Chapter 11: Root Morphology
Test Bank
MULTIPLE CHOICE
1. Root pain due to exposed dentin is caused by gingival recession. Exposed spots of dentin can stimulate pulpal nerves through the cementoenamel junction (CEJ).
a. Both statements are true.
b. The first statement is true, the second is false.
c. The first statement is false, the second is true.
d. Both statements are false.
ANS: B
Gingival recession exposes the tooth root and causes pain because the thin, fragile cementum has bare areas of exposed dentin. Pulpal nerves are stimulated through dentinal tubules in exposed spots of dentin.
REF: p. 104
2. Pressure and temperature responses are elicited by all of the following EXCEPT one. Which one is the EXCEPTION?
a. Bone
b. Periodontal ligament
c. Gingiva
d. Pulp tissue
ANS: D
Pressure and temperature responses are not elicited by pulp tissue. Instead the nerve tissue within the bone, periodontal ligament, and gingiva elicits these responses. Root canals can only respond to pain.
REF: p. 105
3. Blood vessels traveling through the apical foramen support nerves and odontoblasts because the blood supply enables delivery of essential nutrients as well as removal of harmful products.
a. Both the statement and the reason are correct and related.
b. Both the statement and the reason are correct but are NOT related.
c. The statement is correct, but the reason is NOT correct.
d. The statement is NOT correct, but the reason is correct.
e. NEITHER the statement NOR the reason is correct.
ANS: A
Blood vessels comprised of arteries, veins, and lymph tissues nourish and replenish the nerves and odontoblasts. As these vessels enter and exit the apical foramen they enable circulation of nutrients and oxygen throughout the pulp chamber. Critically important, they also provide a system to remove harmful products such as carbon dioxide.
REF: p. 105
4. Each of the following teeth frequently has two roots EXCEPT one. Which one is the EXCEPTION?
a. Maxillary first premolar
b. Maxillary second premolar
c. Mandibular first molar
d. Mandibular second molar
ANS: B
While maxillary premolars can have one or two roots, the maxillary second premolar most frequently has only one root. The maxillary first premolar often has two roots. All mandibular molars usually have two root roots, a mesial and a distal.
REF: p. 209
5. Maxillary molar root trifurcations are located on each of the following surfaces EXCEPT one. Which one is the EXCEPTION?
a. Mesial
b. Distal
c. Lingual
d. Buccal
ANS: C
Maxillary molars have a trifurcation between their three roots. Because there is a large lingual (palatal) root, there is not a trifurcation on the lingual surface. The three different furcation areas for maxillary molars are located between: the two buccal roots; the distobuccal and lingual roots; and the mesiobuccal and lingual roots.
REF: p. 107
6. Orthodontics requires a sustained pressure to move teeth to a new location. Osteoblasts respond to the new location by forming new bone.
a. Both statements are true.
b. The first statement is true; the second is false.
c. The first statement is false; the second is true.
d. Both statements are false.
ANS: A
Orthodontics, the gradual movement of teeth to a new location, is accomplished by exerting a sustained pressure for a prolonged time period. While osteoblastic (bone formative) activity is essential to formation of new bone in the new location, osteoclastic (bone destructive) activity is also necessary to dissolve bone so that teeth will move.
REF: p. 106
7. Teeth with curved roots afford resistance to apical and distal forces but are vulnerable to occlusal forces. Roots with triangular cross section are particularly vulnerable to lateral displacement.
a. Both statements are true.
b. The first statement is true, the second is false.
c. The first statement is false, the second is true.
d. Both statements are false.
ANS: D
Teeth with curved roots afford resistance to occlusal, apical, and distal forces. Roots with triangular cross sections (canines) offer resistance to lateral displacement.
REF: p. 105
8. Root canal therapy in third molars is considered very unpredictable because the tooth is located so far distally in the mouth.
a. Both the statement and the reason are correct and related.
b. Both the statement and the reason are correct but are NOT related.
c. The statement is correct, but the reason is NOT correct.
d. The statement is NOT correct, but the reason is correct.
e. NEITHER the statement NOR the reason is correct.
ANS: C
Root canal therapy is considered very unpredictable in third molars because the roots are usually curved. An additional obstacle, the roots tend to be fused. Gaining access to the apex of roots with such challenging anatomy poses great difficulty. While it is true that the distal location of third molars poses great challenge, this feature is less daunting than anatomical considerations.
REF: p. 109
9. Mandibular premolars typically have two pulp canals. Maxillary first premolars are more likely than maxillary second premolars to have two pulp canals.
a. Both statements are true.
b. The first statement is true, the second is false.
c. The first statement is false, the second is true.
d. Both statements are false.
ANS: C
Mandibular premolars usually have only one canal. Maxillary premolars often have two canals; the first is more likely to have two canals than the second.
REF: p. 109
10. During hypercementosis, excess cementum is deposited
a. Along the CEJ
b. Irregularly, throughout the root surface
c. At the dentinocemental junction
d. At the apex of the root
ANS: D
During hypercementosis, a process of extreme excess cementum production, a formation called a cementoma is deposited at the apex of the root. This process is usually associated with bone destruction and/or trauma. The newly formed excess cementum is different from the rest that lines the root.
REF: p. 105
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