3D Printing Applications — MCQs
Rate of newly synthesized osteoid mineralization can be best estimated by -
Which of the following pontic designs requires a surgical procedure?
All of the following are described surgical procedures for CTE V except -
In immediate denture, why is clear acrylic stent or surgical template given soon after extraction?
Which prosthesis is shown below in the X-ray?
Which of the following bone defects offers the best chance for bone fill?
What is the primary use of stainless steel in orthodontics?
All of the following are true regarding the application of POP Cast except -
All of the following factors affect osseointegration EXCEPT:
Agnes hunt traction is used for which of the following conditions?
3D Printing Applications Indian Medical PG Practice Questions and MCQs
Question 1: Rate of newly synthesized osteoid mineralization can be best estimated by -
- A. Calcein stain
- B. Tetracycline labeling (Correct Answer)
- C. Von Kossa stain
- D. Alizarin red stain
Explanation: ***Tetracycline labeling*** - **Tetracycline** is incorporated into newly forming bone (osteoid) at the mineralization front because of its **calcium-chelating properties**. - By administering two doses of tetracycline at a known interval, the distance between the two fluorescent bands can be measured to calculate the **mineralization apposition rate**, which reflects the rate of new osteoid mineralization. *Calcein stain* - **Calcein** is another fluorescent marker that can be used for bone labeling, similar to tetracycline, but it is less commonly used in clinical practice. - While it labels mineralizing bone, the question asks for the **best** method for estimating the *rate* of mineralization, for which tetracycline's historical and established two-dose method is superior. *Von Kossa stain* - The **Von Kossa stain** highlights mineralized bone by precipitating silver in areas where calcium salts are present, thus indirectly staining the mineral component. - It does not directly assess the *rate* of mineralization or the difference between newly synthesized and pre-existing mineralized bone. *Alizarin red stain* - **Alizarin red S** is a dye that stains calcium deposits a red-orange color, making it useful for identifying areas of mineralization. - Like Von Kossa, it indicates the presence of calcium but does not provide a quantitative measure of the *rate* at which newly formed osteoid is mineralizing over time.
Question 2: Which of the following pontic designs requires a surgical procedure?
- A. Ovate (Correct Answer)
- B. Modified ridge lap
- C. Saddle
- D. Sanitary
Explanation: ***Ovate*** - The **ovate pontic** design requires a surgical procedure to create a **concave depression** in the edentulous ridge. - This design provides an aesthetic emergence profile, mimicking a natural tooth, and facilitates hygiene by allowing **flossing** beneath the pontic. *Modified ridge lap* - This design is a compromise between aesthetics and hygiene, with the tissue-contacting surface being **convex** and minimally contacting the ridge. - It does not require any surgical preparation of the soft tissue, as it rests superficially on the ridge. *Saddle* - The **saddle pontic** design broadly covers the edentulous ridge, making it highly aesthetic but very difficult to clean due to its **concave tissue-facing surface**. - No surgical procedure is typically involved in its initial placement, though it is now largely contraindicated due to plaque accumulation. *Sanitary* - Also known as a **hygienic pontic**, this design has **no contact** with the edentulous ridge. - It is often used in posterior regions where aesthetics are less critical, emphasizing hygiene without any surgical intervention.
Question 3: All of the following are described surgical procedures for CTE V except -
- A. Dwyer's osteotomy
- B. Salter's osteotomy (Correct Answer)
- C. Posteromedial soft tissue release
- D. Triple Arthrodesis
Explanation: ***Salter's osteotomy*** - **Salter's osteotomy** is a procedure primarily used for treating **developmental dysplasia of the hip (DDH)**, aiming to redirect the acetabulum. - It is not a described surgical procedure for the correction of **congenital talipes equinovarus (CTEV)**. *Dwyer's osteotomy* - **Dwyer's osteotomy** is a surgical procedure performed on the **calcaneus** to correct **hindfoot varus**, typically seen in CTEV. - It involves removing a wedge of bone from the lateral aspect of the calcaneus. *Posteromedial soft tissue release* - This is a common and traditional surgical procedure for correcting severe **CTEV** by addressing the contracted soft tissues on the medial and posterior aspects of the foot. - It involves releasing structures such as the **tibial tendon**, **flexor digitorum longus**, **flexor hallucis longus**, and the **posterior ankle joint capsule**. *Triple Arthrodesis* - **Triple arthrodesis** is a salvage procedure that involves fusing three joints in the foot: the **talonavicular**, **calcaneocuboid**, and **subtalar** joints. - It is used in older children or adolescents with severe, rigid, or recurrent CTEV, often after failed conservative or primary surgical treatments.
