Management of endodontic file separated in severe apical curvature of root canal

AIM-To report a clinically favorable treatment outcome following the separation of an endodontic file within a severely curved apical region of a maxillary premolar. INTRODUCTION - An unfortunate complication during root canal therapy is the breakage of an endodontic file. This can impede proper cleaning of the root canal system and potentially reduce the likelihood of successful treatment. Managing a separated file presents a considerable challenge for clinicians, who may consider options such as leaving the fragment, bypassing it, attempting its removal, or resorting to surgical procedures. CASE PRESENTATION - A 59-year-old female patient was referred to our department for the retreatment of her maxillary left second premolar. On a panoramic radiograph, a previous root canal filling, appearing relatively satisfactory, was observed along with a severe apical curvature and a periapical lesion around the canal's apex (Fig. 1). The root canal filling was removed down to the curvature through the use of Gates-Glidden burs and a reciprocating file system. Due to the inability of reciprocating files to reach beyond the curvature, this portion was instrumented using pre-curved hand files. During the final shaping of the pre-curved apical section, a size 30 file separated right at the curvature. Given that no straight-line access to the coronal aspect of the separated file was present, it was determined that attempting fragment removal, even with the assistance of a dental operating microscope, would be useless. At this stage, the canal was irrigated with a 1% sodium hypochlorite solution, and the smear layer was removed using a 10% citric acid solution. Subsequently, a calcium hydroxide paste was placed as an intracanal medicament (Fig. 2). During the following appointment, attempts were made to bypass the fractured file using hand files; however, the fragment was displaced further apically into the periapical tissues. A decision was made to obturate the canal, observe the area, and surgically remove the fragment later if deemed necessary. Following the obturation of only the apical segment of the canal, the patient was referred to the prosthodontic department for the final restoration. A radiograph was taken to evaluate the new position of the fragment and the cana obturation (Fig. 3). A clinical examination conducted five years and eight months later demonstrated a satisfactory outcome, and a followup radiograph showed healing of the periapical lesion (Fig. 4). DISCUSSION - Conservative removal of separated endodontic instrument performed with minimal damage to root dentin is the most preferred option for this complication. However, in our case the constraints of the root canal anatomy prevented this approach. Considering that a separated instrument, whether inside or outside the canal, does not necessarily lead to treatment failure, and given that the fracture occurred late in the instrumentation process after the canal had been thoroughly cleaned, we determined that only periodic radiographic and clinical evaluations would be required. Moreover, a previous case-control study demonstrated that the prognosis is not substantially diminished when a fractured instrument remains within the root canal (Spili et al., 2005). CLINICAL RELEVANCE - A well-considered decision regarding the management of a separated instrument should take into account various elements, including the canal morphology, the point at which the instrument fractured, the dentist's skill, the available armamentarium, and possible complications, tailoring the approach to each specific situation. In our case, by pushing the fractured fragment into the periapical area, it was positioned where the body's natural defenses are more effective against any remaining bacteria. It's worth noting that in certain instances, relatively straightforward, conservative, and inexpensive methods can address this complication.