Factors Affecting Intracanal Instrument Fracture

Several parameters have been implicated in the fracture process of root canal instruments. Factors such as the operator’s skill and proficiency, the shape of the access cavity, the anatomy of the root canal, the design and manufacturing of the instrument, the motors used to drive the instruments and their particular operating parameters, the instrumentation technique, the existence of a glide path, the number of uses, the sterilization method, and the corrosion by irrigants have attracted the attention of both clinicians and researchers. Most of the available evidence concerns rotary nickel-titanium instruments, while very few studies have analyzed the fracture of stainless steel files. Contradictory findings are not uncommon due to the wide variation in the methodology of the studies and the large number of confounders involved, but, overall, the operator and the root canal anatomy appear to be the most influential parameters.