Browsing UNILAG Journal of Medicine, Science & Technology by Author "Adeleye, O.A"
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- ItemOpen AccessDeformation Behaviour of Led and Hiled Cured Dental Resin Microhybrid and Nanofilled Composites(University of Lagos Press, Akoka, 2016) Adeleye, O.A; Fakinlede, O.A; Ajiboye, J.S; Adegbulugbe, I.CThe deformation behavior of commercial microhybridresin 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 microhybridresin 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 Electro Force 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, microhybridresin 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.
- ItemOpen AccessThe Effects of Resin Matrix Composition, Filler Volume and Particle Size on the Mechanical Properties of Dental Resin Composites(University of Lagos Press, Akoka, 2016) Adeleye, O.A; Fakinlede, O.A; Makinde, J.TThe behaviour of dental resin composites (DRC’s) under mechanical loading has been of concern in dentistry as it determines their clinical application. The aim of this study is therefore to check the effect of the resin matrix composition, filler volume and particle size on the mechanical properties of DRC’s. In this experimental in-vitro study, six types of composite resins were used as follows: Two(2) Micro hybrid- Super Cor (SC) and Natural look(NL); Two(2) hybrid- Alpha dent (AD) and Henry Schein (HS) and two(2) Nano hybrid- i-Xcite(IX) and Fusion(FS),each with varying resin matrix composition, filler volume and particle size. Samples were prepared in aluminum molds and light cured using Optilight Max GNATUS light curing unit at constant time intervals of 20 seconds as specified in literature and designed by curing light manufacturers. The specimens were stored in distilled water at 37°C for 48 hours. Subsequently, the specimens were subjected to tensile test and three point loading using the BOSE Electro Force 3200 system at cross head speed of 1.0mm/min and varying speed of 0.5, 2.0 and 5.0mm/min. Henry Schein 20/20 (hybrid;bis-GMA;56%) exhibited flexural strength of 17MPa but tensile strength of 29.7MPa amongst the group. i-Xcite (nanohybrid; bis-GMA,TEGDMA,UDMA;76.5%) showed the flexural strength of 138MPa and relatively low tensile strength of 25.3MPa. All resin types showed increasing flexural strength with increasing strain rate. Tensile and Flexural strength are dependent on the resin matrix composition, the filler particle size and then the filler volume in that order. Keywords: