# Evaluating the Impact of Artificial Saliva Formulations on Stainless Steel Integrity
## 3 Results and Discussion
### Morphological and Chemical Composition
In the case of samples stored in Afnor saliva (Figure 3A), it can be observed that Fe is uniformly distributed, indicating no selective leaching; Cr is homogeneously present, suggesting an intact passive layer; Ni is evenly spread, with no major depletion; and Cl and Na are present superficially, not penetrating deeply. It can be concluded that the surface remained stable and that corrosion resistance was maintained. For the sample stored in Fletcher saliva (Figure 3B), regarding its elemental composition mapping, Fe presents minor surface irregularities, suggesting early interaction; Cr is slightly disrupted with potential signs of passive film attack; Ni shows slight depletion in localized areas; Cl displays structured deposition patterns, possibly along defects or grain boundaries; and Na has accumulation in defined areas, likely in its salt form. From the figure, it can be seen that early passive-layer breakdown is likely caused by an interaction between fluoride and chloride. Figure 2: SEM images of 316L stainless steel stored for 7 days in artificial saliva by Afnor (**A**), Fletcher (**B**) and Fusayama/Meyer (**C**). Figure 3C shows EDX mapping of the sample stored in Fusayama/Meyer saliva (pH 6.34, acidic) after 7 days. As can be seen, the Fe is strongly depleted in certain areas and has an uneven distribution. Cr is fragmented and less intense, showing damage to the passive layer, and Ni is less uniform, which is indicative of elemental leaching. Cl shows strong, widespread penetration indicating corrosive attack and Na is dispersed broadly, which is linked with corrosion activity. There is clear evidence of aggressive corrosion and the loss of protective elements. The Fusayama/Meyer saliva shows the strongest corrosive effect, with visible damage and pitting after 7 days. SEM images of samples stored for 28 days in artificial saliva--Afnor, Fletcher, and Fusayama/Meyer --can be seen in Figure 4. Regarding Figure 4A--Afnor Saliva (pH 7.64, neutral)--it can be observed that at a low magnification the sample shows mild intergranular corrosion and micro-pits and, at a medium/high magnification, slight surface roughening and grain boundary exposure are visible, but the sample still remains relatively intact, which can be interpreted as minor surface evolution and the passive film being mostly preserved. As for the Fletcher saliva (pH 8.07, with Fluoride)--Figure 4B shows that crystalline corrosion products are clearly visible, possibly fluoride-related salts, and a high-magnification reveals pitting and passive film disruption. With respect to the Fusayama/Meyer saliva (pH 6.34, acidic) after 28 days (Figure 4C), large spherical deposits are present, covered with spiky, filamentous structures and severe corrosion with precipitated compounds suggests a loss of the original alloy material. This can be interpreted as strong acidic corrosion with aggressive material degradation. Figure 5 presents EDX elemental mapping (28 days) for 316L stainless steel stored in Afnor, Fletcher, and Fusayama/Meyer artificial saliva. When considering the Afnor saliva (pH 7.64, neutral) (Figure 5A), the Fe, Cr, and Ni remain uniform with only minor signal dimming, but the Cl and Na remain at superficial levels, not indicating deep corrosion. The EDX mapping shows that the composition remains mostly stable; excellent passivation is retained. Regarding the Fletcher saliva (pH 8.07, with Fluoride) (Figure 5B), the Fe and Ni signals show slight depletion, the Cr is slightly disrupted, and the Cl and Na are more intense and diffuse compared to the 7-day data; thus, it can be concluded that surface corrosion is progressing and fluoride likely plays a key role. When considering  
Figure 3: EDX mapping of 316L stainless steel stored for 7 days in artificial saliva by Afnor (**A**), Fletcher (**B**), and Fusayama/Meyer (**C**).