Q.1 Which metallic biomaterial is most commonly used for permanent cardiovascular stents due to its excellent corrosion resistance?
Stainless steel 316L
Titanium alloy Ti‑6Al‑4V
Cobalt‑chrome alloy (Co‑Cr)
Nitinol (NiTi alloy)
Explanation - Stainless steel 316L provides high corrosion resistance, good mechanical strength, and is cost‑effective, making it the standard choice for many permanent stents.
Correct answer is: Stainless steel 316L
Q.2 What is the primary reason for adding vanadium (V) to titanium alloys used in orthopedic implants?
To increase electrical conductivity
To improve biocompatibility
To enhance strength and fatigue resistance
To reduce density
Explanation - Vanadium acts as an α‑stabilizer, increasing the alloy's tensile strength and fatigue life without compromising biocompatibility.
Correct answer is: To enhance strength and fatigue resistance
Q.3 Which property of Nitinol makes it especially suitable for self‑expanding vascular stents?
Superelasticity
High thermal conductivity
Low modulus of elasticity
Magnetic susceptibility
Explanation - Nitinol exhibits superelastic behavior at body temperature, allowing it to deform and then recover its shape, ideal for self‑expanding stents.
Correct answer is: Superelasticity
Q.4 In the context of metallic biomaterials, what does the term "passivation" refer to?
Removal of surface oxides
Formation of a protective oxide layer
Increasing electrical resistance
Heat treating to improve hardness
Explanation - Passivation is the process where a thin, stable oxide film forms on the metal surface, protecting it from further corrosion in the body.
Correct answer is: Formation of a protective oxide layer
Q.5 Which metallic biomaterial exhibits the highest Young’s modulus among the following options?
Titanium (Ti‑6Al‑4V)
Stainless steel 316L
Cobalt‑chrome alloy
Nitinol
Explanation - Cobalt‑chrome alloys have a Young’s modulus of ~210 GPa, higher than titanium (~110 GPa) and stainless steel (~190 GPa).
Correct answer is: Cobalt‑chrome alloy
Q.6 Why is magnesium considered a promising biodegradable metallic biomaterial for bone fixation devices?
It has a very low melting point.
It naturally forms a protective oxide in the body.
It degrades safely while stimulating bone growth.
It has the highest electrical conductivity among metals.
Explanation - Magnesium alloys corrode in physiological environments, gradually transferring load to healing bone and releasing Mg²⁺ ions that support bone regeneration.
Correct answer is: It degrades safely while stimulating bone growth.
Q.7 Which surface modification technique is most often used to improve the osseointegration of titanium implants?
Anodization
Electroplating with gold
Laser ablation to create micro‑roughness
Polishing to a mirror finish
Explanation - Laser‑induced micro‑rough surfaces increase surface area and promote bone cell attachment, enhancing osseointegration.
Correct answer is: Laser ablation to create micro‑roughness
Q.8 What is the main disadvantage of using cobalt‑chrome alloys for dental implants compared to titanium alloys?
Higher magnetic susceptibility
Lower corrosion resistance
Higher elastic modulus causing stress shielding
Poor biocompatibility
Explanation - Cobalt‑chrome’s high stiffness can lead to stress shielding, where the implant carries too much load, leading to bone resorption.
Correct answer is: Higher elastic modulus causing stress shielding
Q.9 Which of the following metals is NOT typically used in metallic biomaterials due to its toxicity?
Nickel
Chromium
Mercury
Tantalum
Explanation - Mercury is highly toxic and not used in implants; nickel, chromium, and tantalum are incorporated in alloys with controlled release.
Correct answer is: Mercury
Q.10 How does the electrical conductivity of stainless steel compare to that of titanium?
Stainless steel is about 10 times more conductive
Stainless steel is about the same conductivity
Titanium is about 5 times more conductive
Titanium is a semiconductor, stainless steel is not
Explanation - Stainless steel has a conductivity of ~1.4 × 10⁶ S/m, while titanium is around 2.4 × 10⁵ S/m, roughly a factor of 5‑6 lower.
Correct answer is: Stainless steel is about 10 times more conductive
Q.11 Which metallic biomaterial is known for its excellent radiopacity, making it easy to visualize on X‑ray images?
Titanium
Tantalum
Magnesium
Nitinol
Explanation - Tantalum has a high atomic number, providing strong X‑ray attenuation, which is useful for imaging implants.
Correct answer is: Tantalum
Q.12 What is the primary electrochemical reaction responsible for the corrosion of stainless steel in the human body?
Oxidation of Fe²⁺ to Fe³⁺
Reduction of O₂ to H₂O
Passivation breakdown leading to pitting
Electrolysis of water
Explanation - Localized breakdown of the passive Cr₂O₃ layer causes pitting corrosion, the main concern for stainless steel in physiological environments.
Correct answer is: Passivation breakdown leading to pitting
Q.13 Which alloying element is added to titanium to improve its wear resistance for joint replacement applications?
Aluminum
Vanadium
Molybdenum
Zirconium
Explanation - Aluminum stabilizes the α‑phase and increases hardness, improving wear resistance in Ti‑6Al‑4V used for joint prostheses.
Correct answer is: Aluminum
Q.14 In metallic biomaterials, what does the term “stress shielding” refer to?
The shielding of electromagnetic fields by the metal
The reduction of mechanical load on surrounding bone due to a stiff implant
A protective coating that shields the metal from corrosion
The use of a metal that shields radiation
Explanation - A high‑modulus metal can take too much load, causing the adjacent bone to lose stress stimulus and weaken over time.
Correct answer is: The reduction of mechanical load on surrounding bone due to a stiff implant
Q.15 Which metallic biomaterial can be electrically stimulated to promote bone healing?
Magnesium alloy
Titanium alloy
Cobalt‑chrome alloy
Stainless steel
Explanation - Titanium’s biocompatibility and moderate conductivity allow for safe electrical stimulation, enhancing osteogenesis.
