The Effects of Irradiation Distances and Energy Densities on the Nanomechanical Properties of Dental Composites
This study evaluated the influence of changing light energy density, as a result of the use of different distance levels of irradiation, on the nanohardness and modulus of elasticity of four composite materials. Two nano-composites (Filtek Z-350 XT; Tetric-N-Ceram), a submicron hybrid composite (Spectrum TPH3) and a microhybrid composite (Filtek P90) were used. Eighteen composite discs were fabricated from each material and divided into three groups. Samples were light-cured at three distance levels: direct contact (44 J/cm2), 2 mm distance (32.8 J/cm2) and 4 mm distance (19.2 J/cm2). Samples were then subjected to nanomechanical testing by means of a Berkovich indenter probe. Although, at higher energy density, nano-based composites showed the highest nanohardness values, no significant differences among the materials were found at all three levels of distance (p > 0.05). However, all materials, except STPH3, showed significant differences in elastic modulus values between 4 mm and other levels of irradiation (p < 0.05). Therefore, moving the tip of an LED unit, with 1100 mW/cm2, 4 mm away may affect the modulus of elasticity and, therefore, the longevity of the restorations.
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Document Type: Research Article
Publication date: 01 August 2017
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- Journal of Biomaterials and Tissue Engineering (JBT) is an international peer-reviewed journal that covers all aspects of biomaterials, tissue engineering and regenerative medicine. The journal focuses on the broad spectrum of research topics including all types of biomaterials, their properties, bioimplants and medical devices, biofilms, bioimaging, BioMEMS/NEMS, biosensors, fibers, tissue scaffolds, tissue engineering and modeling, artificial organs, tissue interfaces, interactions between biomaterials, blood, cells, tissues, and organs, regenerative medicine and clinical performance.
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