Fracture of nickel titanium rotary instrument during root canal treatment and re‐treatment: a 5‐year retrospective study

Abstract

The fracture incidence of K3 instruments was significantly greater during root canal re-treatment than root canal treatment, mainly with small instruments and in the apical third of the canals.

Prevalence of middle mesial canal and radix entomolaris of mandibular first permanent molars in a western Chinese population: an in vivo cone-beam computed tomographic study

“…The present study evaluated 487 mandibular rst molars with an RE using Schneider's method and showed that the angles of the RE root curvature in the BL and MD orientations were 40.69±14.37° and 17.58±7.84°, respectively; it was also found that most RE canals exhibited severe curvature in the BL orientation and exhibited moderate curvature or a straight appearance in the MD orientation, which is in agreement with previous studies. It is usually known that there is an increased risk of instrument fracture with an increasing angle of curvature [48][49][50]. Attention should be taken to avoid instrument fracture or perforation for the treatment of this additional unexpected canal since they are usually short and severely curved.…”

Cyclic Fatigue, Torsional Resistance, and Angular Deflection of Two Heat-Treated Files: M-Wire Versus New F-Wire Technology

“…Instrument fracture is the most common accident that occurs during the chemo-mechanical preparation when NiTi file systems are used [9][10][11]. Different thermal treatments seem to decrease its incidence [18,19], however, they are not able to eliminate it.…”

“…Different thermal treatments seem to decrease its incidence [18,19], however, they are not able to eliminate it. Cyclic fatigue, torsional resistance, and angle of distortion are important points for a better understanding of file fracture [9][10][11]. Therefore, the present study evaluated these variables comparing a new endodontic rotary file system heat-treated by new technology (CricEndo E2/F-Wire) with a traditional system heat-treated by a well-known technology (Protaper Next X2/M-Wire).…”

“…The type of NiTi alloy used, cross-sectional shape and area, core diameter, taper, tip size of the instrument, and manufacturing processes of the files are the determinant factors for cyclic fatigue, torsional resistance, and angle of rotation [10]. Planning to control these biases, instruments with similar designs, and the same length (25 mm) were used.…”

“…Among procedural errors that occur during the chemo-mechanical preparation, instrument fracture is the most frequent [9,10]. It is commonly assumed that instrument fractures are often caused by two different mechanisms-torsional and cyclic failures.…”