Nickel–titanium rotary instrument fracture: a clinical practice assessment

By Di Fiore P, Genov K, Komaroff E, Li Y, Lin L.

Date: 09/2016
Journal: JOE


•Purpose: to prospectively determine the incidence of nickel–titanium rotary instrument fracture in an endodontic clinical practice setting.

•N= 1403 teeth (354 anterior, 320 premolar, 729 molars)


•11 residents had to do all their cases with 1 system during the study. 3 used ProFile, 3 Protaper,3 K3 and 2 GT rotary .

•Torque 3, speed 350 r.p.m.  It has to be coronally flared, minimum apical preparation #30. completed in 1-2 h.

•Instruments were discarded if any distortion occurred.

•If fractured occur, straight and angled RG was taken and curvature was determined by schneider (straight <10°, moderate 10–25°, or severe >26°). Position ,length, size .system , canal, # of uses was recorded.

Most highlighted Results:

•26 instrument fractured, overall incidence (0.39%). No significant difference among groups.


•Size tip 20-40, average length of fractured instrument 2mm. 0.06 taper fractured the most.

•17/29 fractured at their 3rd use.

•There was a relatively equal distribution of fractures amongst the instrument sizes 20–40 and majority of the instruments that fractured 88% had large tapers ranging from 0.06 to 0.09.