Tips to avoid instrument separation in endodontics.

procedural accidents and obstacles to normally routine therapy, at almost any stage of treatment. One of these procedural problems is intracanal instrument fracture. Fractured root canal instruments may include endodontic files (Figure 1) and Gates Glidden burs. Instruments are made from nickel titanium (NiTi), stainless steel or carbon steel. Fracture often results from incorrect use or overuse of an endodontic instrument, and seems to occur most commonly in the apical third of a root canal. This demonstrates the importance of correct training in the use of rotary NiTi files. The relatively recent advent of rotary NiTi root canal instruments has led to a perceived high risk of instrument fracture. Fracture of rotary NiTi instruments may occur without warning, even with brand new instruments. Distortion of rotary NiTi instruments is often not visible without magnification. Fracture of stainless steel files is preceded by instrument distortion, serving as a warning of impending fracture. Much research has been undertaken to understand the reasons for instrument fracture and how it may be prevented rather than treated. It goes without saying that prevention is always the best approach. A review of the literature reveals that the average prevalence of retained fractured endodontic hand instruments (mostly stainless steel files) is approximately 1.6% and the average clinical fracture frequency of rotary NiTi instruments is approximately 1.0%. Therefore, the frequency of fracture of rotary NiTi instruments may actually be lower than that for stainless steel hand files. This is contrary to popular anecdotal belief. It is important to note that the reasons for fracture of rotary NiTi instruments (Figures 2 and 3) are complex and multifactorial. One of the most important factors is the operator’s skill and experience. Operator-related factors, such as proficiency with the instruments and the decision on the number of uses of the instruments, may help to explain the variation in the prevalence of fractured instruments reported among the various studies. The purpose of this article is to provide clinical tips to assist in the prevention of instrument separation.