# Evaluating the Impact of Artificial Saliva Formulations on Stainless Steel Integrity
## 3 Results and Discussion  
### Morphological and Chemical Composition  
Figure 1 presents the SEM analysis of sample 316L before immersion in artificial saliva. The surface appears smooth and homogeneous, with no evidence of pitting, delamination, or significant defects. Minor parallel striations suggest mechanical polishing marks from sample preparation, which are typical and do not indicate surface damage. At higher magnification, elongated surface grooves and shallow micro-scratches become visible. These features are consistent with surface finishing and have not yet initiated corrosion or passive layer breakdown. The surface remains intact and free from corrosion pits. Fine features such as polishing textures and grain boundary traces can be discerned. No surface oxidation or particulate deposits are detected. The uniform contrast suggests a stable passive oxide film, typical for 316L in ambient conditions. These baseline images establish a reference morphology for direct comparison with post-immersion samples. The absence of corrosion features supports the initial chemical stability of the 316L alloy and underscores the subsequent changes observed in artificial saliva as the effects of environmental interaction rather than pre-existing flaws. Figure 2 presents the SEM surface analysis of the 316L stainless steel samples after 7 days of immersion in three types of artificial saliva--Afnor (neutral pH), Fletcher (basic with fluoride), and Fusayama/Meyer (acidic). The results are compared at three magnifications per condition and are supported by visual observations related to corrosion or surface alterations. For Figure 2A, immersed in Afnor saliva (pH 7.64, neutral), at a low magnification the surface appears clean and well-preserved, with visible machining or polishing marks. No major pitting, cracks, or corrosion products are visible. At medium and high magnification, the surface is smooth, with minor scratches and very limited particulate accumulation. No significant pitting or localized attacks are evident. The passive Cr\({}_{2}\)O\({}_{3}\) layer likely remained intact, showing minimal signs of corrosion. In the case of Figure 2B with Fletcher saliva (pH 8.07, basic with fluoride), at a low magnification, a slightly rougher texture compared to A can be seen. Fine scratches appear to be more irregular and there are hints of localized dull patches. At a medium magnification, the surface shows early signs of corrosion or film breakdown, with uneven morphology, but at a high magnification the nanometer- to micrometer-scale roughening and etching-like features suggest fluoride attack. This surface shows incipient degradation under fluoride exposure, with signs of passive film destabilization. For Figure 2C--Fusayama/Meyer Saliva (pH 6.34, mildly acidic)--at a low magnification, the sample shows a clearly rougher and duller surface, suggesting more widespread corrosion. Machining marks are nearly obliterated. At a medium magnification, the widespread roughening and etching are consistent with acid  
Figure 1: SEM images of 316L stainless steel before immersion in artificial saliva. induced attack, and at a high magnification the corrosion morphology is well developed, with multiple small pits or corrosion product clusters. Fusayama/Meyer saliva shows the strongest corrosive effect, with visible damage and pitting after 7 days. Figure 3 shows the energy dispersive X-ray (EDX) mapping results for 316L stainless steel samples immersed for 7 days in three types of artificial saliva: Afnor (A), Fletcher (B), and Fusayama/Meyer (C). The elemental distributions of Fe, Cr, Ni, Cl, and Na were observed to assess the surface integrity and elemental leaching that resulted from electrochemical interactions in each environment.