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  • 1.
    Al-Maqdasi, Zainab
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gong, Guan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. RISE SICOMP.
    Nyström, Birgitha
    RISE SICOMP.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Characterization of wood and Graphene Nanoplatelets (GNPs) Reinforced Polymer CompositesManuscript (preprint) (Other academic)
  • 2.
    Almeida, Nuno A.F.
    et al.
    Mechanical Engineering Department & TEMA, University of Aveiro, Campus Universitário de Santiago.
    Rodrigues, Joana
    Physics Department & I3N, University of Aveiro, Campus Universitário de Santiago.
    Silva, Patricia
    Mechanical Engineering Department & TEMA, University of Aveiro, Campus Universitário de Santiago.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Soares, Manuel J.
    Physics Department & I3N, University of Aveiro, Campus Universitário de Santiago.
    Monteiro, Teresa
    Physics Department & I3N, University of Aveiro, Campus Universitário de Santiago.
    Lopes-da-Silva, José A.
    Chemistry Department & QOPNA, University of Aveiro, Campus Universitário de Santiago.
    Marques, Paula A.A.P.
    Mechanical Engineering Department & TEMA, University of Aveiro, Campus Universitário de Santiago.
    Pressure dependent luminescence in titanium dioxide particles modified with europium ions2016In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 234, p. 137-144Article in journal (Refereed)
    Abstract [en]

    Particles of titanium dioxide were prepared in the presence of europium ions (TiO2:Eu) by a solvothermal method and thermal annealed in air at 500 °C. The spectroscopic properties of TiO2:Eu particles were analyzed indicating that the Eu3+ ions are likely distributed at the surface or near the surface of the titanium dioxide particles. The photoluminescence analysis showed that the intraionic emission was strongly sensitive to reduced pressure conditions, as seen by its absence under vacuum conditions. The ion emission was re-established as soon as the atmosphere was restored. Additionally, the ion integrated emission intensity follows a linearly dependence with pressure in the range of 150 to 800 mbar revealing a high sensitivity to small variations in pressure, which is an unprecedented result. This innovation will allow the study of new technologies in the area of low vacuum sensors where TiO2:Eu may act as the active element of an optical sensor for a pressure device.

  • 3.
    Belotti, Luca
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Vadivel, Hari
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Influence of counter surface topography on the tribological behavior  of  hybrid UHMWPE composites2018Conference paper (Refereed)
  • 4.
    Bryant, Micheal
    et al.
    Leeds University, UK.
    Rituerto, Jorge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Neville, Anne
    Leeds University, UK.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Exploring the oxide reformation kinetics of CoCrMo alloys in simulated body fluids” Oral presentation2016Conference paper (Refereed)
  • 5.
    Coelho, Margarida
    et al.
    Department of Mechanical Engineering, University of Aveiro.
    Torrao, Guilhermina
    Department of Mechanical Engineering, University of Aveiro.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Gracio, Jose
    Department of Mechanical Engineering, University of Aveiro.
    Nanotechnology in automotive industry: research strategy and trends for the future – small objects, big impacts2012In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 12, no 8, p. 6621-6630Article in journal (Refereed)
    Abstract [en]

    The goal of this paper is to emphasize and present briefly the nanotechnology science and its potential impact on the automotive industry in order to improve the production of recent models with an optimization of the safety performance and a reduction in the environmental impacts. Nanomaterials can be applied in car bodies as light weight constructions without compromising the stiffness and crashwortiness, which means less material and less fuel consumption. This paper outlines the progress of nanotechnology applications into the safety features of more recent vehicle models and fuel efficiency, but also emphasis the importance of sustainable development on the application of these technologies and life cycle analysis of the considered materials, in order to meet the society trends and customers demands to improve ecology, safety and comfort.

