## 4 Discussion
The elevated copper content of the alloy contributed to the enhancement of the mechanical and physical characteristics, such as a reduction in the formation of the gamma-2 phase, diminished corrosion, and increased strength [68]. To establish baseline values, the specimens were immersed in artificial saliva immediately following the completion of the restoration procedures. The initial measurements were subsequently obtained after a 2 h incubation period. Although the complete setting of amalgam restorations typically occurs within 24 h post-operatively, patients are generally advised to abstain from eating for at least 2 h to avoid potential disturbances in the integrity or flow characteristics of the restoration. This protocol was adopted to simulate clinical conditions as closely as possible. The unstimulated salivary flow rate in the human oral cavity is reported to exceed 0.25 mL/min, which equates to approximately 15-20 mL per hour [69]. Accordingly, in this experimental setup, the specimens were incubated in 50 mL of artificial saliva--an amount that approximates the average salivary volume present over a 2 to 3 h period. In the initial measurement phase, the mercury concentration released from a single-surface amalgam restoration on one tooth was determined to be 0.043 \(\pm\) 0.009 \(\upmu\)g/mL. In contrast, a three-surface restoration on a single tooth released a significantly higher concentration of 0.060 \(\pm\) 0.004 \(\upmu\)g/mL. Statistical analysis confirmed a significant difference between Group 1 and Group 2, with Group 2 exhibiting higher mercury levels. In Group 3, which comprised two teeth restored with a total of six amalgam surfaces, the measured mercury release was 0.083 \(\pm\) 0.005 \(\upmu\)g/mL--higher than that observed in Group 2. Overall, the data demonstrated a clear, positive correlation between the quantity of mercury released and the increase in both the number of restored teeth and the total surface area of amalgam present. In each group, statistically significant differences in mercury release were observed between baseline and Day 2, baseline and Day 7, and baseline and Day 30. However, the progression of mercury release did not follow a linear trajectory. It was noted that the rate of release did not remain consistent over time when compared to the initial baseline levels. This trend may be attributed to the formation of a corrosion-like layer on the surface of the amalgam over time, likely resulting from a passivation effect. Such a layer may serve as a barrier, thereby limiting further mercury emission as the material ages [70, 71, 72]. It is presumed that the mercury dissolution rate decreases over time due to the progressive growth and thickening of the tin oxide film in aqueous environments. In all types of dental amalgam, the primary source of mercury release is the gamma-one phase, which forms the matrix of the structure and is rich in mercury. In low-copper amalgams, the gamma-two phase can form a thicker tin oxide layer, thereby effectively limiting mercury release. At this point, the use of a single type of amalgam material in our study presents a limitation, as it precludes a comparative evaluation of this phenomenon across different amalgam compositions [64, 73]. It is now established that dental amalgam continuously releases elemental mercury (Hg\({}^{0}\)), leading to exposure in individuals with fillings made from this material. Although the amount of Hg\({}^{0}\) released from amalgams is often described as minute, their safety is not determined solely by the quantity of the dose. Instead, it is the comparison of this dose to established'safe' levels or thresholds for anticipated harm that determines their significance concerning health risks. Regardless of the magnitude, even a minute dose can pose a risk if the substance is sufficiently toxic and the exposure exceeds a reference level deemed \"safe\" [31]. The primary limitation of this study was the inability to use extracted human teeth.