Introduction: The aim of this study was to evaluate under scanning electronic microscopy the enlargement and deformation of the apical foramen of curved mesiobuccal roots with both reciprocating and rotary single-file systems made of a newly heat-treated alloy through the use of Reciproc Blue (REC Blue; VDW, Munich, Germany) and XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland).
Methods: Forty mesiobuccal roots of mandibular and maxillary molars presenting a curvature ranging from 20°-40° were used in this study. The apical foramens were initially scanned with a scanning electronic microscope under 200× magnification. Roots were divided into 2 groups (n = 20): the REC Blue group instrumented with the REC Blue system and the XPS group instrumented with the XPS system. Both groups were instrumented at the foramen. The apical foramens were scanned after root canal preparation. The area, circularity, and ratio of the Feret diameters were calculated from each image. The Kolmogorov-Smirnov, Mann-Whitney, and Wilcoxon tests were used for statistical analysis (P ≤ .05).
Results: The area of the foramen increased significantly after canal shaping with REC Blue and XPS. The variation of the area was significantly greater with XPS. However, there were no significant differences in circularity and the ratio of the Feret diameters with both instruments.
Conclusions: No transportation was found when using REC Blue and XPS. The newly heat-treated nickel-titanium alloy did not promote deformation of the apical foramen in curved canals.
Keywords: Curved canals; foraminal deformation; foraminal enlargement; heat-treated nickel-titanium; scanning electron microscopy.
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