Abstract
Background: Root canal preparation is a critical step in endodontic treatment, particularly in curved canals, where complications such as perforation and transportation can occur. The palatal groove of the maxillary first premolar is often considered a risk zone, and the amount of remaining dentin plays a significant role in the tooth's prognosis and fracture resistance after treatment. Objective: This study aims to compare the canal shaping ability and preservation of the original canal anatomy using three different file systems: TruNatomy, Protaper Gold, and One Curve in the curved root canals of maxillary first premolars. Materials and Methods: Forty-two human maxillary first premolars with mature apices and canal curvatures between 25 and 35 degrees were selected. The teeth were randomly assigned into three groups (n=14 per group). Canal preparation was performed using the TruNatomy, Protaper Gold, and One Curve file systems according to the manufacturers' instructions. Pre- and post-preparation scans were obtained using cone beam computed tomography (CBCT) at 2, 3, 5, and 7 mm from the apex. Parameters such as canal transportation, centering ability, and residual dentin were evaluated. Statistical analysis was performed using Kruskal-Wallis and One-way ANOVA tests, with significance set at p<0.05. Results: The TruNatomy system showed less canal transportation in both mesiodistal and buccolingual directions. Furthermore, the TruNatomy group preserved more residual dentin compared to the Protaper Gold and One Curve groups. However, no significant differences were found between the three file systems regarding canal transportation, centering ability, or the amount of residual dentin. Conclusion: All three file systems (TruNatomy, Protaper Gold, and One Curve) are effective and safe for root canal preparation, with no significant differences observed in their ability to preserve canal anatomy and residual dentin.