Structure and Function of the Dentin Pulp Complex _ Endodontic MCQs

Structure and Function of the Dentin Pulp Complex _ Endodontic MCQs

1. The mature dental pulp
A) Resembles embryonic connective tissue and therefore is rich in stem cells
B) Is a low-compliance system that responds to changes in fluid volume by expansion and contraction
C) Heals rapidly after injury because of a rich collateral circulation
D) Is derived from the dental lamina

2. Von Korffs fibers are thought to be:
A) Remnants of the lateral lamina that persist near the basement membrane after the initiation of ameloblasts.
B) Terminal nerve fibers that enter the predentin and regulate the calcification front.
C) The terminal odontoblastic processes before initial calcification.
D) The first formed collagen fibers located between the preodontoblasts and extending toward the basal lamina.

3. Hertwigs epithelial root sheath:
A) Is derived from the enamel organ and forms cementum.
B) Consists of the inner and outer enamel epithelium.
C) Is derived from the epithelial rests of Malassez.
D) Is composed of cells that differentiate into cementoblasts.
E) Separates the root from the connective tissues before eruption.

4. All of the following statements about the dentinal tubules are correct except one. Which is the exception:
A) The tubule diameter near the pulp-dentin interface is approximately 2 to 3m.
B) In the coronal dentin, the tubules have an S-shaped curvature.
C) The intertubular spacing remains constant, because the deposition of peritubular dentin is internal.
D) Lateral microtubules contain branches of the odontoblastic process.
E) No peritubular dentin is present in the predentin area.

5. The structure of peritubular dentin:
A) Is similar to that of intertubular dentin in collagen and mineral content.
B) Has a lower collagen content than intertubular dentin.
C) Restricts removal by acids because of the low sulfated proteoglycan and mineral content.
D) Adds strength and structural support to the intertubular dentin.
E) Is formed only in the presence of a vital odontoblastic process.

6. Which of the following statements best describes dentinal fluid:
A) Plasma proteins are present in concentrations similar to those of blood plasma.
B) The fluid in dentin is homogeneous and uniform.
C) The fluid is an ultrafiltrate of blood in the pulpal capillaries.
D) Slow outward movement of dentinal fluid activates mechanoreceptors, producing pain.
E) Dentinal fluid is necessary for maintaining the physical properties of dentin.

7. Which of the following distinguishes the odontoblast from other mesenchymal cell lines
A) Secretion of phosphophoryn
B) Production of type I collagen
C) Production of sialoprotein
D) Production of alkaline phosphatase
E) Presence of multiple nucleoli

8. The lamina limitans is:
A) An electron-dense membrane that lines the dentinal tubule.
B) Another term for the vital odontoblastic process.
C) The peripheral peritubular dentin.
D) Composed of microfilaments and microtubules.
E) A layer between the predentin and dentin which regulates calcification.

9. Odontoblastic production of:
A) Proteoglycans takes place in the Golgi complex before secretion at the base of the odontoblastic process.
B) Collagen consists of synthesis of procollagen, secretion of tropocollagen, and aggregation of fibrils on the outer odontoblastic membrane.
C) Proteoglycans increases calcification of predentin by increasing transport of calcium through the microtubules.
D) Lysosomal enzymes is an important first-line defense against microbial invasion.

10. Pulpal fibroblasts:
A) Are equally distributed throughout the pulp.
B) Synthesize type I and type III collagen
C) Are end-line cells incapable of differentiation
D) Have a polygonal morphologic shape when mature

11. Dendritic cells
A) Are similar to Langerhans cells found in the epidermis and mucous membranes:
B) Are primarily phagocytic cells that are centrally located in the pulp.
C) Provide a population of replacement cells for disintegrating odontoblasts.
D) Are specialized cells that transmit pain impulses toward the central nervous system via the spinothalamic pathway.
E) Present antigens to polymorphonuclear leukocytes.

12. Which of the following statements about lymphocytes is correct:
A) Lymphocytes are not found in normal pulp tissues.
B) B lymphocytes usually are found in the pulp and are responsible for antigen presentation to macrophages.
C) T4 (helper) lymphocytes predominate in normal pulp.
D) T8 (suppressor) lymphocytes are the predominant subset in normal pulp.

13. The principal proteoglycan(s) of the dental pulp:
A) Are fibronectin, laminin, and tenascin.
B) Are hyaluronic acid, dermatan sulfate, heparin sulfate, and chondroitin sulfate.
C) Are hyaluronic acid and dermatan sulfate during active dentinogenesis.
D) Is chondroitin sulfate when mineralization activity is low.
E) Are not affected by inflammation because of their hydrophilic nature and colloidal state.

14. Type IV collagen typically is:
A) Absent from the pulp.
B) A component of the ground substance and provides structure for the body of the pulp.
C) Found in basement membranes.
D) Synthesized by odontoblasts at the mineralization front and regulates calcification rates.
E) Synthesized by osteoclasts and is absent from the dental pulp.

