## 4 Discussion
Moreover, the universal ability to match with each color might be attributed to the high translucency, which aids in light reflection from the wall of the tooth, thereby enabling the tooth to mimic similar shades [23]. Moreover, in the present study, the color stability levels of the composites (FT and OM) were measured after specimens had been submerged in cola and coffee for 2 weeks. The restorative composites demonstrated significant differences in cola compared to coffee. FT showed better stain resistance in cola compared to OM, while OM showed comparable stain resistance to FT in coffee. The possible explanation for the color changes is the small filler particles and acidic properties, which erode the surface texture and increase water sorption when teeth are exposed to the fluids, allowing for greater levels of restorative staining, affecting light transmission [24; 25]. It has been observed that the pH of cola ranges between 1.5 and 2, which enables an acceptable \(\Delta\)E change for resin composites [26]. It has also been suggested that the ability of OM to mimic similar shades to surrounding teeth is due to the filler particles being the same size [26]. In addition, [PERSON] et al. reported that nanocomposites with smaller particles produce smoother surfaces, reducing surface stains [27]. Furthermore, the lower filler content and the smaller structure of the monomers contributes greatly to the material discoloration, especially under the influence of beverages. A higher filler content directly improves the translucency due to optimal optical scattering of the composite [28]. A study by [PERSON] [29] showed higher translucency values for composites with high filler contents compared to materials with low filler contents, which also influences the blending effect [30]. However, in the present study, the filler content was not a variable and both resin composites contained similar filler contents; therefore, further studies are warranted to assess the influence of the filler size, shape, and proportions on the color stability of resin composites. Studies have identified that color changes of less than 3.5 \(\Delta\)E are not detectable by the naked eye [30]. In the present study, except for shade B1, all FT and OM-C samples showed color differences of less than 3.5 \(\Delta\)E. This suggests that although the color changes were higher for OM-C samples than FT samples, the changes were clinically undetectable, suggesting a possible indication of OM-C in clinical patients. Overall, within the experimental limitations, the OM resin composite showed variable color matching and color stability, which was not comparable to the conventional restorative material. The clinical application of in vivo studies is greater than in vitro studies as they demonstrate accurate outcomes based on the impacts of oral conditions. Oral conditions and ageing influence the color stability of resin composites. As the impacts of aging were not assessed in the present study, future studies are recommended to assess the color stability of OM with ageing. In addition, the surface polish and finish of resin materials impacts their translucency, color stability, and aesthetic outcomes. However, in the present study, the effect of the surface finish was not assessed for the OM single-shade resin. Therefore, further studies investigating the influence of the surface finish, ageing, occlusal loads, and clinical conditions on OM are warranted.