes may result in plastic deformation or breakage of the points.