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The lower jaw is frequently exposed to fracture, by accidents, violence, accidental falls, sports injuries, pathological fracture, etc. We have investigated the behaviour of mandibular bone in a particular clinical case of fracture, in which we experimentally applied two osteosynthesis plates and analyzed the effects of occlusal loading on the fracture line by finite element method. We observed that in this case, maximum deformations occur in the mandibular condyles and the maximum and minimum normal stresses occur in the osteosynthesis plates. Even if bite and mastication determine important efforts on osteosynthesis plates, titanium alloy supports well these loads, and, as an important aspect, the bone parts during healing are not the object of excessive mechanical loads. Keywords: FEA, mastication, osteosynthesis, fracture, mandible

In this paper is presented an experimental, theoretical and numerical study about the use of a biodegradable composite material in the manufacturing process of the suspension elements for plane sieves used in mills from bakery industry. The material was obtained by reinforcing an unsaturated polyester resin with cotton fabric. Tensile tests were performed for materials having one, three, five and seven layers of cotton fabric and the optimum solution was chosen. The material properties, obtained from the experimental tests, were used in a finite element model realized for the strength calculus of the suspension element. The numerical results were validated analytically. The study confirms that the biodegradable materials can be used for manufacturing of the suspension elements of a plansifter and can be adapted for other parts or industrial structures. Keywords: sifting, biodegradable material, polyester resin, finite element, cotton

Computerized reconstruction of anatomical structures is becoming very useful for developing anatomical teaching modules and animations. The first computer-aided 3D reconstruction was achieved in 1965 by Glaser and Van der Loos. With the improvements in computer hardware and software tools, computerized modeling of anatomical structures has become very useful for visualizing complex 3D forms. Three-dimensional visualization of various microanatomic structures using special preparation and staining methods is important. Although databases exist consisting of serial sections derived from frozen cadaver material, plastination represents an alternate method for developing anatomical data useful for computerized reconstruction. Plastination is used as an excellent tool for studying different anatomical and clinical questions. The sheet plastination technique is unique because it offers the possibility to produce transparent slices series, which can easily be processed morphometrically. A female pelvis was obtained, plastinated, sectioned and subject to 3D computerized reconstruction using WinSURF modeling system (SURFdriver Software). Qualitative observations revealed that the morphological features of the model were consistent with those displayed by typical cadaveric specimens. Morphometric analysis indicated that the model did not significantly differ from a sample of cadaveric specimens. This data supports the use of plastinates for generating tissues sections useful for 3D computerized modeling. Keywords: plastination, 3D reconstruction, anatomy, female pelvis, urinary bladder, uterus

The use of thermoplastic aligners has a vast history in the orthodontic field. These appliances have several indications regarding mild malocclusions, tooth replacement, retainers after active treatment, etc. The manufacturing protocol is simple and easy to apply. Several tooth movements are harder to obtain ( torque, intrusion, correction of rotations). The aligners must be well fitted and provide enough stiffness in order to maintain the desired orthodontic effect and minimize the unwanted dental movements or anchorage loss. We evaluated a manufacturing protocol for such appliances and analyzed how thermoplastic thickness material, due to the manufacturing process , can influence orthodontic treatment. Several foils were sectioned and measured before and after the manufacturing protocol(0.5mm;0.8mm;1 mm). Although some differences were observed due to foil types and thickness, the appliances are rigid and capable of assuring orthodontic success. Keywords: orthodontic aligners, thermoplastic materials, foil thickness reduction

The aim of this paper is based on neural network model for tribological analyses of an Epoxy composite system. The created epoxy based composites with aramidic powders, were tribologically tested with diverse parameters in order to obtain the following properties: wear rate and friction coefficient. With all the studied tribological properties was created a Neural Network (NN) model. The created NN model can perform optimisations for concentration of aramidic powder in final used composites for different domains of applications. Keywords: epoxy composites, bloc on ring, friction coefficient, neural network analysis, optimisations

