ENDODONTIC HAND INSTRUMENTS - CUTTING EFFICIENCY, INSTRUMENTATION OF CURVED CANALS, BENDING AND TORSIONAL PROPERTIES

In an assessment of the usefulness of different root canal instruments , two aspects are of particular interest for the endodontist: the cutt ing efficiency of the instruments and their ability to enlarge curved canals without undesirable changes of the canal shape such as the form ation of zips and elbows. This review paper is based on own investigat ions on the cutting efficiency and instrumentation of curved canals. A dditionally, two parameters which are described in ISO 3630-1, resista nce to bending and resistance to fracture, are discussed. With regard to cutting efficiency in rotary motion, flexible stainless steel reame rs and K-files clearly display the best results and are superior to co nventional stainless steel as well as titanium-based reamers and K-fil es. Regarding cutting efficiency in linear motion, stainless steel Hed strom files made by certain manufacturers are significantly superior t o stainless steel and titanium-based Hedstrom files of other brands. F lexible stainless steel instruments with modified noncutting tips clea rly produce the best canal shape in curved canals. With only rare exce ptions, all the instruments tested fulfilled the requirements of the I SO standard concerning resistance to fracture and resistance to bendin g.