Dorkhan M.,MalmoUniversity |
de Paz L.E.C.,MalmoUniversity |
Skepo M.,Lund University |
Svensater G.,MalmoUniversity |
Microbiology | Year: 2012
The use of dental implants to treat tooth loss has increased rapidly over recent years. 'Smooth' implants showing high long-term success rates have successively been replaced by implants with rougher surfaces, designed to stimulate rapid osseointegration and promote tissue healing. If exposed in the oral cavity, rougher surfaces may promote bacterial adhesion leading to formation of microbial biofilms which can induce peri-implant inflammation. Streptococcus oralis is an early colonizer of oral surfaces and has been recovered from titanium surfaces in vivo. The purpose of this study was to examine the adherence of clinical strains of S. oralis to titanium with smooth or moderately rough surface topography and to determine the effect of a saliva-or serum-derived coating on this process. Adherence was studied using a flow-cell system with confocal laser scanning microscopy, while putative adhesins were analysed using proteomics of bacterial cell wall proteins. This showed that adherence to moderately rough surfaces was greater than to smooth surfaces. Serum did not promote binding of any of the studied S. oralis strains to titanium, whereas a saliva coating increased adherence in two of three strains tested. The higher level of adherence to the moderately rough surfaces was maintained even in the presence of a saliva coating. The S. oralis strains that bound to saliva expressed an LPXTG-linked protein which was not present in the non-adherent strain. Thus strains of S. oralis differ in their capacity to bind to saliva-coated titanium and we propose that this is due to differential expression of a novel adhesin. © 2012 SGM Printed in Great Britain.
Safdar A.,MalmoUniversity |
He H.Z.,MalmoUniversity |
Wei L.-Y.,MalmoUniversity |
Snis A.,Arcam |
Chavez De Paz L.E.,MalmoUniversity
Rapid Prototyping Journal | Year: 2012
Purpose - Ti-6Al-4V is one of the most attractive materials being used in aerospace, automotive and medical implant industries. Electron beam melting (EBM) is one of the direct digital manufacturing methods to produce complex geometries of fully dense and near net shape parts. The EBM system provides an opportunity to built metallic objects with different processing parameter settings like beam current, scan speed, probe size on powder, etc. The purpose of this paper is to determine and understand the effect of part's thickness and variation in process parameter settings of the EBM system on surface roughness/topography of EBM fabricated Ti-6Al-4V metallic parts. Design/methodology/approach - A mathematical model based upon response surface methodology (RSM) is developed to study the variation of surface roughness with changing process parameter settings. Surface roughness of the test slabs produced with different parameter settings and thickness has been studied under confocal microscope. Response surface methodology was used to develop a multiple regression model to correlate the effect of variation in EBM process parameters settings and thickness of parts on surface roughness of EBM produced Ti-6Al-4V. Findings - It has been observed that every part produced by EBM system has detectable surface roughness. The surface roughness parameter Ra varies between 1-20 mm for different samples depending upon the process parameter setting and thickness. The Ra value increases with increasing sample thickness and beam current, and decreases with increase in offset focus and scan speed. Originality/value - Surface roughness is related to wear and friction property of the material and hence is related to the life time and performance of the part. Surface roughness is an important property of any material to be considered as biomaterial. The surface roughness of the material depends upon the manufacturing method and environment and hence it is controllable either during fabrication or by post processing. From the 1st order regression model developed in this study, it is also evident that sample thickness, scan speed and beam current have relatively more effect on roughness value then the offset focus. With the model obtained equation, a designer can subsequently select the best combination of sample thickness and process parameter values to achieve desired surface roughness. © 2012 Emerald Group Publishing Limited.
Brunklaus B.,Chalmers University of Technology |
Thormark C.,MalmoUniversity |
Baumann H.,Chalmers University of Technology
Building Research and Information | Year: 2010
Does passive housing really have better environmental performance than conventional housing? Three passive houses and four conventional houses were compared using a life cycle assessment (LCA) methodology. The comparison also provided an actor analysis for the building supply chain and building inhabitants. Results are presented for two scenarios: 'conventional choices' and 'green choices' by the actors. The comparison confirms that passive houses have lower energy use than conventional houses, but when the environmental impact of energy production is taken into consideration, the outcome is less clear. Conventional houses can be equally good environmentally in terms of global warming, acidification, or radioactive waste as typical passive houses with electrical heating depending on the actors' choices. Actor analysis shows that inhabitants' and material producers' electricity choice are very important, while other choices (e.g. green transport) are less important. The findings highlight the importance of environmentally responsible decisions throughout the whole life cycle and the need for appropriate behaviours and actions, along with implications for improved communication. © 2010 Taylor & Francis.
International Journal of Law in the Built Environment | Year: 2012
Findings – Based on this study, five dimensions of transparency are identified, namely transparency in transaction procedure, legal information, financing, taxation and transaction costs. The essential points are that an increase in cross-border transactions increases demand for easy access to information held in other countries. The studied literature focuses on the coordination of legal systems, making systems more uniform and legally secured, and on broadening of the mortgage market. The study highlights the complexities involved in achieving transparency, as well as the length of time that this will take to achieve in practice.Purpose – The purpose of this paper is to provide a theoretical framework for the subsequent analysis of the European Union internal market’s concept of transparency in residential real estate transactions. Specifically, it seeks to identify the essential factors that should be addressed within any such analysis.Design/methodology/approach – The study is based on a review of the literature on the general concept of transparency, and on other related aspects.Originality/value – The paper identifies different dimensions of transparency in residential real estate transactions. There is little prior research in the area which focuses specifically on residential transactions. The study therefore draws upon work in other areas, including financial markets and taxation, and places this within a residential housing context. © Emerald Group Publishing Limited.
Jansson H.,MalmoUniversity |
Wahlin A.,MalmoUniversity |
Johansson V.,MalmoUniversity |
Akerman S.,MalmoUniversity |
And 3 more authors.
Journal of Periodontology | Year: 2014
Background: Periodontal research has traditionally focused on the site level, regarding etiology, pathogenesis, and treatment outcome. Recently, some studies have indicated that the presence of periodontal disease is associated with reduced quality of life. The aim of this study is to investigate the impact of periodontal disease experience on the quality of life. Methods: This cross-sectional study includes 443 individuals. Clinical and radiographic examinations were performed; in conjunction, the oral health-related quality of life of all participants was assessed using the Swedish short-form version of the Oral Health Impact Profile (OHIP-14). Based on marginal bone loss, measured on radiographs, three different groups were identified: participants with loss of supporting bone tissue of less than one third of the root length (BL-), loss of supporting bone tissue of one third or more of the root length in <30% of teeth (BL), or loss of supporting bone tissue of one third or more of the root length in 30% of teeth (BL+). Results: The effect of periodontal disease experience on quality of life was considerable. For the BL- group, the mean OHIP-14 score was 3.91 (SD: 5.39). The corresponding mean values were 3.81 (SD: 5.29) for the BL group and 8.47 (SD: 10.38) for the BL+ group. The difference among all groups was statistically significant (P 0.001). A comparison among the mean OHIP-14 scores in the different groups (BL-, BL, and BL+) revealed significant differences in six of seven conceptual domains. Conclusions: The BL+ individuals experienced reduced quality of life, expressed as the OHIP-14 score, compared with the BL and BL- participants. J Periodontol 2014;85: 438-445.