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Endodontics MCQ (Comprehensive Document for Exam Preparation)
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APPENDIX
Chapter review questions
Graham Rex Holland, Mahmoud Torabinejad
CHAPTER 1 5. From where does the signal initiating enamel formation
The Biology of Dental Pulp and originate?
Periradicular Tissues a. odontoblasts
1. What stage of tooth formation involves the beginning of b. undifferentiated cells
invagination of the developing tooth structure? c. inner enamel epithelium
a. bud stage d. outer enamel epithelium
b. cap stage
c. bell stage ANS: a
d. follicular stage Once dentin formation has begun, the cells of the inner
dental epithelium begin to respond to a signal from the
ANS: b odontoblasts and begin to deposit enamel.
The bud becomes invaginated at the cap stage. REF: Early Development of Pulp
REF: Early Development of Pulp
6. When does the dental papilla become the dental pulp?
2. What is the bell-shaped structure that develops from the a. bud stage
tooth bud? b. cap stage
a. dental papilla c. early bell stage
b. dental follicle d. late bell stage
c. odontoblast layer
d. enamel organ ANS: d
Odontoblasts begin to lay down dentin in the late bell stage.
ANS: d From this point on, the tissue within the invagination is
The bell-shaped downgrowth is the enamel organ. It is ecto- known as the dental pulp.
dermal in origin and will be responsible for amelogenesis. REF: Early Development of Pulp
REF: Early Development of Pulp
7. What is the first thin layer of dentin that is formed?
3. From what are odontoblasts derived? a. predentin
a. neural crest b. primary dentin
b. local stem cells c. mantle dentin
c. osteoblasts d. root sheath
d. internal dental epithelium
ANS: c
ANS: a The first thin layer of dentin formed is called mantle dentin.
The odontoblasts are derived from cells originating and The direction and size of the collagen fibers in mantle dentin
migrating from the neural crest. differ from those in the subsequently formed circumpulpal
REF: Early Development of Pulp dentin.
REF: Early Development of Pulp
4. From where is differentiation of the odontoblasts
controlled? 8. Epithelial cell rests of Malassez are remnants of what?
a. outer dental epithelium a. odontoblasts
b. inner dental epithelium b. cementoblasts
c. dental papilla c. epithelial root sheath
d. dental follicle d. dental follicle
ANS: b ANS: c
The differentiation of odontoblasts from undifferentiated Epithelial cell rests of Malassez are cell remnants of the epi-
ectomesenchymal cells is initiated and controlled by the thelial root sheath that persist in the periodontium in close
ecto- dermal cells of the inner dental epithelium of the proximity to the root after root development has been com-
enamel organ. pleted. They are normally functionless, but in the presence of
REF: Early Development of Pulp inflammation, they can proliferate and under certain condi-
tions may give rise to a radicular cyst.
REF: Root Formation
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APPENDIX BCHAPTER REVIEW QUESTIONS
9. Which cells secrete the hyaline layer of Hopewell- 13. What does the dental pulp form as a defensive
Smith? response?
a. inner cells of Hertwig’s epithelial root sheath a. tertiary dentin
b. outer cells of Hertwig’s epithelial root sheath b. secondary dentin
c. cells of the dental follicle c. globular dentin
d. cells of the dental papilla d. peritubular dentin
ANS: a ANS: a
After the first dentin in the root has formed, the basement In the mature tooth, the odontoblasts form dentin in response
membrane beneath Hertwig’s sheath breaks up, and the to injury, particularly when the original dentin thickness has
inner- most root sheath cells secrete a hyaline material over been reduced due to caries, attrition, trauma or restorative
the newly formed dentin. After mineralization has occurred, procedures.
this becomes the hyaline layer of Hopewell-Smith, which REF: Pulp Function (Defense)
helps bind the soon to be formed cementum to dentin
REF: Root Formation 14. Approximately how many odontoblasts are present in the
crown of a newly erupted tooth?
