DEFORMATION BEHAVIOUR OF LED AND HILED CURED DENTAL RESIN MICROHYBRID AND NANOFILLED COMPOSITES

O. A. Adeleye; O. A. Fakinlede; J. S. Ajiboye; I. C. Adegbulugbe

O. A. Adeleye Department of Systems Engineering, University of Lagos, Lagos, Nigeria
O. A. Fakinlede Department of Systems Engineering, University of Lagos, Lagos, Nigeria
J. S. Ajiboye Department of Mechanical Engineering, University of Lagos, Lagos, Nigeria
I. C. Adegbulugbe Department of Restorative Dentistry, College of Medicine of the University of Lagos, Idiaraba

Keywords: Deformatio, Dental-resin, Microhybrid, Nanofilled, Viscoelastic-viscoplastic

Abstract

The 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.