الفهرس 
TitleOnly 14 pages are availabe for public view
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Abstract
Acrylic based resins are frequently used in daily dental practice, as they are able to provide the essential properties and necessary characteristics to be used in diverse functions. Most common use of the materials includes denture bases and denture liners, orthodontic appliances and temporary crowns. Polymethylmethacrylate (PMMA) is generally used as a common component of acrylic materials due to its optical properties, biocompatibility and aesthetics. The popularity of PMMA materials is based on its low cost, relative ease of use, reliance on simple processing equipment, lightweight, and color matching ability.
However, acrylic resin denture base materials are low in strength, brittle, and low in thermal conductivity also, low mechanical properties against impact, bending, and fatigues are important issues to be addressed in order to improve acrylic polymers properties for removable acrylic appliances and dentures.
Today, the revolutionary development of nanotechnology has become the most highly energized discipline in science and technology. The intense interest in using nanomaterials stems from the idea that they may be used to manipulate the structure of materials to provide dramatic improvements in electrical, chemical, mechanical and optical properties.
This work aimed to explore the possibility of improving the physical properties of acrylic resin by adding small concentrations of silver (Ag) and gold (Au) nanoparticles.
In the present study, different types of nanomaterials were prepared such as Ag and Au nanoparticles using chemical reduction process. The prepared Ag and Au nanoparticles were characterized using Transmission Electron Microscope (TEM) to determine the morphology and the size of nanoparticles.
According to adding Ag and Au nanoparticles to heat cure acrylic resin, the specimens were grouped as the following:
group 1: 5 specimens of acrylic materials were used as the control group.
group 2: 5 specimens of acrylic materials were mixed with 20µl AgNPs of concentration 1mM.
group 3: 5 specimens of acrylic materials were mixed with 20µl AgNPs of concentration 1 µM.
group 4: 5 specimens of acrylic materials were mixed with 20µl AuNPs of concentration 1mM.
group 5: 5 specimens of acrylic materials were mixed with 20µl AuNPs of concentration 1 µM.
group 6: 5 specimens of acrylic materials were mixed with 20µl AuNPs and 20µl AgNPs of concentration 1mM.
• Scanning electron microscope (SEM) was used to characterize the dispersion and distribution of gold and silver nanoparticles in the specimens.
The results of the present work are:
For Au nanoparticles they were spherical in shape and there is a variation in particle sizes ranging from 5.76 nm to 15.5 nm with an average size 9.42 nm while For Ag nanoparticles they were also spherical in shape. However there is a variation in particle sizes ranging from 12.2 nm to 16.4 nm with an average size 14.3 nm.
The morphology of the samples in cross-section show that an increase in Au NPs and Ag NPs concentrations caused aggregation of nanoparticles and pores in the samples by extra content, resulting in changes in the fractured surfaces. Linear attenuation coefficient measurement results show that the attenuation coefficients for acrylic polymers modified by different concentrations of Au NPs and Ag NPs give higher values than blank acrylic polymer.
In dielectric properties measurement, the electrical conductivity of blank acrylic polymer and acrylic polymers modified by different concentrations of Au NPs and Ag NPs showed a continuous increased with the increase in frequency. However, the electrical conductivity of acrylic polymers modified by different concentrations of Au NPs and Ag NPs showed more increase than blank acrylic polymer at high frequency. The increment of the dielectric conductivity followed the order of acrylic resin with gold nanoparticles of 1 mM > acrylic resin with silver nanoparticles of 1 mM > acrylic resin with gold and silver nanoparticles of 1 mM > acrylic resin with gold nanoparticles of 1 µM > acrylic resin with silver nanoparticles of 1 µM > blank acrylic resin.