بنك أسئلة أمراض اللثة

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1. 1.Which type of epithelium forms the attachment of the gingiva to the tooth surface?

   • أ.Junctional epitheliumإجابة صحيحة
   • ب.Sulcular epithelium
   • ج.Oral gingival epithelium
   • د.Keratinized col epithelium

   لماذا: The junctional epithelium attaches to the tooth surface via hemidesmosomes and the internal basal lamina. It is a non-keratinized stratified squamous epithelium that forms the base of the gingival sulcus. This attachment is central to the dentogingival unit.

2. 2.The junctional epithelium is attached to the tooth surface primarily by which structures?

   • أ.Desmosomes only
   • ب.Anchoring collagen fibrils
   • ج.Tight junctions
   • د.Hemidesmosomes and the internal basal laminaإجابة صحيحة

   لماذا: The junctional epithelium adheres to the tooth through hemidesmosomes and an internal basal lamina. This specialized attachment allows renewal and repair while maintaining a seal. It differs from attachment to connective tissue, which uses an external basal lamina.

3. 3.Which of the following gingival tissues is normally keratinized or parakeratinized?

   • أ.Sulcular epithelium
   • ب.Junctional epithelium
   • ج.The col in posterior interdental areas
   • د.Outer surface of the free and attached gingivaإجابة صحيحة

   لماذا: The outer (oral) surface of the free and attached gingiva is typically keratinized or parakeratinized, providing resistance to masticatory forces. Sulcular and junctional epithelia are non-keratinized. The col is also non-keratinized, making it vulnerable to disease.

4. 4.The interdental gingiva in the posterior region between contacting teeth is best described as having what shape?

   • أ.A rolled bulbous margin
   • ب.A flat plateau
   • ج.A single pointed papilla
   • د.A valley-like depression called the colإجابة صحيحة

   لماذا: In posterior areas with broad contacts, the interdental gingiva forms a saddle-shaped concavity called the col that lies apical to the contact point. The col is non-keratinized and considered a site predisposed to periodontal disease. Anteriorly, the papilla is more pyramidal.

5. 5.Which gingival fiber group encircles the tooth in a ring-like fashion and is not attached to cementum?

   • أ.Circular fibersإجابة صحيحة
   • ب.Dentogingival fibers
   • ج.Transseptal fibers
   • د.Alveologingival fibers

   لماذا: Circular fibers course through the free gingiva and encircle the tooth like a ring or cuff. Unlike most gingival fibers, they are not attached to the tooth or bone. They help maintain the contour and position of the free gingiva.

6. 6.The transseptal fibers of the gingiva run in which direction?

   • أ.From cementum of one tooth to cementum of the adjacent tooth over the crestإجابة صحيحة
   • ب.From cementum to alveolar crest
   • ج.From cementum to the free gingiva
   • د.From alveolar crest to the gingiva

   لماذا: Transseptal fibers extend interproximally from the cementum of one tooth, over the alveolar crest, to the cementum of the adjacent tooth. They form a continuous ligament linking teeth in the arch. They are reconstituted even after periodontal surgery.

7. 7.Which principal fiber group of the periodontal ligament is most numerous and resists intrusive (axial) forces?

   • أ.Alveolar crest fibers
   • ب.Horizontal fibers
   • ج.Apical fibers
   • د.Oblique fibersإجابة صحيحة

   لماذا: The oblique fibers are the most numerous PDL fiber group and run from the cementum obliquely coronally to the bone. They resist vertical masticatory (intrusive) forces by converting them into tension on the alveolar bone. This orientation suspends the tooth in its socket.

8. 8.The alveolar crest fibers of the periodontal ligament function primarily to resist which type of force?

   • أ.Intrusive forces
   • ب.Extrusive forces only
   • ج.Rotational and lateral tilting forcesإجابة صحيحة
   • د.Compressive apical forces

   لماذا: Alveolar crest fibers extend from the cementum just below the CEJ to the alveolar crest. They help resist lateral (tilting) and rotational forces and counterbalance coronal thrust. They also help retain the tooth within the socket.

9. 9.Sharpey fibers are best defined as which of the following?

   • أ.The terminal ends of principal fibers embedded in cementum and boneإجابة صحيحة
   • ب.Elastic fibers within the PDL
   • ج.Nerve fibers of the PDL
   • د.Collagen fibers of the gingiva only

   لماذا: Sharpey fibers are the mineralized terminal portions of the principal periodontal ligament fibers embedded into cementum on one side and alveolar bone on the other. They anchor the tooth to the socket. They are fully mineralized in cellular cementum only at their periphery.

10. 10.Which cells within the periodontal ligament are considered the progenitor cells capable of forming cementum, bone, and PDL fibers?

    • أ.Odontoblasts
    • ب.Ameloblasts
    • ج.Undifferentiated mesenchymal (progenitor) cellsإجابة صحيحة
    • د.Mast cells

    لماذا: The PDL contains undifferentiated mesenchymal progenitor cells that can differentiate into cementoblasts, osteoblasts, and fibroblasts. This population underlies the regenerative potential of the periodontium. Epithelial cell rests of Malassez are also present but are epithelial in origin.