Correct answer is: Titanium alloy
Q.16 What is the main advantage of using porous metallic scaffolds for bone tissue engineering?
Higher electrical conductivity
Reduced weight and improved vascularization
Increased magnetic susceptibility
Enhanced corrosion resistance
Explanation - Porosity lowers density, allows tissue ingrowth, and facilitates nutrient flow, supporting bone regeneration.
Correct answer is: Reduced weight and improved vascularization
Q.17 Which metallic biomaterial exhibits shape memory behavior useful for minimally invasive implants?
Stainless steel 316L
Titanium alloy Ti‑6Al‑4V
Nitinol (NiTi alloy)
Cobalt‑chrome alloy
Explanation - Nitinol’s martensitic transformation enables shape memory, allowing devices to be inserted in a compact form and expand at body temperature.
Correct answer is: Nitinol (NiTi alloy)
Q.18 Which metallic biomaterial is most suitable for temporary fixation devices that need to degrade after healing?
Stainless steel
Titanium alloy
Magnesium alloy
Cobalt‑chrome alloy
Explanation - Magnesium degrades safely in vivo, eliminating the need for a second surgery to remove the hardware.
Correct answer is: Magnesium alloy
Q.19 What is the typical range of corrosion rate (mm/year) for a well‑passivated titanium implant in physiological conditions?
0.01–0.1 mm/year
0.5–1.0 mm/year
2–5 mm/year
10–20 mm/year
Explanation - Titanium forms a stable TiO₂ layer, resulting in very low corrosion rates typically below 0.1 mm/year.
Correct answer is: 0.01–0.1 mm/year
Q.20 Which of the following metals is known for its low magnetic susceptibility, making it suitable for MRI‑compatible implants?
Stainless steel 316L
Cobalt‑chrome alloy
Titanium
Nickel
Explanation - Titanium’s low magnetic susceptibility reduces image artifacts and safety concerns in MRI environments.
Correct answer is: Titanium
Q.21 In the context of metallic biomaterials, what does the term “biocompatibility” primarily refer to?
Ability to conduct electricity
Resistance to mechanical fatigue
Compatibility with biological tissue without causing adverse reactions
Ease of machining
Explanation - Biocompatibility means the material does not induce toxicity, inflammation, or rejection when implanted.
Correct answer is: Compatibility with biological tissue without causing adverse reactions
Q.22 Which alloying element in stainless steel contributes most to its corrosion resistance in the body?
Chromium
Manganese
Nickel
Carbon
Explanation - Chromium forms a stable Cr₂O₃ passive layer that protects stainless steel from corrosion.
Correct answer is: Chromium
Q.23 What is the main reason for coating metallic implants with hydroxyapatite (HA)?
To increase electrical conductivity
To improve corrosion resistance
To promote bone bonding (osseointegration)
To make the surface magnetic
Explanation - HA mimics the mineral component of bone, encouraging direct bone‑to‑implant contact.
Correct answer is: To promote bone bonding (osseointegration)
Q.24 Which metallic biomaterial is most commonly used for pacemaker leads due to its flexibility and biostability?
Stainless steel
Cobalt‑chrome alloy
Nitinol
Titanium
Explanation - Nitinol’s superelasticity provides the flexibility needed for leads while maintaining corrosion resistance.
Correct answer is: Nitinol
Q.25 What is the principal advantage of using a Ti‑6Al‑4V alloy over commercially pure titanium for load‑bearing implants?
Higher electrical conductivity
Lower cost
Higher strength and fatigue resistance
Better magnetic properties
Explanation - The addition of Al and V strengthens the alloy, making it suitable for high‑load applications like hip stems.
Correct answer is: Higher strength and fatigue resistance
Q.26 Which phenomenon can cause sudden failure of a metallic implant under cyclic loading?
Creep deformation
Pitting corrosion
Fatigue fracture
Thermal expansion
Explanation - Repeated loading leads to crack initiation and propagation, eventually causing catastrophic failure.
Correct answer is: Fatigue fracture
Q.27 What is the typical elastic modulus of cortical bone, and how does it compare to that of stainless steel?
≈30 GPa; bone is stiffer than stainless steel
≈30 GPa; bone is much less stiff than stainless steel (~190 GPa)
≈200 GPa; bone and stainless steel have similar stiffness
≈100 GPa; bone is twice as stiff as stainless steel
Explanation - Cortical bone’s modulus (~30 GPa) is an order of magnitude lower than stainless steel, which can lead to stress shielding.
Correct answer is: ≈30 GPa; bone is much less stiff than stainless steel (~190 GPa)
Q.28 Which metallic biomaterial is least likely to cause allergic reactions in patients?
Nickel‑containing stainless steel
Cobalt‑chrome alloy
Titanium
Nickel‑titanium alloy (Nitinol)
Explanation - Titanium is highly biocompatible and has a low incidence of hypersensitivity compared with nickel‑containing alloys.
Correct answer is: Titanium
Q.29 How does the surface roughness of a metallic implant affect its osseointegration?
Higher roughness always decreases bone growth
Moderate micro‑roughness enhances bone cell attachment
Smooth surfaces improve bone bonding
Roughness has no effect on osseointegration
Explanation - Micro‑rough surfaces increase surface area and promote protein adsorption, which improves bone cell adhesion.
Correct answer is: Moderate micro‑roughness enhances bone cell attachment
Q.30 Which of the following is a major concern when using cobalt‑chrome alloys in joint replacements?
Low wear resistance
High susceptibility to pitting corrosion
Release of metal ions causing metallosis
Inability to be sterilized
Explanation - Wear particles and corrosion can release Co and Cr ions, potentially leading to inflammatory responses (metallosis).
Correct answer is: Release of metal ions causing metallosis
Q.31 What is the primary function of a TiO₂ layer on titanium implants?
