Composite Grafts — MCQs
All of the following factors affect osseointegration EXCEPT:
Which one of the following is not a wound closure technique?
Best procedure for an injury to the leg with exposed bone and skin loss:
Which of the following bone defects offers the best chance for bone fill?
Feature of third-degree burn:
Gold standard procedure to reduce recurrence of pterygium after surgical excision is
A Wolfe graft is a
In Split thickness graft, which part of the skin is/are included?
Which of the following statements about mesh skin grafts is not correct?
Wound contraction can be most effectively minimized by:
Composite Grafts Indian Medical PG Practice Questions and MCQs
Question 1: All of the following factors affect osseointegration EXCEPT:
- A. Biocompatibility of implant material.
- B. Implant design.
- C. Patient's blood type (Correct Answer)
- D. Status of the host bed.
Explanation: ***Patient's blood type*** - A patient's **blood type** (e.g., A, B, AB, O) is determined by antigens present on red blood cells and plays no direct role in the biological processes of bone healing or the integration of a dental implant with bone. - While systemic factors can influence osseointegration, blood type itself does not affect the cellular and molecular mechanisms required for direct bone-to-implant contact. *Biocompatibility of implant material* - The **biocompatibility** of the implant material (e.g., **titanium**) is crucial for osseointegration, as it must not elicit adverse reactions and must permit host bone growth on its surface. - Materials that are cytotoxic or inflammatory will prevent bone apposition and lead to fibrous encapsulation rather than direct bone contact. *Implant design* - **Implant design**, including features like **surface roughness**, thread pitch, and macro-geometry, significantly influences the initial stability and long-term success of osseointegration. - A greater surface area and appropriate surface treatments can enhance bone cell attachment and differentiation, promoting faster and stronger bone integration. *Status of the host bed* - The **status of the host bone bed** refers to its quality and quantity (e.g., bone density, vascularity), which are critical for the biological processes of osseointegration. - Adequate bone volume and good bone quality provide a stable foundation and sufficient blood supply for bone regeneration around the implant.
Question 2: Which one of the following is not a wound closure technique?
- A. Composite graft
- B. Vascular graft (Correct Answer)
- C. Partial thickness skin graft
- D. Musculocutaneous flap
Explanation: ***Vascular graft*** - A **vascular graft** is a tube-like structure used to bypass or replace a diseased or damaged blood vessel. - Its primary purpose is to **restore blood flow**, not to close a wound on the body surface or replace missing tissue. *Partial thickness skin graft* - A **partial thickness skin graft** involves transplanting the epidermis and a portion of the dermis to cover a wound. - This is a common and effective technique for **wound closure**, particularly for large surface area wounds or burns. *Composite graft* - A **composite graft** is a graft consisting of multiple tissue types, such as skin, cartilage, and fat, often used for reconstruction. - This is a direct method of **wound closure** and tissue replacement, particularly in areas requiring structural support and soft tissue coverage. *Musculocutaneous flap* - A **musculocutaneous flap** involves the transfer of skin, subcutaneous tissue, and an underlying muscle to cover a wound. - This is a versatile **wound closure technique** that provides robust soft tissue coverage and blood supply to complex defects.
Question 3: Best procedure for an injury to the leg with exposed bone and skin loss:
- A. Full thickness grafting
- B. Skin flap
- C. Split skin grafting
- D. Pedicle flap (Correct Answer)
Explanation: ***Pedicle flap*** - A pedicle flap provides **vascularized tissue** that can cover exposed bone, which requires a robust blood supply for healing and protection. - This method ensures good **tissue viability** and bulk, crucial for areas with high functional demands and potential for infection like the lower leg. *Full thickness grafting* - **Full-thickness skin grafts** are generally too thin to adequately cover exposed bone and do not provide sufficient vascularity or padding. - They rely entirely on the recipient bed for vascularization, which is poor over exposed bone, leading to a high risk of **graft failure**. *Skin flap* - While a generic "skin flap" implies a vascularized tissue transfer, it is less specific than a pedicle flap, which ensures continuous blood supply from the donor site until full integration. - The term "skin flap" alone doesn't specify if it's a local, regional, or free flap, and **pedicle flaps** are often the most direct and reliable solution for lower leg bone exposure. *Split skin grafting* - **Split-thickness skin grafts** are very thin and contain only a portion of the dermis, making them unsuitable for covering exposed bone or tendons. - They would likely **fail to take** due to lack of a vascular bed and offer no padding or protection against further injury.
Question 4: Which of the following bone defects offers the best chance for bone fill?
