title: Measurement of the cutting efficiency of endodontic instruments: a new concept.
abstract: The cutting efficiency of endodontic instruments was measured using an original experimental technique that incorporates new concepts to simulate clinical conditions. Five designs of #ISO 030 endodontic instruments, K-reamer (Maillefer), Flexofile (Maillefer), Helifile (Micro-mega), K-flex (Kerr), and Unifile (De Trey), were chosen and their cutting efficiency assessed at their full working length of 16 mm on two Plexiglas parallelepipeds tilted to follow the 2% conicity of the instruments. For each instrument, four series of 25 cuts were carried out and each cut made on a new flat, smooth Plexiglas surface with an even hardness of 33 VHN. Instruments were tested under a simulated clinical condition of a quarter clockwise turn ROTARY MOTION followed by a PULL ACTION at 16 mm/s rate, with a fixed load on the instrument of 325 g. Water irrigation at a rate of 85 ml/s was supplied before each procedure. Cutting efficiency was evaluated in terms of mass of Plexiglas cut (using a Mettler analytic balance with accuracy of 3 x 10(-5) g) per unit of energy used by the instrument, i.e. mg/J. Unifile was found to have the best cutting efficiency of 0.80 +/- 0.01 (Mean +/- SD) and lowest cutting efficiency loss followed by Flexofile 0.70 +/- 0.03 then Helifile 0.36 +/- 0.01 then K-flex 0.51 +/- 0.07. K-reamer was found to have the lowest cutting efficiency of 0.16 +/- 0.05.
authors.affiliation: Department of Endodontics C.R.O., INSERUM U424, University Louis Pasteur of Strasbourg, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Haïkel
authors.forename: R
authors.initials: R
authors.lastname: Serfaty
authors.forename: T T
authors.initials: TT
authors.lastname: Lwin
authors.forename: C
authors.initials: C
authors.lastname: Allemann
mesh_terms: D003762:Dental Instruments / Q000592:standards*; D004526:Efficiency; D005069:Evaluation Studies as Topic; D008422:Materials Testing; D020366:Methylmethacrylate; D008768:Methylmethacrylates; D008961:Models, Structural; D015203:Reproducibility of Results; D018915:Root Canal Preparation / Q000295:instrumentation*
chemical_list: D008768:Methylmethacrylates; D020366:Methylmethacrylate