## 4 Discussion
(2022) analyzed 4 mm \(\times\) 6 mm samples, which were sectioned and tested for hardness using a Vickers indenter, applying a 100 g load for 15 s. This study demonstrates that FUJI IX GP FAST and RivaSilver achieved comparable hardness values, with FUJI IX GP FAST showing slightly higher values. Both were superior to bulk-fill and self-adhesive resins, highlighting the durability of glass ionomer cements in pediatric dentistry, even after wear from brushing. This supports their application in pediatric dentistry. The response of materials to acid exposure revealed that toothpaste offered some protective effects, but only in specific instances. The roughness was analyzed using an optical profilometer, the standard method for assessing tissue loss in vitro and in situ duringerosion simulations [33]. The application of toothpaste after the first demineralization cycle on RivaSilver and FUJI IX GP FAST did not decrease roughness but instead increased it. However, after two demineralization cycles, a protective effect was observed. These findings contrast with the study by [PERSON] et al. (2016) [34], which evaluated the effectiveness of various toothpastes on glass ionomer cement restorations made on extracted bovine teeth, subjected to demineralization cycles, and assessed for wear at the enamel-cement interface. In that study, no positive effect of toothpaste was noted after multiple demineralization processes. However, the materials and experimental conditions differed from those in the present study, with the acid process simulated over five days and samples immersed in 250 mL of citric acid, shaken on an orbital shaker while a toothpaste and distilled water mixture was applied for two minutes at hourly intervals. The samples were also immersed in artificial saliva throughout the experiment [14; 35]. FUJI IX GP FAST exhibited low roughness values, a result that contradicts the findings of [PERSON] et al. (2015) [36], where the analyzed glass ionomer had the highest roughness values compared to other materials. However, the glass ionomer was compared with different materials, including giomer, amalgomer, and glass carbomer, which differ significantly from those examined in this study. Conversely, SDR flow+ resin, consistent with [PERSON] et al. (2020), displayed high roughness values, which may be due to its lower filler content and the polymerization modulator chemically incorporated into the center of the polymerizable resin [37]. This study analyzed various bulk-fill composites by creating 30 disc-shaped samples (10 mm \(\times\) 12 mm) using a stainless steel mold and Mylar sheets to ensure material uniformity. The samples were photopolymerized for 20 s, followed by surface roughening and polishing, with the roughness measured using a profilometer [38]. Overall, resin-containing materials, such as SDR flow+ and Vertise Flow, showed lower surface roughness values after acid attacks compared to RivaSilver, a resin-free glass ionomer cement. This finding aligns with [PERSON] (2010), who stated that filler particles enhance the mechanical strength of materials, a crucial factor for posterior restorations [39]. This study underscores the need for further research on RivaSilver and FUJI IX GP FAST, given that their roughness values deviated from the typical behavior of other glass ionomer cements. There is limited scientific literature on these materials, particularly in comparison to other non-glass ionomer materials. Furthermore, roughness due to wear revealed different values compared to those recorded after acid exposure. Notably, after both 20 and 60 min of brushing, RivaSilver recorded the lowest roughness values, followed by SDR flow+ and Vertise Flow, while FUJI IX GP FAST recorded the highest values overall. These results diverge from those of [PERSON] et al. (2000), who, in comparing the wear resistance of glass ionomer restorative materials, concluded that the wear resistance of FUJI IX GP FAST was comparable to that of metal-reinforced GIC, microfilled, and minifilled composites [40].