Geometric analysis of root canals prepared by four rotary NiTi shaping systems.

Introduction: A great number of nickel-titanium (NiTi) rotary systems with noncutting tips, different cross-sections, superior resistance to torsional fracture, varying tapers, and manufacturing method have been introduced to the market. The purpose of this study was to evaluate and compare the effect of 4 rotary NiTi preparation systems, Revo-S (RS; Micro-Mega, Besancon Cedex, France), Twisted file (TF; SybronEndo, Amersfoort, The Netherlands), ProFile GT Series X (GTX; Dentsply, Tulsa Dental Specialties, Tulsa, OK), and ProTaper (PT; Dentsply Maillefer, Ballaigues, Switzerland), on volumetric changes and transportation of curved root canals.

Methods: Forty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 25° to 40° were divided according to the instrument used in canal preparation into 4 groups of 10 samples each: group RS, group TF, group GTX, and group PT.

Four curious cases of cone-beam computed tomography.

Cone-beam computed tomography (CBCT) has become popular, and its many inherent advantages are indisputable. Nevertheless, CBCT is prescribed cautiously because the radiation dosage is higher than that of conventional radiography. When and to what extent should CBCT be prescribed for orthodontic patients? The purpose of this article is to present 4 curious cases in which a considerable discrepancy was found between the conventional panoramic radiograph and the CBCT view.