10. What morphologic changes occur over time due to the a. 10,000 to 20,000/mm2
dental pulp? b. 45,000 to 65,000/mm2
a. The root canal diameter increases. c. 100,000 to 150,000/mm2
b. The pulp horns grow higher into the cup tips. d. 200,000 to 250,000/mm2
c. The overall size of the pulp chamber is reduced.
d. The layer of cementum thickens. ANS: b
In the coronal part of the pulp space, the odontoblasts are
ANS: c numerous, relatively large, and columnar in shape. They
The pulp space becomes asymmetrically smaller over time number between 45,000 and 65,000/mm2 in that area.
due to continued, albeit slower, production of dentin. There REF: Cells of the Dental Pulp (Odontoblasts)
is a pronounced decrease in the height of the pulp horn and a
reduction in the overall size of the pulp chamber. In molars, 15. Which of the following cell types is an antigen-
the apical-occlusal dimension is reduced more than the recognition cell in the dental pulp?
mesial-distal dimension. a. odontoblasts
REF: Anatomic Regions and Their Clinical Importance b. macrophages
c. neutrophils
11. The apical foramen is: d. all of the above
a. surrounded by dentin
b. narrowest in young teeth ANS: a
c. variable in size and location The odontoblast has several types of receptors on or within
d. the widest portion of the canal its cell membrane. Toll-like receptors (TLR2 and TLR4),
when activated by components of gram-positive bacteria
ANS: b (lipoteichoic acid), cause the odontoblasts to release proin-
Variation in the size and location of the apical foramen influ- flammatory cytokines (Fig. 1.12). This indicates that the
ences the degree to which blood flow to the pulp may be odontoblasts can act as antigen-recognition cells when bacte-
compromised after a traumatic event. rial products penetrate the dentin.
REF: Anatomic Regions and Their Clinical Importance REF: Cells of the Dental Pulp (Odontoblasts)
12. The apical constriction is: 16. What is the most prominent antigen-presenting cell in the
a. easily located radiographically dental pulp?
b. the ideal end point of root canal cleansing a. lymphocyte
c. present in all teeth b. odontoblast
d. formed by Hertwig’s epithelial root sheath c. stem cell
d. dendritic cell
ANS: b
The narrowest portion of the canal is referred to as the apical ANS: d
constriction. A constriction is not clinically evident in The most prominent immune cell in the dental pulp is the
all teeth.7 Theoretically, it is the point where the pulp termi- dendritic cell. These are antigen-presenting cells present
nates and the PDL begins and would be the ideal point for most densely in the odontoblast layer and around blood
a procedure aimed at removing the pulp. However, clinically, vessels. REF: Cells of the Immune System
it is not always possible to locate that point.
REF: Anatomic Regions and Their Clinical Importance
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APPENDIX BCHAPTER REVIEW QUESTIONS
17. What type of collagen is most prominent in the dental 20. What would be a typical level for interstitial pressure in
pulp? an area of inflammation in a dental pulp?
a. type I a. −20 mmHg
b. type II b. −6 mmHg
c. type III c. +6 mmHg
d. type IV d. +20 mmHg
ANS: a ANS: d
The predominant collagen in dentin is type I, whereas both Swelling results from increased formation of interstitial
type I and type III collagen are found within pulp in a ratio tissue fluid because of increased permeability of the
of approximately 55 : 45. Odontoblasts produce only type I capillaries. In other tissues, such as skin (in which
collagen for incorporation into the dentin matrix, whereas inflammation was first described), the increased production
fibroblasts produce both types I and III. Pulpal collagen is of tissue fluid results in swelling. Because the dental pulp is
present as 50 nm-wide fibrils several microns long. They within a rigid, noncom- pliant chamber, it cannot swell, and
form bundles that are irregularly arranged, except in the the increased interstitial fluid formation results in an increase
periphery, where they lie approximately parallel to the in tissue fluid pressure. REF: Vascular Changes During
predentin surface. The only fibers present in the pulp are Inflammation
tiny, 10-15 nm-wide beaded fibrils of fibrillin, a large
glycoprotein. Elastic fibers are absent from the pulp. The 21. Which type of nerves can be recruited to the pain system
proportion of collagen types is constant in the pulp, but with of the dental pulp in inflammation?
age there is an increase in the overall collagen content and a. Aα
an increase in the organization of collagen fibers into b. Aβ
collagen bundles. Normally, the apical portion of pulp c. Aδ
contains more collagen than the coronal pulp. REF: d. C
Extracellular Components (Fibers)
ANS: b
18. Which of the following is not a type of pulp stone? A small percentage of the myelinated axons (1% to 5%) are
a. free faster-conducting Aβ axons (6 to 12 µm in diameter). In
b. attached other tissues, these larger fibers can be proprioceptive or
c. embedded mechano- receptive. Their role in the pulp is uncertain, but it
d. floating is now known from other tissues that in inflammation, these Aβ
fibers can be recruited to the pain system.
ANS: d REF: Pulpal and Dentinal Nerves
Three types of pulp stones have been described: free stones,
which are surrounded by pulp tissue; attached stones, which
are continuous with the dentin; and embedded stones, which
are surrounded entirely by dentin, mostly of the tertiary type.