  • 6.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biocompatibility, Mechanical and Tribological properties of GO reinforced thermoplastic polymer”. Flow Process Composite Materials Conference2018Conference paper (Refereed)
  • 7.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biointerface characterization of metal on metal implant materials using XPS and ToF-SIMS: comparison of human serum, synovial fluid, MEM and water2008Conference paper (Other academic)
  • 8.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biological responses and osteointegration to UHMWPE based nano-composites2014Conference paper (Refereed)
  • 9.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Biomaterials and biotribology2009In: Thule: Kungl. Skytteanska samfundets årsbok 2009, Umeå: Kungl. Skytteanska samfundet , 2009, p. 117-127Chapter in book (Other (popular science, discussion, etc.))
  • 10.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Design and manufacturing of Graphene Oxide reinforced high performing thermoplastics hybrid composites for Tribological applications2018Conference paper (Other academic)
  • 11.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Effect of light power density variation on dental light-cure resin composites2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dental resin based composites are tooth-colored filling materials composed of synthetic resins and particulate ceramic reinforcing filler particles. The resin system also contains molecules that promote and/or modify the polymerisation reaction of the dimethacrylate resin monomers. The filler is bonded to the cured polymer with a film of silane coupling agent covering the filler particles. That silane film is also bonded to the reinforcing filler particles. Dental composites have been used as restorative materials for anterior applications since the 60s. Their tooth matching ability, ability to bond to tooth tissues and their lack of mercury have also promoted them as an alternative to dental amalgam for use in posterior teeth. Favourable results from long-term clinical trails demonstrate that when placed correctly, composites can produce esthetical posterior restorations with acceptable longevity ( el-Mowafy et al., 1994: Taylor et al., 1994 ), although not yet comparable to amalgams (Mjor). Significant problems still remain to be solved and limit their usefulness in the routine practice of dentistry. One of the most significant problems today relates to large material contraction during intra-oral polymerisation of composites. The hardening of composites is the result of polymerisation reactions involving dimethacrylate monomers. A rigid and heavily cross-linked polymer network is produced which surrounds the inert filler particles. The extent of this reaction, the degree of conversion, dictates many of the physical and mechanical properties of the composites. The degree of cure is influenced by many factors, including the light energy used to activate the reaction (Rueggeberg and Jordan, 1993). A reduction in volume, here termed shrinkage, occurs when the monomer polymerises. That shrinkage, which is more than 10-20 times higher in microns than what occurs when an amalgam sets, is caused by a change from van der Waal bonding to covalent bond formation. During that reaction, the monomer molecules rearrange and move closer together (Oleinik, 1986). The magnitude of the shrinkage is dictated by the extent of the reaction, as well as by the nature of the monomers. Research program In the currently ongoing study we are studying the effect of light intensity on polymerisation-induced strain, degree of conversion, volumetric changes and modulus of elasticity of two commercial dental composites. The objective is to test the hypothesis that low light intensity and increased curing time can be used to cure composites with better performance than high intensity cured composites. The benefits with the low intensity long time cure could be improved marginal integrity without loss of mechanical and physical properties. MethodsPolymerisation strain: Small ring shape samples were prepared and cured with three different light intensities (800, 450 and 200 mW/cm2). The polymerisation strain was measured by strain gages. The temperature increase was also measured. The sources of increased temperature are heat generated from the lamp as well as exothermal heat from curing. Volumetric shrinkage: The overall volumetric shrinkage was measured using water and mercury displacement methods. Degree of conversion: The effect of light intensity irradiation time on degree of conversion was measured by spectroscopy (FT- Raman). Modulus of Elasticity: One important factor influencing residual stresses is the stiffness of the dental composite. A miniature tensile machine for small sample size was used to measure the Young's modulus for two materials cured with different light intensities. ResultsA decrease in light intensity decreased the residual strain for the different material systems being evaluated. As long as the lower light intensity was compensated with an increased curing time, degree of conversion, Young's modulus and volumetric shrinkage were compared to high intensity cure for shorter time. The temperature increase, though, was lower for the low intensity cure than for the high intensity cure, even if longer time was used for the low intensity cure. DiscussionThe above results support the proposed hypothesis. A lower light intensity delays gelation, allowing the material to flow more initially. Such flow decreases the induced strain. Another important factor is the lower increase in temperature, which also decreases the thermal shrinkage that occurs during cooling back to room temperature. Differences between the two materials can also be related to differences in molecular structures between the two composites. An important conclusion is that for these materials, the polymerisation reaction is controlled by the total light energy supplied to the dental composite.

  • 12.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Effect of hydrothermal ageing on wear mechanism and friction behaviour of PTFE composite2017In: Effect of hydrothermal ageing on wear mechanism and friction behaviour of PTFE composites, 2017Conference paper (Refereed)
  • 13.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Graphene oxide reinforced UHMWPE composites in Tribological applications2016Conference paper (Refereed)
  • 14.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Improved tribological performance of water lubricated bearings: using hybrid nanodiamond polymeric composites2016Conference paper (Refereed)
  • 15.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Investigation of the mechanical and the thermal properties of HMWPE-blended vitamin E/nanofillers composites2017In: The 9thInternational Biotribology Forum. The 9thChinese Biotribology and Implant Engineering Satellite Forum of 6th World Tribology Congress (WTC), 2017Conference paper (Refereed)
  • 16.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Manufacturing of bionano-composite: CNT reinforced UHMWPE composite2007Conference paper (Other academic)
  • 17.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Manufacturing parameters and Tribological characterisation of carbon reinforced UHMWPE composites “in orthopaedic applications2015Conference paper (Refereed)
  • 18.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Manufacturing parameters and Tribological characterisation of carbon reinforced UHMWPE composites-in orthopaedic applications2015In: International Tribology Conference, 2015Conference paper (Refereed)
  • 19.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Nanoparticle reinforced UHMWPE for orthopaedic applications “parameters affecting the manufacturing process and mechanical properties2015Conference paper (Refereed)
  • 20.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Past, present and future of the polymeric based devices in orthopaedic applications2015Conference paper (Refereed)
  • 21.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Processing of high performance thermoplastic multiscale composites for tribological applications2018In: 45th Leeds-Lyon Symposium on Tribology, 2018Conference paper (Refereed)
  • 22.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Reactivity of XPS Ion-etched CoCrMo and TiAlV alloys in physiological medium2009Conference paper (Other academic)
    Abstract [en]

