Discussion
omnichroma, Omnichroma
CAVITY
The wide use of the shades of adhesive composite as esthetic restoration in anterior and posterior teeth paid attention to its multiple steps and the time consumption that posed challenges for dentists [The color stability and surface characteristics of the two single-shade resin composites depend on the different compositions, fillers, particle size, and distributed resin matrix. A commercially available supra-nanofiller resin composite (omnichroma) was compared against a nanohybrid resin composite (Venus pearl). Nanotechnology applications introduced in the fillers size range within 0.1- 100 nm to improve properties [The esthetic and mechanical properties of resin composite are influenced not only by their chemical composition but also by the environment to which they are exposed such as chemical agents found in saliva, foods, and beverages either intermittently or continuously. Coffee is an intense stain [In this study, each step was made to standardize the methodology; the specimens’ thickness of 2 mm for the light cure unit, and the curing time was adjusted to 40 s with 20 s exposure time for the top and 20 s for the bottom, respectively [In the current in-vitro study, a static immersion was done for all specimens for one day and 14 days, equivalent to one month and 14 months of consumption, respectively [Visual perception of color is a psychological point-view and, unfortunately, depends on the observer's skill [Color measurement is usually done by using the CIELAB color system [Surface roughness refers to the finer irregularities of the surface texture that refers to the action of the production process or the material’s features [Regarding color stability, the specimens immersed in the coffee solution reported a more significant color change when compared to the specimens immersed in distilled water. This result could be due to the adsorption and absorption of the yellow stains, which have low polarity. This low polarity of yellow stain can penetrate deeper layers of resin composite [Perceptibility and acceptability thresholds determine if a color variation is perceptible and whether it is acceptable or not. The current study's perceptibility threshold (ΔEGroup O2 and V2 demonstrated unacceptable color change after 14 days of immersion in distilled water which was consistent with a study that had an unacceptable color change of resin composite after immersion in distilled water for five days [Nanohybrid (Venus Pearl) composite was more color unstable than nano-filled composite (Omnichroma). According to the data provided by the manufacturer (Kulzer GmbH) who claimed that, Venus Pearl with novel low shrinkage composition of tricyclodecane (TCD)-urethane monomer, which is characterized by big molecular size that demonstrate good chemical stability [Both resin composite materials exhibited statistically significant difference behavior regarding surface roughness at baseline. The O groups showed superior surface smoothness than the V groups, which could be related to the smaller filler size 4 and higher filler loading [A strong and positive correlation between color stability and surface roughness results, as mentioned in (Table The mean color values and surface roughness after 14 days were the highest for both Groups O1 and V1. It could be due to increased interaction between the resin and the chemicals. More water penetration inside the resin with staining substances of the coffee solution occurred. These conclusions agree with many previous studies [It was stated that when inorganic fillers deboned from the resin matrix, this may leave voids, resulting in surface roughness, forming a surface susceptible to external stains [Although the present study confirmed the detrimental effects of tested solutions on single-shade resin composite material, our study has several limitations. Similarly to other in vitro studies, there are factors affecting the restorations in the oral cavity: microbiota, saliva circulation, temperature, and pH changes. Therefore, the oral cavity could not be imitated precisely [