[Clinical analysis of the fracture of nickel-titanium instruments during root canal therapy].
OBJECTIVE
To analyze the clinical fracture of nickel-titanium instruments and its causes.


METHODS
68 Profile and NiTiflex files broken during the clinical root canal instrumentations in two years were collected. The analysis was carried out regarding the relation between the broken files and the distribution in the teeth, canal, degree of curvature of canals, and the relation between amount of the broken files and the period.


RESULTS
The majority of the clinical fracture of nickel-titanium instruments were flexural fatigue which frequently occurred in molar, the midpoint of the curvature, canal with curves > 30 degrees and very complex canals. Amount of the broken nickel-titanium instruments in the first year was twice than that in second year.


CONCLUSIONS
The fracture of nickel-titanium instruments is closely related to the anatomy of the root canal, the operator's experience and the usage of instrument and so on.
Department of Operative Dentistry and Endodontics, School of Stomatology, Wuhan University, Wuhan 430079, China.
Ya
Y
Shen
Bin
B
Peng
Bing
B
Fan
Zhuan
Z
Bian
Ming-Wen
MW
Fan
D003762:Dental Instruments / Q000009:adverse effects*; D006801:Humans; D009532:Nickel; D012390:Root Canal Therapy / Q000295:instrumentation*; D014025:Titanium
C040654:titanium nickelide; D009532:Nickel; D014025:Titanium