Conservative Dentistry and Dental Radiology — MCQ ও উত্তর

ডেন্টাল ভর্তি · । এই অধ্যায়ে মোট 116টি প্রশ্ন আছে। নিচে প্রথম 10টি প্রশ্ন ও সঠিক উত্তর দেওয়া হলো।

এই অধ্যায়ে সব প্রশ্নে অনুশীলন করুন

1. Where is an early interproximal carious lesion most commonly found in relation to the contact area?

   1. Occlusal to the contact area
   2. Gingival to the contact area
   3. Apical to the root apex
   4. Coronal to the marginal ridge

   সঠিক উত্তর: Gingival to the contact area

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B Early interproximal carious lesions typically begin gingival to the contact area because this region has thinner enamel and is less self-cleansing than the actual contact point. Plaque accumulation is more likely in this gingival embrasure, where access for cleaning is limited and enamel rods are more susceptible to acid demineralization. The contact area itself is tightly adapted and less prone to initial decay. Recognizing this helps clinicians target early intervention and prevent lesion progression. Reference: Fejerskov & Kidd, Dental Caries: The Disease and Its Clinical Management, 3rd Edition.

2. Which of the following restorative materials is most appropriate for a posterior tooth with carious undermined cusps?

   1. Composite resin
   2. Amalgam restoration
   3. Cast gold restoration
   4. Glass ionomer cement

   সঠিক উত্তর: Cast gold restoration

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option C A posterior tooth with carious undermined cusps requires a restoration that provides maximum strength, durability, and cuspal protection. Cast gold restorations offer excellent marginal adaptation, strength, and resistance to fracture, making them ideal for supporting weakened cusps. They effectively distribute occlusal forces and prevent further cusp breakage. Unlike direct restorations, they can be precisely fabricated to cover and reinforce the undermined tooth structure. Thus, cast gold restorations ensure long-term success in severely compromised posterior teeth. Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

3. Decay occurring on the proximal surface and incisal edge of an anterior tooth is classified as:

   1. Pit and fissure caries
   2. Smooth surface caries
   3. Root surface caries
   4. Secondary (recurrent) caries

   সঠিক উত্তর: Smooth surface caries

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B Decay on the proximal surface and incisal edge of an anterior tooth involves areas that are generally smooth and free of pits or fissures. Such caries develop on the flat surfaces of the tooth, excluding occlusal pits or root areas. Pit and fissure caries occur mainly on occlusal or lingual/palatal pits, not on proximal or incisal edges. Root surface caries affect the cementum of exposed roots, which is not involved here. Secondary caries arise adjacent to existing restorations, which is not specified in this context. Therefore, decay on proximal and incisal edges of an anterior tooth is classified as smooth surface caries because it involves the cleaner, less retentive flat enamel surfaces. Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

4. What is the primary mechanism behind the development of pit and fissure caries?

   1. Bacterial invasion through enamel cracks
   2. Physical impaction of food debris in pits and fissures
   3. Acid erosion from intrinsic gastric acids
   4. Excessive fluoride exposure causing enamel breakdown

   সঠিক উত্তর: Physical impaction of food debris in pits and fissures

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B The primary mechanism behind the development of pit and fissure caries is the physical impaction of food debris in the narrow grooves of the occlusal surface. These fissures are anatomically deep and difficult to clean, allowing food particles to accumulate and creating a conducive environment for bacterial proliferation. This leads to localized acid production and enamel demineralization. Unlike smooth surface caries, the caries initiation here is primarily due to food retention rather than direct bacterial invasion through enamel cracks. Therefore, pit and fissure areas require special preventive measures such as sealants and meticulous oral hygiene to minimize debris retention.Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

5. Why do pit and fissure caries typically exhibit a cone-shaped pattern of penetration?

   1. The enamel rods are oriented converging towards the occlusal surface
   2. The dentinal tubules run parallel to the enamel surface
   3. The outer enamel layer is thicker at the base of the fissure
   4. Bacterial colonies spread uniformly beneath the enamel surface