    Introduction: Osteolysis induced by wear particles in metal-on-polyethylene hip implants has been the key motivation to look for alternative bearings and in fact emergence and development of new metal-on-metal (MOM) implant materials for joint replacement. However, while the volume of wear particles produced in metal-on-metal articulations is lower in MOM implants, it is clear that the smaller size of the metal wear particles has a dramatic effect on the number of particles produced per unit volume of wear. Although various surface and interface characterization methods have been applied to study the physical wear, corrosion and implant surface interactions with biological environments, presently the local and systematic effects of metal debris in body are poorly understood. Materials and Methods: Cobalt-chromium-molybdenium (CoCr) and titanium-aluminum-vanadium (TiAlV) alloys have been used in MOM implants extensively. Metallic samples were cut and mirror polished. In the present study the samples were immersed in four different biological lubricants (Human serum, synovial fluid and MEM) for 10 min, 1 hr, and 5 days of immersion and then studied by X-ray Photoelectron Spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). XPS determined the chemistry of elements located whit in the top few nanometers of materials. Significant differences in the absorbed layers and differences in the corrosive nature of CoCr implant substrates immersed in different media were found. Results and discussion: Spectra from P2p3/2, O1s, Ca2p3/2, C1s and N1s were collected. Metallic substrates behaved differently when immersed in the same lubricant for different time intervals. The three lubricants reacted different with metallic surfaces. Larger calcium deposits occurred in supersaturated physiological solutions. Deposition of calcium phosphate was different on CoCr and TiAlValloys depending on the lubricant and the immersion period. Specimens immersed into synovial fluid gave thinner oxide layers and lower calcium phosphate deposits. For all specimens, water immersion resulted in thicker oxide layer. Conclusion: Passivation of the metal surface is fundamental to corrosion resistance where a metallic oxide (like chromium oxide) barrier protects the underlying metal from further corrosion. The amount and purity of the oxide layer on immersed specimens depends on the density and thickness of the overlying deposits of calcium phosphate (Figure 1), proteins and other adsorbed molecules, as well the contaminations. The ration of Cr2O3 to Cr was calculated for CrCo alloy and was related to the thickness and/or concentration of the oxide in different lubricants. The lower calcium phosphate deposit in synovial fluid might be due to the present of components such as GAG and associated proteins, which stop the calcium deposition due to the circulation of the fluid in the effective joint space. ToF-SIMS measurements showed that the resulting corrosion products depend upon the nature of the environment. The thickness of the calcium phosphate deposits was different for different metal substrate.

  • 23.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    UHMWPE composites for bearing applications; manufacturing and tribological characterisation2016Conference paper (Refereed)
  • 24.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    UHMWPE in Orthopaedic Devices 2010Conference paper (Refereed)
  • 25.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Variables affecting stress development and resin conversion in light-cured dental composites2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The general aim of this dissertation was to identify and investigate factors that can be used to minimize stress development in light cured dental resins without compromising the conversion level of the polymer. Modulus of elasticity, polymerization contraction strain, degree of conversion and shrinkage of light-cure dental composites were determined after curing with three different light power densities where total irradiated energy (J/cm2) kept constant. FT-Raman spectroscopy was employed to determine the degree of conversion. The cure kinetic of light cured resins was studied by use of photocalorimetry (photo-DSC). Dynamic mechanical thermal (DMTA) analysis was used to investigate how different light curing methods affected glass transition and tangent delta of light curable dental resins when the temperature changed from 0 to 200°C. Optical properties of dental composites were studied. Three different filler types, two different surface treatments and eight different filler fractions per filler type and surface treatment were investigated. Light transmission was measured for the different composite compositions at sample thicknesses of 1 to 5 mm by use of a universal power meter. As long as the total light energy remained the same, the modulus of elasticity remained constant for each composite, even though the power density differed. Composite thickness, irradiance time, composition of the light cure composite and irradiation value had significant impact on degree of conversion. The irradiance value did not significantly affect on the transition temperature value. Initiator, co-initiators and light irradiance value had all significant impact on cure behavior. Different filler types and filler surface treatments had significant effects on light absorption. In general, light absorption increased linearly with filler fraction and sample thickness of the cured composites. Conclusion: Low rather than high light irradiance values decrease stress levels in composites, and comparable conversion levels are reached as long as the total light energy value remains the same for low versus high irradiance. By increasing the composite thickness above 2 mm but not exceeding 6 mm, energy levels exceeding 30 J are needed to achieve acceptable levels of degree of conversion. Different irradiance values do not affect the final Tg of tested composites as long as the total light energy remains the same. By using appropriate photo initiator/co-initiator combination and soft-start curing it is possible to achieve slow curing and high DC within a 40 s. As expected, different filler particle properties have significant effects on light absorption during curing making it important to consider these differences when one tries to develop a general light curing strategy for light curable dental resins.

  • 26.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Belotti, Luca
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Effect of surface roughness and hygrothermal aging of multiscale carbon reinforced UHMWPE composites2018Conference paper (Refereed)
  • 27.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Enqvist, Evelina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Grácio, José
    Nanotechnology Research Division, University of Aveiro.
    Gonçalves, Gil
    Nanotechnology Research Division, University of Aveiro.
    Marques, Paula
    Nanotechnology Research Division, University of Aveiro.
    Biotribolological behaviour of reinforced UHMWPE2010Conference paper (Other academic)
    Abstract [en]

