Bone Morphogenetic Proteins — MCQs
Type I collagen is present in all EXCEPT:
What is the primary reason for the failure of cervical restorations?
Buttressing bone formation is the periodontal tissue response to an increase in occlusal forces seen in
Healing of bone is affected by:
Which of the following bone defects offers the best chance for bone fill?
Pioneer of distraction osteogenesis is:
In osteoporosis, bone formation is increased by which drug?
Which of the following is not a neural plate inducer?
Bone marrow biopsy shows increased plasma cells with 'clock-face' chromatin pattern and perinuclear halo. Diagnosis?
Bone marrow biopsy shows increased plasma cells with 'clock-face' chromatin pattern and perinuclear halo. Diagnosis?
Bone Morphogenetic Proteins Indian Medical PG Practice Questions and MCQs
Question 1: Type I collagen is present in all EXCEPT:
- A. Ligament
- B. Aponeurosis
- C. Cartilage (Correct Answer)
- D. Bone
Explanation: Cartilage - **Type II collagen** is the predominant collagen found in hyaline and elastic cartilage (the typical forms of cartilage), providing their characteristic tensile strength and resilience [2]. - Type I collagen is NOT the primary collagen in cartilage, making this the correct answer. - Note: Fibrocartilage is a specialized form that does contain Type I collagen, but standard cartilage refers to hyaline and elastic types. *Ligament* - **Type I collagen** is the primary structural component of ligaments, providing high tensile strength to connect bones and stabilize joints. - Its presence allows ligaments to withstand significant pulling forces without stretching excessively. *Aponeurosis* - **Type I collagen** is abundant in aponeuroses, which are flat sheet-like tendons that connect muscles to bones or other muscles. - This type of collagen provides the necessary tensile strength for these broad connective tissues. *Bone* - **Type I collagen** is the most abundant collagen in bone matrix, accounting for approximately 90% of its organic content [1]. - It forms a robust scaffold that gives bone its flexibility and tensile strength, working in conjunction with mineralized components like hydroxyapatite [1].
Question 2: What is the primary reason for the failure of cervical restorations?
- A. Inadequate moisture control (Correct Answer)
- B. Marginal gingivitis
- C. Cuspal flexure
- D. None of the options
Explanation: ***Inadequate moisture control*** - **Moisture contamination** during bonding procedures in the cervical region significantly compromises the **seal** and longevity of restorations. - The **gingival margin** and proximity to salivary glands make isolation challenging, leading to bond degradation and eventual failure. *Marginal gingivitis* - While marginal gingivitis can complicate restorative procedures and patient comfort, it is not a direct primary cause of restoration failure. - It indicates **poor oral hygiene** and inflammation of the gingiva adjacent to the restoration, often a consequence rather than a cause of failure. *Cuspal flexure* - **Cuspal flexure** primarily affects posterior teeth with extensive restorations, causing stresses that can lead to fracture or debonding of the restoration or tooth structure. - This phenomenon is less relevant to **cervical restorations**, which are generally not subjected to significant occlusal forces or flexure.
Question 3: Buttressing bone formation is the periodontal tissue response to an increase in occlusal forces seen in
- A. Stage I injury
- B. Stage II repair (Correct Answer)
- C. Stage III repair
- D. None of the options
Explanation: **_Stage II repair_** - In response to increased occlusal forces, buttressing bone formation is a reparative mechanism where the **alveolar bone thickens** to better withstand these forces. - This adaptive change is characteristic of the **Stage II repair phase**, aiming to reinforce the supportive structures around the tooth. *Stage I injury* - This stage typically involves the **initial damage** to the periodontal tissues, such as widening of the periodontal ligament space or increased vascularity. - **Buttressing bone formation** is a reparative, not an initial injury, response. *Stage III repair* - Stage III repair is usually associated with more **severe or chronic injury**, often involving a more pronounced remodeling or even degenerative changes if the forces are persistent and overwhelming. - While repair continues, buttressing bone formation is most characteristic of the **active phase of adaptation** in Stage II. *None of the options* - Buttressing bone formation is a well-documented biological response to increased occlusal forces and is particularly relevant in the context of **periodontal adaptation and repair**. - Therefore, one of the provided stages is the correct answer.
