Department of Biomedical Engineering

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Browsing Department of Biomedical Engineering by Author "Ajiboye, J.S"

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  • Item
    Open Access
    Deformation Behavior of Led And Hiled Cured Dental Resin Microhybrid and Nanofilled Composites
    (UNILAG Journal of Medicine, Science and Technology, 2016) Adeleye, O.A; Fakinlede, O.A; Ajiboye, J.S; Adegbulugbe, C.I
    The deformation behavior of commercial microhybrid resin based composite (20/20 composite) and nanofilled composite (Light Cured Universal Composite) cured with the conventional Light Emitting Diode (LED) and exponential Light Emitting Diode (HiLED) under various loading condition have been investigated. Deformation of restorations such as shrinkage and shearing from curing and mastication have been a major concern for clinicians because of void and crack formations in restored tooth structure which affects the mechanical properties of the resin composites. Samples of microhybrid resin based composite (20/20 composite) and nanofilled composite (Light Cured Universal Composite) were molded with copper foil molds with standard dimension 2 x 2.5 x 8mm, photo-cured by both conventional Light Emitting Diode (LED) and exponential Light Emitting Diode (HiLED) and then tested on the ElectroForce 3200 for their deformation behavior and mechanical properties. Effects of variation of strain rate and curing time were also investigated. The results showed that, out of the four groups of samples studied, microhybrid resin based composite (20/20 composite) cured with exponential Light Emitting Diode (HiLED) exhibited highest tensile strength of 28 MPa. The loading and unloading of the samples exhibited hysteresis responses and path dependence nonlinear behavior. At stress values less than 4 MPa, rate dependent recoverable (viscoelasticity) deformation was observed in all the four groups of samples but at stress values beyond 4 MPa rate dependent irrecoverable (viscoplasticity) deformation was observed. Finally, it was observed that increasing curing time leads to increasing tensile strength for materials cured by both methods.
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    Open Access
    Viscoelastic-Viscoplastic Material Model for Nonlinear Deformation of Dental Resin Composites
    (21st International Conference on Computer Methods in Mechanics, 2015, Gdansk, Poland, 2015) Adeleye, O.A; Fakinlede, O.A; Ajiboye, J.S; Adegbulugbe, C.I
    The rate-dependence, recoverable and irrecoverable nonlinear deformation behavior of microhybrid and nanofilled dental resin composites cured with the conventional light emitting diode (LED) and exponential light emitting diode (HiLED) composites under uniaxial loading is here presented. Experimental study based on displacement controlled multiple stress creep recovery (MSCR) tests revealed hysteresis loop in loading and unloading states indicating an inherent viscoelastic nature, and at stress values less than 4 MPa, rate dependent recoverable strains were observed. But at stress values higher than 4 MPa, irreversible strains were observed which also indicates viscoplasticity. Hence a viscoelastic-viscoplastic constitutive model can be used to represent the material deformation behavior for the dental resin composite.