## 4 Discussion
Additionally, the results of this study revealed that the silica-containing toothpastes increased the surface roughness of the composites by brushing. When the surface roughness values were evaluated after one month of brushing, the toothpaste groups presented similar effectivity. However, the surface roughness value was lower in SW + PP than in SW, and lower surface roughness values were found in SIR + PP than in SIR. According to these results, it can be interpreted that using PP toothpaste with an RDA of 105 together with a conventional toothpaste with low RDA may not cause an increase in the surface roughness of the conventional paste. The literature stated that the surface roughness and filler size of the composite resin do not change during the brushing procedure [37]. However, the average surface roughness value of a large filler containing composite resin may increase with brushing [37]. Various studies declared that the surface roughness of microhybrid composite resins was higher than the nanohybrid resins after brushing with whitening toothpastes [45,47,48]. [PERSON] et al. declared that surface roughness and color stability of nanohybrid and microhybrid composites decreased after the brushing procedure with a whitening toothpaste [49]. In the present study, after one month of brushing there was no difference between the surface roughness values of the composite groups. This can be explained by the fact that, despite the difference in filler content of the microhybrid and nanohybrid composites, the filler particle distance, chemical bonds between the filler particles, and the conversion value after polymerization might also be effective on surface roughness [44]. In terms of SRI, it can be said that the discoloration procedure does not change the surface roughness scores (Tables 7 and 8). Although there are toothpastes with different RDA values, no difference was observed in terms of SRI in all periods. This result was similar to the Ra results of this study and may be attributed to the size or distribution of silica and the abrasive substance of the selected toothpastes (Table 7). Regarding composite materials, it was observed that the one-month brushing procedure increased the SRI scores in all groups (Table 8), similar to the Ra results in this study. The ELS composite group had a higher SRI score than the other composite groups after one month of brushing, and it may be related to the filler particle size or polishability feature of this composite [44]. Surface roughness values alone may be insufficient to provide information about the general surface. In previous studies, SRI was performed on SEM and stereomicroscope images [23]. Since there is no other index to evaluate the material surface from images, this scoring system was used to evaluate the surface in the present study. [PERSON] et al. highlight the importance of resin infiltration techniques for addressing discolorations that remain resistant to conventional polishing and whitening [50]. They underscore the need for restorative protocols that consider both surface roughness and long-term color stability. This study also emphasizes the importance of regular me chanical plaque control and draws attention to the fact that the fluoride ion found in toothpastes inhibits the bacterial metabolism in dental plaque and the use of fluoride-containing toothpaste [50]. In the present study, all toothpaste groups include fluoride content and silica. All toothpaste groups provide mechanical plaque removal due to their abrasive content. The present study has some limitations. The in vitro conditions may not completely simulate the natural oral environment. Saliva circulation, pH and temperature changes, and pellicle formation may also affect the integrity of resin-based composite materials. The brushing simulator in this study brushed the composites with only forward and backward movements, which might not have simulated the real-time brushing pattern completely.