Increase electrical conductivity
Provide a decorative finish
Act as a protective barrier against corrosion
Reduce the material’s density
Explanation - TiO₂ is chemically stable and prevents further oxidation of the underlying titanium.
Correct answer is: Act as a protective barrier against corrosion
Q.32 Which metallic biomaterial can be magnetically guided to a target location inside the body?
Titanium
Stainless steel 316L
Cobalt‑chrome alloy
Nitinol
Explanation - Stainless steel is ferromagnetic, enabling external magnetic fields to manipulate the implant.
Correct answer is: Stainless steel 316L
Q.33 What is the effect of adding palladium (Pd) to stainless steel used in surgical instruments?
Improves magnetic properties
Increases hardness and corrosion resistance
Reduces electrical conductivity
Makes the alloy biodegradable
Explanation - Pd enhances the passive film and hardness, extending the lifespan of surgical tools.
Correct answer is: Increases hardness and corrosion resistance
Q.34 Which metallic biomaterial is most suitable for fabricating micro‑electrodes for neural interfaces?
Magnesium
Titanium
Gold‑plated stainless steel
Cobalt‑chrome alloy
Explanation - Gold provides excellent conductivity and biocompatibility while stainless steel offers structural support.
Correct answer is: Gold‑plated stainless steel
Q.35 In corrosion testing of metallic biomaterials, which solution most closely mimics human blood plasma?
0.9% NaCl solution
Phosphate‑buffered saline (PBS)
Ringer’s solution
Simulated body fluid (SBF)
Explanation - SBF contains ion concentrations similar to plasma, providing a realistic corrosion environment.
Correct answer is: Simulated body fluid (SBF)
Q.36 What is the main benefit of using a porous tantalum structure for spinal fusion cages?
Higher electrical conductivity for nerve stimulation
Excellent radiopacity and bone ingrowth
Low cost compared with titanium
Magnetic properties that aid in placement
Explanation - Porous tantalum’s high X‑ray visibility and favorable pore architecture encourage bone integration.
Correct answer is: Excellent radiopacity and bone ingrowth
Q.37 Which property of Nitinol makes it unsuitable for permanent load‑bearing orthopedic implants?
Low fatigue strength
Superelasticity at body temperature
Potential nickel ion release
High thermal conductivity
Explanation - Nickel can leach from Nitinol, posing toxicity and allergic concerns for long‑term implants.
Correct answer is: Potential nickel ion release
Q.38 Which metallic biomaterial exhibits the highest specific strength (strength-to-weight ratio)?
Stainless steel
Cobalt‑chrome alloy
Magnesium alloy
Titanium alloy
Explanation - Magnesium’s low density combined with decent strength gives it a superior specific strength compared with heavier metals.
Correct answer is: Magnesium alloy
Q.39 When a metallic implant is subjected to cyclic loading, what term describes the gradual accumulation of permanent deformation?
Creep
Fatigue
Stress relaxation
Strain hardening
Explanation - Creep is time‑dependent plastic deformation under a constant load, which can be accelerated by cyclic stresses.
Correct answer is: Creep
Q.40 Which alloy is specifically designed to reduce the release of nickel ions while retaining mechanical strength?
Ti‑6Al‑4V
Co‑Cr‑Mo
Beta‑titanium (Ti‑Nb‑Zr)
Stainless steel 304
Explanation - Beta‑titanium alloys replace nickel with niobium and zirconium, lowering ion release and maintaining strength.
Correct answer is: Beta‑titanium (Ti‑Nb‑Zr)
Q.41 What is the purpose of anodizing titanium implants?
To increase magnetic susceptibility
To create a thicker TiO₂ layer for better corrosion resistance
To make the surface smoother
To reduce the elastic modulus
Explanation - Anodizing grows a controlled oxide layer, enhancing corrosion resistance and sometimes allowing color-coding.
Correct answer is: To create a thicker TiO₂ layer for better corrosion resistance
Q.42 Which metallic biomaterial is most commonly used for dental crowns due to its aesthetic properties?
Cobalt‑chrome alloy
Gold‑palladium alloy
Stainless steel
Titanium
Explanation - Gold‑palladium provides a natural tooth-like color and good biocompatibility for dental restorations.
Correct answer is: Gold‑palladium alloy
Q.43 What is the typical range of electrical conductivity for magnesium alloys used as biodegradable implants?
1–5 × 10⁶ S/m
5–10 × 10⁶ S/m
0.1–0.5 × 10⁶ S/m
10–15 × 10⁶ S/m
Explanation - Magnesium alloys have moderate conductivity, generally between 1 and 5 × 10⁶ S/m, lower than pure magnesium.
Correct answer is: 1–5 × 10⁶ S/m
Q.44 Which factor most strongly influences the rate of corrosion for a metallic implant in vivo?
Implant’s color
Surface roughness
Presence of chloride ions in bodily fluids
Implant’s magnetic properties
Explanation - Chloride ions promote pitting corrosion, especially in stainless steel and other alloys.
Correct answer is: Presence of chloride ions in bodily fluids
Q.45 What is the main advantage of using a Ti‑Nb alloy over Ti‑6Al‑4V for spinal implants?
Higher density
Lower elastic modulus matching bone
Higher electrical conductivity
Better magnetic properties
Explanation - Ti‑Nb alloys can be tailored to have a modulus closer to cortical bone (~50–70 GPa), reducing stress shielding.
Correct answer is: Lower elastic modulus matching bone
Q.46 Which metallic biomaterial is most commonly used for the body of a pacemaker due to its biostability and manufacturability?
Stainless steel
Titanium
Cobalt‑chrome alloy
Aluminium
Explanation - Titanium offers excellent biostability, low density, and is easy to machine, making it ideal for pacemaker housings.
Correct answer is: Titanium
Q.47 In the context of metallic biomaterials, what does “creep‑rupture” describe?