Question 4: Healing of bone is affected by:
- A. Hypoxia
- B. Micromovement
- C. Muscle interposition
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Hypoxia**, **micromovement**, and **muscle interposition** are all factors known to impede or negatively affect the normal healing process of a bone fracture. - The successful healing of a bone fracture relies on a series of biological events that can be disrupted by these adverse conditions, leading to delayed union or non-union. *Hypoxia* - **Hypoxia**, or insufficient oxygen supply, impairs the metabolic activity of cells essential for bone healing, such as osteoblasts and chondrocytes. - It interferes with **angiogenesis**, the formation of new blood vessels, which is critical for delivering nutrients and oxygen to the healing bone. *Micromovement* - Excessive **micromovement** at the fracture site prevents the formation of a stable callus and can stimulate the development of fibrous tissue or cartilage instead of bone. - While some motion is beneficial, uncontrolled or excessive micromotion can lead to a **non-union** or pseudarthrosis, as it constantly disrupts the delicate tissue bridges attempting to form. *Muscle interposition* - **Muscle interposition** refers to muscle tissue becoming trapped between the bone fragments, physically separating them and preventing direct bone-to-bone contact. - This physical barrier inhibits the formation of the **fracture hematoma** and subsequent callus, thus mechanically hindering the healing process.
Question 5: 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 6: Pioneer of distraction osteogenesis is:
- A. Codivilla
- B. Snyder
- C. Ilizarov (Correct Answer)
- D. Alexander
Explanation: ***Ilizarov*** - **Gavriil Abramovich Ilizarov** is widely recognized as the pioneer of **distraction osteogenesis**, developing the biological principles and surgical techniques in the 1950s. - His method involved gradually separating a corticotomy site to stimulate new bone formation, a technique now fundamental in limb lengthening and reconstructive surgery. *Codivilla* - **Alessandro Codivilla** was an Italian surgeon who performed limb lengthening in the early 20th century, but his method involved acute distraction, which often led to complications like joint subluxation and non-union. - His work predated Ilizarov's systematic approach to gradual distraction and neo-osteogenesis. *Snyder* - **Snyder** is not specifically recognized as a pioneer in the early development of distraction osteogenesis in the same historical context as Ilizarov or Codivilla. - His contributions, if any, are not central to the fundamental principles or widespread adoption of the technique. *Alexander* - The name **Alexander** is not directly associated with the pioneering work or development of distraction osteogenesis in orthopedic surgery. - While many surgeons have contributed to advancements in the field, Alexander is not credited with its fundamental principles.
Question 7: In osteoporosis, bone formation is increased by which drug?
- A. Estrogen
- B. Bisphosphonates
- C. Teriparatide (Correct Answer)
- D. Calcitonin
Explanation: ***Teriparatide*** - Teriparatide is a recombinant form of **parathyroid hormone (PTH)** that, when administered intermittently, stimulates **osteoblast activity** leading to increased **bone formation**. - It is an **anabolic agent** used in osteoporosis to build new bone rather than just prevent bone loss. *Estrogen* - Estrogen is primarily used to prevent **bone loss** by **inhibiting osteoclast activity** and supporting bone mineralization. - It does not directly **increase bone formation** but rather maintains bone density. *Bisphosphonates* - Bisphosphonates inhibit **osteoclast-mediated bone resorption** by inducing apoptosis in osteoclasts. - They primarily **decrease bone breakdown** and do not directly stimulate new bone formation. *Calcitonin* - Calcitonin is a hormone that **inhibits osteoclast activity** and thus reduces bone resorption. - It is not a bone-forming agent but rather acts to **decrease bone breakdown** and is used for pain relief in vertebral fractures.
Question 8: Which of the following is not a neural plate inducer?
