Aim: The aim of this case report is; to present the root canal treatment of the right mandibular second premolar, whose

treatment could not be completed due to complex root canal anatomy.

Case: A 25-year-old male patient without any systemic disease was admitted with the complaint of pain in the lower

right posterior region. In the anamnesis taken from the patient, root canal treatment was started in the clinic he visited

previously, but the treatment could not be completed due to he canals that could not be found.In the clinical examination

of the patient, percussion and palpation sensitivity, caries and temporary filling were detected in the right mandibular

second premolar.Radiographic examination revealed periodontal ligament widening and the presence of two roots.Local

anesthesia was applied and root canal treatment was started under rubber-dam isolation. In the first session, the temporary

filling was removed and after the caries was completely cleaned, the access cavity was shaped with ultrasonic tips and

the root canal entrances were determined. Three root canals were identified, two buccal and one lingual. Working lengths

were determined by apex locator and periapical x-ray. Root canals were enlarged with files working with 4-angle rotation

and calcium hydroxide was applied to the root canals. In the second session, calcium hydroxide was removed from the

root canals using sodium hypochlorite and EDTA with sonic activation. Root canals were dried with paper point and

filled with resin based root canal sealer and gutta percha using the lateral condensation technique. Coronal restoration

was completed with composite filling.

Results: After all the root canals were identified and expanded, the patient’s clinical symptoms resolved.

Conclusion: Complex anatomies can be encountered in mandibular premolar teeth. In these cases, it is important to

detect the root canals without missing them and to complete the treatment for the success of the root canal treatment.