Question 4: In immediate denture, why is clear acrylic stent or surgical template given soon after extraction?
- A. For trimming jagged bone margins (Correct Answer)
- B. Condition tissues
- C. For impression taking
- D. Contain socket healing substances
Explanation: ***For trimming jagged bone margins*** - A clear acrylic stent aids in visualizing the underlying bone during surgery, allowing the clinician to **trim any sharp or jagged bone margins** post-extraction. - This process is crucial for creating a smooth, even ridge that will properly support the immediate denture and prevent **pressure sores** or discomfort. *Condition tissues* - Tissue conditioning is typically performed with a soft reline material placed inside an existing denture or a temporary base to improve the health of abused oral tissues. - A clear acrylic stent is a rigid device used during surgery and does not possess properties to condition tissues. *For impression taking* - Impressions for immediate dentures are taken *before* extractions to capture the existing dentition and soft tissue contours, which are then used to fabricate the denture. - A clear acrylic stent is used *during* the surgical phase, after extractions, to guide bone reshaping, not for taking an impression. *Contain socket healing substances* - While some materials can be placed in extraction sockets to aid healing, the primary purpose of a clear acrylic surgical template is mechanical guidance for bone reduction. - It itself does not typically contain or deliver healing substances to the socket.
Question 5: Which prosthesis is shown below in the X-ray?
- A. Articular resurfacing
- B. Thompson prosthesis
- C. Austin Moore's prosthesis (Correct Answer)
- D. Birmingham hip replacement
Explanation: ***Austin Moore's prosthesis*** - The image clearly shows a **femoral stem with a long intramedullary component** and an **integrated prosthetic head** that articulates directly with the native acetabulum. This is characteristic of a hemiarthroplasty design, specifically resembling an Austin Moore prosthesis. - This type of prosthesis is commonly used for **femoral neck fractures** in older patients, replacing only the femoral head and neck rather than the entire hip joint. *Articular resurfacing* - **Articular resurfacing** involves capping the femoral head and lining the acetabulum with metallic implants, preserving more bone than a traditional total hip replacement. - The X-ray image does not show a cap on the femoral head or a separate acetabular component, which are features of resurfacing. *Thompson prosthesis* - The **Thompson prosthesis** is another type of hemiarthroplasty, but it typically has a **shorter, bulkier femoral stem** and a **relatively smaller head** compared to the Austin Moore prosthesis shown. - While both Thompson and Austin Moore prostheses are hemiarthroplasties, the specific shape and length of the stem in the X-ray are more consistent with an Austin Moore design. *Birmingham hip replacement* - The **Birmingham hip replacement** is a type of **hip resurfacing arthroplasty**, which, as explained earlier, involves capping the femoral head and is not depicted in this image. - It maintains more of the patient's original bone structure compared to conventional total hip replacement but still requires both femoral and acetabular components.
Question 6: 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 7: What is the primary use of stainless steel in orthodontics?
