Endodontics 172 DentalUpdate April 2008 Stephane Simon Influence of Fractured Instruments on the Success Rate of Endodontic Treatment Abstract: The fracture of an instrument is a recognized complication in endodontics. The immediate response to a fractured instrument is frequently to regard the treatment as a failure. Several factors must, however, be taken into account to evaluate the prognosis of the tooth in this situation. The objective of the endodontic treatment with or without a fractured instrument remains the same, namely to disinfect the root canal system and prevent its recontamination. The time at which file fracture occurred during treatment and the degree of canal infection should be considered when determining the potential effect of instrument fracture on treatment outcome. Patients must be informed about an instrument fracturing in their tooth for ethical and legal reasons. The aim of this paper is to attempt to place fractured instruments in context, not to provide an in depth description of fractured instrument management techniques. Clinical Relevance: To understand the influence of fractured instruments on prognosis in endodontics. Dent Update 2008; 35: 172-179 Rotary Nickel Titanium (NiTi) instruments can help the clinician to achieve excellent endodontic results, provided that the operator uses them carefully, following sensible protocols including the establishment of straight line access and a glide path. Instrument fracture is not limited to NiTi files and it is important to maintain an adequate quality control programme, including not over using instruments and disposing of damaged files during treatment. The success of endodontic treatment is affected negatively by inappropriate shaping, disinfection and obturation of the root canal system. It may take several months, or even years, for objective evidence of failure to appear radiographically as patients rarely experience pain. This can lead to patient confusion in regard to the relationship between failure and treatment carried out several years earlier. The fracture of an endodontic instrument during shaping can be a devastating experience for the practitioner. This paper explores whether a fragment of instrument left in the canal during root canal treatment should be considered a factor in failure and, if it is, how does it influence the prognosis? Stephane Simon, FDS, MSc, Clinical Lecturer in Endodontics, Honorary Associate Specialist, University of Birmingham School of Dentistry (UK) and University of Paris 7 (France), Pierre Machtou, FDS, PhD, Professor of Endodontology, University of Paris 7 (France), Phillip Tomson, BDS, MFDS RCSEd, MFDS RCSEng, Clinical Lecturer and Honorary Specialist Registrar in Restorative Dentistry, University of Birmingham School of Dentistry, Nick Adams, BDS, MSc, MRD RCS(Eng), Specialist in Endodontics, Clinical Lecturer and Honorary Associate Specialist, University of Birmingham School of Dentistry and Philip Lumley, BDS, MDentSci, PhD, FDS RCPS, Professor of Endodontology and Honorary Consultant in Restorative Dentistry, University of Birmingham School of Dentistry, UK. Is instrument fracture new to rotary NiTi? A NiTi instrument, contrary to generally accepted belief, is not more fragile than a stainless steel instrument of equivalent size; fractured instruments occurred long before the introduction of rotary NiTi instruments. Radiographic evidence of treatment performed before 1991 shows remnants of endodontic instruments (stainless steel files, Lentulos®, thermocompactors, reamers, etc) left in root canals. The effect of fractured instruments on prognosis became of greater interest following the introduction of rotary NiTi instruments since this resulted in a number of dental surgeons becoming aware of the problem through their own experience. To date, no study has demonstrated clearly that the number of fractured instruments has increased since the implementation of rotary NiTi instrumentation. Clinical studies have shown a relatively low rate of instrument fracture with these techniques: 2.7% 1 and 3.7%. 2 It was suggested that the fractures that did occur were caused by Pierre Machtou, Phillip Tomson, Nick Adams and Philip Lumley