Rotary instrumentation

Mechanical preparation with rotary nickel-titanium instruments is one of the latest developments in endodontic preparation. Several different instrument designs are available, however, most use the crown down principle for the instrumentation and enlargement of the canal. The coronal and mid parts of the canal are opened first with high taper instruments so that only a small part of the instrument is engaged with the canal wall, while the tip is free of contact. Finally, the apical preparation is finished with instruments engaged only with the most apical part of the canal. - There are usually no major differences between straight and curved canals.