    Carbon nanoforms exhibit exceptional physical and chemical properties due to their nano-scale dimensions. They also have very high aspect ratio which makes them an excellent reinforcement material for polymer composites. Hydroxyapatite (HA) is the prime constituent of bone generation because of its ability to bond chemically with living bone tissues and positively affect the osteoblasts; this is due to its similar chemical composition and crystal structure to apatite in the human skeletal system. Ultra high molecular weight polyethylene (UHMWPE) is already used as implant material in high stress bearing areas such as hip and knee prosthesis. Wear debris of ultra high molecular weight polyethylene cause osteolysis which is a major reason of long-term failure of total hip replacements. In this study carbon nanoforms together with hydroxyapatite (HA) nanoparticles were used as reinforcement in UHMWPE matrix in order to produce high strength and wear resistant biocomposite with better bioactivity character. Solvent casting and melt blending methods were used during the preparation of this bio-nano composite. The manufacturing process was studied using different characterization methods such as diferencial scanning calorimetry (DSC), scanning electron microscopy (SEM) and Raman-spectroscopy. The tribological behaviour of the manufactured bio-nano composite was studied using pin-on-plate method. Wear and friction of the produced novel composite were studied in different biological lubrications. Different lubrication affected the friction rate and wear, though the results were not statistically different. The reinforced UHMWPE showed superior tribology behaviour in comparison to pure UHMWPE (p>0.05).

  • 28.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Enqvist, Evelina
    Larsson, Roland
    Gracio, José
    University of Aveiro.
    Kumar, Sunil
    University of South Australia.
    Friction, wear and surface characterization of metal-on-metal implant in protein rich lubrications2010In: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Conference paper (Refereed)
    Abstract [en]

    Although various surface and interface characterization methods have been applied to study the physical wear, corrosion and implant surface interactions with biological environments, presently - in metal on metal (MOM) hip implant- the local and systematic effects of interaction between metal surfaces and protein rich lubrication in body are poorly understood. Materials and Methods: Cobalt-chromium-molybdenium (CoCrMo) alloys have been used in MOM implants extensively. In the present study the samples were immersed in four different biological lubricants (Human serum, synovial fluid, MEM and distill water) for 10 min, 1 hr, and 5 days of immersion and then studied by X-ray Photoelectron Spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). XPS determined the chemistry of elements located whit in the top few nanometers of materials. Friction and wear behavior of CoCrMo substrate in different biological lubricatin were also studied. Results and discussion: Spectra from P2p3/2, O1s, Ca2p3/2, C1s and N1s were collected. Metallic substrates behaved differently when immersed in the same lubricant for different time intervals. The four lubricants reacted differently with metallic surfaces. Larger calcium deposits occurred in supersaturated physiological solutions. Deposition of calcium phosphate was different on CoCrMo alloys depending on the lubricant and the immersion period. Specimens immersed in synovial fluid gave thinner oxide layers and lower calcium phosphate deposits. For all specimens, water immersion resulted in thicker oxide layer. Synovial fluid gave lowest coefficient of friction when distill water gave the highest value. Generally wear was higher for disc in comparison to the pin (in the pin on plate test).

  • 29.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Fernberg, Patrik
    Evaluation of manufacturing schemes for carbon nanotube doped epoxy resins and composites2005Report (Other academic)
  • 30.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Griesser, H.
    Ian Wark Research Institute, University of South Australia.
    Biotribocorrosion: time dependence of the surface chemistry of metal-on-metal implants in biological environment2009In: 8th World Biomaterials Congress 2008: Amsterdam, the Netherlands, 28 May - 1 June 2008 ; [WBC 2008], Red Hook, NY: Curran Associates, Inc., 2009, Vol. 4, p. 1978-Conference paper (Refereed)
  • 31.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Höglund, Erik
    Biotribology: surface chemistry characterization of metal-on-metal implants in rich environment2008In: Proceedings of NORDTRIB 2008, 13th Nordic Symposium on Tribology: Scandic Rosendahl Hotel, Tampere, Finland, June 10 - 13, 2008 / [ed] Jaakko Kleemola; Arto Lehtovaara, Tampere: Tampere University of Technology, 2008Conference paper (Refereed)
    Abstract [en]

    Introduction: Osteolysis induced by wear particles in metal-on-polyethylene hip implants has been the key motivation to look for alternative bearings and in fact emergence and development of new metal-on-metal (MOM) implant materials for joint replacement. However, while the volume of wear particles produced in metal-on-metal articulations is lower the number of particles produced is higher per volume of wear, due to the reduced size of wear particles. Although various surface and interface characterization methods have been applied to study the physical wear, corrosion and implant surface interactions with biological environments, presently the local and systematic effects of metal debris are poorly understood. Materials and Methods: Cobalt-chromium-molybdenium (CoCr) alloys have been used in MOM implants extensively. Metallic samples were cut and mirror polished. In the present study The samples were immersed in four different biological lubricants (Human serum, synovial fluid, MEM and Milli-Q water) for 10 min, 1 hr, and 5 days of immersion and then studied by X-ray Photoelectron Spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). XPS determined the chemistry of elements located whitin the top few nanometers of materials. Significant differences in the absorbed layers and differences in the corrosive nature of Ti and CoCr implant substrates and wear particles were found. Results and discussion: Spectra from P 2p3/2, O1s, Ca2p3/2, C1s and N1s were collected. Metallic substrates behaved differently when immersed in the same lubricant. The four lubricants reacted different with metallic surfaces. Larger calcium deposits occurred in supersaturated physiological solutions. Deposition of calcium phosphate was different on CoCr alloys depending on the lubricant and the immersion period. Specimens immersed into synovial fluid gave thinner oxide layers and lower calcium phosphate deposits. For all specimens, water immersion resulted in thicker oxide layer. For many reactive metals, dissolution of ions from the metal surface takes place along with thickening of the metal oxide during passivation, or surface corrosion.Conclusion: Glycoaminoglycans (GAG) and related proteins may hinder calcium phosphate deposition on samples immersed in synovial fluid. ToF-SIMS measurements showed that the resulting corrosion products depend upon the nature of the environment. The thickness of the calcium phosphate deposits was different for different metal substrate.

