This report describes the case of a 23 years old male patient who presented with the chief complaint of pain in mandibular right lower first molar tooth. Detailed clinical and radiographic examination revealed acute pulpitis in lower right second premolar and first molar teeth. During root canal instrumentation, a rotary instrument separated at the apical third of mesiobuccal canal. After careful assessment, it was decided to bypass the instrument and obturate the root canal space with warm vertical compaction using thermoplasticized gutta percha and resin based sealer materials. After considering the curvature of canal, thin root of tooth and location of broken instrument in the apical third of canal space, attempts of instrument removal were ruled out as a treatment option for the patient. Bypassing the broken instrument fragment with pre-curved hand files of small sizes was chosen as a predictable treatment option since it is not associated with removal of excessive remaining dentin from the roots of the teeth. Hence, teeth do not become weak and risk of post-operative root fracture is minimized. Due to successful bypassing and preparation of root canal space beyond broken instrument, canal was shaped, cleaned and disinfected adequately. Decision of instrument bypassing or removal should be taken with extreme care. Bypassing the instrument in apical third of root canal space with thin rooted teeth is the most conservative and practical approach, and objectives of adequate shaping and cleaning of canals can be achieved successfully without compromising remaining tooth structure.

separated instrument, instrument bypassing, resin based sealer, curved canals