Crown preparation and cementation are two critical parameters for the success of a prosthetic treatment. Marginal fit is important because a large marginal opening allows plaque and oral liquids to penetrate, resulting in micro-leakage, caries and periodontal disease. The purpose of this study is evaluating and comparing the marginal fit of Cr-Ni metallic crowns using three different wax-up techniques made on molars, extracted because of orthodontic reasons. The freshly extracted teeth were kept in artificial saliva to reduce penetration of microorganisms and simulating oral environment. In vitro cementation with Ketac Cem was carried out after disinfection and drying. Samples were maintained for 24 h at 37oC in distilled water and then gold plated. The marginal gap was analyzed using scanning technique with an electronic microscope in several points for every surface of each tooth. Data were statistically analyzed. Measuring the internal fit requires sectioning of specimens and allows obtaining a small number of samples (1-2 per specimen) which means a limited number of measurements per specimen. Another problem consists in the reduced size of the samples after sectioning. The scanning technique enhances measurements of the marginal gap without sectioning and provides an objective evaluation of preparation and cementation techniques. Key words: scanning electron microscopy, marginal gap, crowns

Low-volume production components represent a possibility to create prototypes from the same process and materials that someone use for the final product and to bring new products to market instead of waiting for final components to arrive from the machine shop. Additive FDM create geometrical products through the deposition of ABS (Acrylonitrile-Butadiene-Styrene) filaments layer by layer satisfying this necessity. Since the specialized literature offers little information on the properties of such plastic materials, in this paper the authors present some experimental procedures in order to evaluate the elastic and mechanical properties of such a plastic material. The specimens have been printed on a 3D “ULTIMAKER –2” printer. Keywords: Acrylonitrile-Butadiene-Styrene, Fused Deposition Modeling, 3D printing, integrated software home manufaturing

The puropose of this paper was the approaching the patology of the oral mucosa in older patients, induced by acrylic resins in removable dentures. Prosthetics resolves many problems in older adults (mastication, aesthetics, phonation, etc.) but the wearing of dentures has consequences on all the living tissues in contact with them. The reactions of buccal mucosa are the result of mechanic irritations, plaque build-up and of toxic and/or allergic action of the denture materials, therefore the field cannot be neglected. An essential aspect of the clinic goal of removable prosthetic restorations is the consistency between the biomaterials used, their biological integration, the approached technological line, and the particularity of the prosthetic field of the older patient. Keywords: oral mucosa, acrylic resins, removable dentures, irritating toxic phenomena, biocompatible

The viscous flow over a shrinking permeable sheet with partial slip is investigated. The flow is governed by a third-order nonlinear differential equation and heat transfer by a second-order differential equation. The equations of motion are solved analitically by Optimal Homotopy Perturbation Method (OHPM). This procedure is highly efficient and it controls the convergence of the approximate solutions. A few examples are presented, showing the exceptionally good agreement between the analytical and numerical solutions. OHPM is very efficient in practice, ensuring a very rapid convergence after only one iteration. Keywords: Optimal homotopy perturbation method, viscous flow, partial slip, shrinking sheet,heat transfer

Gingival enlargement is also known as gingival hyperplasia or hypertrophy and it is an abnormal overgrowth of gingival tissues. This type of lesions can be produced by a large group of pathologic processes. The most common are the reactive hyperplasia which develops in response to a chronic tissue injury that stimulates an excessive tissue repair response. Often, dental prosthesis have been reported to cause this type of lesions due to a mechanical chronic irritation or by a reaction of the oral tissue to substances released into the oral environment by the materials used in manufacturing this type of prosthesis. One of these substances is the methylmethacrylate (PMMA), a widely used in dentistry. The first step in treatment of these lesions is the removal of the irritative factor which sometimes can lead to healing depending on the type of lesion. The challenge is to differentiate a lesion caused by a mechanical irritation from a lesion in which the cytotoxicity of PMMA may be the cause. Often, surgery is the only treatment option for the first situation. When we have an irritative reaction and a cytotoxicity reaction, we must treat them both. Keywords: methylmethacrylate, acrylic resin, TNF alfa, citotoxicity