The effect of refractive index of fillers and polymer matrix on translucency and color matching of dental resin composite

Abstract

Objective When restorative resin composites absorb light from the surrounding tooth structures, it creates a color-match, which is known as ‘a chameleon effect’. In this study, series of co-monomer mixtures were prepared with an increasing refraction index (RI) and mixed with glass fillers. The aim of this study was to optimize the mismatch of RI of resin/fillers to create the chameleon effect. Materials and Methods BisGMA/TEGDMA resins were prepared with seven different mix fractions from 20 to 80%. Two different series (A&B) of submicron (Ø 0.7 μm) silanized fillers (70 wt%) (A: Schott RI = 1.53, B: Esschem RI = 1.54) were mixed with resins (30 wt%). Disc-shaped specimens (1 mm thickness, Ø10 mm) for each composite combination ( n = 3) were prepared and light cured for 20 s. Commercial resin composite (OmniChroma, Tokuyama Dental) was used as control. The translucency parameter (TP) was measured using a spectrophotometer. The color matching abilities of the experimental composites were visually analyzed. Data were statistically analyzed using ANOVA. Results The composition of resin and type of fillers had a statistically significant effect on TP values ( p < .05). The highest TP values were achieved around 50%-50% fractions of Bis-GMA and TEGDMA for series A and around 60%-40% fraction of Bis-GMA and TEGDMA for series B. Data showed that a high or low fraction of BisGMA resulted in a low translucent composite. Experimental resin composite (80% Bis-GMA) from series A was behaving similarly to Omnichroma in reference to TP values and color matching. Conclusions Including fillers with RI of 1.53 into BisGMA/TEGDMA resin with RI of 1.524 resulted in composite resin providing a good color match with surrounding structure ‘chameleon effect’.

Effects of Sr/F-Bioactive Glass Nanoparticles and Calcium Phosphate on Monomer Conversion, Biaxial Flexural Strength, Surface Microhardness, Mass/Volume Changes, and Color Stability of Dual-Cured Dental Composites for Core Build-Up Materials

“…The results showed that the additives slightly reduced the DC of the experimental materials due probably to the mismatch between the refractive index (RI) of fillers and monomers. The RI of fillers was expected to fall within 1.4–1.5 [ 55 ] to match with the RI of the monomer mixture such as UDMA/TEGDMA (RI~1.45) [ 10 ]. Although the actual refractive indices of MCPM and Sr/F-BGNPs are not known, the result indicated that the effect of the additives on the reduction of DC upon light activation was minimal (~2%) compared to that reported in the previous studies (~4–10%) [ 8 , 10 ].…”

Rational durability of optical properties of chameleon effect of Omnichroma and Essentia composite thermocycled in black dark drinks (in vitro study)

“…One of the main goals of aesthetic restorative dentistry is to develop a restoration that matches the optical qualities of the natural tooth. The current trend of reducing clinical restorative treatment time and simplifying color matching has promoted dental manufacturers to compete to develop a universal resin composite (single shade) that might potentially match a wide variety of classic shades (Oivanen et al 2021).…”

Accelerated Aging Effects on Color Change, Translucency Parameter, and Surface Hardness of Resin Composites

“…Translucency is an optical property that lies between opacity and transparency in terms of the amount of light that can pass through a material. Unlike transparent materials, translucent materials scatter light rays and prevent objects behind the material from being seen clearly [ 4 ]. The translucency parameter (TP) is used to assess the translucency of restorative materials.…”