Question

Metals are commonly used as biomaterials mainly because of their:

• A. High strength and toughness
• B. High corrosion rate
• C. Low density
• D. Optical transparency

Hint:

Think of structural load bearing: when replacing a human hip or femur, the material must handle hundreds of pounds of daily mechanical force without cracking. Only high strength, high-toughness materials like metals can reliably survive these cyclic loads.

Answer 1

The Correct Option is A

Concept: Metallic biomaterials (such as Titanium alloys, Stainless Steel 316L, and Cobalt-Chromium alloys) are extensively utilized in orthopedic and dental applications like hip stems, bone plates, dental implants, and joint replacements.

Step 1: Identifying the primary structural demand of load-bearing implants.
Implants replacing structural skeletal components must withstand massive cyclic mechanical loads, shear stress, and compression forces exerted daily by human movement without undergoing sudden brittle fracture or permanent plastic warping.

Step 2: Matching properties to performance.

• High Strength: Ensures that the metallic device can handle heavy physiological mechanical loads safely.
• Toughness: Refers to a material's ability to absorb kinetic energy and deform plastically without fracturing under sudden stress. High fracture toughness prevents catastrophic failure within the body.

Step 3: Ruling out other options.

• High corrosion rate (Option B): This is highly dangerous because corrosion releases toxic metallic ions into tissue, causing severe inflammation. Ideal biomaterials must have low corrosion rates.
• Low density (Option C): Most structural metals (except titanium) possess high densities compared to natural bone tissue.
• Optical transparency (Option D): Metals are opaque materials due to free electrons reflecting light photons. Therefore, high strength and toughness is the undisputed primary reason for choosing metals, verifying Option (A).