Immediate fracture under high load
Failure due to long‑term exposure to high temperature
Breakage after prolonged exposure to a constant load at elevated temperature
Corrosion‑induced cracking
Explanation - Creep‑rupture is the ultimate failure mode after time‑dependent plastic deformation under stress, relevant for high‑temperature applications.
Correct answer is: Breakage after prolonged exposure to a constant load at elevated temperature
Q.48 Which alloying element in cobalt‑chrome alloys improves wear resistance for artificial hip joints?
Molybdenum
Aluminum
Nickel
Silicon
Explanation - Molybdenum enhances hardness and wear resistance, making Co‑Cr‑Mo alloys suitable for high‑stress joint surfaces.
Correct answer is: Molybdenum
Q.49 What is the primary reason for using a porous titanium coating on a stainless steel implant?
To increase electrical conductivity
To improve corrosion resistance and osseointegration
To make the implant magnetic
To reduce manufacturing cost
Explanation - A porous Ti coating provides a biocompatible surface that encourages bone growth and adds a protective barrier.
Correct answer is: To improve corrosion resistance and osseointegration
Q.50 Which metallic biomaterial is most suitable for a temporary orthopedic fixation device that needs to be removed after bone healing?
Cobalt‑chrome alloy
Titanium alloy
Stainless steel 316L
Magnesium alloy
Explanation - Magnesium degrades over time, eliminating the need for a second surgery to extract the hardware.
Correct answer is: Magnesium alloy
Q.51 How does the presence of a passive oxide layer affect the electrical impedance of a metallic implant?
It decreases impedance, improving conductivity
It increases impedance, acting as an insulating barrier
It has no effect on impedance
It makes impedance temperature‑dependent
Explanation - Oxide layers are poor conductors, raising the overall impedance of the metal‑fluid interface.
Correct answer is: It increases impedance, acting as an insulating barrier
Q.52 Which metallic biomaterial exhibits the best combination of low density, moderate strength, and biodegradability?
Stainless steel
Titanium alloy
Magnesium alloy
Cobalt‑chrome alloy
Explanation - Magnesium’s low density (~1.7 g/cm³), adequate strength, and ability to degrade make it uniquely suited for temporary load‑bearing implants.
Correct answer is: Magnesium alloy
Q.53 What is the most common reason for failure of metallic dental implants?
Electrical short‑circuiting
Corrosion leading to peri‑implantitis
Magnetic interference with MRI
Excessive thermal expansion
Explanation - Corrosion can release metal ions, provoking inflammation and infection around the implant.
Correct answer is: Corrosion leading to peri‑implantitis
Q.54 Which metallic biomaterial can be 3‑D printed directly using selective laser melting (SLM) technology?
Pure copper
Titanium alloy (Ti‑6Al‑4V)
Stainless steel 304
All of the above
Explanation - SLM can process many metals, including titanium alloys, stainless steel, and copper, enabling complex implant geometries.
Correct answer is: All of the above
Q.55 Which parameter is most critical when designing a metallic stent to avoid restenosis?
Electrical resistance
Strut thickness and radial strength
Magnetic permeability
Surface reflectivity
Explanation - Proper balance ensures the stent expands adequately without excessive material that could provoke tissue overgrowth.
Correct answer is: Strut thickness and radial strength
Q.56 Why is the alloy Ti‑13Nb‑13Zr considered a “beta‑type” titanium alloy?
It contains high amounts of β‑stabilizing elements
It is magnetic
It has a higher carbon content
It is used only for dental applications
Explanation - Nb and Zr are β‑stabilizers that promote the low‑modulus β‑phase, giving the alloy a reduced stiffness.
Correct answer is: It contains high amounts of β‑stabilizing elements
Q.57 Which metallic biomaterial is most widely used for the frame of a total knee replacement?
Cobalt‑chrome alloy
Magnesium alloy
Stainless steel
Titanium alloy
Explanation - Co‑Cr‑Mo offers high wear resistance and strength necessary for the high‑load knee joint.
Correct answer is: Cobalt‑chrome alloy
Q.58 What is the effect of adding silicon (Si) to magnesium alloys used as biodegradable implants?
Increases corrosion rate dramatically
Improves mechanical strength and corrosion resistance
Makes the alloy magnetic
Reduces the melting point
Explanation - Si refines grain structure, enhancing strength and forming a more protective surface film.
Correct answer is: Improves mechanical strength and corrosion resistance
Q.59 Which metallic biomaterial can be safely used in patients with severe MRI scans without causing image distortion?
Stainless steel 316L
Cobalt‑chrome alloy
Titanium
Nickel‑titanium alloy (Nitinol)
Explanation - Titanium’s low magnetic susceptibility minimizes artifact and heating during MRI.
Correct answer is: Titanium
Q.60 What is the typical corrosion potential (E_corr) of Ti‑6Al‑4V in simulated body fluid?
-0.2 V vs. SHE
-0.5 V vs. SHE
+0.3 V vs. SHE
+0.1 V vs. SHE
Explanation - Ti‑6Al‑4V generally shows a negative corrosion potential around –0.2 V, indicating a passive behavior in SBF.
Correct answer is: -0.2 V vs. SHE
Q.61 Which metallic biomaterial is often alloyed with copper to improve its antibacterial properties?
Stainless steel
Titanium
Magnesium
Cobalt‑chrome
Explanation - Cu‑bearing stainless steels exhibit enhanced antibacterial activity while maintaining mechanical performance.
Correct answer is: Stainless steel
Q.62 Which surface treatment is most effective for reducing bacterial adhesion on metallic implants?
Polishing to a mirror finish
Anodic oxidation
Hydrogel coating
Electropolishing
Explanation - Hydrogel layers create a hydrated, non‑adhesive surface that hinders bacterial colonization.
Correct answer is: Hydrogel coating
Q.63 What is the main advantage of using a Ti‑Zr alloy over pure titanium for dental implants?