  • 32.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Lindberg, A.
    Umeå universitet.
    Dijken, J.W.V. van
    Umeå universitet.
    The effect of flow-composite on interfacial-chemistry and morphology of dentin/bonding2008Conference paper (Other academic)
    Abstract [en]

    Objectives: to study the interfacial bond of self-etching primer to coronal and root dentin with and without the use of flow composite. Methods: morphology, structural characteristics and interaction at the interfaces were studied with Raman micro-spectroscopy and SEM. Coronal (superficial) dentin and root (deep) dentin were prepared from eight non-carious extracted premolars. Immediately after extraction, teeth were carefully cleaned and stored in chlorhexidine digluconate solution prior to preparation. Smear-layer was generated by wet grinding with 600 grit silicon carbide polishing paper for 10 s. A self etching primer Xeno III (Dentsply) was applied according to manufacturer instruction. Half of the specimens were covered with a thin layer of Tetric flow (Ivoclar Vivadent) prior to curing. A 1mm slice was cut of the mesial and distal surface of the teeth with a low speed diamond saw to uncover the interfacial margins and hybrid layer. A modified Nakabayashi method, using HCl and HNO3 followed by NaOCl, was used to show the penetration depth of the monomers. SEM images from 750 to 6000 magnification were collected from dentin/bonding interfaces. Raman spectrums were collected at 1µm intervals across the dentin/bonding interface and provided chemical information. Degree of demineralization as function of depth was calculated. Results: No difference in degree of demineralization was seen between coronal and root dentin. It was slightly lower by using a thin layer of flow prior to curing. The thickness of the dentin/bonding hybrid layer was less for samples with flow and its morphology of hybrid layer and interfacial structure was significantly different. Conclusion: Flow composite had an undesirable affect on the physical-chemistry structure of dentin bonding with a self etching primer. HL and bonding tags morphology was significantly different by using flow composite. No significant different were observed between root and coronal dentin interfaces.

  • 33.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Marques, Paula
    University of Aveiro.
    Gracio, Jose
    University of Aveiro.
    Enqvist, Evelina
    Gonçalves, Gil
    University of Aveiro.
    Novel bio nano-composite for biomedical application2010In: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Conference paper (Refereed)
    Abstract [en]

    Carbon nanoforms exhibit exceptional physical and chemical properties due to their nano-scale dimensions. They also have very high aspect ratio which makes them an excellent reinforcement material for polymer composites. Hydroxyapatite (HA) is the prime constituent of bone generation because of its ability to bond chemically with living bone tissues and positively affect the osteoblasts; this is due to its similar chemical composition and crystal structure to apatite in the human skeletal system. Ultra high molecular weight polyethylene (UHMWPE) is already used as implant material in high stress bearing areas such as hip and knee prosthesis. Wear debris of ultra high molecular weight polyethylene cause osteolysis which is a major reason of long-term failure of total hip replacements.In this study carbon nanoforms together with hydroxyapatite (HA) nanoparticles were used as reinforcement in UHMWPE matrix in order to produce high strength and wear resistant biocomposites with better bioactivity character. Solvent casting and melt blending methods was used during the preparation of this bio-nano composite. The phase compositions and the surface morphology of the nanocomposite material have been studied using X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), and micro-Raman spectroscopy. Nanoindentation technique was used to determine the elastic modulus and hardness of the nanocomposites with different weight% of HA and carbonnanoforms concentrations. The tribologic behaviour of this nano composite was studied using pin-on-plate method. Wear and friction of the produced nano-composites were studied in different biological lubrications.

  • 34.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    McLaren, Heather
    Leeds University, UK.
    Neville, Anne
    Leeds University, UK.
    Bryant, Micheal
    Leeds University, UK.
    Tribological performance of PEEK and a PEEK composite in reciprocating sliding under various conditions2018Conference paper (Refereed)
  • 35.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Melk, Latifa
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Fracture toughness and thermal characterisation of GO based UHMWPE composites2018Conference paper (Refereed)
  • 36.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Nilsson, Greger
    SICOMP AB, Swedish Institute of Composites.
    Undersökning av rotstift av kompositmaterial2004Report (Other academic)
  • 37.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ramanenka, Dmitrij
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Enqvist, Evelina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Mechanical and thermal characterisation of novel UHMWPE-nano composite: A copmarrative study against virgin UHMWPE2012Conference paper (Refereed)
  • 38.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Söderholm, Karl-Johan M.
    University of Florida.
    How filler properties, filler fraction, sample thickness and light source affect light attenuation in particulate filled resin composites2005In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 21, no 8, p. 721-730Article in journal (Refereed)
    Abstract [en]

    The way by which variables such as filler type, filler surface treatment and light source affect light attenuation in particulate filled resin composites was presented. Mixture of 50 wt% bisGMA and 50wt% TEGDMA consisting of a photo-initiatior and a co-initiator was prepared. Three different filler types, HBB, SBB, and KU, which were either silane surface treated or not, were added to that mixture in eight different volume percentage. It was observed that of the two light sources, more light was absorbed by the composite when the laser light was used. It was also observed that the HBB filler absorbed most light and the KU filler the least.

