Diagnostic value of cone beam computed tomography for root canal morphology assessment - a micro-CT based comparison.

OBJECTIVES: The aim of this study was to assess cone beam computed tomography (CBCT) as a root canal anatomy diagnostic tool by comparison with micro-CT gold-standard. MATERIALS AND METHODS: 216 two-rooted mandibular molars were first scanned in a CBCT device (200 µm voxel size) and posteriorly in a micro-CT scanner (19.61 µm). The volumes were sequentially screened to classify main root canal anatomy according to Vertucci classification, and for the presence of lateral canals and apical deltas, in both mesial and distal roots. RESULTS: Both methods revealed a higher prevalence of Vertucci Type II and IV in the mesial root, and Vertucci Type I in the distal root. The percentage of agreement for main root canal anatomy classification between CBCT and micro-CT scores was high (85.2%). CONCLUSION: Sensibility to detect both lateral canals and apical deltas with CBCT was low. These results attest to the fact that minor anatomical changes might be difficult to identify with CBCT imaging, hampering its diagnostic value.

Design, Metallurgical Features, and Mechanical Behaviour of NiTi Endodontic Instruments from Five Different Heat-Treated Rotary Systems.

The current study aimed to compare the F1 endodontic instruments from five different heat-treated rotary systems regarding their design, metallurgical properties, and mechanical performance. Five F1 root canal shaping instruments (ProTaper Gold [PTG], Premium Taper Gold, Go-Taper Flex, EdgeTaper Platinum, and Super Files Blue)-plus, a conventional ProTaper Universal (PTU)-which were evaluated regarding their design, nickel/titanium ratio, phase transformation temperatures, microhardness, cyclic fatigue, and torsional and bending strengths. Mood's median test was used for the statistical comparison with a significance set at 5%. The instruments were similar regarding the nickel/titanium ratio and overall design. Go-Taper Flex had the closest transformation temperatures to PTG. PTU and Go-Taper Flex had the highest microhardness (408.3 and 410.5 HVN). The time to fracture of Super Files Blue was three and seven times higher than PTG and PTU, respectively. No difference was observed in the maximum torque to fracture among PTG (1.30 N·cm) and the other systems, except for the Premium Taper Gold (1.05 N·cm) and Go-Taper Flex (1.10 N·cm). Significantly lower bending loads than PTG (269.2 gf) were observed for the EdgeTaper Platinum (158.3 gf) and Premium Taper Gold (103.5 gf) instruments. Super Files Blue outperformed PTG in the cyclic fatigue test, while EdgeTaper Platinum and Premium Taper Gold were more flexible. Premium Taper Gold and Go-Taper Flex showed lower torsional strength.

Evaluation of Design, Metallurgy, Microhardness, and Mechanical Properties of Glide Path Instruments: A Multimethod Approach.

INTRODUCTION: This study aims to compare the design, metallurgy, microhardness, and mechanical properties of 3 glide path nickel-titanium (NiTi) instruments. METHODS: A total of 132 ProGlider (Dentsply Sirona, Ballaigues, Switzerland), Edge Glide Path (EdgeEndo, Johnson City, TN), and R-Pilot instruments (VDW, Munich, Germany) (44 per group) were selected. Design was assessed through stereomicroscopy (blades, helical angle, measuring lines, and deformation) and scanning electron microscopy (symmetry, cross section, tip, and surface finishing). NiTi ratios were measured by energy-dispersive X-ray spectroscopy and phase transformation temperatures by differential scanning calorimetry. Microhardness and mechanical performance (torsion, bending, and buckling resistance tests) were also evaluated. Statistical analyses were performed with the Mood median test with a significance set at 5%. RESULTS: The Edge Glide Path had the lowest number of blades and the R-Pilot the greatest helical angle. All instruments had an almost equiatomic NiTi ratio, while showing different cross sections and tip geometries. The Edge Glide Path had a smoother surface finishing. The R-Pilot showed martensitic characteristics at room temperature, whereas mixed austenite plus R-phase was observed in the other instruments. The R-Pilot had higher results on the microhardness (436.8 hardness Vickers number), maximum torsion (0.9 Ncm), and buckling load (0.7 N) tests (P < .05), whereas the Edge Glide Path had a superior angle of rotation (683.5°) and the ProGlider was more flexible (144.1 gf) (P < .05). CONCLUSIONS: Differences in the design of the instruments and the phase transformation temperatures accounted for their mechanical behavior. The R-Pilot showed the highest torque, buckling, and microhardness, whereas the ProGlider instrument was the most flexible.

Mechanical Performance and Metallurgical Features of ProTaper Universal and 6 Replicalike Systems.

INTRODUCTION: This study aimed to compare the ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland) system with 6 replicalike instruments regarding instrument design, mechanical performance, and alloy characteristics. METHODS: New rotary instruments (size 20/.07v) of PTU and 6 replicalike systems (EdgeTaper [EdgeEndo, Johnson City, TN], U-File [Dentmark, Ludhiana, India], Go-Taper Universal [Access, Shenzhen, China], Super Files [Flydent, Shenzhen, China], Multitaper [Proclinic Expert, Besançon, France], and Pluri Taper [Bestdent, Shenzhen, China]) (n = 329) were selected and evaluated regarding their design, mechanical performance, and metallurgical characteristics. The results were compared using the nonparametric Mood median test and 1-way analysis of variance with the significance level set at 0.05. RESULTS: Replicalike instruments were similar to PTU regarding design, maximum torque to fracture (P > .05), and ratio of nickel and titanium elements. Scanning electron microscopy revealed differences in the geometry of the tip and finishing surfaces. Time to fracture of Go-Taper Universal (50.0 seconds) was similar to PTU (44.0 seconds) (P > .05), but the U-File (63.5 seconds), Edge Taper (87.5 seconds), and Super Files (130 seconds) showed significantly higher values (P < .05). The highest maximum torque was observed in the Super Files instrument (P < .05), but no statistical difference was noted among the other instruments (P > .05). The angle of rotation before rupture of the Multitaper (574°) and Pluri Taper (481°) was higher than PTU (354°) (P < .05). Differential scanning calorimetric analysis showed clear differences on the transformation temperatures among the tested instruments. The R-phase start and finish temperatures of PTU were 11.0°C and -18.0°C, respectively. CONCLUSIONS: Overall, replicalike instruments were similar to PTU regarding the torsional resistance, geometric design, and near equiatomic proportions of nickel and titanium elements. In 3 of the 4 mechanical tests, the EdgeTaper (torque, angle of rotation, and bending load) and Go-Taper Universal (time to fracture, torque, and angle of rotation) systems were similar to PTU.