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Statement of problem: Daily disinfection of maxillofacial prosthesis may reduce their service-life and lead to replacement. Purpose: The purpose of this study was to evaluate possible alterations in the mechanical behavior of two maxillofacial elastomers after application of four different disinfection procedures. Material and methods: The materials tested were two maxillofacial elastomers, a commercially available polydimethylsiloxane (PDMS) and an experimental chlorinated polyethylene (CPE). Different disinfection procedures such as microwave exposure, hypochlorite solution, neutral soap and a commercially antimicrobial solution, were applied for a period which simulates one year of a real service life. Mechanical behavior was investigated through tensile and microindentation tests in various depths. Mathematical models were fitted to tensile curves. Alterations in tensile parameters (maximum stress, maximum strain, elasticity and viscoelasticity parameter) were subjected to two way ANOVA and Tukey's post hoc tests (α=05). Results: Most of the tensile parameters presented significant alterations among different disinfection procedures and maxillofacial materials which became also harder. Microwave exposure caused greater changes in PDMS and CPE elastomer whereas commercial antimicrobial solution and neutral soap did not significantly affect them. Microindentation and tensile tests revealed similar changes in materials' elastic modulus and hardness whereas the observed changes were greater into smaller depths. Conclusions: Tensile and microindentation properties of PDMS and CPE elastomers presented changes after disinfected with four different procedures. Changes in the surface of both materials were more intense than in the bulk of the materials. Microwave exposure affected most the two elastomers, so concerning the findings of this study is not recommended for the disinfection of the examined PDMS and CPE elastomers. Moreover, microwave exposure and hypochlorite solution caused greater changes in the surface (3. μm) of CPE samples as indicated by microindentation results. PDMS affected less from the commercial antimicrobial agent and CPE from neutral soap, which seems to be the most suitable disinfection techniques. © 2013 Elsevier Ltd.

The degradation of maxillofacial prosthetic elastomers that occur during physical weathering is usually responsible for the replacement of the prosthesis. In this study the mechanical behaviour of a polydimethylsiloxane (PDMS) elastomer was investigated, after 1 year outdoor weathering in two different weathering locations in Greece (Thessaloniki, Athens). The hypothesis investigated was that irradiation time did not affect the measured properties. Specimens (Elastomer 42) were prepared according to manufacturer's instructions and exposed to solar radiation for 1 year. Compression, tensile and nanoindentation tests were performed before and after the exposure. Compression and tensile data were also subjected to analysis of variance (ANOVA) and Tukey Post hoc tests at a level of α = .05. These properties were selected due to their clinical significance for fabrication and maintenance of a facial prosthesis. According to statistical analysis all the measured properties changed significantly after outdoor weathering. More specifically, most of the properties presented significant changes after six months of weathering. The observed changes also depended on the weathering locations. The hypothesis investigated was rejected. Material A became harder and the observed differences in the mechanical behaviour resulted from photo-degradation and hydrolysis that might occur due to weathering. The study also provides new information about maxillofacial prosthetics serviceability obtained from nanoindentation tests. © 2011 Elsevier Ltd. All rights reserved.

Ground-level ozone concentrations were estimated for Greece during a summer period of the year 2000 using the regional air quality model UAM-V off-line coupled with the mesoscale meteorological model MM5. An anthropogenic NOx, NMVOCs and CO emission inventory and biogenic NMVOCs emission data were used to support model simulations. The evaluation analysis indicates a quite satisfactory model performance in reproducing ozone levels. The simulated mean ozone concentrations are above the 32-ppb EU phytotoxicity limit over almost all continental and maritime areas of Greece. Over the greater part of the country, the background mean ozone levels range from 40 to 55 ppb. Ozone values higher than the 55-ppb EU human health protection limit reaching 60 ppb dominate part of the southern Aegean Sea that is influenced by the Athens urban plume. In the areas where anthropogenic emission densities are high, the mean ozone levels vary between 20 and 40 ppb. Over the greater part of Greece, the simulated mean daily maximum ozone concentrations range from 50 to 65 ppb. More enhanced maximum ozone concentrations up to 95 ppb mainly dominate over the greater areas of the two largest Greek urban centres (Athens and Thessaloniki) and over the continental and maritime areas south of Athens which are under the influence of the urban plume. © 2008 Springer Science+Business Media B.V.

The mean annual variability and covariability of the basic air pollutants (Smoke, O-3, SO2, NO2) monitored in 9 stations of the Greater Athens area, is studied for the period 1991-94. On the rime series of each pollutant Factor Analysis has been applied in order to define the main modes of variation and to group the stations in subgroups with a particular annual variation. The results showed that NO2, is the only one exhibiting different annual variation in the coastal than in the inland stations. This is due to the Etesian winds which in summer affect the penetration of the sea breeze over the land. Fresenius Environmental Bulletin