This research studied the influence of RI mismatch of resin/fillers components on translucency and chameleon effect (color matching) of experimental resin composite. If there is a mismatch between the RI of the filler and the resin matrix, the filler may rise the opacity of the materials owing to extreme refraction and reflection at the filler-matrix interfaces. The refractive index of the fillers should vary from 1.47 to 1.52 and match that of the cured resin matrix. Resin composites additionally include an organic matrix with a RI that varies from those of the inorganic fillers. The effect of the loading ratio, type and particle size of the fillers on the appearance of resin composites has been explored in literature in several studies. In case of materials containing different components, such as resin composites, the different components like the inorganic fillers and the resin matrix are needed to have similar refractive indices (RI) in order to become highly translucent. A shift in the refractive index usually results in a shift in the direction of light.
![polymer refractive index database polymer refractive index database](https://i1.rgstatic.net/publication/325691781_Chemometric_modeling_of_refractive_index_of_polymers_using_2D_descriptors_A_QSPR_approach/links/5b2ca789a6fdcc8506bc9614/largepreview.png)
A translucent material permits light to pass into its structure, but it disperses light in comparison with transparent material, preventing the objects behind it from being clearly observed. Translucency could be defined as middle state of opacity and transparency. However, the chameleon effect of resin composites was influenced also by the variation in the initial color and size of the restoration. translucency within the resin composite are capable to produce a chameleon effect attributed to the reflection of the adjacent tooth color and transference of its own color into the nearby tooth structure, which would lead to enhanced color matching. It has been stated that the materials showing sufficient light diffusivity, i.e. This trend or wish of shortening the restorative procedure time and simplifying color matching leads to competition between dental manufacturers to develop a universal resin composite (single shade), which could possibly match a wide range of classical shades. Accordingly, dental practitioners are always searching for an effective method to handle their clinical procedures involving simple techniques and reduced practical steps to decrease total time and costs. It was stated that regular dental practitioners working in public dental services consume over half of their working hours applying direct resin composite restorations. In addition, resin composites are accessible in multiple opacities, typically referred to as dentin, body or opaque and enamel or translucent, with the goal of mimicking the dentin and enamel optical properties. The color difference of natural teeth promoted manufacturers to develop resin composite systems that involve many colors where layering techniques have been suggested. Translucency and color have the highest effect on the natural tooth appearance among these esthetic characteristics, since they are the most easily observed.
![polymer refractive index database polymer refractive index database](https://ars.els-cdn.com/content/image/1-s2.0-S0927025621001853-ga1.jpg)
Color, translucency, opalescence and fluorescence are optical properties that give the natural tooth its essential appearance. One of the key objectives of esthetic restorative dentistry is to create restorations that complement the natural tooth's optical properties.