  • 39.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, K J
    University of Florida, Gainesville.
    Young's modulus and degree of conversion of different combination of light-cure dental resins2009In: Open Dentistry Journal, ISSN 1874-2106, E-ISSN 1874-2106, Vol. 3, p. 202-207Article in journal (Refereed)
    Abstract [en]

    Objectives: To evaluate Young's modulus and degree of conversion of several combinations of bisGMA,To evaluate Young's modulus and degree of conversion of several combinations of bisGMA, UEDMA, TEGDMA light-cure dental resin.Methods: Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and UEDMA. Small universal testing machine and photo-calorimetry were used for the tests. The results were evaluated using ANOVA and Duncan's multiple range tests and regular t-test. Results: Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (p<0.05). Degree of conversion was significantly (p<0.05) higher when the wt% of TEGDMA was high in the mixtures than for highly concentrated bis-GMA (resin mixtures with TEGDMA in comparison to mixture with bisGMA had higher degree of conversion). DC% was significantly higher (p<0.05) for binary mixtures of UEDMA and TEGDMA, and significantly lower for 100 wt% bis-GMA´(p<0.05). The DC% values were between 53.1%±0.9% (100% bisGMA) and 85.6%±1% (80% UEDMA-20% TEGDMA). The concentration of bisGMA, in the monomer mixture, affected DC% and Young's modulus oppositely. Conclusions: The differences in the values for DC% were mostly justified by the differences in the molecular structures of The differences in the values for DC% were mostly justified by the differences in the molecular structures of the different monomers. It was also revealed that higher DC% does not always result in a higher Young's modulus, because molecular and network structural parameters play major roles in the final physical properties of the mixtures.

  • 40.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Cure kinetic behavior of light-cure dental composites2003Article in journal (Other academic)
    Abstract [en]

    Objective: To investigate differences in cure kinetic behaviours of different photo and co-initiator systems used in dental light-cure composites. Method: A resin system (50 wt.% of bisGMA and 50 wt.% of TEGDMA) was mixed with either campherquinone (CQ) or 1-phenyl-1,2-propanedione (PPD) as photo-initiator. N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), N,N-diethanol-p-toluidine (DEPT) and 2-dimethylaminoethyl methacrylate (DMAEMA) were used as co-initiators respectively. Complex cure behaviour of 24 experimental mixtures made from 2 photoinitiators, 4 co-initiators, 3 curing light/time was studied with differential Scanning Calorimetery (DSC). Six specimens of each composition were cured either with 800 mW/cm2 for 40 s, soft start curing for 60 s or LED for 40 s. The DSC results were analysed using ANOVA and Duncan's multiple range test and regular t-test. Result: Rate of polymerisation was significantly (p<0.05) higher when materials were cured with 800 mW/cm2 compare to soft start and LED curing methods when the final degree of conversion values did not differ significantly (p>0.05). Compared to campherquinone, the photo-initiator PPD reduced the maximal DC% and rate of the polymerisation significantly (p<0.05). PPD was not a suitable photo-initiator when cured with LED since the blue spectra emitting from the used LED lamp does not cover the optimal activation wavelength for PPD properly. The highest DC% measured at the end of curing was for CQ & DABE 74%±1 cured with 800 mw/cm2 for 40s and the lowest was for PPD&DMAEMA 22%±1.1 when material was cured with LED for 40s. Use of DEPT resulted in significant decreases in degree of conversion (p<0.05). Conclusion: It was concluded that intrinsic slow cure might be obtained with certain compositions of photo & co-initiators and curing methods without impairing the final extent of degree polymerzation.

  • 41.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    University of Florida.
    How light irradiance and curing time affect monomer conversion in light-cured resin composites2003In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 111, no 6, p. 536-542Article in journal (Refereed)
    Abstract [en]

    We tested the hypothesis that the degree of conversion of a light-cured dental composite relates to the calculated (s × mW cm-2 = mJ cm-2) rather than to the irradiance value (mW cm-2) of the light source. Two light-curable composite resins were cured with three different light irradiance values over different curing times. The specimens tested were 2, 4 or 6 mm thick, and the degree of conversion values were measured with Raman spectroscopy on the top and the bottom surfaces of the specimens. The highest conversion value of one of the materials was just below 60%, while the maximal conversion value of the other material was just below 65%. That difference in conversion values could be related to differences in monomer systems used in the two composites. By considering light energy per square centimeter (J cm-2) rather than light irradiance (mW cm-2), we found that equivalent energy values gave similar conversion values for a certain sample thickness. From these findings, we conclude that our experimental results support our hypothesis.

