الفهرس 
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Abstract
The aim of our study was to evaluate the effect of different beverages (instant coffee; Nescafe classic, red wine and cola drink; Pepsi cola); with and without brushing; on a nanohybrid ormocer (Admira fusion) and a nanohybrid dimethacrylate based composite (Grandio) concerning their: surface hardness, surface roughness, color stability, water sorption and solubility.
Dental resin composite restorative materials are becomingly the most common direct restorative materials due to the increased esthetic demands. Hence the oral cavity is one of the most challenging environments, thus, these resin composite materials are subjected to a lot of challenges that might deteriorate their physical and mechanical properties.
Specimens from each type of dental resin composite were prepared and divided into two main groups according to brushing or non-brushing procedure. Then each group was further subdivided into four subgroups according to the used beverages.
Vickers hardness tester was used to record the surface microhardness, stylus profilometer for surface roughness and spectrophotometer for color. These readings were recorded before and after the immersion in the different beverages for 30 days. Water sorption and solubility were done according to the ISO 4049. The immersion cycles were 5 minutes 3 times per day and the brushing was done 1 hour after the last cycle.
Results of surface microhardness showed higher values for Grandio before the immersion in the used beverages. Regarding the change in surface microhardness, the highest values were recorded upon immersion in Pepsi cola and Red wine and the least were in the control subgroup. The change was higher in the brushing subgroups. Grandio exhibited higher change in surface microhardness.
Results of color stability showed that the highest color change was recorded upon immersion in Nescafe classic and the least was in the control subgroup. The change was lower in the brushing subgroups. Grandio exhibited higher color changes.
Results of surface roughness showed higher values for Grandio before the immersion in the used beverages. Regarding the change in surface roughness, the highest value was recorded upon immersion in Pepsi cola and the least was in the control subgroup. The change was higher in the brushing subgroups. Admira fusion exhibited higher change in surface microhardness.
Results of water sorption showed that the highest values were recorded in the control subgroup and the least were upon immersion in Red wine and Pepsi cola. The water sorption was lower in the brushing subgroups. Admira fusion showed higher water sorption values.
Results of solubility showed that the highest values were recorded upon immersion in Red wine for the non-brushing groups and Pepsi cola for the brushing ones and the least were in the control subgroup. The solubility was higher in the brushing subgroups. Admira fusion showed higher solubility values