Experimental and computational approach for evaluating the mechanical characteristics of dental composite resins with various filler sizes

This study aimed to investigate the influence of particle size of fillers on flexural properties of dental composite resins by laboratory testing with computational analysis validation. Four kinds of silica fillers with mean particle sizes of 3.3, 4.3, 7.9, and 15.5 μm were used. Filler content was kept constant at 70 mass% (or 53.8 vol.%). The three-point bending test was performed with a constant loading speed of 1.0 mm/min, and a span length of 20 mm using an Instron machine, in order to measure flexural strength and modulus of composite resins with various particle sizes. Test specimens were 2-mm wide, 2-mm thick, and 25-mm long rectangular bars. Furthermore, a numerical simulation using three-dimensional finite element (FE) analysis was performed to investigate stress distribution in composite resins under loading. As a result, flexural strength decreased with increasing particle size of the filler of the composite resins (p < 0.05). On the other hand, there was no significant difference in Young’s modulus among composite resins with various filler sizes (p > 0.05). Moreover, FE analysis indicated that stress concentration increased with increasing particle size in agreement with experimental results of flexural strength. In conclusion, within the limitations of this investigation, we confirmed that flexural strength of composite resins decreased with increasing filler particle size. In addition, FE analysis was effective for evaluating stress distributions of dental composite resins with various filler sizes.     

Preparation of scratch and abrasion resistant polymeric nanocomposites by monomer grafting onto nanoparticles, 1 FTIR and multi‐nuclear NMR spectroscopy to the characterization of methacryl grafting

Nano‐sized silica and alumina particles were used as fillers for polymer reinforcement and scratch resistant coatings. For favorable embedding within the polyacrylate matrix the surface of the fillers was chemically modified by reaction with methacroyloxy (propyl)trimethoxysilane. The formation of covalent Si(Al)—O—Si—C bonds between functional groups from silane and OH groups on silica and alumina was demonstrated by means of FTIR and MAS NMR spectroscopy. The reactivity of the various surface silanols towards the coupling agent and the yield of surface Si—O—Si bonds were estimated by ²⁹Si CP MAS NMR data     

Effective use of optimized, high-dose (50 kGy) gamma irradiation for pathogen inactivation of human bone allografts

The safety of tissue allografts has come under increased scrutiny due to recent reports of allograft-associated bacterial and viral infections in tissue recipients. We report that 50 kGy of gamma irradiation, nearly three times the dose currently used, is an effective pathogen inactivation method when used under optimized conditions that minimize damage to the tissue. Cancellous bone dowels treated with a radioprotectant solution and 50 kGy of optimized irradiation had an ultimate compressive strength and modulus of elasticity equal to conventionally irradiated (18 kGy) and non-irradiated control bone grafts. We subjected bone dowels treated with this pathogen inactivation method to an in vitro cytotoxicity test using three different mammalian cell lines and concluded that the treated grafts were not cytotoxic. The log reduction of nine pathogens spiked into radioprotectant-treated bone irradiated to 50 kGy was also tested. We achieved 4.9 logs of inactivation of a model virus for HIV and hepatitis C and 5 logs inactivation of a model virus for human parvovirus B-19. Complete inactivation (6.0-9.2 logs) of seven clinically relevant microorganisms was demonstrated. The results show that a combination of radioprotectants and optimized, high-dose gamma irradiation is a viable method for producing safer cancellous bone grafts that have the mechanical strength of existing grafts.     

The effects of high dose irradiation on the cross-linking of vitamin E-blended ultrahigh molecular weight polyethylene

Vitamin E-stabilized, highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is a promising oxidation and wear resistant UHMWPE with improved mechanical strength in comparison with the first generation, irradiated and melted UHMWPE. One approach of incorporating vitamin E in UHMWPE is through blending of vitamin E in UHMWPE powder followed by consolidation and radiation cross-linking. However, radiation cross-linking efficiency of UHMWPE decreases in the presence of vitamin E. Therefore an optimum vitamin E concentration and radiation dose level need to be determined to achieve a cross-link density comparable to 100-kGy irradiated and melted UHMWPE, which has shown excellent wear properties in vivo. We investigated the cross-link density and mechanical properties of vitamin E-blended UHMWPEs as a function of vitamin E concentration in the blend and gamma irradiation doses up to 200kGy. We found that 0.3wt% vitamin E-blended UHMWPE could not be cross-linked above a cross-link density achieved at a radiation dose of 65kGy for virgin UHMWPE and 1.0wt% vitamin E-blended UHMWPE could not be cross-linked above a cross-link density achieved at a radiation dose of 25kGy for virgin UHMWPE even when the these UHMWPEs were irradiated to a radiation dose of 200kGy. In addition, higher plasticity at vitamin E concentrations at and above 0.3wt% indicated that increased chain scissioning may be prevalent. Since the wear resistance of this irradiated UHMWPE would be expected to be low, vitamin E concentrations equal to or above 0.3wt% are not recommended for subsequent irradiation to achieve a wear resistant cross-linked UHMWPE. The long-term oxidative stability of irradiated blends with low vitamin E concentrations has yet to be studied to determine an optimum between cross-link density and long-term oxidative stability.     