  • 42.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Berglund, Lars
    Kungliga tekniska högskolan, KTH.
    Effect of light intensities variations on bulk curing of dental composites2002In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 81, no Suppl. 1Article in journal (Refereed)
    Abstract [en]

    The light intensity used during curing of light curable dental composites is believed to affect the residual stress level. In this study we tested the hypothesis that low light intensity and long but clinically acceptable light curing time, can produce composites with physical/clinical properties (e.g. volumetric shrinkage, linear contraction stress, degree of conversion (DC%) and Young's modulus) comparable to those of high light intensity cured composites. Methods: Two dental composites, Z100 and Z250, were investigated. Specimens were cured with light intensities of 200, 450 and 800 mW/cm2 for 140, 60 and 35 s from a distance of 7 mm. Linear contraction strains were measured with strain-gages attached to stainless steel rings serving as molds (8 mm in diameter and 4 mm high). DC% was measured at the top and the bottom of samples as well through the bulk using FTIR. Volumetric polymerization shrinkage was determined using a water displacement method. Young's modulus was determined in tension on composite specimens with dimensions of 8 x 50 x 1 mm. Results: Polymerization stress level decreased significantly (p<0.05) when cured with 200 mW/cm2 rather than with 800 mW/cm2. Reduction in light intensity did not decrease the DC% values significantly, nevertheless the most dramatic differences existed between top and bottom surfaces (p<0.05) rather than among curing groups. Measured modulus and volumetric shrinkage values were no significantly different (p>0.05) between different light intensity groups. Conclusion: Low light intensity decreased the residual stress and DC% values (through the depth of cure) significantly (p<0.05), but did not significantly affect the Young's modulus and the volumetric shrinkage values. The lower residual stress values, reflected by lower strain levels in the metal rings used during measurement, suggest that more stress relaxation occurs in the low light intensity group during cure. Our results support the proposed hypothesis

  • 43.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Berglund, Lars
    Kungliga tekniska högskolan, KTH.
    Effect of light-intensity variations on bulk curing of dental composites2002In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 81, no Suppl 1Article in journal (Other academic)
  • 44.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Berglund, Lars
    How light-intensity and cure-time affect monomer conversion in light-cured composites2002In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 81, no Suppl 1Article in journal (Refereed)
  • 45.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan
    Florida University.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Quantitative measurements of dental light beam (halogen versus LED)2005Conference paper (Other academic)
  • 46.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Department of Dental Biomaterials, University of Florida.
    Dynamic mechanical thermal analysis of two light-cured dental composites2005In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 21, no 10, p. 977-983Article in journal (Refereed)
    Abstract [en]

    ObjectivesClinical observations suggest that some composite resins are more often linked to post-operative sensitivity than others. These differences may relate to differences in modulus of elasticity and polymerization rates among materials. The aim of this study was to identify viscoelastic behavior of two light curable composites and determine whether significant differences in viscoelastic behavior exist between the two materials when light cured at each of three different irradiance values.MethodsTwo composites (Z100 and Z250 by 3M ESPE) were evaluated. Six specimens per composite and irradiance value (250, 500 and 850 mW/cm2) were made. The curing times were chosen to produce a fixed energy value of 30 J/cm2 independent of irradiation value. Dynamic mechanical thermal analysis (DMTA) was performed in single cantilever clamped mode.ResultsThere were significant differences in transition temperatures between the two materials and the three frequencies at their glass transition temperatures, while significant differences did not exist at the lower transitions. The glass transition of Z250 was lower and narrower than that of Z100. Z250 exhibited lower storage modulus values. The irradiance values did not affect any of the transition temperatures significantly.SignificanceThe lower and more distinct Tg of Z250 suggests that Z250 cures more efficiently than Z100. The lower storage modulus of Z250 suggests that Z250 develops less stress in the tooth than Z100 during curing if shrinkage is the same for the two materials. The findings suggest that the material chosen, rather than irradiance, determines the stress level developed during light curing.

  • 47.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    How degree of conversion and E-modulus of light-cure dental-resins interact2006In: 84th General Session and Exhibition of the IADR and 1st Meeting of the Pan-Asian-Pacific Federation: Brisbane Convention and Exhibition Centre, Brisbane, Queensland (Australia), 28 Jun-1 Jul 2006, IADR , 2006Conference paper (Other academic)
    Abstract [en]

    Objectives: To investigate how E-modulus, degree of conversion (DC%) and rate of polymerization of the most used monomer resins in dental light-cure composites interact. Methods: Young's modulus and DC% were studied for 21 different resin combinations of three commonly used dental monomers, bis-GMA, TEGDMA and UEDMA (combinations of 0, 20, 40, 60 and 100 wt% as it is illustrated in the figure). For each resin combination 6 specimens were tested. Small Instron and differential scanning calorimetry (photo-calorimetry) were used as testing machines. The results were tested using ANOVA and Duncan's multiple range tests and regular t-test. Results: Rate of polymerization was significantly (p<0.05) higher when the wt% of the TEGDMA was high in the mixtures compare to highly concentrated bis-GMA. DC% was significantly high (p<0.05) for binary mixture of UEDMA and TEGDMA. The DC% was significantly lower for 100 wt% bis-GMA (p<0.05). The calculated values for DC% were between 53.1%± 0.9% and 85.6%±1%. Young's modulus values varied between 2.37± 0.15 GPa and 4.15± 0.2 GPa. It was noticeable that by adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (p<0.05). There were no significant (p>0.05) differences between Young's modulus values when the monomer mixtures contained bis-GMA, TEGDMA and UEDMA at different concentration levels. The higher the concentration of bisGMA in the monomer mixture, the lower was the degree of conversion. However, Young's modulus increased at higher concentration of bis-GMA. Conclusions: The differences in the values for degree of conversion were mostly justified by the differences in the molecular structures of the different monomers. It was also revealed that higher degree of conversion does not always result in a higher Young's modulus, because molecular and network structural parameters play major roles in the final mechanical/physical properties of the mixtures.