Higher elastic modulus
Improved corrosion resistance and similar biocompatibility
Lower cost
Magnetic properties for easier placement
Explanation - Adding Zr enhances corrosion resistance without compromising the favorable biological response.
Correct answer is: Improved corrosion resistance and similar biocompatibility
Q.64 Which factor most directly influences the fatigue life of a metallic implant?
Implant color
Surface finish and presence of micro‑cracks
Electrical conductivity
Magnetic susceptibility
Explanation - Surface imperfections act as stress concentrators, reducing fatigue strength.
Correct answer is: Surface finish and presence of micro‑cracks
Q.65 Which metallic biomaterial is commonly used for making bio‑resorbable sutures?
Stainless steel
Magnesium alloy
Titanium alloy
Gold
Explanation - Magnesium’s controlled degradation makes it suitable for temporary suture wires that disappear after healing.
Correct answer is: Magnesium alloy
Q.66 What is the purpose of adding carbon (C) to stainless steel used for surgical instruments?
To increase magnetic susceptibility
To improve hardness and tensile strength
To lower the melting point
To make the steel biodegradable
Explanation - Carbon forms carbides that increase hardness and strength, enhancing instrument durability.
Correct answer is: To improve hardness and tensile strength
Q.67 Which metallic biomaterial is most likely to cause an allergic reaction due to nickel content?
Titanium
Cobalt‑chrome alloy
Stainless steel 316L
Magnesium alloy
Explanation - 316L contains ~10 % nickel, a known allergen for some patients.
Correct answer is: Stainless steel 316L
Q.68 In the context of metallic biomaterials, what does the term “modulus mismatch” refer to?
Difference in magnetic permeability between implant and tissue
Difference in elastic modulus between implant and bone
Difference in electrical conductivity between implant and blood
Difference in thermal expansion coefficients
Explanation - Modulus mismatch leads to stress shielding and can impair bone remodeling.
Correct answer is: Difference in elastic modulus between implant and bone
Q.69 Which alloy is specifically engineered to have a low elastic modulus comparable to that of cortical bone?
Ti‑6Al‑4V
Co‑Cr‑Mo
Beta‑type Ti‑Nb‑Ta alloy
Stainless steel 304
Explanation - Beta‑type alloys containing Nb and Ta can achieve moduli around 50–70 GPa, close to bone.
Correct answer is: Beta‑type Ti‑Nb‑Ta alloy
Q.70 What is the primary advantage of using a porous cobalt‑chrome lattice for a hip implant cup?
Higher electrical conductivity
Improved bone ingrowth and reduced stress shielding
Reduced manufacturing cost
Increased magnetic properties
Explanation - Porosity allows bone tissue to infiltrate the structure, distributing load more evenly.
Correct answer is: Improved bone ingrowth and reduced stress shielding
Q.71 Which metallic biomaterial has the highest melting point, making it suitable for high‑temperature sterilization?
Titanium
Cobalt‑chrome alloy
Stainless steel
Magnesium
Explanation - Co‑Cr alloys melt above 1300 °C, tolerating autoclave temperatures without degradation.
Correct answer is: Cobalt‑chrome alloy
Q.72 Which property of magnesium alloys is most critical for ensuring safe degradation rates in the body?
Electrical conductivity
Grain size
Alloying element composition
Magnetic susceptibility
Explanation - Elements such as Al, Zn, and rare earths modify corrosion kinetics, controlling degradation speed.
Correct answer is: Alloying element composition
Q.73 Which metallic biomaterial is most often used for cranial fixation plates due to its radiolucency?
Titanium
Stainless steel
Cobalt‑chrome alloy
Nickel‑titanium alloy
Explanation - Titanium is radiolucent enough to allow post‑operative imaging while still providing strength.
Correct answer is: Titanium
Q.74 What is the main purpose of adding molybdenum (Mo) to stainless steel for biomedical use?
To increase magnetic susceptibility
To improve pitting corrosion resistance
To reduce density
To enhance electrical conductivity
Explanation - Mo stabilizes the passive film and reduces the susceptibility to localized corrosion in chloride‑rich environments.
Correct answer is: To improve pitting corrosion resistance
Q.75 Which metallic biomaterial is most suitable for a load‑bearing spinal cage that must be visible under X‑ray?
Titanium
Cobalt‑chrome alloy
Tantalum
Magnesium
Explanation - Tantalum’s high atomic number offers strong radiopacity while providing adequate mechanical strength.
Correct answer is: Tantalum
Q.76 What is the effect of a high elastic modulus metal on the surrounding bone over time?
Bone remodeling accelerates
Bone density decreases due to stress shielding
Bone becomes more flexible
No effect on bone
Explanation - The stiff implant carries most of the load, reducing mechanical stimulus for bone maintenance, leading to resorption.
Correct answer is: Bone density decreases due to stress shielding
Q.77 Which metallic biomaterial is most often employed in the construction of bio‑electronic interfaces for muscle stimulation?
Stainless steel
Titanium
Gold
Cobalt‑chrome alloy
Explanation - Gold provides excellent conductivity and biocompatibility, essential for reliable electrical stimulation.
Correct answer is: Gold
Q.78 Which of the following is NOT a typical method for assessing the corrosion behavior of metallic biomaterials?
Potentiodynamic polarization
Electrochemical impedance spectroscopy
Tensile testing
Immersion testing in simulated body fluid
Explanation - Tensile testing evaluates mechanical strength, not corrosion behavior.
Correct answer is: Tensile testing
Q.79 What is the principal advantage of using a Ti‑6Al‑4V alloy for load‑bearing orthopedic implants compared to pure titanium?
Higher corrosion resistance
Lower cost
Higher tensile strength and fatigue resistance
Magnetic properties
Explanation - Alloying with Al and V significantly improves mechanical performance while retaining biocompatibility.
Correct answer is: Higher tensile strength and fatigue resistance
Q.80 Which metallic biomaterial is most prone to galvanic corrosion when coupled with stainless steel in the body?