REF: Calcifications
19. What would be a typical level for interstitial pressure in a
dental pulp?
a. −20 mmHg
b. −6 mmHg
c. +6 mmHg
d. +20 mmHg
ANS: b
The hydraulic pressure in the pulpal capillaries falls from
35 mmHg at the arteriolar end to 19 mmHg at the venular
end. Outside the vessel, the interstitial fluid pressure varies,
but a normal figure would be 6 mmHg.
REF: Vascular Physiology
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APPENDIX BCHAPTER REVIEW QUESTIONS
Chapter review questions
Ashraf F. Fouad, Anthony J. Smith
CHAPTER 2 4. Why are deeper carious lesions more injurious to the
Protecting the Pulp and Promoting dental pulp?
Tooth Maturation a. increased dentin permeability in deeper areas and
1. What is a “pulp cap”? greater cellular injury to odontoblasts
a. an early stage of tooth development b. increased length of the dentinal tubule in deeper areas
b. capping of the exposed pulp with a thin layer of inert c. decreased density of dentinal tubules in deeper areas
lining or base material d. decreased diameter of dentin tubules in deeper areas
c. capping of exposed vital pulp tissue by placing a layer
of mineral trioxide aggregate (MTA) ANS: a
d. a method of isolation used during root canal Dentin permeability increases exponentially with increasing
treatment cavity depth, as both the diameter and density of dentinal
tubules increase with cavity depth (Fig. 2.5).17 Thus the
ANS: c deeper the cavity, the greater the tubular surface area into
The exposed pulp may be protected immediately by covering which potentially toxic substances can penetrate and diffuse
it and placing a restoration. Pulp capping is the treatment of to the pulp. The length of the dentinal tubules beneath the
an exposed vital pulp by sealing the pulpal wound with a cavity is also important. The farther substances have to
dental material, such as calcium hydroxide or mineral diffuse, the more they will be diluted and buffered by the
trioxide aggregate (MTA), to stimulate the formation of dentinal fluid. A remaining dentin thickness of 1 mm is often
reparative dentin and maintenance of a vital pulp. regarded as sufficient to shield the pulp from most forms of
REF: Vital Pulp Therapy irritation. As cavity depth increases, odontoblast survival is
increasingly compromised and there is a greater likelihood of
2. What is the effect on blood flow to the pulp when local odon- toblast death.
anesthet- ics with vasoconstrictors are used during REF: Cavity Depth/Remaining Dentin Thickness
restorative procedures?
a. It is reduced by 10% of its normal rate. 5. Why does a blast of compressed air directed at freshly
b. It is reduced to less than half of its normal rate. exposed dentin create a sensation of pain?
c. It is unchanged. a. It frightens the patient.
d. It is increased by 25% because of stress on the pulp b. The air is cold.
tissue. c. It causes a rapid outward movement of fluid in patent
dentinal tubules.
ANS: b d. It causes a rapid inward movement of fluid in patent
When most local anesthetics containing vasoconstrictors are dentinal tubules.
used in restorative dentistry, the blood flow to the pulp is
reduced to less than half of its normal rate. In the case of ANS: c
lidocaine with epinephrine, this effect is entirely due to the A prolonged blast of compressed air aimed onto freshly
vasoconstrictor. exposed vital dentin causes a rapid outward movement of
REF: Local Anesthesia fluid in patent dentinal tubules through strong capillary
forces. Rapid outward flow of fluid in the dentinal tubules
3. What is dentin “blushing”? stimulates nociceptors in the dentin pulp, thus producing
a. the color of newly erupted teeth due to large pulp pain.
chambers REF: Cavity Drying and Cleansing
b. the use of a masking color during restorative
procedures 6. What is the most important characteristic of any restor-
c. vascular injury (hemorrhage) of pulp tissue, often ative material in determining its effect on the pulp tissue?
during crown preparation a. heat generated by the material
d. an esthetic concern requiring laminate restorations b. speed with which the material sets
c. ability to form a marginal seal
ANS: c d. life expectancy of the restorative material
The “blushing” of dentin during cavity or crown preparation
is thought to be due to frictional heat resulting in vascular ANS: c
injury (hemorrhage) in the pulp. The dentin takes on an The most important characteristic of any restorative material
under- lying pinkish hue soon after the operative procedure. in determining its effect on the pulp is its ability to form a
REF: Cavity/Crown Preparation seal that prevents the leakage of bacteria and their products
e4 onto dentin and then into the pulp.
REF: Microleakage
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