Tabriz University of Medical Sciences Journal of Dental Research, Dental Clinics, Dental Prospects 2008-210X 20 2 2026 06 30 Effects of Three Different Niti Rotary Instruments on Dentin Cracks After Root Canal Preparation 120 125 10.34172/joddd.42346 EN Rhona Mariana Untari https://orcid.org/0009-0002-1058-2625 Wignyo Hadriyanto Rachmat Sriwijaya https://orcid.org/0000-0002-7448-0567 Margareta Rinastiti https://orcid.org/0000-0002-6892-8302 Journal Article 10.34172/joddd.42346 2025 02 19 2026 06 02 Introduction: This study aimed to examine the effects of three distinct nickel–titanium (NiTi) rotary instruments on dentin crack formation during root canal preparation in various root segments. Methods: Thirty premolars with a single straight root canal were prepared using three rotary instruments, namely, ProTaper Next, ProTaper Gold, and HyFlex Controlled Memory (CM). Results: The ProTaper Next produced the most dentin cracks, whereas HyFlex CM produced the fewest. Most cracks occurred in the coronal third of the root compared with the middle third. Dentin crack formation is a significant problem in root canal treatment and can lead to treatment failure. Therefore, an appropriate rotary instrument and technique for root canal preparation must be selected to minimize the risk of dentin crack formation. Conclusion: The results can guide clinicians in selecting the most suitable rotary instrument for successful endodontic treatment. In addition, irrigating with 2.5% NaOCl and saline for 1 min after preparation could help reduce the incidence of dentin cracks. Further research can explore new methods to minimize the risk of dentin crack formation during root canal preparation and improve the success rate of endodontic treatment.