  • 48.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Department of Dental Biomaterials, University of Florida.
    Influence of light-curing procedures and photo-initiator/co-initiator composition on the degree of conversion of light-curing resins2005In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 16, no 1, p. 47-52Article in journal (Refereed)
    Abstract [en]

    Objective: The hypothesis that the degree and rate of conversion can be modified favourably by using different light-curing procedures and different photo initiator/co-initiator combinations was tested.Method: A photo-initiator (0.02 mM/g resin); either camphorquinone (CQ) or 1-phenyl-1,2-propanedione (PPD), was mixed with bisGMA:TEGDMA (50:50 by weight). In addition, a co-initiator (0.04 mM/g resin); either N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), or 2-dimethylaminoethyl methacrylate (DMAEMA), was added. These six combinations were subjected to three curing conditions (standard curing, soft-start curing or LED curing). The conversion levels (DC) were determined with differential scanning calorimetry (DSC). The DSC results were analysed using a general linear model (GLM) and Duncans multiple range test and regular t-test.Results: The fastest conversion initially was obtained by standard curing, followed by LED curing and soft-start curing. After 40 s of curing, conventional curing and soft-start curing produced a higher DC than LED curing. However, strong interactions occurred between the different variables (curing method, initiator and co-initiator). Initially, CQ was more efficient than PPD, but after 40 s, this difference was insignificant.Conclusion: By using soft-start curing and an appropriate photo initiator/co-initiator combination it is possible to achieve slow curing and a high DC at within a curing time of 40 s.

  • 49.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Berglund, Lars A.
    Luleå tekniska universitet.
    Effect of light power density variations on bulk curing properties of dental composites2003In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 31, no 3, p. 189-196Article in journal (Refereed)
    Abstract [en]

    Objective. The hypothesis that low light intensity and long but sufficient curing time can produce composites with volumetric shrinkage, degree of conversion (DC%) and Young's modulus (E-modulus) comparable to those of high light intensity cured composite was tested, when the contraction strain and heat generation were lower with low light intensity curing. Methods. Dental composites (Z100 and Z250, 3M ESPE) were investigated. Specimens were cured with light intensities of 200, 450 and 800 mW/cm2 for 140, 60 and 35 s from a distance of 7 mm. Strain-gages were used for contraction strain measurements. DC% was measured at the top and the bottom of 4 mm thick samples using FT-Raman spectroscopy. Volumetric polymerization shrinkage was determined using a water displacement method. E-modulus was determined in tension on composite specimens. Results. The results were analyzed using ANOVA and Duncan's multiple range tests and regular t-test. Polymerization stress level decreased significantly (p<0.05) when cured with 200 mW/cm2 rather than with 800 mW/cm2. Temperature rises were significantly different (p<0.05) for different composites and light intensity values. Reduction in light intensity did not decrease the DC% values significantly at the top surfaces. The most dramatic differences existed between top and bottom surfaces (p<0.05) rather than among curing groups. Measured E-modulus and volumetric shrinkage values were not significantly different (p>0.05) between different light intensity groups. Conclusion. DC%, E-modulus and the volumetric shrinkage values in cured composites were not affected by low light intensity, however, the contraction strain and polymerization's exotherm were decreased. Thus our results support the proposed hypothesis.

  • 50.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Tavassoli, Sara
    Department of Carilogy and Preventive Dentistry, Tehran.
    Mehran, Majid
    Department of Carilogy and Preventive Dentistry, Tehran.
    Shear bond strength of sealant to primary and permanent enamel2010Conference paper (Refereed)
    Abstract [en]

    Objectives: The purpose of this study was to compare the effect of phosphoric acid, one-bottle adhesive and self-etching adhesive on shear bond strength (SBS) of light-curing sealant to ungrounded primary and permanent enamel.Methods: In this in vitro study 30 primary molars and 30 permanent premolars were cleaned and divided to 6 groups (n=10). The following materials used on flattest, peripheral surface (mesial or distal) of permanent (groups 1,3,5) and primary (groups 2,4,6) teeth. Group 1&2 (control): acid etching + light-Curing sealant (Concise 3M-ESPE). Group 3&4 (SB): acid etching +2 layer bonding agent (Single Bond 3M-ESPE) + sealant. Group 5&6 (PLP): self etching adhesive (Prompt L-Pop 3M-ESPE) +sealant. The teeth were thermocycled 500 cycles between 5„a and 55„a with a dwell time of 30s. For shear bond strength testing, the load was applied vertically from the Zwick universal testing machine with load cell 10KN to the base of the mold at a cross-head speed of 5 mm/min. Then two way variance analysis (Between-Subject Effect) and multiple comparisons (Post Hoc Test-LSD) were performed. Failure mode was determined in a stereomicroscope at x20. Result: There was no significant difference in SBS between control (1&2), and PLP (5&6) groups, neither between SB (3&4) and PLP (5&6) groups (P>0.5). But there was significant difference in SBS between control and SB (3&4) groups (P=0.22). However, the SBS to primary enamel were lower than those to permanent enamel (P<0.5). Conclusion: The self-etching adhesive Prompt L-Pop, is as effective as conventional acid-etching in mediating a bond between a light-curing sealant and ungrounded human enamel. Applying Single Bond adhesive under fissure sealant would be beneficial for increasing the bond strength.

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