Demineralized Bone Matrix — MCQs

10 questions

Which of the following statements are correct about Kiel bone? 1. Xenograft 2. Allograft 3. Treated by detergent, sterilized, and freeze-dried 4. Ox or calf bone denatured with 20% H2O2, acetone, and sterilized

Which of the following statements regarding collagen synthesis is incorrect?

Which is the first bone to start ossifying?

Which statement is incorrect about the pathology of the bone tumor?

Healing of bone is affected by:

Classification system of bone tumors is -

Periosteal matrix acts on bone tissue to bring about:

Which of the following tests is not used to assess the biocompatibility of dental materials?

Calcium requirement above the normal during the first six months of lactation is -

Q10

The bone matrix has the following crystals -

Demineralized Bone Matrix Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following statements are correct about Kiel bone? 1. Xenograft 2. Allograft 3. Treated by detergent, sterilized, and freeze-dried 4. Ox or calf bone denatured with 20% H2O2, acetone, and sterilized

A. 2 & 4
B. 2 & 3
C. 1 & 3
D. 1 & 4 (Correct Answer)

Explanation: ***1 & 4*** - **Kiel bone** is a type of **xenograft**, meaning it is derived from a different species (usually ox or calf). - It is prepared by **denaturing** ox or calf bone with 20% H2O2 and acetone, followed by sterilization, to reduce antigenicity and ensure safety. *2 & 4* - This option incorrectly states that Kiel bone is an **allograft**, while it is, in fact, a **xenograft**. - The preparation method of denaturing with 20% H2O2 and acetone, and sterilization, correctly describes Kiel bone processing. *2 & 3* - This option incorrectly identifies Kiel bone as an **allograft** and states that it is treated by detergent, sterilized, and freeze-dried. - While some bone grafts are treated this way, it is not the specific processing for Kiel bone, which uses H2O2 and acetone. *1 & 3* - This option correctly identifies Kiel bone as a **xenograft**, but incorrectly states its processing involves detergent, sterilization, and freeze-drying. - The distinguishing feature of Kiel bone preparation is the use of **H2O2 and acetone** for denaturing.

Question 2: Which of the following statements regarding collagen synthesis is incorrect?

A. Hydroxylation of lysine occurs in ER
B. Synthesized in ribosomes as preprocollagen
C. Triple helix assembly occurs in ER
D. Hydroxylation of proline occurs in Golgi apparatus (Correct Answer)

Explanation: ***Hydroxylation of proline occurs in Golgi apparatus*** - This statement is incorrect because the **hydroxylation of proline** residues occurs in the **endoplasmic reticulum** (ER), not the Golgi apparatus. - This step is critical for forming stable **triple helix** structures of collagen and requires **vitamin C**. *Synthesized in ribosomes as preprocollagen* - This statement is correct. Collagen synthesis begins in the cytoplasm, where mRNA is translated by **ribosomes** into **preprocollagen**, which contains a signal peptide. - The signal peptide directs the nascent polypeptide chain into the lumen of the **endoplasmic reticulum**. *Hydroxylation of lysine occurs in ER* - This statement is correct. Following entry into the ER, specific **lysine** residues are hydroxylated by **lysyl hydroxylase** to form hydroxylysine. - This hydroxylation, along with that of proline, is crucial for **cross-linking** and stability of the collagen molecule. *Triple helix assembly occurs in ER* - This statement is correct. After hydroxylation and glycosylation of some residues, three procollagen alpha chains self-assemble to form a **triple helix** within the **endoplasmic reticulum**. - This assembly is stabilized by **disulfide bonds** at the C-terminal ends and molecular chaperones.

Question 3: Which is the first bone to start ossifying?

