Impact of manual and mechanical glide path preparation on surface defects of nickel-titanium rotary instruments

Nickel-titanium (NiTi) rotary instruments are widely used for root canal preparation (RCP) but remain prone to fracture partly due to surface defects. Glide path preparation (GPP) may reduce stress and fatigue, improving procedural safety. This study evaluated the effects of manual and mechanical GPP on surface defects compared with no GPP.

Endodontic access cavities were prepared in sixty extracted mandibular molars. The teeth were randomly assigned to each of the following groups (n = 20). Group 1: GPP with a #13.02 rotary glide path file (C Path File, Fanta Dental, Guangdong, China), Group 2: GPP manually with a #10.02 stainless steel K-File (EndoArt K Files, İnci Dental, Türkiye), Group 3 (Control): No GPP. Mesibuccal canal of each tooth was shaped with an unused 10.04 NiTi rotary file (Smart Gold, İnci Dental, Türkiye) which was sterilized and imaged with scanning electron microscopy (SEM) before and after RCP. The images were compared in terms of flute disruption, microcracks, tip deformation, blade distortion, surface pitting, as well as fractures by using the Fisher-Freeman-Halton test and Pearson's Chi-square test, with the level of significance set at 5% (α = 0.05) for all analyses.

Tip deformation was the most frequent baseline defect, with no significant intergroup difference (p>0.05). After RCP, microcracks were more common in the no GPP group (p=0.031). Significant differences were observed in blade distortion (p<0.001), surface pitting (p=0.005), and fracture formation (p=0.002). Both manual and mechanical GPP significantly.

Both manual and mechanical GPP significantly reduced surface defects on NiTi rotary instruments compared with no GPP. No significant difference was found between the manual and mechanical techniques.