- A. 3 Walled defect (Correct Answer)
- B. Hemisepta
- C. Osseous crater
- D. 2 Walled defect
Explanation: ***3 Walled defect*** - A **3-walled defect** provides the best prognosis for bone fill because it retains the most natural bone structure, enhancing the ability to contain bone graft material effectively. - The presence of three bony walls offers **excellent support and blood supply** for graft survival and successful bone regeneration. *Hemisepta* - A **hemisepta** refers to a one-walled defect, which offers very limited containment for graft materials. - It has a **poor prognosis** for bone fill due to insufficient support and rapid loss of grafting material. *Osseous crater* - An **osseous crater** is a two-walled defect where the buccal and lingual walls are present, but the interproximal walls are missing. - While better than a one-walled defect, it still presents challenges in graft containment and has a **less predictable outcome** compared to a 3-walled defect. *2 Walled defect* - A **2-walled defect** offers less containment and support for bone graft materials compared to a 3-walled defect. - The reduced number of walls means there is a **higher chance of graft material displacement** and a slower healing process.
Question 5: Feature of third-degree burn:
- A. Whole dermis destroyed (Correct Answer)
- B. Pain present
- C. Transudation of fluid present
- D. Erythematous in appearance
Explanation: ***Whole dermis destroyed*** - A **third-degree burn** involves the complete destruction of the **epidermis** and **dermis**, extending into the subcutaneous tissue. - This extensive damage results in a leathery, stiff, and often waxy white, brown, or charred black appearance. *Pain present* - Third-degree burns typically cause **no pain** in the burned area itself because the nerve endings in the dermis have been completely destroyed. - While there may be pain surrounding a third-degree burn due to less severe burn areas, the core third-degree area is numb. *Transudation of fluid present* - **Transudation of fluid** (blister formation and significant edema) is a prominent feature of **second-degree burns**, where the epidermis separates from the dermis. - In third-degree burns, the skin is destroyed, and the protein-rich fluid tends to **coagulate** within the damaged tissues rather than forming blisters or freely transuding. *Erythematous in appearance* - **Erythema** (redness) is characteristic of **first-degree burns** and **superficial second-degree burns**, due to vasodilation in the intact dermis. - Third-degree burns are typically **waxy white, leathery, charred black, or brown**, not red, due to the destruction of blood vessels and tissue necrosis.
Question 6: Gold standard procedure to reduce recurrence of pterygium after surgical excision is
- A. Thiotepa
- B. Amniotic membrane grafting
- C. Conjunctival autograft (Correct Answer)
- D. Beta-radiation
Explanation: ***Conjunctival autograft*** - **Conjunctival autografting** involves transplanting a piece of healthy conjunctiva from the superior bulbar conjunctiva to the bare scleral bed after pterygium excision, acting as a barrier to fibrovascular proliferation. - This technique has consistently shown the **lowest recurrence rates** in comparative studies, making it the **gold standard** for preventing pterygium recurrence due to its high success rate and safety profile. *Thiotepa* - **Thiotepa** is an **antimetabolite** that inhibits DNA synthesis and cell proliferation, used topically post-excision to reduce recurrence by suppressing fibroblast activity. - While it can lower recurrence rates compared to simple excision, its efficacy is generally **less than conjunctival autografting**, and it carries risks of corneal toxicity and limbal stem cell deficiency. *Amniotic membrane grafting* - **Amniotic membrane grafting** involves placing processed amniotic membrane over the scleral bed, which has anti-inflammatory, anti-scarring, and pro-epithelialization properties. - It is an effective option, especially for **large pterygia** or for patients at high risk of recurrence, but its recurrence rates are generally **not as low as those achieved with conjunctival autografting**, and the graft can sometimes detach. *B- radiation* - **Beta-radiation** (strontium-90) is a form of adjuvant therapy applied to the scleral bed immediately after pterygium excision to inhibit fibroblast proliferation and reduce recurrence. - It is effective but associated with potential complications such as **scleral melt**, corneal scarring, and cataract formation, making it a less preferred option than conjunctival autografting, especially in primary cases.