Titanium
Cobalt‑chrome alloy
Magnesium
Gold
Explanation - Magnesium has a much more negative electrode potential, leading to rapid galvanic corrosion when in contact with stainless steel.
Correct answer is: Magnesium
Q.81 Which of the following alloys is considered “beta‑stable” and often used for low‑modulus implants?
Ti‑6Al‑4V
Ti‑Nb‑Zr
Co‑Cr‑Mo
Stainless steel 316L
Explanation - Nb and Zr are β‑stabilizers, maintaining the low‑modulus β‑phase at room temperature.
Correct answer is: Ti‑Nb‑Zr
Q.82 What is the main reason for coating metallic implants with a thin layer of silicon carbide (SiC)?
To improve magnetic properties
To increase electrical conductivity
To provide a hard, wear‑resistant, and biocompatible surface
To reduce density
Explanation - SiC coatings are chemically inert, hard, and can act as a barrier against corrosion and wear.
Correct answer is: To provide a hard, wear‑resistant, and biocompatible surface
Q.83 Which metallic biomaterial is commonly used for the electrodes of deep brain stimulators?
Stainless steel
Cobalt‑chrome alloy
Platinum‑iridium alloy
Titanium
Explanation - Pt‑Ir provides excellent conductivity, corrosion resistance, and biocompatibility for chronic neural interfaces.
Correct answer is: Platinum‑iridium alloy
Q.84 What is the typical range of Young’s modulus for a porous titanium scaffold with 70% porosity?
5–10 GPa
20–30 GPa
50–70 GPa
100–120 GPa
Explanation - High porosity dramatically reduces stiffness, bringing the modulus into the range of cancellous bone.
Correct answer is: 5–10 GPa
Q.85 Which metallic biomaterial is most widely used for the head of a screw in spinal fixation due to its combination of strength and MRI compatibility?
Stainless steel
Cobalt‑chrome alloy
Titanium alloy
Nickel
Explanation - Titanium offers high strength, low magnetic susceptibility, and good biocompatibility, making it ideal for MRI‑safe screws.
Correct answer is: Titanium alloy
Q.86 In a corrosion cell, which region acts as the anode?
Area where metal gains electrons
Area where metal loses electrons
Area protected by passive film
Area with highest chloride concentration
Explanation - At the anode, metal oxidation occurs, releasing electrons and metal ions into the solution.
Correct answer is: Area where metal loses electrons
Q.87 Which alloying element is added to titanium to improve its fatigue resistance for aerospace and biomedical applications?
Aluminum
Vanadium
Molybdenum
Copper
Explanation - Vanadium stabilizes the α‑phase and enhances fatigue strength without compromising corrosion resistance.
Correct answer is: Vanadium
Q.88 Which of the following metallic biomaterials is least likely to cause an artifact in a CT scan?
Stainless steel 316L
Cobalt‑chrome alloy
Titanium alloy
Gold
Explanation - Titanium’s low atomic number reduces beam attenuation, resulting in fewer artifacts.
Correct answer is: Titanium alloy
Q.89 What is the main reason for using a beta‑type titanium alloy (e.g., Ti‑Nb‑Zr) in femoral stems?
Higher density
Lower modulus to reduce stress shielding
Higher magnetic susceptibility
Increased corrosion rate
Explanation - Beta‑type alloys can be tuned to have a modulus closer to bone, mitigating stress shielding effects.
Correct answer is: Lower modulus to reduce stress shielding
Q.90 Which metallic biomaterial can be electroplated with a thin layer of hydroxyapatite to enhance bone bonding?
Stainless steel
Titanium
Cobalt‑chrome alloy
Magnesium
Explanation - Titanium surfaces can be electroplated with HA, improving osteoconductivity while retaining corrosion resistance.
Correct answer is: Titanium
Q.91 What is the effect of increasing the nitrogen content in stainless steel used for orthopedic implants?
Reduces corrosion resistance
Increases hardness and strength
Makes the alloy magnetic
Lowers melting point
Explanation - Nitrogen acts as an interstitial solid solution strengthener, raising yield strength and hardness.
Correct answer is: Increases hardness and strength
Q.92 Which metallic biomaterial is most appropriate for a bio‑electronic pacemaker lead that requires both flexibility and high fatigue resistance?
Stainless steel
Titanium
Nitinol
Cobalt‑chrome alloy
Explanation - Nitinol’s superelasticity provides flexibility, while its fatigue resistance ensures long‑term reliability.
Correct answer is: Nitinol
Q.93 What is the primary purpose of adding a thin titanium nitride (TiN) coating on metallic surgical tools?
To make them magnetic
To increase surface hardness and reduce wear
To improve electrical conductivity
To lower the melting point
Explanation - TiN provides a hard, wear‑resistant surface that also improves corrosion resistance.
Correct answer is: To increase surface hardness and reduce wear
Q.94 Which metallic biomaterial typically exhibits a negative coefficient of thermal expansion, potentially leading to tensile stresses during heating?
Stainless steel
Titanium
Copper
Magnesium
Explanation - Copper contracts upon heating (negative CTE), which can induce tensile stresses in composite structures.
Correct answer is: Copper
Q.95 Which alloy is most often used for the frame of a cranial fixation plate because it combines strength, corrosion resistance, and MRI compatibility?
Stainless steel 316L
Cobalt‑chrome alloy
Titanium alloy
Nickel‑titanium alloy
Explanation - Titanium offers the needed mechanical properties and low magnetic susceptibility for safe MRI scanning.
Correct answer is: Titanium alloy
Q.96 Which factor most influences the rate of ion release from a metallic implant into surrounding tissue?
Implant’s electrical resistance
Surface area to volume ratio
Color of the metal
Magnetic permeability
Explanation - A larger surface area relative to volume accelerates corrosion and ion release.