A. Femur
B. Clavicle (Correct Answer)
C. Tibia
D. Mandible

Explanation: ***Clavicle*** - The **clavicle** is the **first bone to begin ossification** in the human body, starting around the **5th-6th week of gestation**. - It ossifies via **intramembranous ossification**, making it unique among long bones [1]. - This early ossification is a key landmark in fetal skeletal development and is consistently taught across medical curricula. *Mandible* - The **mandible** begins ossification around the **6th week of gestation**, shortly after the clavicle [1]. - While it is one of the earliest bones to ossify, it is **not the first**. - It also undergoes intramembranous ossification [1]. *Femur* - The **femur**, a long bone, begins ossification around the **7th-8th week of gestation** [1]. - It ossifies via **endochondral ossification**, which typically occurs later than intramembranous ossification [1]. *Tibia* - The **tibia** also begins ossification around the **7th-8th week of gestation**. - Like the femur, it follows the endochondral ossification pathway.

Question 4: Which statement is incorrect about the pathology of the bone tumor?

A. Tumor has distinct margin
B. Tumor arises from epiphyseal to metaphyseal region
C. Eccentric lesion
D. Chemotherapy is the treatment of choice for all bone tumors. (Correct Answer)

Explanation: ***Tumor has distinct margin*** - A **distinct margin** often indicates a benign tumor, while malignant tumors typically show **infiltrative margins**. - In bone tumors, particularly malignant ones, the lack of clear demarcation is a key pathological feature. *Chemotherapy is the treatment of choice* - While chemotherapy may be used for certain **malignant bone tumors**, it is not the first-line treatment for most bone tumors [1]. - The primary treatment is often **surgical excision**, especially for localized lesions [1]. *Tumor arise from epiphyseal to metaphyseal region* - While some tumors can originate in these areas, many actually arise from the **diaphyseal** region in bone tumors like osteosarcoma. - This option misrepresents the common locations where various tumors develop, as osteochondromas tend to develop near the epiphyses of limb bones [2]. *Eccentric lesion* - Many bone tumors do indeed present as **eccentric lesions**, especially benign ones like **osteochondromas**. - However, this feature does not apply universally, as some malignant tumors can also be **central or infiltrative** in nature. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 673-674. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 672-673.

Question 5: 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 6: Classification system of bone tumors is -

A. Enneking (Correct Answer)
B. Edmonton
C. TNM
D. Manchester

Explanation: ***Enneking*** - The **Enneking staging system** is widely used for primary **bone tumors**, particularly sarcomas. - It classifies tumors based on their histological grade, local extension, and presence of metastases, which guides surgical planning and prognosis. *Edmonton* - The **Edmonton classification** is primarily used for **periprosthetic fractures** around hip and knee replacements. - It does not classify primary bone tumors but rather describes fracture patterns related to prosthetic implants. *TNM* - The **TNM (Tumor, Node, Metastasis)** classification is a general staging system used for many types of cancer, but it's not the primary system for bone tumors. - While applicable for some bone cancers, the **Enneking system** provides a more specific functional and anatomical assessment for limb-sparing surgery in bone sarcomas. *Manchester* - The **Manchester staging system** is primarily used for **lymphoma**, particularly Hodgkin lymphoma. - It describes the extent of lymph node involvement and extralymphatic disease, completely unrelated to bone tumors.

Question 7: Periosteal matrix acts on bone tissue to bring about:

A. Bone modeling (Correct Answer)
B. Bone resorption only
C. Cartilage formation
D. Bone mineralization only

Explanation: ***Bone modeling*** - The **periosteum** is a vital outer layer of bone that plays a crucial role in bone growth, repair, and **modeling** [1]. - **Bone modeling** involves changes in bone size and shape, often through independent processes of bone formation and resorption on different surfaces, which the periosteal matrix actively contributes to [1]. *Bone resorption only* - While **bone resorption** is a component of bone remodeling, the periosteal matrix is involved in both bone formation and resorption, not exclusively resorption [2]. - Focusing solely on resorption neglects the periosteum's role in **bone deposition** and overall bone shape changes [1]. *Cartilage formation* - The periosteum does not primarily lead to **cartilage formation**; its main role is in bone tissue [3]. - Cartilage formation is typically mediated by chondrocytes, usually in different developmental contexts or repair processes [4]. *Bone mineralization only* - **Bone mineralization** is the process by which inorganic minerals (chiefly calcium phosphate) are deposited into the organic matrix of bone [3]. - While the periosteum contributes to the formation of the organic matrix, its role extends beyond just mineralization to the overall **structuring and reshaping of bone** [1].

