Condylar Displacement in Patients with Compound TMJ Disc Displacement in the Frontal Plane on Tomograms

Condylar displacement on TMJ tomograms taken in the intercuspal position in the frontal plane is a phenomenon described in the literature. However, there is no research on the reason for these disturbances. Introducing MR imaging for TMJ investigation has created new possibilities to explain this phenomenon. 34 TMJ tomograms were taken in 17 patients with TMJ disc displacement in the frontal plane. In 17 (50%) TMJs lateral and in 17 (50%) TMJs medial disc displacement on the basis of MR imaging was diagnosed. The tomograms facililated diagnosis of lateral displacement of the condyles in 15 (44%) TMJs, medial displacement in 3 (9%) TMJs and in the remaining 16 (47%) TMJs superior central condylar displacement

Investigation of structural-geometric parameters and elemental composition of spherical VT20 alloy powders

Purpose: Identification of structural-geometrical parameters, technological properties and elemental composition of spherical powders in a wide fraction range with respect to the VT20 alloy has been carried out. This is important for evaluating the optimum filling of a given volume by mixture of powders of different fractions during 3D printing. Design/methodology/approach: During the investigation of spherical Ti-alloy powders, a comprehensive approach was performed using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Dynamic Light Scattering (DLS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The surface morphology of the powders was studied on a Tuescan Vega 3 Scanning Electron Microscope. Using the Quantax energy dispersive spectrometer, element distribution maps were obtained and histograms of element distribution in the investigated powders were constructed. ICP-MS analysis was performed to clarify the elemental composition. DLS analysis using Malvern's Zetasizer Nano-ZS equipment allowed us to determine the functional parameters (hydrodynamic radius – Rh, zeta potential – z and specific conductivity) of particles of titanium alloy powder that indirectly indicate a tendency to form conglomerates. Findings: According to the microscopic examinations, the VT20 alloy powder consists of globular-shaped particles with the lamellar traces on their surfaces. The uniformity of the chemical element distribution within each fraction of the investigated powders was confirmed by EDS, and the full conformity of the powder fractions with the elemental composition of the VT20 alloy was confirmed by ICP-MS. The DLS method allowed to establish that the formation of conglomerates would not occur within the studied fractions of the VT20 alloy powder. Research limitations/implications: The use of high sensitive investigation methods gives understanding of the mechanisms of fine structure formation and possibility to control the processes of powder coagulation in the stage of electrostatic interactions. Practical implications: The obtained results can be used for the formation of fine spherical particles of the powder, but at the same time, these technologies can be extended for the particles of non-spherical shape. Originality/value: The DLS method allowed to establish that the formation of conglomerates would not occur within the studied fractions of the VT20 alloy powder. This, in turn, will improve powder melting during 3D printing. The measured zeta potential values allowed us to reveal mechanisms of fine structure formation and to control the processes of powder coagulation in the stage of electrostatic interactions