Aim: The aim of this case is to perform root canal treatment of a mandibular premolar tooth with s-shaped canal anatomy in accordance with the canal anatomy.

Case: A 47-year-old female patient applied to the clinic with the complaint of pain in the lower left lower region. In the clinical examination, percussion sensitivity was detected in tooth number #45. The electric pulp test of the related tooth revealed that it was non-vital. Endodontic access cavity was opened with rubber dam application under local anesthesia and periapical radiograph was taken to determine working length. The canal preparation was started with a #8 K type stainless steel file and preparation up to a #25 K type Ni-Ti file was done with hand instruments. Afterwards, canal preparation was performed with TruNatomy Orifice Modifier, TruNatomy Glider (17.02), TruNatomy Small (20.04) and TruNatomy Prime (26.04), respectively. Irrigation was done with 2.5% NaOCl between each file. Calcium hydroxide was placed as an intracanal medicament.

Results: After 1 week, the patient’s complaints were resolved in the second session and calcium hydroxide was removed chemomechanically. After the canals were dried with paper point, the canals were filled with the lateral compaction method using a resin-based canal sealer and gutta-percha.

Conclusion: Understanding the complex root canal morphology and choosing a canal preparation technique more suitable for such morphology, will contribute to successful endodontic treatment. In s-shaped canal anatomies, files with an appropriate angle and made of alloy should be selected to preserve the original form of the canal. The TruNatomy file offers minimally invasive preparation without disturbing the canal anatomy.