Question 8: Which of the following tests is not used to assess the biocompatibility of dental materials?

A. Implantation test
B. Sensitization test
C. Ames test (Correct Answer)
D. Buehler test

Explanation: ***Ames test*** - This test is a **mutagenicity assay** that assesses the ability of a chemical to cause mutations in DNA, primarily used to identify potential **carcinogens**. - While related to safety, it does not directly evaluate the **biocompatibility** (tissue response and interaction) of a material in a biological system. *Buehler test* - The Buehler test is a common method for assessing **sensitization potential** of a material, often used to evaluate whether a material causes an allergic contact dermatitis. - This is a direct measure of an adverse biological response and thus contributes to the overall assessment of **biocompatibility**. *Implantation test* - This test involves placing the material directly into an animal tissue (e.g., muscle, subcutaneous tissue) to evaluate the **local tissue response** over time. - It assesses aspects like **inflammation**, encapsulation, and tissue integration, which are primary indicators of a material's **biocompatibility**. *Sensitization test* - These tests, like the Buehler test mentioned, aim to identify if a material can induce an **allergic reaction** in a host. - Detecting such immune responses is crucial for determining if a material is safe for long-term contact with biological tissues, making it an essential part of **biocompatibility assessment**.

Question 9: Calcium requirement above the normal during the first six months of lactation is -

A. 75 mg/day
B. 400 mg/day
C. 550 mg/day
D. 600 mg/day (Correct Answer)

Explanation: ***600 mg/day*** - The increased calcium requirement during the first six months of lactation is primarily due to the significant amount of calcium secreted in **breast milk** for infant bone development. - During lactation, approximately **210-300 mg of calcium per day** is lost through breast milk, and considering **absorption efficiency** and maintaining maternal **bone density**, an additional **600 mg/day** above baseline requirements is recommended. - This additional intake helps meet the demands of milk production and prevent maternal bone demineralization during the period of **peak lactation**. *400 mg/day* - While calcium needs are elevated in lactation, an additional **400 mg/day** is insufficient to fully compensate for the calcium loss through breast milk during the initial, high-volume milk production phase. - This amount does not adequately account for both milk calcium content and the need to maintain maternal bone health during the first six months of lactation. *550 mg/day* - This increment is close but is generally considered slightly below the recommended additional intake for optimal maternal health and infant nutrition during **peak lactation**. - Adequate calcium intake is crucial as insufficient levels can lead to a negative calcium balance and increased risk of maternal **osteoporosis**. *75 mg/day* - An additional **75 mg/day** is a negligible increase and is far too low to meet the substantial calcium demands during the first six months of lactation. - This amount would be grossly inadequate considering that lactating mothers lose approximately **210-300 mg of calcium per day** into breast milk alone, not accounting for maternal physiological needs.

Question 10: The bone matrix has the following crystals -

A. Calcium pyrophosphate
B. Calcium hydroxyapatite (Correct Answer)
C. Calcium phosphate
D. Calcium sulphate

Explanation: ***Calcium hydroxyapatite*** - The primary mineral component of bone matrix is **calcium hydroxyapatite**, which gives bone its rigidity and strength [1]. - These crystals are formed from **calcium and phosphate ions** arranged in a specific crystalline structure within the collagen fibers [1]. *Calcium pyrophosphate* - **Calcium pyrophosphate dihydrate (CPPD)** crystals are associated with **pseudogout**, a condition causing joint inflammation, not the normal bone matrix [1]. - They are found in articular cartilage and synovial fluid, not as a structural component of healthy bone. *Calcium phosphate* - While hydroxyapatite is a form of **calcium phosphate**, simply "calcium phosphate" is too general and does not specify the exact crystalline structure found in bone [1]. - Many calcium phosphate compounds exist, but **hydroxyapatite** is the specific and most abundant one in bone [1]. *Calcium sulphate* - **Calcium sulfate** is not a naturally occurring mineral component of the bone matrix in vertebrates. - It is sometimes used in medical applications as a **bone graft substitute** or a drug delivery system, but not as an endogenous component.

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