Question 7: A Wolfe graft is a
- A. Partial thickness skin graft
- B. Pinch skin graft
- C. Pedicle graft
- D. Large full thickness skin graft (Correct Answer)
Explanation: ***Large full thickness skin graft*** - A **Wolfe graft** is a type of **large full-thickness skin graft** that includes the epidermis and entire dermis. - Due to its full thickness, it provides better cosmetic results and less contracture compared to split-thickness grafts, but requires optimal **vascularization** at the recipient site. - The term "Wolfe graft" specifically refers to the **large size** of the full-thickness graft, distinguishing it from smaller grafts. *Partial thickness skin graft* - A **partial-thickness skin graft** (also known as a split-thickness skin graft) includes the epidermis and only a portion of the dermis. - While easier to harvest and more likely to **take** in less ideal recipient beds, they are known for more contraction and a less cosmetic appearance. *Pinch skin graft* - A **pinch graft** is a small, conical piece of skin, including the epidermis and dermis, taken by pinching the skin. - These grafts are generally less aesthetically pleasing, have limited applications, and are often used for small, non-cosmetic defects. *Pedicle graft* - A **pedicle graft** (or flap) is a section of tissue that remains attached to its original site at one or more points, maintaining its own **blood supply**. - Unlike a free graft, it is not completely detached from the donor site, allowing for transfer of more complex tissues like muscle or bone.
Question 8: In Split thickness graft, which part of the skin is/are included?
- A. Epidermis and dermis
- B. Epidermis only
- C. Epidermis and part of dermis (Correct Answer)
- D. Epidermis, dermis and part of subcutaneous tissue
Explanation: ***Epidermis and part of dermis*** - A **split-thickness skin graft** includes the entire **epidermis** and only a **portion of the dermis**. - This allows for easier engraftment and donor site healing due to less deep tissue removal. *Epidermis and dermis* - This describes a **full-thickness skin graft**, which includes the entire epidermis and the entire dermis. - While it provides better cosmetic results and less contraction, it requires a more complex donor site closure. *Epidermis only* - A graft consisting only of the epidermis would be too thin to be clinically useful and would likely not survive. - The dermis provides structural support and a blood supply critical for graft viability. *Epidermis, dermis and part of subcutaneous tissue* - This typically refers to a **composite graft** or a **flap**, not a split-thickness skin graft. - These grafts include deeper tissues, such as subcutaneous fat, to provide bulk and specialized structures.
Question 9: Which of the following statements about mesh skin grafts is not correct?
- A. They allow egress of fluid collections under the graft.
- B. They permit coverage of large areas.
- C. They “take” satisfactorily on granulating bed.
- D. They contract to the same degree as a grafted sheet of skin. (Correct Answer)
Explanation: ***They contract to the same degree as a grafted sheet of skin.*** - This statement is incorrect because **meshed skin grafts** undergo **greater primary and secondary contraction** compared to unmeshed, full-thickness sheet grafts. - The fenestrations in the meshed graft allow for stretching and expansion, but this also contributes to increased contraction as the graft heals and remodels. *They allow egress of fluid collections under the graft.* - The **fenestrations** created by the meshing process provide small openings that facilitate the **drainage of seroma or hematoma** from beneath the graft. - This feature is crucial for graft survival as fluid accumulation can lift the graft, impairing nutrient diffusion and leading to graft failure. *They permit coverage of large areas.* - Meshing a skin graft allows it to be **expanded to cover an area up to 1.5 to 9 times larger** than the original harvested skin. - This is particularly useful in managing **large burn wounds** or extensive skin defects where donor sites are limited. *They “take” satisfactorily on granulating bed.* - Meshed grafts tend to tolerate **less ideal recipient beds**, such as those with some granulation tissue or minor contamination, better than sheet grafts. - The fenestrations allow for drainage and better adherence, which can compensate for a suboptimal underlying bed.
Question 10: Wound contraction can be most effectively minimized by:
- A. Allowing secondary granulation
- B. Full thickness grafting (Correct Answer)
- C. Split skin graft
- D. Dressing with placenta
Explanation: ***Full thickness grafting*** - **Full-thickness skin grafts** include the epidermis and full dermis, which contains **fewer myofibroblasts** than split-thickness grafts, thus minimizing contraction. - The greater amount of dermal tissue acts as a **mechanical barrier** to prevent excessive wound contraction, providing a more stable and aesthetically pleasing result. *Allowing secondary granulation* - Healing by **secondary intention** involves substantial granulation tissue formation, which is rich in **myofibroblasts** and leads to significant wound contraction. - This method of healing is often used for infected or contaminated wounds but results in the **most contraction**. *Split skin graft* - **Split-thickness skin grafts** contain only a portion of the dermis, making them prone to **moderate to significant wound contraction**. - While better than secondary intention, the thin dermal layer provides less resistance to the contractile forces of the **myofibroblasts**. *Dressing with placenta* - **Placental tissue dressings** can promote wound healing by providing growth factors and a scaffold for regeneration. - However, they do not inherently prevent or minimize **wound contraction** in the same way that a full-thickness graft mechanically does, as they do not replace the entire dermal layer.
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