Incidence of ni-ti rotary instrument fractures in patients treated between 2014-2019 in TOGU Faculty of Dentistry, Department of Endodontics: a 6-year retrospective study

Aim: The aim of this retrospective study; By determining the incidence of fracture in molar teeth of Ni-Ti rotary instruments; To reveal the relationship of this incidence with root canal treatment or retreatment, to determine in which canal and at which level of the canal the instrument breaks, and to reveal the relationship between the curvature of the root and the fracture of Ni-Ti rotary file. Materials and Methods: 9496 endodontic cases who underwent root canal treatment or retreatment in Tokat Gaziosmanpaşa University, Faculty of Dentistry, Department of Endodontics between 2014-2019 were included in our study. In the examined patients, 389 cases were found to have broken instruments. In cases with broken tools; The type of treatment, type of tooth and canal, and the level of the broken instrument in the canal were recorded. Radiographs of the patients were transferred to ImageJ 1.3 (ImageJ; US National Institutes of Health, Bethesda, Maryland). The length of the broken piece was determined in mm via the program. The curvature of the root canal was determined using the Schneider method on the ImageJ program. Results: The incidence of Ni-Ti rotary instrument fracture in retreatment (6.1%) of lower and upper molar teeth was found to be higher compared to primary root canal treatment (3.8%) (p<0.05). More fractured instruments were observed in lower molars than upper molars (p<0.05). The majority of the broken Ni-Ti rotary instruments were seen in the MB canals and the apical third of the canals. It was observed that the risk of file fracture was higher in teeth with severely and moderately curved canals compared to straight ones. The length of the broken Ni-Ti instruments varies in the range of 0.95-10.2 mm. The mean fracture instrument length was found to be 3.05 mm. Conclusion: The incidence of Ni-Ti rotary instrument fractures in lower and upper molars was found to be higher in retreatment compared to primary root canal treatment. The arch (mandibular), root third (apical), and root canal curvature had a significant effect on the incidence of instrument fractures.