Key Engineering Materials Vol. 638

Abstract: In this paper, a numerical analysis is undertaken in order to establish the three dimensional linear displacementsof tumors located inside the lung. In this way, the position of the tumor can be emphasized in various stages of the breathing process, helping thus the healthcare professionals both in surgical operations and in performing transbronchial biopsy. First, a geometrical model of the lung and airways was achieved with a 3D reconstruction program using CT scan images. The model was then imported in the ANSYS finite element software, which was used to perform the numerical simulations. The breathing process was simulated by applying external pressure on the surfaces of the lung. The values of this pressure were chosen as to correspond to the inspiration phase of the breathing process. Finally, conclusions are drawn regarding the values of the displacement of the nodules during breathing.

Abstract: The adaptation of bones to mechanical loads or bone remodeling can be simulated using specific mathematical models in conjunction with the finite element method. There are several theories proposed within the literature for the prediction of the bone behavior under mechanical loads and all have been used successfully, within certain limits of prediction details, but no unanimous acceptance have been reported yet. Within this context, it is important to know the differences and similarities between the results which these theories can produce, in order to improve their interpretation. On the basics of the above observation, the paper presents the comparison between density distributions achieved using three different models of bone remodeling: the original strain energy density equation developed at the University of Nijmegen, the principle of cellular accommodation incorporated into the Nijmegen model and the variant developed at the University of Manchester obtained by adding the quadric term which eliminates the density accumulation at physiologically unrealistic high loads. It is shown, using a suggestive test problem, that the three models generate significantly different results.

Abstract: Introduction. Implant-associated infections in orthopedics represent a major challenge for diagnosis and treatment. Sonication is an alternative method for the diagnosis in prosthetic infections, with a higher sensitivity compared to the conventional periprosthetic cultures. Our aim was to compare the results of conventional culturing and sonication process in per prosthetic joint infections. Material and method. We followed up in a period of 7 years (2007-2014) patients who underwent to total joint arthroplasty, and fracture fixation with internal fixation in the University Emergency Hospital of Bucharest. Conventional and sonication fluid culturing was performed in order to compare the results of it. In 3 cases the cultures after sonication was negative in 9 cases Methicilin resistant (MR) staphylococcus was isolated. Sonication Results Our study involved 34 patients with an average age of 63.08 ±10.65SD. In 3 cases the cultures after sonication was negative in 9 cases Methicilin resistant (MR) staphylococcus was isolated, in 1 case Serratia Marcescens and another case with Staphylococcus Warmei. Discussion Our study underlines the importance of the etiological diagnosis with the application of sonication Coclusions The sonication technique is simple and can be performed in the most of microbiological laboratories. Sonication has the benefit of the etiological diagnosis either in mono-microbial and poli-microbial implant-associated infections, with a higher sensitivity than standard culturing.

Abstract: Biomaterials have upgraded the field of plastic surgery to an impressive level. In this article attention is focused on the biomaterials that have allowed major advances in plastic, reconstructive and aesthetic surgery and the possible future prospects in this field. Consequently, we highlight surgical applications of polymer biomaterials like silicone, polymethylmethacrylate, polyester, nylon, polyethylene, polypropylene, cyanoacrylate and polytetrafluoroethylene, currently in use all over the world.

Abstract: Cranioplasty represent surgical repairs of defects or deformities of the skull which may come as a result of trauma or congenital malformations. The notable advance in cranioplasties came with the experimental groundwork in bone grafting, performed in the late 19th century, based on which, the use of autografts for cranioplasty became popular in the early 20th century. With the First and Second World Wars alternative metals and plastics were needed to cover large cranial defects suffered in combat as precious metals became scarce. As time passed metallic bone substitutes have gradually become obsolete and modern non-immunogenic plastics such as Polymethylmethacrylate (PMMA) snf Polyetheretherketone (PEEK) replaced them, the major downside of the technique being represented by the high costs. The authors present a statistic of 25 patients treated over a period of 4 years in 3 major neurosurgical units – which beneffited from the neurosurgical use of biomaterials for the repair of major cranial defects following congenital malformations, post-surgical cranial defects or trauma of the skull. We excluded large bone flaps for decompressive craniotomy. The authors used PMMA (Polymethylmethacrylate) and PEEK-based implants. There were 12 cases in which PMMA was used and 13 cases in which PEEK-based implants were used. The authors present a personal comparrison between the two materials. At the same time, the authors perform a comprehensive review of how the techniques have evolved from simple metal to modern biopolymers and how the modern technology will impact the future of cranial reconstruction