Correct answer is: Surface area to volume ratio
Q.97 Which metallic biomaterial is widely used for the construction of bio‑resorbable bone screws due to its favorable degradation profile?
Stainless steel
Magnesium alloy
Titanium alloy
Cobalt‑chrome alloy
Explanation - Magnesium degrades safely over months, providing temporary fixation while bone heals.
Correct answer is: Magnesium alloy
Q.98 What is the primary advantage of using a porous tantalum coating on a titanium hip stem?
Improved electrical conductivity
Enhanced osseointegration and load transfer
Reduced manufacturing cost
Increased magnetic susceptibility
Explanation - The porous tantalum layer encourages bone ingrowth and distributes stresses more evenly.
Correct answer is: Enhanced osseointegration and load transfer
Q.99 Which metallic biomaterial is most suitable for a permanent pacemaker casing that must resist corrosion in a saline environment?
Stainless steel 304
Titanium
Copper
Aluminium
Explanation - Titanium’s stable oxide film provides excellent resistance to saline corrosion, crucial for implanted electronics.
Correct answer is: Titanium
Q.100 Which of the following is a common cause of increased corrosion for stainless steel implants in the oral cavity?
Low temperature
High pH (alkaline conditions)
Presence of fluoride ions
Absence of oxygen
Explanation - Fluoride ions can disrupt the passive layer on stainless steel, accelerating pitting corrosion.
Correct answer is: Presence of fluoride ions
Q.101 What is the typical range of Poisson’s ratio for most metallic biomaterials used in implants?
0.1–0.2
0.25–0.35
0.4–0.5
0.6–0.7
Explanation - Metals generally have Poisson’s ratios between 0.25 and 0.35, indicating moderate lateral deformation under axial load.
Correct answer is: 0.25–0.35
Q.102 Which metallic biomaterial is most often used for the construction of vascular grafts that require high flexibility and biocompatibility?
Stainless steel
Cobalt‑chrome alloy
Nitinol
Titanium alloy
Explanation - Nitinol’s superelasticity provides the necessary flexibility while maintaining biocompatibility for vascular applications.
Correct answer is: Nitinol
Q.103 What is the chief reason for using a Ti‑Nb alloy for a femoral stem rather than a conventional Ti‑6Al‑4V alloy?
Higher corrosion rate
Lower elastic modulus to reduce stress shielding
Greater magnetic susceptibility
Increased density
Explanation - Ti‑Nb alloys can be engineered to have a modulus closer to that of bone, mitigating stress shielding.
Correct answer is: Lower elastic modulus to reduce stress shielding
Q.104 Which metallic biomaterial exhibits the best combination of high fatigue strength and low magnetic susceptibility for use in spinal fixation devices?
Stainless steel 316L
Cobalt‑chrome alloy
Titanium alloy
Nickel‑titanium alloy
Explanation - Titanium provides high fatigue resistance and low magnetic response, ideal for MRI‑compatible spinal hardware.
Correct answer is: Titanium alloy
Q.105 What is the main benefit of applying a micro‑arc oxidation (MAO) coating on a titanium implant?
Improves magnetic properties
Creates a thick, porous oxide layer that enhances bone bonding
Reduces density of the implant
Increases electrical conductivity
Explanation - MAO produces a rough, bioactive oxide surface that promotes osseointegration.
Correct answer is: Creates a thick, porous oxide layer that enhances bone bonding
Q.106 Which metallic biomaterial is most suitable for a temporary orthopedic screw that should dissolve within a year?
Stainless steel
Titanium alloy
Magnesium alloy
Cobalt‑chrome alloy
Explanation - Magnesium can be engineered to degrade over 6–12 months, providing temporary fixation.
Correct answer is: Magnesium alloy
Q.107 Which alloy is commonly used for manufacturing bio‑compatible cardiac valve frames because of its high strength and resistance to fatigue?
Cobalt‑chrome alloy
Stainless steel 304
Titanium alloy
Aluminium alloy
Explanation - Co‑Cr alloys combine high strength with excellent fatigue life, making them ideal for valve frames.
Correct answer is: Cobalt‑chrome alloy
Q.108 Which property of a metallic implant most directly influences the generation of heat during MRI scanning?
Electrical conductivity
Elastic modulus
Thermal expansion coefficient
Magnetic susceptibility
Explanation - Materials with higher susceptibility absorb more RF energy, leading to greater heating.
Correct answer is: Magnetic susceptibility
Q.109 What is the primary function of a cathodic protection system for metallic implants?
Increase electrical conductivity
Prevent anodic dissolution of the metal
Reduce magnetic susceptibility
Enhance mechanical stiffness
Explanation - Cathodic protection supplies electrons to the metal, suppressing oxidation and corrosion.
Correct answer is: Prevent anodic dissolution of the metal
Q.110 Which metallic biomaterial is most frequently used for the fabrication of bio‑resorbable vascular stents due to its rapid degradation and sufficient strength?
Magnesium alloy
Zinc alloy
Iron alloy
Stainless steel
Explanation - Magnesium provides a balance between mechanical integrity and a degradation timeline suitable for temporary vascular support.
Correct answer is: Magnesium alloy
Q.111 Which of the following is a typical indicator of pitting corrosion on a stainless steel implant during visual inspection?
Uniform discoloration
Small, localized pits or holes
Cracking across the surface
Overall swelling of the metal
Explanation - Pitting corrosion appears as discrete, often deep pits that can compromise implant integrity.
Correct answer is: Small, localized pits or holes
Q.112 What is the main advantage of using a Ti‑13Nb‑13Zr alloy for a dental implant over conventional Ti‑6Al‑4V?
Higher density
Lower elastic modulus and no aluminum or vanadium
Improved magnetic properties
Higher electrical conductivity
Explanation - Ti‑13Nb‑13Zr eliminates potentially allergenic Al/V and offers a modulus closer to bone, reducing stress shielding.