- A. FGF upregulation
- B. Prechordal mesoderm
- C. High BMP (Correct Answer)
- D. Notochord appearance
Explanation: High BMP - **Bone Morphogenetic Proteins (BMPs)** are primarily involved in promoting epidermal differentiation in the ectoderm, and actively **inhibiting neural differentiation**. - Therefore, high levels of BMP would **prevent neural plate formation**, rather than induce it. *FGF upregulation* - **Fibroblast Growth Factors (FGFs)** are crucial in the early development of the nervous system. - They play a key role in **inducing neural plate formation** and maintaining its identity. *Prechordal mesoderm* - The **prechordal mesoderm**, located anterior to the notochord, is an important signalling center during early embryonic development. - It contributes to the **induction of the forebrain** and plays a role in patterning the anterior neural plate. *Notochord appearance* - The **notochord**, a transient rod-like structure, is a primary inducer of the neural plate. - It secretes factors like **Sonic Hedgehog (Shh)** which induce the overlying ectoderm to differentiate into neuroectoderm, forming the neural plate.
Question 9: Bone marrow biopsy shows increased plasma cells with 'clock-face' chromatin pattern and perinuclear halo. Diagnosis?
- A. MGUS
- B. Plasmacytoma
- C. Multiple myeloma (Correct Answer)
- D. Waldenstrom's macroglobulinemia
Explanation: ***Multiple myeloma*** - The presence of increased **plasma cells** with a distinctive **'clock-face' chromatin pattern** and **perinuclear halo** on bone marrow biopsy is a classic histological feature of multiple myeloma [1]. - These morphological characteristics are indicative of **malignant plasma cell proliferation**, which is the hallmark of this condition [1]. *MGUS (Monoclonal Gammopathy of Undetermined Significance)* - While MGUS also involves a monoclonal plasma cell population, the bone marrow biopsy typically shows a **plasma cell infiltration rate of less than 10%** [1]. - The criteria for MGUS do not usually include a high enough burden of atypical plasma cells to cause significant organ damage or the characteristic histological features seen in myeloma. *Plasmacytoma* - A plasmacytoma is a localized proliferation of plasma cells, which can be solitary bone plasmacytoma or extramedullary [2]. - While the neoplastic plasma cells within a plasmacytoma would exhibit these features, the term plasmacytoma refers to a **single lesion**, whereas the biopsy in the question suggests a systemic involvement implied by "increased plasma cells" as a general finding rather than a specific focal lesion [2]. *Waldenstrom's macroglobulinemia* - This condition is characterized by a proliferation of **lymphoplasmacytic cells** (cells with features of both lymphocytes and plasma cells) that secrete **monoclonal IgM** [2]. - The bone marrow biopsy often shows an infiltrate of these lymphoplasmacytic cells, which are distinct from the predominantly mature plasma cells with typical 'clock-face' chromatin seen in multiple myeloma [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 616-618. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 606-608.
Question 10: Bone marrow biopsy shows increased plasma cells with 'clock-face' chromatin pattern and perinuclear halo. Diagnosis?
- A. Multiple myeloma (Correct Answer)
- B. Waldenstrom's
- C. Plasmacytoma
- D. MGUS
Explanation: ***Multiple myeloma*** - The presence of increased **plasma cells** in the bone marrow with a characteristic **'clock-face' chromatin pattern** and **perinuclear halo** is a classic histopathological finding in multiple myeloma. [1] - These features are indicative of abnormal plasma cell proliferation, which is the hallmark of this **B-cell malignancy**. [1] *Waldenstrom's* - Characterized by **lymphoplasmacytocytic lymphoma** with monoclonal IgM gammopathy, but typically does not show the classic "clock-face" morphology of pure plasma cells in the bone marrow. [1] - While there are plasma cells, the predominant cell type would be **lymphoplasmacytoid cells** with lymphoid features. [2] *Plasmacytoma* - A **localized proliferation of plasma cells** but does not necessarily involve diffuse bone marrow infiltration as described, nor does it typically present as a systemic disease initially. [2] - Although it contains plasma cells, the term suggests a single mass rather than generalized increased plasma cells throughout the marrow. [2] *MGUS* - Stands for **Monoclonal Gammopathy of Unknown Significance** and involves a small clone of plasma cells producing a monoclonal protein, but the bone marrow plasma cell percentage is typically **less than 10%** and does not meet criteria for active myeloma. - It is an **asymptomatic precursor condition** and would not usually show such a striking increase or abnormal morphology suggestive of an overt malignancy. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 616-618. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 606-608.
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