Influence of chemical structure on the fracture behaviour of dimethacrylate composite resins

Previous studies have shown that the fracture resistance of dimethacrylate-based dental composite resins is enhanced by post-curing the matrix. Here, the influence of the chemical nature of the resin matrix is examined by a study of the fracture properties of composite resins formulated from 15 homologous dimethacrylate monomers and filled to 75 wt% with treated silica. The fracture toughness was determined via the double torsion technique and the elastic modulus and flexural strength were measured in flexure. The fracture energy calculated from the fracture toughness and elastic modulus, varied between 60 and 300 J/m2 while the fracture toughness ranged from 0.2 to 2.0 MN/m3/2 and the flexural strength varied from 17 to 111 MPa. The use of a blend of monomers was found to have a synergistic effect on the fracture resistance. Increasing the length of flexible spacer units (methylene or oxyethylene) between the methacrylate groups initially improved the fracture properties; however, beyond a certain length, these properties were impaired.     

Screening of stabilized crosslinked polyethylene using a novel wear tester

A novel pin-on-disk type wear tester is described allowing a rapid screening of different types of polyethylene under both unidirectional and multidirectional sliding motion. The wear of four polyethylene materials sliding against a roughened CoCrMo alloy was evaluated: a non-irradiated UHMWPE, a UHMWPE irradiated with a dose of 25 kGy in air, and two types of crosslinked UHMWPE (100 kGy, air), which were subjected to a stabilization heat treatment in nitrogen at 155 degrees C for 72 hours (XLPE I) and in water at 130 degrees C for 72 hours (XLPE II), respectively.Under multidirectional sliding conditions both types of XLPE exhibited significantly less wear with respect to the 25 kGy irradiated UHMWPE and the non-irradiated UHMWPE, even under the rough counterface conditions applied. Under unidirectional sliding motion both types of XLPE exhibited the highest wear of all materials tested, because the orientation hardening effect acting under linear lubricated condition is less pronounced for crosslinked polyethylene.     

三种方法对硼酸铝晶须表面改性作用及其对复合树脂性能的影响

分别采用三种不同方法对硼酸铝晶须(AlBw)进行表面改性。方法一:将AlBw与商品纳米二氧化硅(SiO2)在一定工艺下直接高温熔附;方法二:将正硅酸乙酯(TEOS)用溶胶-凝胶法水解形成Si-O网络结构的膜,同时包裹于AlBw表面,进一步与商品纳米SiO2高温熔附;方法三:用溶胶-凝胶法在一定工艺条件下使TEOS水解得到纳米SiO2,同时沉积于AlBw表面,然后高温熔附。透射电镜(TEM)和扫描电镜(SEM)观察不同方法改性AlBw后其表面形态的变化。按一定质量比加入树脂基质中,测试树脂弯曲性能,SEM观察断口形貌。结果表明:晶须改性后可以提高复合树脂的弯曲性能,不同改性方法作用不同;商品SiO2纳米颗粒直接熔附于AlBw进行表面改性,复合树脂的弯曲强度达(95.28±4.53)MPa,但AlBw、纳米SiO2间团聚明显;采用TEOS溶胶-凝胶法对AlBw进行表面处理后与商品SiO2纳米颗粒混合,团聚有改善,但分布不均匀;采用TEOS溶胶-凝胶法直接生成纳米SiO2改性AlBw,是一种理想的改性方法,经此法改性的AlBw-SiO2复合体可以显著提高复合树脂的弯曲性能,复合树脂的弯曲强度达(130.29±8.38)MPa,SiO2粒径分布均匀,AlBw表面有分布较均匀的、分散的SiO2纳米颗粒熔附,团聚程度降低。     

