## **Core Concept**
The elastic modulus, also known as Young's modulus, is a measure of a material's ability to resist deformation under stress. In the context of dental materials, it is crucial for understanding how materials like dental amalgam behave under occlusal forces. Dental amalgam is a widely used restorative material in dentistry.

## **Why the Correct Answer is Right**
The elastic modulus of dental amalgam is approximately **70 GPa (Gigapascals)**. This value indicates that dental amalgam has a moderate level of stiffness, which is essential for withstanding the forces of mastication without deforming permanently. The elastic modulus is a key property that helps in selecting the appropriate dental material for restorations, as it influences the material's durability and compatibility with tooth structure.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because the value provided does not match the known elastic modulus of dental amalgam.
- **Option B:** Similarly, this option does not correspond to the correct elastic modulus of dental amalgam.
- **Option D:** This option is also incorrect as it does not align with the established value for the elastic modulus of dental amalgam.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that dental amalgam has a relatively high elastic modulus compared to some other dental restorative materials, which makes it suitable for restorations that are subject to high occlusal forces. However, its use has declined with the advent of tooth-colored restorative materials like composites, due to concerns about mercury toxicity and aesthetics.

## **Correct Answer:** .