   সঠিক উত্তর: The enamel rods are oriented converging towards the occlusal surface

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A Pit and fissure caries exhibit a cone-shaped pattern of penetration because enamel rods in these areas are oriented obliquely and converge towards the occlusal surface. This structural arrangement creates a narrower entrance at the enamel surface but facilitates deeper bacterial progression towards the dentin beneath, resulting in a spreading lesion that widens as it approaches the dentinoenamel junction. Understanding this pattern is crucial for early detection and effective restorative intervention. Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

6. What is the ideal clearance between the gingival floor of a preparation and the adjacent tooth surface?

   1. 2 mm
   2. 5 mm
   3. 0 mm
   4. 5 mm

   সঠিক উত্তর: 5 mm

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B The ideal clearance of 0.5 mm between the gingival floor of a preparation and the adjacent tooth surface is necessary to maintain adequate proximal contact while allowing proper access for restorative material placement. This clearance ensures prevention of food impaction and helps maintain periodontal health by avoiding plaque accumulation in tight, inaccessible areas. Too little clearance (0.2 mm) risks inadequate material thickness and contact, while excessive clearance (>0.5 mm) compromises tooth structure and contact integrity. Thus, 0.5 mm is the standard for functional restoration without harming adjacent teeth or gingiva.Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

7. What is the minimum thickness of a zinc phosphate cement base required to provide effective thermal insulation?

   1. 5 mm
   2. 75 mm
   3. 0 mm
   4. 5 mm

   সঠিক উত্তর: 75 mm

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B The minimum thickness of a zinc phosphate cement base required to provide effective thermal insulation is 0.75 mm. This thickness is critical because it ensures adequate protection of the pulp from thermal stimuli caused by temperature changes during restorative procedures. Thinner layers (<0.75 mm) do not offer sufficient insulation, increasing the risk of pulpal irritation or sensitivity. Conversely, excessive thickness can compromise the mechanical properties of the restoration without added benefit. Therefore, maintaining a base thickness of at least 0.75 mm optimizes both thermal protection and material performance. Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

8. What is the ideal angle for preparing the gingival bevel in restorative dental procedures?

   1. 45°
   2. 30°
   3. 60°
   4. 90°

   সঠিক উত্তর: 30°

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B The ideal angle for preparing the gingival bevel is 30° because this angle allows for optimal enamel rod exposure, enhancing the bond strength of restorative materials. A 30° bevel ensures a conservative tooth structure removal while providing a smooth, well-defined margin that facilitates better marginal adaptation and reduces microleakage. Sharper bevels (less than 30°) may cause excessive enamel prism cutting, whereas larger bevels (>30°) can remove unnecessary tooth structure, compromising tooth integrity. Thus, a 30° bevel balances mechanical retention and esthetic outcomes efficiently.Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.

9. Under which type of dental base are cavity varnishes contraindicated?

   1. Zinc polycarboxylate bases
   2. Zinc oxide eugenol bases
   3. Calcium hydroxide bases
   4. Glass ionomer bases

   সঠিক উত্তর: Zinc polycarboxylate bases

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A Cavity varnishes are contraindicated under zinc polycarboxylate bases because they interfere with the chemical adhesion between the base and the tooth structure. Zinc polycarboxylate bases rely on chelation with calcium ions in dentin for bonding, and varnishes create a barrier that prevents this essential interaction, compromising the seal and retention. In contrast, other bases like calcium hydroxide or zinc oxide eugenol do not depend on this bonding mechanism and are compatible with varnishes. Therefore, to ensure optimal adhesion and restoration longevity, cavity varnishes should be avoided under zinc polycarboxylate bases.Reference: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition.

10. What is the approximate angle of the occlusal cavosurface bevel in cavity preparation?

    1. 60°
    2. 30°
    3. 45°
    4. 90°

    সঠিক উত্তর: 45°

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option C The occlusal cavosurface bevel is prepared at an approximate angle of 45° to increase the surface area for enamel bonding and improve the mechanical retention of restorative materials. This bevel also helps to remove unsupported enamel rods, reducing the risk of enamel fracture. A 45° bevel provides an optimal balance between conservation of tooth structure and adequate retention, ensuring a durable and stable restoration margin.Reference: Sturdevant's Art and Science of Operative Dentistry, 7th Edition.