Strong and bioactive composites containing nano-silica-fused whiskers for bone repair

Self-hardening calcium phosphate cement (CPC) sets to form hydroxyapatite with high osteoconductivity, but its brittleness and low strength limit its use to only non-stress bearing locations. Previous studies developed bioactive composites containing hydroxyapatite fillers in Bis-GMA-based composites for bone repair applications, and they possessed higher strength values. However, these strengths were still lower than the strength of cortical bone. The aim of this study was to develop strong and bioactive composites by combining CPC fillers with nano-silica-fused whiskers in a resin matrix, and to characterize the mechanical properties and cell response. Silica particles were fused to silicon carbide whiskers to roughen the whisker surfaces for enhanced retention in the matrix. Mass ratios of whisker:CPC of 1:2, 1:1 and 2:1 were incorporated into a Bis-GMA-based resin and hardened by two-part chemical curing. Composite with only CPC fillers without whiskers served as a control. The specimens were tested using three-point flexure and nano-indentation. Composites with whisker:CPC ratios of 2:1 and 1:1 had flexural strengths (mean+/-SD; n=9) of (164+/-14) MPa and (139+/-22) MPa, respectively, nearly 3 times higher than (54+/-5) MPa of the control containing only CPC fillers (p<0.05). The strength of the new whisker-CPC composites was 3 times higher than the strength achieved in previous studies for conventional bioactive composites containing hydroxyapatite particles in Bis-GMA-based resins. The mechanical properties of the CPC-whisker composites nearly matched those of cortical bone and trabecular bone. Osteoblast-like cell adhesion, proliferation and viability were equivalent on the non-whisker control containing only CPC fillers, on the whisker composite at whisker:CPC of 1:1, and on the tissue culture polystyrene control, suggesting that the new CPC-whisker composite was non-cytotoxic.     

Calorimetric study of extracellular tissue matrix degradation and instability after gamma irradiation

Native extracellular tissue matrix (ECM) is increasingly used for tissue repair and regeneration. The kinetics of gamma irradiation damage on human dermis ECM was studied by differential scanning calorimetry (DSC). Dermis ECM was irradiated at a low-dose rate of 0.23 kGy h(-1) in order to study the progression of ECM damage as the gamma dose increased from 0 to 32 kGy. The study showed that the effect of gamma irradiation above 2 kGy was predominantly peptide chain scission. As the gamma dose increased, the stability of irradiated ECM decreased further, and multiple ECM domains of different stability were detected. Even a moderate gamma dose (7-12 kGy) could decrease the onset denaturation temperature of ECM to below body temperature. DSC analysis also showed partial and spontaneous protein denaturation in gamma-irradiated, rehydrated ECM at 37 degrees C. In vitro rehydration tests confirmed that a significant fraction of the irradiated ECM disintegrated into minute ECM fragments at 37 degrees C, although the irradiated ECM appeared to be normal at 4 degrees C and room temperature. DSC data were correlated well to effects of gamma irradiation on ECM microstructure, mechanical property and in vitro cell response reported earlier by us. A model was presented to describe the kinetics of gamma-irradiation-induced alterations of tissue ECM properties.     

A depth profile of oxidation and gel fraction in gamma-irradiated silane crosslinked and ultra high molecular weight polyethylenes

The depth profile of oxidation index and gel fraction has been measured for two silane crosslinked poly(ethylene) (SXLPE) acetabular cups (one gamma irradiated in air, and one non-irradiated, both with a shelf-life of 13 years) and for two UHMWPE components (one gamma irradiated in air and one non-irradiated, with shelf-lives of 13 and 7 years, respectively). Only the irradiated UHMWPE exhibited any variation in these properties with depth. The oxidation profile (maximum 1 mm below surface) has been explained to result from reduced levels of diffused oxygen with depth, giving rise to a balance of alkyl and peroxyl radicals (and hence maximum carbonyl production) just below the surface. The gel fraction profile (maximum 4 mm below surface) is also attributed to the lower levels of diffused oxygen with depth, causing crosslinking to dominate in the bulk and chain scission to dominate at the surface. The resistance to oxidative degradation in the non-irradiated SXLPE was attributed to the use of antioxidants in the polymer processing.     

