# Evaluating the Impact of Artificial Saliva Formulations on Stainless Steel Integrity
## 1 Introduction  
Biomaterials science is an interdisciplinary field that demands a deep understanding of engineering, biology, and medical sciences. It involves both fundamental and applied research focused on exploring interactions between living systems and biomaterials, designing medical devices to support biological structures, and addressing the needs of patients and healthcare professionals [1, 2]. Stainless steels are among the most commonly used metallic biomaterials, extensively employed in the manufacturing of medical implantsand various biomedical devices. In particular, 316L stainless steel, characterized by its low carbon content (<0.03%) and molybdenum addition (\(-\)2-3%), is widely utilized in biomedical applications due to its outstanding properties, such as excellent mechanical performance and high biocompatibility [3; 4]. Medical-grade stainless steel (SS) is a type of metal widely used in manufacturing biomedical devices and implants [5]. The surface properties of a material play a crucial role in influencing its biocompatibility, corrosion resistance, antibacterial activity, and tissue regeneration potential [6]. [PERSON] et al. [7] examined the corrosion behavior of stainless steel in artificial saliva with varying fluoride concentrations. Their findings revealed that exposure to fluoride ions leads to an increase in corrosion current density within the passivated region. Additionally, the presence of fluoride expands the passivation range of stainless steel alloys. The significance of pH in metal corrosion is well established, as dietary habits, including the consumption of carbonated beverages and desserts, can influence intraoral pH. The pH in the oral cavity is known to fluctuate considerably depending on factors such as food and beverage intake, microbial metabolism, and systemic health conditions. Reports in the literature indicate that salivary pH can range from highly acidic values around 4.0 (due to frequent sugar consumption or gastroesophageal reflux) to alkaline conditions exceeding 8.5, particularly after exposure to bicarbonate-rich saliva or antibacterial rinses [8; 9]. These pH variations play a critical role in modulating the corrosion behavior of dental materials and should be considered when simulating in vitro environments. [PERSON] observed that a reduction in pH narrows the passive range in the cyclic potentiodynamic curves of stainless steel dental arch wires, suggesting that the stability of the passivated film diminishes in acidic environments [7]. Research by [PERSON] et al. [10] found that stainless steel prefabricated crowns submerged in artificial saliva with a lower pH released higher amounts of nickel (Ni). [PERSON] et al. [11] found that copper-containing 304 stainless steel exhibits significantly greater biofilm inhibition compared to copper-free 304 stainless steel. Additionally, in S. mutans-containing artificial saliva, the Cu-containing alloy demonstrated a lower corrosion current density (i_corr), higher polarization resistance (R_p), and greater charge transfer resistance (R_ct). [PERSON] et al. evaluated the corrosion resistance of 316L stainless steel in two artificial saliva solutions with varying pH and chloride concentrations, aiming to assess its suitability for orthodontic applications. The study concluded that an increase in pH combined with a higher chloride concentration resulted in the lowest corrosion resistance, whereas a decrease in pH with a lower chloride concentration led to improved corrosion resistance [12].  
The aim of this study is to investigate the effects of three different artificial saliva formulations on the structural and surface characteristics of stainless steel. By analyzing variations in pH, chloride concentration, and other relevant parameters, this research seeks to assess the material's suitability for biomedical applications, particularly in dental and orthodontic environments.