Correct answer is: Lower elastic modulus and no aluminum or vanadium
Q.113 Which metallic biomaterial is commonly used for the fabrication of cranial plates that need to be both strong and radiolucent?
Titanium
Cobalt‑chrome alloy
Stainless steel
Gold
Explanation - Titanium provides sufficient strength while being sufficiently radiolucent for postoperative imaging.
Correct answer is: Titanium
Q.114 Which of the following processes can be used to produce a gradient in porosity within a metallic implant?
Hot isostatic pressing (HIP)
Selective laser melting (SLM)
Cold rolling
Electroplating
Explanation - SLM allows precise control of melt‑pool geometry, enabling spatial variation in porosity.
Correct answer is: Selective laser melting (SLM)
Q.115 What is the typical range of corrosion current density (i_corr) for a well‑passivated titanium alloy in simulated body fluid?
10⁻¹⁰ A/cm²
10⁻⁶ A/cm²
10⁻³ A/cm²
10⁻¹ A/cm²
Explanation - i_corr values for Ti alloys are usually around 10⁻⁶ A/cm², indicating very low corrosion rates.
Correct answer is: 10⁻⁶ A/cm²
Q.116 Which metallic biomaterial is most commonly used for the fabrication of cochlear implant electrodes?
Stainless steel
Titanium
Platinum‑iridium alloy
Nickel‑titanium alloy
Explanation - Pt‑Ir offers superior conductivity, corrosion resistance, and biocompatibility for chronic neural stimulation.
Correct answer is: Platinum‑iridium alloy
Q.117 Why is it important to limit the amount of nickel in a metallic implant for patients with known allergies?
Nickel reduces the implant’s strength
Nickel can cause severe allergic dermatitis and systemic reactions
Nickel increases magnetic susceptibility
Nickel accelerates corrosion
Explanation - Nickel is a common allergen; excessive release can trigger hypersensitivity responses.
Correct answer is: Nickel can cause severe allergic dermatitis and systemic reactions
Q.118 Which metallic biomaterial is typically chosen for the fabrication of a bone‑anchored hearing aid fixture because of its high biocompatibility and low modulus?
Stainless steel
Titanium
Cobalt‑chrome alloy
Magnesium alloy
Explanation - Titanium’s excellent biocompatibility and moderate modulus make it ideal for osseointegrated hearing devices.
Correct answer is: Titanium
Q.119 What is the main effect of increasing the porosity of a metallic scaffold on its mechanical properties?
Increases Young’s modulus
Decreases Young’s modulus and strength
Increases density
Improves electrical conductivity
Explanation - Higher porosity reduces the load‑bearing cross‑section, lowering stiffness and strength.
Correct answer is: Decreases Young’s modulus and strength
Q.120 Which metallic biomaterial is most often used for the manufacturing of orthopedic pins that must be removed after a short healing period?
Stainless steel
Titanium
Magnesium alloy
Cobalt‑chrome alloy
Explanation - Stainless steel provides adequate strength for temporary fixation and is easily removed without degradation concerns.
Correct answer is: Stainless steel
Q.121 What is the principal cause of corrosion fatigue in metallic implants?
High temperature exposure
Simultaneous mechanical cyclic loading and corrosive environment
Magnetic field exposure
Electrical current passing through the implant
Explanation - The combination accelerates crack initiation and propagation, leading to premature failure.
Correct answer is: Simultaneous mechanical cyclic loading and corrosive environment
Q.122 Which metallic biomaterial is most suitable for a permanent, load‑bearing joint replacement that must retain its mechanical properties for decades?
Magnesium alloy
Stainless steel 316L
Cobalt‑chrome alloy
Aluminium alloy
Explanation - Co‑Cr provides high wear resistance, strength, and long‑term stability for joint arthroplasty.
Correct answer is: Cobalt‑chrome alloy
Q.123 Which surface modification method is primarily used to create a nanostructured TiO₂ layer on titanium implants?
Electropolishing
Anodic oxidation
Mechanical polishing
Laser ablation
Explanation - Anodic oxidation can generate controlled nanostructured TiO₂ layers that improve bioactivity.
Correct answer is: Anodic oxidation
Q.124 Which metallic biomaterial typically exhibits the lowest magnetic susceptibility among commonly used implant metals?
Stainless steel
Cobalt‑chrome alloy
Titanium
Nickel
Explanation - Titanium’s magnetic susceptibility is an order of magnitude lower than that of Fe‑based alloys.
Correct answer is: Titanium
Q.125 What is the major advantage of using a Ti‑6Al‑4V alloy for dental implant abutments over pure titanium?
Higher corrosion resistance
Higher tensile strength and fatigue resistance
Lower cost
Magnetic properties for easier removal
Explanation - Alloying enhances mechanical performance while preserving biocompatibility and corrosion resistance.
Correct answer is: Higher tensile strength and fatigue resistance
Q.126 Which metallic biomaterial is commonly used for the construction of a heart valve frame that must endure billions of cycles?
Stainless steel
Cobalt‑chrome alloy
Titanium alloy
Magnesium alloy
Explanation - Co‑Cr alloys have exceptional fatigue endurance required for heart valve operation.
Correct answer is: Cobalt‑chrome alloy
Q.127 What is the typical range of corrosion potential (E_corr) for a high‑grade stainless steel (316L) in simulated body fluid?
-0.5 V vs. SHE
-0.2 V vs. SHE
+0.1 V vs. SHE
+0.4 V vs. SHE
Explanation - Stainless steel 316L shows a passive corrosion potential around –0.2 V in physiological solutions.
Correct answer is: -0.2 V vs. SHE
Q.128 Which metallic biomaterial is most appropriate for an implant that must be visible under fluoroscopy during a surgical procedure?
Titanium
Stainless steel
Cobalt‑chrome alloy
Tantalum
Explanation - Tantalum’s high radiopacity makes it easily seen under fluoroscopic imaging.
Correct answer is: Tantalum