Color properties of polymethylmethacrylate material incorporated with gold nanoparticles

The aim of this study was to investigate the influence of the addition of different concentrations of gold nanoparticles (AuNPs) on color parameters of nano-modified polymethyl methacrylate (PMMA) prosthesis base material as well as their mutual comparison. In our investigation, we used AuNPs produced by new technologies Ultrasonic Spray Pyrolysis (USP) method, from the precursor solution from Au (III)acetate. The addition of highly dispersed AuNP in PMMA (ProBase Hot, Ivoclar Vivadent, Liechtenstein), followed by the formation of nano-modified polymer composite is performed in a special way. Four groups of samples by uniform dimensions of 50 x 50 x 4 mm, and with different AuNPs concentration (PMMA-AuNP1 0,12%, PMMA-AuNP2 0,43%, PMMA-AuNP3 0,74% and control group) were performed.The color values show that L * (light) PMMA-AuNP1 sample is slightly lower than the base sample, while the PMMA-AuNP2 and PMMA-AuNP3 have a higher value. The basic sample has the highest C * value, so it is the most saturated (most colorful). The basic sample also has the highest value of b * (more yellow shades), while the other three samples have a lower b * value (more blue shades). Also, the color angle h is smaller than the basic one for all three samples (closer to the red color axis a +). Color changes in base resins were significantly affected by the addition of gold nanoparticles (p˃0.05). The color differences ΔE * are in the range from 2,6 – 4,9. The addition of AuNPs at the tested concentrations does not have a statistically significant effect on the change in material translucency of PMMA/AuNPs nanocomposite.