Abstract: In the contemporary dentistry the highly esthetic prosthetic restorations are readily achievable knowing the patient's expectations, communicating effectively with the dental technician and selecting appropriate materials and technologies. One of the important factors that influence the ceramic resistance in the metal-ceramic restorations is the design of the framework. A design of the framework that provides support for cusps may therefore be advantageous in preventing the fracture of the plating ceramics. The outer geometry of the metal-ceramic restorations is strongly defined by anatomical and physiological circumstances. Although a change in the framework design does not necessarily affect the external form of the restoration, a thicker frame automatically implies a thinner layer of veneering and vice versa.In this study we present a series of clinical cases in which we have used different techniques for modeling the wax patterns of the future metal structure according to several clinical features. There are presented techniques for obtaining the layouts for the metallic structures of partial or total esthetic metal-ceramic restorations, dental supported or implant supported, classic techniques and innovative techniques that allow previewing the final aspect of restoration and the transfer of clinical data for a highly functional prosthesis.The wax patterns are exact copies of future prosthetic parts, so should be done with great care. The ergonomics had made place also at this level currently existing a multitude of techniques and materials that facilitate the dental technician’s work.

Abstract: Due to fact that an intrauterine device with low dose hormonal mechanism of action - the 13.5 mg levonorgestrel-releasing intrauterine system has been just launched in Romania, the undesirable reactions have not been studied and reported. This system has a hormonal mechanism of action, releasing progesterone, with a particular delivering rate of levonorgestrel. Bleeding irregularities are among the very common adverse reactions reported by phase II and III studies. We performed this study in order to determine a profile of bleeding disorders after 2 months of therapy with the 13.5 mg levonorgestrel-releasing intrauterine system.

Abstract: Hydrocephalus is a medical condition consisting of an abnormal accumulation of cerebrospinal fluid in the ventricles of the brain. This may cause increased intracranial pressure, progressive enlargement of the head, followed by ischemia, convulsions, tunnel vision, and mental disability and even death. This affection usually appears due to the blockage of cerebrospinal fluid (CSF) flow in the ventricles or in the subarachnoid space surrounding the brain. In a person without hydrocephalus, CSF continuously circulates through and around the brain, its ventricles and the spinal cord and is continuously drained away into the circulatory system. Alternatively, the condition may result from an overproduction of the CSF, from a congenital malformation blocking normal drainage of the fluid, or from complications of head injuries or infections.In the treatment of hydrocephalus, the implementation of perfectly tolerable materials enables surgeons to carry out a progressive drainage of excess cerebrospinal fluid towards other cavities of the body. By today’s standards silicone based biomaterials are the sum of all progress in biomaterial science, immunology and pathology. Lack of an immune signature, chemical and biological stability, perfect adhesion resistance and many more ultrastructure-related features come as perfect proof for the impact material science has on medicine. Future biomaterials, coated with antibiotics or antibodies are now closer than ever to be implemented in medicine.

Abstract: Based on different statistics, we could consider that the most frequent operation in plastic surgery is breast surgery with the support of mammary implants. Some women have from the beginning those aesthetic features to seduce the audience but others need some improvements by using artificial implants and surgical techniques to obtain similar results. In the last time, specialists from medicine and engineering try to find out technical solutions to obtain good quality mammary implants using advanced polymeric biomaterials or surface modifying techniques, in order to assure more time lasting for these implants and less reactivity from the human body. Today, the mammary implants are manufactured currently by a silicone elastomer shell filled with cohesive silicone gel or with saline liquid. In this paper we present aspects from our experience in which we operated more than 500 patients who need aesthetic improvements with mammary implants for different clinical situation like breast augmentation, breast reconstruction after oncologic surgery and breast asymmetry.

Abstract: In the past the porcelain building technique was as follows: applying the opaque, building the dentin, layering the enamel and adding the translucent material [1]. But when one talks about dental restorations the only role model to think of is the corresponding natural tooth. The demands of today’s dentists and patients have spurred the authors to seek new ceramic systems [2]. A bioesthetic restoration is only possible when the dental technician bases its build-up technique on precise observations of the natural teeth in order to create the most exact copy possible [3]. The case study here was to try and achieve a high level of esthetic restoration in the posterior area using a complex build-up technique and compare the results with the natural teeth. We have granted sufficient time to analyze the layering of the dentition enamel and translucency and tried to correctly match the surface texture. The technician has focused his attention especially on the occlusal surface because of its morphologic complexity.The conclusion is that a high level of esthetic restoration can be obtained with a very good color match if instructions are followed and close attention to details is being paid. The abrasion and wear over time causes the transparent layer covering the dentin to diminish and easily trick an inexperienced eye. Surface characterization using whitish opaque enamel for the cusp ridges, edges and grooves and the use of individually stained opaque on the metal frame for the natural color impression effect coming from the inside are efficient solutions for achieving close to nature esthetics.