Irradiated Cerastes cerastes Venom as a Novel Tool for Immunotherapy

Immunotherapy is the most effective treatment for the snake bites. The antivenoms are commonly obtained by hyperimmunization of animals that suffer from venom toxicity. The present report describes gamma irradiation effects on Cerastes cerastes venom. Doses of 1 kGy and 2 kGy gamma radiations were used for venom detoxification. These treated venoms did not have any residual lethal effects until 10 LD₅₀. Immunological analysis of sera raised against native and irradiated venoms, showed that elicited antibodies to irradiated venoms were able to recognize native venom. Anti-2 kGy irradiated venom had more protective ability than anti-native venom, as tested in mice.     

Irradiated Cerastes cerastes venom as a novel tool for immunotherapy

Immunotherapy is the most effective treatment for the snake bites. The antivenoms are commonly obtained by hyperimmunization of animals that suffer from venom toxicity. The present report describes gamma irradiation effects on Cerastes cerastes venom. Doses of 1 kGy and 2 kGy gamma radiations were used for venom detoxification. These treated venoms did not have any residual lethal effects until 10 LD₅₀. Immunological analysis of sera raised against native and irradiated venoms, showed that elicited antibodies to irradiated venoms were able to recognize native venom. Anti-2 kGy irradiated venom had more protective ability than anti-native venom, as tested in mice.     

Trace concentrations of vitamin E protect radiation crosslinked UHMWPE from oxidative degradation

The effect of very low concentrations of Vitamin E on the stability and mechanical behavior of UHMWPE remains unknown. We tested the hypothesis that the oxidation resistance of Vitamin E-blended UHMWPE would be influenced by trace doses of antioxidant, resin, and radiation treatment. Trace concentrations (< or =500 ppm w/w%) of alpha-tocopherol (Vitamin E) were blended separately with GUR 1020 and 1050 resins and molded into disks. From each disk, three groups of 10 mm thick blocks were machined: (1) no irradiation (control); (2) 30 kGy of gamma irradiation in nitrogen; and (3) 75 kGy of gamma irradiation in air. Specimens were subjected to three aging protocols: (a) no aging (control); (b) two weeks and (c) four weeks of accelerated aging in accordance with ASTM F 2003 (i.e., 70 degrees C and 5 atm oxygen). The minimum concentration of Vitamin E needed to stabilize UHMWPE during our accelerated tests depended upon the method of radiation processing. For the 30 and 75 kGy irradiated materials, the addition of 125 ppm or more Vitamin E was sufficient to maintain baseline mechanical and chemical properties through two weeks of accelerated aging. For these groups, the addition of 375 ppm or 500 ppm, respectively, was necessary to maintain baseline mechanical and chemical properties throughout the four-week accelerated aging period. UHMWPE resin molecular weight did not have an effect on oxidation behavior. The results of this experiment therefore supported our hypotheses that trace concentrations of Vitamin E, coupled with radiation treatment-but not resin grade-influence the mechanical and oxidative degradation behavior of UHMWPE.     

Effects of gamma-irradiation on physical and biologic properties of crosslinked hyaluronan tissue engineering scaffolds

Hydrogels containing divinyl sulfone (DVS)-crosslinked hyaluronan (HA) (hylans) are potentially useful implant biomaterials because of their non-cytotoxicity and -antigenicity. However, to successfully fulfill their intended role in vivo, their properties (e.g., mechanics, pore size, surface topography, hydrophilicity, swelling) must be modulated to match the demands of the target application. This study explored whether controlled irradiation with gamma (gamma) can strengthen hylans and modulate their physical and biologic properties, as has previously been shown to be possible with other natural and synthetic polymers. Hydrated hylans containing two different amounts of DVS were irradiated in vacuum to increasing doses of gamma (0-13.5 kGy). The properties of the irradiated gels were compared with those of non-irradiated controls. Changes to bulk structure were evaluated using swelling tests, surface topography and pore structure were evaluated using scanning electron microscopy, mechanics were evaluated using unconfined compression tests, and surface hydrophilicity was evaluated by measuring contact angle changes. Irradiated gels exhibited lower swelling capacity, structural weakening, increase in elasticity, surface texturing, increased pore size, and decreased surface hydrophilicity in direct correlation with received dose. Cells adhered and proliferated readily on the irradiated gel surfaces but not on control gels. The irradiated gels, however, deteriorated during long-term (<60 days) storage. Irradiation of hylans in a lyophilized state instead resulted in gels that were more compact, swelled less, and exhibited smaller pores than their hydrated counterparts. The results show that gamma-irradiation, although useful to modulate hylan gel properties, presents challenges of degradation that may be associated with its generation of free-radicals, HA chain fragmentation, and disruption of DVS crosslinks, particularly when the gels are irradiated in their native hydrated state (>98% water content). Future studies will optimize parameters for gamma-mediated modulation of hylan properties through irradiation under water-free conditions.     