15. Which of the following statements about innervation of the pulp is correct:
A) Myelinated fibers are the last major structures to appear in the developing pulp.
B) Autonomic fibers are afferent neurons that regulate microcirculation.
C) A-beta and A-delta fibers exist in equal numbers and are stimulated by fluid movement in the dentinal tubules.
D) The dental papilla contains both myelinated and unmyelinated fibers.
E) A-delta and C fibers have separate functions.

16. Electric pulp testing in young teeth:
A) May be unreliable because of the late development of A-delta fibers.
B) Results in a sharp, rapid response because of the predominance of C fibers in the pulp.
C) Does not differ from more mature normal teeth that do not have calcific metamorphosis.
D) Is best accomplished with cold because of the predominance of A-delta fibers in the pulp.

17. All of the following reasons, except one, could explain why a necrotic pulp might respond to testing or mechanical manipulation. Which is the exception:
A) The nerve fibers may be resistant to necrosis.
B) Nerve bundles are more resistant to autolysis.
C) C fibers remain active despite hypoxia.
D) The cell body of the neuron lies outside the pulp.
E) A-delta fibers have a lower stimulation threshold for stimulation with hypoxia.

18. All of the following statements about deafferentation are correct except one. Which is the exception:
A) It is the process of degeneration of neurons centrally after nerve resection.
B) Pain may be a result of this process.
C) Transsynaptic degenerative changes may be reflected in the sensory cortex.
D) With pulp extirpation, degeneration of nerves can extend beyond the trigeminal ganglion.
E) It is the elimination of pain transmission to the central nervous system as a result of application of a local anesthetic to the nerve.

19. Which of the following statements about pulp testing is correct:
A) C fibers are normally stimulated by electrical pulp testing but do not respond to thermal pulp testing.
B) C fibers are normally stimulated by thermal pulp testing but do not respond to electrical pulp testing.
C) C fibers normally have a high threshold and require a more intense stimulus than A-delta fibers.
D) A-delta fibers normally respond to thermal stimulation better than C fibers; however, the two fiber groups respond the same to electrical pulp testing.

20. Which of the following statements about dentinal sensitivity is correct:
A) The movement in the tubules is translated into electrical signals by sensory receptors in the tubules or the pulp.
B) The rate of fluid flow is not a factor in producing an electrical stimulus.
C) The inward flow of fluid produces a more pronounced sensory nerve response.
D) A change in temperature must occur at the pulp-dentin interface to produce for a sensory response.
E) Application of heat causes expansion of the dentin; this widens the dentinal tubules, drawing fluid from the pulp into the dentin and producing sensory stimulation.

21. Which of the following statements about neuropeptides is correct:
A) Sympathetic agents used in local anesthesia can modify the release of calcitonin gene related peptide.
B) The primary function of neuropeptides is the production of pain.
C) Neuropeptides are released only with tissue injury, and their actions contribute to tissue damage, creating a vicious cycle of inflammation.
D) They are released by odontoblasts and fibroblasts after sensory stimulation and efferent messages are received from the central nervous system.

22. All of the following statements about pulpal hyperalgesia are correct except one. Which is the exception:
A) The condition is marked by a decreased pain threshold and an increased response to stimulation.
B) An enhanced response to a stimulus results, but spontaneous pain is not a characteristic.
C) Increased pressure may be a contributing factor.
D) Upregulation of tetrodotoxin-resistant sodium channels in inflamed tissues makes local anesthesia more difficult.
E) Silent nerve fibers in the pulp become sensitized and may be activated.

23. Which of the following statements about the vascular supply of the pulp is correct:
A) Arteries enter the pulp and give rise to arterioles, which branch and form a capillary network in the subodontoblastic zone.
B) Capillary blood flow in the coronal portion of the pulp is twice that in the radicular portion of the pulp.
C) Arteriovenous anastomoses are present throughout the pulp but are more common in the coronal tissue.
D) The volume of pulp occupied by vessels is higher than in most tissues, approaching 25.
E) The pulp has the highest volume of blood flow of oral tissues and most visceral organs.

24. Reactionary dentin is best described as:
A) Atubular and amorphous, as seen in calcific metamorphosis.
B) Tertiary dentin formed by the original odontoblasts.
C) An area of tubule sclerosis below an advancing carious lesion.
D) Reparative dentin formed by cells replacing the original odontoblasts.
E) Dentin showing decalcification as a result of the selective removal of peritubular dentin.

25. Which of the following best describes pulpal calcification:
A) The radiographic appearance of pulp stones in the chamber indicates pathosis.
B) Idiopathic pulpal pain has been shown to be caused by laminated pulp stones that cause an alteration in blood flow.
C) Calcific metamorphosis results in a high incidence of necrosis when canal obliteration is complete.
D) Calcifications typically consist of carbonated hydroxyapatite.