- A. To enhance the strength of dental materials
- B. For making clasps in partial dentures
- C. To replace gold restorations in teeth
- D. In the fabrication of orthodontic wires (Correct Answer)
Explanation: ***In the fabrication of orthodontic wires*** - Stainless steel is widely used in orthodontics for **wires** due to its excellent **strength**, **formability**, and corrosion resistance. - Its **elasticity** allows for controlled force application to move teeth effectively and predictably. *To enhance the strength of dental materials* - While stainless steel is strong, its primary orthodontic use is not as an additive to **enhance** other bulk dental materials like composites or ceramics. - Other materials or processing methods are typically used for strengthening restorative or prosthetic dental materials. *For making clasps in partial dentures* - Stainless steel can be used for clasps, but **cobalt-chromium alloys** or **wrought wire clasps** made from other alloys are more common in partial dentures for their specific mechanical properties and biocompatibility. - The context of the question points to a primary orthodontic application beyond general prosthodontics. *To replace gold restorations in teeth* - Stainless steel is not typically used as a direct replacement for **gold restorations** (inlays, onlays, crowns) in permanent dentition due to aesthetic and long-term wear considerations. - While stainless steel crowns are used in pediatric dentistry, they serve a different purpose than replacing gold in adults.
Question 8: All of the following are true regarding the application of POP Cast except -
- A. It can be applied in presence of extreme swelling
- B. Gangrene is known complication of a tight plaster cast
- C. Putting the Plaster roll in warm water hastens setting time
- D. It is anhydrous Calcium phosphate (Correct Answer)
Explanation: ***It is anhydrous Calcium phosphate*** - **Plaster of Paris (POP)** is chemically **calcium sulfate hemihydrate** (CaSO₄·½H₂O), not anhydrous calcium phosphate. - Adding water to calcium sulfate hemihydrate causes an exothermic reaction, forming **calcium sulfate dihydrate**, which is the hardened cast. *Putting the Plaster roll in warm water hastens setting time* - **Warm water** increases the rate of the chemical reaction that causes POP to set, thus **hastening the setting time**. - While it speeds up setting, excessively hot water can lead to a cast that sets too quickly or becomes brittle. *It can be applied in presence of extreme swelling* - Applying a non-flexible POP cast in the presence of **extreme swelling** is contraindicated because swelling will rapidly resolve, making the cast loose and ineffective. - Furthermore, if swelling increases unexpectedly under a tight cast, it can lead to dangerous **compartment syndrome**. *Gangrene is known complication of a tight plaster cast* - A **tight plaster cast** can compromise blood supply to the limb by compressing arteries and veins, potentially leading to **ischemia**. - Prolonged ischemia due to a tight cast can cause **tissue necrosis** and ultimately **gangrene** if not identified and treated promptly.
Question 9: 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 10: Agnes hunt traction is used for which of the following conditions?
- A. Flexion deformity of the hip (Correct Answer)
- B. Trochanteric fracture
- C. Fracture of the shaft of the humerus
- D. Low backache
Explanation: **Explanation:** **Agnes Hunt Traction** is a specialized form of traction used specifically for the correction of **Flexion Deformity of the Hip**. The underlying medical concept involves applying traction to the affected limb while the contralateral (normal) limb is immobilized in a plaster cast in a position of maximum flexion. This stabilizes the pelvis and prevents compensatory lumbar lordosis, allowing the traction to act directly on the hip joint to gradually stretch the flexor contractures. **Analysis of Options:** * **A. Flexion deformity of the hip (Correct):** It is the classic indication. By neutralizing pelvic tilt, it effectively reduces fixed flexion deformities (FFD). * **B. Trochanteric fracture:** These are typically managed with skeletal traction (like Hamilton Russell traction) or, more commonly, surgical fixation (DHS or PFN). * **C. Fracture shaft of humerus:** This is managed using a U-slab, hanging cast, or skin traction like **Dunlop’s traction** (though Dunlop's is primarily for supracondylar fractures). * **D. Low backache:** This is usually managed with **Pelvic traction**, which helps in relieving muscle spasms and distracting the neural foramina. **High-Yield Clinical Pearls for NEET-PG:** * **Thomas Splint:** Used for immobilization of fractures of the shaft of the femur. * **Bryant’s Traction (Gallows):** Used for femur fractures in children below 2 years of age (weight <15-18kg). * **Russell’s Traction:** Used for trochanteric and subtrochanteric fractures; it uses a sling under the knee. * **Buck’s Traction:** A simple skin traction used for temporary immobilization of hip fractures or to reduce muscle spasms. * **90-90 Traction:** Commonly used in pediatric femoral shaft fractures to maintain the hip and knee at 90 degrees of flexion.
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