Silica-filled elastomer/methacrylate systems as soft liners

Denture soft lining materials are compliant cushions used at the oral tissue-denture interface. They are generally required to have sufficient compliance to redistribute mastication load, as well as an adequate modulus for long-term dimensional stability and control over the water uptake. This study investigated the effect of using silane treated fumed silica as a filler on the properties of experimental soft lining materials based on blends of isoprene-styrene (SIS) block co-polymer and mixtures of methyl methacrylate (MMA) and 1,6-hexandiol dimethacrylate (HDMA). The overall elastomer/monomer ratios were maintained, whereas the monomers ranged from 10 to 60% HDMA. The silica filler level was maintained at 10 wt% with respect to SIS. The properties investigated were the dynamic mechanical parameters of storage modulus (E′) and tan δ as a function of temperature and the quasi-static mechanical parameters of ultimate tensile strength (UTS) and elongation to break (E _b) as well as absorption properties that were carried out in water and saline. In both unfilled and filled systems there was an increase in E′ and a decrease in tan δ with an increase in HDMA. Silica addition tended to increase E′ and substantially reduce tan δ in materials with less than 20% HDMA. UTS decreased with filler and HDMA content, however, E _b was greater for filled systems. Generally, in the long term, the water uptake decreased with increasing HDMA content and E′. The silanated silica further reduced the water uptake, indicating a cross-linking effect, thus increasing the restraining force on droplet growth. The uptake in saline was significantly reduced indicating an osmotically controlled uptake process.     

Effect of resin hydrophilicity and water storage on resin strength

This study evaluated the change in the ultimate tensile strength (UTS) of five polymerised resin blends of increasing hydrophilicity, after ageing in distilled water or silicon oil. Resin blocks were prepared from each resin blend by dispensing the uncured resin into a flexible, embedding mould, containing multiple cavities. The resins were polymerised in the moulds under nitrogen at 551.6 kPa and light-activated at 125 degrees C for 10 min. After dry ageing for 24 h at 37 degrees C, the middle third of each resin specimen was trimmed into an 'I' shape. Fifteen control specimens were randomly selected from each resin blend for baseline UTS evaluation. The UTS of the experimental specimens were determined after 1, 3, 6 and 12 months of ageing in water or oil. The UTS of each group of resins at different storage periods in water or oil were analysed using the Friedman multiple ANOVA on ranks and Dunn's multiple comparison tests at 95% confidence level. Significant reduction (p < 0.01) in UTS was observed in Groups II-V resins after 12-month storage in water, while the most hydrophobic Group I resin showed no significant change (p > 0.05) in the same period. The percentage reduction in UTS increased with the hydrophilicity of the resin blends. Long-term water storage of hydrophilic resin blends such as those employed in dentine adhesives, resulted in a marked reduction in their mechanical strength that may compromise the durability of resin-dentine bonds.     

Mechanical properties of BIS-GMA resin short glass fiber composites

The use of short glass fibers as a filler for dental restorations or cement resins have not been examined extensively. The mechanical properties and untreated glass fibers (5 microns dia x 25 microns) in Bis-phenol A glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) resin were investigated for possible use as a restorative dental composite or bone cement. Compression, uniaxial tension and fracture toughness tests were conducted for each filler composite mixtures of 40, 50, 60 and 70%. Set time and maximum temperature of polymerization were determined. The results show that the elastic modulus, tensile strength and compressive strength are dependent on the percent of filler content. Elastic modulus and compressive yield (0.2%) strength of silane treated glass fibers filled composite increased from 2.26 to 4.59 GPa and 43.3 to 66.6 MPa, respectively, wtih increasing the filler content while the tensile strength decreased from 26.7 to 18.6 MPa. The elastic modulus of the untreated composite was less than that of the silane treated fiber composite. The tensile strength and compressive strengths were 20 to 50% lower than those of silane treated composites. The fracture toughness of the silane treated glass fiber additions were not significantly different from the untreated additions. The highest fracture toughness was obtained at 50% filler content with 1.65 MPa m.5. Set time increased from 3.5 to 7.7 minutes with increased filler content and peak temperature dropped from 68.3 to 34 degrees C. The results of this study indicate that the addition of silane coated glass fiber to BIS-GMA resin increased the elastic modulus, tensile and compressive strengths compared with non-treated fibers. The addition of either treated or non-treated fibers increased the set time of the material and decreased the maximum temperature.     

