Vieira Anne Rafaella Tenório, Silva Guilherme Ferreira da, Silva Emmanuel João Nogueira Leal da, Vivan Rodrigo Ricci, Amorim João Vitor Oliveira de, Lima Thaine Oliveira, Neto Raimundo Sales de Oliveira, Duarte Marco Antonio Hungaro, Alcalde Murilo Priori
Department of Operative Dentistry, Endodontics, and Dental Materials, Bauru School of Dentistry, University of São Paulo - USP, Bauru, Brazil.
Department of Endodontics, School of Dentistry, State University of Rio de Janeiro (UERJ), Rio de Janeiro, Brazil.
Restor Dent Endod. 2025 Aug;50(3):e28. doi: 10.5395/rde.2025.50.e28. Epub 2025 Jul 24.
This study aimed to assess the effect of cross-section geometry on the mechanical properties of nickel-titanium (NiTi) instruments by comparing two instruments with identical tip size, taper, and thermal treatment but differing in cross-section design.
One hundred four NiTi rotary instruments, being S-shaped and triangular cross-section, manufactured with Blueish thermal treatment, were tested (n = 52 per group). Differential scanning calorimetry was employed, and the metal mass volume and cross-section area were assessed. The cyclic fatigue, torsional, and bending resistance tests were assessed. Data were analyzed using the Kolmogorov-Smirnov and Student t tests, and the level of significance was set at 5%.
The instruments exhibited similar start and finish temperatures of phase transformation. The S-shaped instruments had significantly lower metal mass volume and cross-sectional area (p < 0.05). S-shaped instruments demonstrated superior cyclic fatigue resistance, greater angular deflection, and lower bending stiffness (p < 0.05).
Cross-section geometry significantly influences the mechanical properties of NiTi rotary instruments.
本研究旨在通过比较两种尖端尺寸、锥度和热处理相同但横截面设计不同的器械，评估横截面几何形状对镍钛（NiTi）器械力学性能的影响。
测试了104支采用蓝色热处理制造的S形和三角形横截面的NiTi旋转器械（每组n = 52）。采用差示扫描量热法，并评估金属质量体积和横截面积。评估了循环疲劳、扭转和抗弯曲试验。使用Kolmogorov-Smirnov检验和学生t检验分析数据，显著性水平设定为5%。
器械表现出相似的相变起始和结束温度。S形器械的金属质量体积和横截面积显著更低（p < 0.05）。S形器械表现出更好的循环疲劳抗性、更大的角偏转和更低的弯曲刚度（p < 0.05）。
横截面几何形状显著影响NiTi旋转器械的力学性能。
