Mandibular cortical width measurement based on dental panoramic radiographs with computer-aided system

The paper presents a method of the determining a mandibular cortical width on dental panoramic radiographs. Cortical width of lower border of mandible may potentially be associated with recognition of osteoporosis in postmenopausal women. An algorithm to perform a semiautomatic cortical width measurement in a given region of interest was developed. The algorithm is based on separate extraction of lower and upper boundaries of cortical bone. Results of boundaries extraction performed on 34 panoramic radiographs of healthy and osteoporotic individuals are presented, together with automatic measurements of particular distances. They were compared with results of hand-made measurements done by two maxillofacial radiologists. Presented algorithm may potentially be useful for screening patients with osteoporosis

Coefficients of Propeller-hull Interaction in Propulsion System of Inland Waterway Vessels with Stern Tunnels

Propeller-hull interaction coefficients - the wake fraction and the thrust deduction factor - play significant role in design of propulsion system of a ship. In the case of inland waterway vessels the reliable method of predicting these coefficients in early design stage is missing. Based on the outcomes from model tests and from numerical computations the present authors show that it is difficult to determine uniquely the trends in change of wake fraction and thrust deduction factor resulting from the changes of hull form or operating conditions. Nowadays the resistance and propulsion model tests of inland waterway vessels are carried out rarely because of relatively high costs. On the other hand, the degree of development of computational methods enables’ to estimate the reliable values o interaction coefficients. The computations referred to in the present paper were carried out using the authors’ own software HPSDKS and the commercial software Ansys Fluent

Use of fractal analysis for bone assessment

Since Mandelbrot announced the concept of the fractal geometry, fractal analysis has been used in the description of various structures found in nature and biosignals. It has been used to interpret biological phenomena such as nervous tissue, vascular system, the electrical conductivity of the heart and EEG. In dentistry, there have been many attempts to analyze the structure of jaw bones to assess periodontal disease and osteoporosis. Many authors indicate that bone tissue has a fractal structure, and that the fractal analysis can be inexpensive and convenient screening instrument in the diagnosis of systemic diseases that cause changes in the image of bones. This article is a review of applications of fractal analysis in bone evaluation

Assessment of the prevalence of radix entomolaris and distolingual canal in mandibular first molars in 15 countries: a multinational cross-sectional study with meta-analysis

Aim: The aim of this study was two-folded: i) to assess the prevalence of Distolingual Canal (DLC) and Radix Entomolaris (RE) in Mandibular First Molars (M1Ms), using Cone Beam Computed Tomography (CBCT) images and ii) to assess the impact of sociodemographic factors on the prevalence of these conditions worldwide. Methods: CBCT images were scanned retrospectively and the ones including bilateral M1Ms were included in the study. The evaluation was performed by 1 researcher in each country, trained with CBCT technology. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating axial sections from coronal to apical. The presence of DLC and RE in M1Ms (yes/no) was identified and recorded. Results: Six thousand three hundred four CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries regarding the prevalence of both RE and DLC (P .05). Conclusion: The overall prevalence of RE and DLC in M1Ms was 3% and 22%. Additionally, both RE and DLC showed substantial bilaterally. These variations should be considered by endodontic clinicians during endodontic procedures in order to avoid potential complications

Logistic Conditions of Container Transportation on the Oder Waterway

The paper contains the analysis of the possibility of container transportation on the Oder Waterway (the Gliwice Canal, the canalized stretch of the Oder River, and the regulated stretch of the Oder River), on the assumption that the waterway complies with conditions of class III European waterway. The analysis is based on the concept of modern motor cargo vessel, adjusted to hydraulic parameters of waterway. The vessel is designed for ballasting when passing under bridges. The amount of ballast water that enables transportation of two tiers of containers is given. The costs of waterborne transportation are compared to the costs of rail transportation of containers on selected shipping routes

Heeling Moment Acting on a River Cruiser in Manoeuvring Motion

By using fully theoretical method the heeling moment due to centrifugal forces has been determined for a small river cruiser in turning manoeuvre. The authors applied CFD software for determination of hull hydrodynamic forces, and open water characteristics of ducted propeller for estimation of thrust of rudder-propellers. Numerical integration of equations of 3DOF motion was used for prediction of ship trajectory and time histories of velocities, forces and heeling moment

A Comparison between the Implant Stability Quotient and the Fractal Dimension of Alveolar Bone at the Implant Site

Objectives. Fractal analysis of the radiographic pattern of bone has been used to evaluate its quantitative properties. However, the relation between initial implant stability and quality of bone remains unclear. The objective of this study was to evaluate RFA values in relation to the fractal dimension of bone where the implant was inserted. Material and Methods. A total of 50 two-stage dental implants were placed in the maxilla and mandible of 32 patients. After implant placement, an implant stability quotient (ISQ) was measured in two perpendicular planes. On intraoral digital periapical radiographs, three 35x35 pixels’ regions of interest (ROIs) were chosen covering the bone adjacent to the neck (ROI 1), middle (ROI 2), and apical (ROI 3) part of the implant, respectively. For every ROI, a fractal dimension (FD) was calculated. A linear correlation, as well as a logistic regression analysis, was used to identify a possible relation between the ISQ and FD values for every ROI in the maxilla and mandible. Results. The ISQ and FD values were found to be correlated at ROI 1 for the maxilla. There was no linear correlation between ISQ and FD values in any of the three ROIs in the mandible. However, logistic regression analysis showed that in ROI 1 and ROI 3 the values of FD and ISQ are statistically important and may be used to express the difference between maxilla and mandible. Conclusion. The fractal dimension of alveolar bone measured from intraoral digital radiographs alone may be an insufficient parameter to determine initial implant stability

The Primary Outbreaks of Burkitt Lymphoma in the Oral Cavity. A Report of Two Cases, Review of the Literature and Dental Implications

Two cases of Sporadic Burkitt’s lymphoma in children aged 11 and 8 years with primary symptoms in the oral cavity are reported. The first symptoms of the disease appeared in the oral cavity and were initially misdiagnosed as an inflammatory condition in one case and incidental findings not associated with the primary reason for visiting the dentist’s office in the second case. Biopsies of the lesions revealed the actual cause of the observed changes and contributed to the prompt initiation of polychemotherapy treatment. A review of current literature presents the known symptoms of Burkitt’s Lymphoma in the oral cavity and the available diagnostic methods. The role of the primary care physicians—the pedodontist and paediatrician—in the diagnostic and therapeutic process is discussed

Influence of severe plastic deformation induced by HE and ECAP on the thermo-physical properties of metals

abstractEN: The study is aimed at comparing the changes which occur in the microstructure and thermo-physical properties of pure copper (99.9%) and when copper alloyed with chromium and zirconium subjected to severe plastic deformation (SPD). The plastic deformation techniques employed were hydrostatic extrusion (HE), equal channel angular pressing (ECAP), and a combination of these two processes. The materials thus obtained had an ultra-fine-grained structure with the thermo-physical properties differing from those of the untreated materials. It appeared that there is a correlation between the deformation method employed and the thermo-physical properties of the materials, such as diffusivity and specific heat.score: 8collation: 278-28