水对3种双固化复合树脂冠核材料弯曲性能的影响

背景：口腔湿热环境会对牙科核材料的力学性能产生影响。 目的：观察水对3种双固化复合树脂冠核材料质量变化率及弯曲性能的影响。 方法：将LuxaCore Smartmix Dual、Para core和Clearfil DC Core 三种牌号双固化复合树脂材料制成      25 mm×2 mm×2 mm标准试件,于(37±1) ℃的蒸馏水中保存 0 d、1 d、1周、2周、3周和1个月后称质量,计算其质量变化率,并在万能试验机上测试三点弯曲性能。 结果与结论：3种复合树脂的质量变化率均随着浸泡时间的增加而增加;对于相同浸泡时间下,3种树脂的质量变化率由大到小排列次序为：LuxaCore Smartmix Dual>ParaCore>Clearfil DC Core。LuxaCore Smartmix Dual树脂强度随浸泡时间的增加而降低;ParaCore树脂强度在浸泡3周内变化不显著(P > 0.05),浸泡时间1个月时强度显著降低(P < 0.05);Clearfil DC Core树脂强度在整个浸泡过程中没有显著性差异(P > 0.05)。LuxaCore Smartmix Dual树脂模量在整个浸泡时间内呈现出下降趋势,但在最初2周的浸泡时间内无明显变化(P > 0.05),当浸泡时间达到3周和1个月时模量显著降低(P < 0.05);与浸泡前比,ParaCore和Clearfil DC Core两种复合树脂的模量值均下降,但这种变化不显著(P > 0.05);3种复合树脂的弯曲性能随着质量变化率的升高而呈现出波动式下降的趋势。综合显示在3种树脂中,Clearfil DC Core的耐水性最佳。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

The effect of resin formulation on the degree of conversion and mechanical properties of dental restorative resins

The goal of this study was to determine the effects of resin formulation variables, such as diluent concentration, catalyst type and concentration and cure mode, on the degree of conversion of carbon double bonds and mechanical properties of dental restorative resins. Diametral tensile strength, compressive strength, hardness, flexural modulus and strength, and dynamic mechanical properties were tested, and the results were correlated to the degree of conversion results obtained by infrared analysis. The results showed a significant correlation between increased mechanical properties and higher degrees of conversion. Enhanced conversions were achieved by incorporating higher diluent and lower inhibitor concentrations into the resins. Ambient temperature properties were similarly enhanced by lower inhibitor concentrations, but were not enhanced by higher diluent concentration. Dynamic mechanical properties testing at oral and elevated temperatures elucidated possible differences in resin microstructure and network quality. The storage moduli decreased over the dental temperature range and was lower at all temperatures for resins with lower conversions. The glass transition temperature was also lower in resins with poorer conversions, suggesting that these resins may be more unstable at oral temperatures than more highly converted resins. Dynamic mechanical properties were most closely correlated to degree of conversion in these polymeric systems.     

Change in blood test after irradiation with high doses for inactivation of Lassa virus

In 2006 we had a patient with Lassa fever in the University Hospital of Frankfurt. To insure a short turn-around time from the laboratory, it was necessary to have blood which was not contaminated with viruses. One method of achieving this is by irradiating the blood with high doses of ionising radiation. Inactivation of arena viruses requires doses between 12 kGy and 20 kGy, depending on temperature. In this study we investigated if plasma and serum parameters are changed by irradiation with 5 kGy, 10 kGy, 15 kGy, 20 kGy or 40 kGy of 10 MeV electrons. For the 22 serum parameters measured there was no influence of radiation up to 20 kGy. Only at 40 kGy was a significant decrease noted. For the six plasma parameters the values were significantly dose dependent. To correct this a mathematical function was defined. It is possible to inactivate Lassa virus with high doses of radiation. Most of the measured blood values don’t change. For those which were influenced it was possible to define a mathematical function.