Manual instrumentation

The correct way to use manual preparation instruments is based on their structure. In hedstroem files the angle between the cutting blade and the long axis is nearly 90 degrees, which makes hedstroem suitable only for filing. In K-file the angle is between that of hedstroem and reamer. Accordingly, K-files can be used as files and in rotary motion, best in balanced force technique but also by continuous rotation. In reamers the angle is lowest which makes reamers effective in continuous rotation with the clock. Reamers are ineffective as files.
Most manual preparation instruments in endodontics are modifications of these three basic types with some new properties such non-active tip and super elastic metal (NiTi). However, their use is also determined by the angle between the cutting blade and the long axis.