objective: to study the accuracy of spiral tomography in the determination of implant angulation. materials and methods: eighteen gutta-percha filled points on dry mandibles were selected for implant placement. a translucent acrylic template was fabricated for each mandible. after preparing tomographic images (2 mm slice thickness, cranex tome), the ideal axis of the implant was traced. the ang...

the vast majority of mandibular second molars have two roots with three root canals; however, variations in molar root canal anatomy are not uncommon. to the best of our knowledge, four rooted mandibular second molar with three mesial roots and one distal root has never been reported. herein, we present the endodontic management of a four rooted mandibular second molar tooth, diagnosed with the...

Sturgeon is one of the most important species of the Caspian Sea aquatics. Unfortunately, this species faces the threat of extinction today. This makes specific studies on any type of sturgeons more important than before. Studies like histological studies, radiology, and sonography, all require a complete understanding of the anatomy of this fish. Since pilot studies showed some misconceptions ...

Manufactured single crystal components using Ni-base super alloys are routinely used in the hot sections of aero engines and industrial gas turbines due to their outstanding high temperature strength, toughness and resistance to degradation in corrosive and oxidative environments. To control the quality of the single crystal turbine blades, particular attention has been paid to grain selection,...

the main objective of this case report is to present a rare root canal configuration of maxillary molar with seven root canals; three mesiobuccal, two palatal and two distobuccal canals diagnosed during treatment procedure confirmed by spiral computed tomography. a thorough knowledge of root canal morphology, proper clinical and radiographic examination, and use of dental operating microscopes ...

Auroral spiral is one of the auroral vortex structures. Here, we propose a model to explain formation structure based on three-dimensional particle-in-cell simulations. In our model, an arc develops through precipitations electrons accelerated during magnetic reconnection in acceleration region. The morphology at low altitudes can be modified by electron-scale flux ropes, which are generated se...

This paper describes the application of the Finite-Volume Time-Domain (FVTD) method to characterize the influence of the substrate on Archimedean spiral antennas. The unstructured mesh of the FVTD method permits to model precisely the fine spiral structure and the thin underlying substrate. Time-domain numerical results permit to demonstrate how the substrate affects the distribution of current...

We present Smoothed Particle Hydrodynamics (SPH) simulations of the response of gas discs to a spiral potential. These simulations show that the commonly observed spurs and feathering in spiral galaxies can be understood as being due to structures present in the spiral arms that are sheared by the divergent orbits in a spiral potential. Thus, dense molecular cloud-like structures generate the p...