Kaplan Dental Flashcards
1. Which type of dentin is most regular in structure? A. Primary dentin B. Secondary dentin C. Reparative dentin D. All have the same regular structure
The correct answer is A. All dentin is formed by odontoblasts located at the border of the pulp and
dentin. It consists of tubules surrounding odontoblastic processes, as well as intertubular dentin. In
primary dentin, the tubules are regular in pattern. In secondary dentin, formed later in life, tubules are
less regular, less numerous and more wavy. Reparative dentin (sclerotic dentin) forms in response to
caries, heat, deep fillings, etc. It is least regular and most wavy, and tubules are least numerous.
2. Which cusp becomes smaller and less conspicuous as you go from maxillary first to second to third molar? A. Mesiobuccal B. Mesiolingual C. Distobuccal D. Distolingual
The correct answer is D. The MB, ML, and DB cusps of the maxillary molars are the largest, and
form the primary cusp triangle, or trigon, of the tooth. The distolingual cusp is the smallest, and is not
part of the trigon. It is sometimes referred to as the talon or talon cusp. It is most noticeable in the first
molar, less noticeable in the second, and often absent in the third molar. The maxillary third molar
therefore often does not have the rhomboid appearance of a maxillary molar, and the occlusal aspect
will appear triangular or heart-shaped instead.
3. The masseteric sling is composed of the masseter and the: A. medial pterygoid B. lateral pterygoid C. anterior digastric D. temporalis
The correct answer is A. The masseteric sling is a powerful pair of muscles which wrap underneath
the angle and ramus of the mandible and act to both support and close (elevate) the mandible. On the
lateral surface of the mandible we find the masseter, while on the medial surface we find the medial
pterygoid. Although the temporalis (choice D) also strongly elevates, it is not part of this structure. The
lateral pterygoid (choice B) attaches to the condyle and TMJ disc, and pulls the condyles forward and
laterally. The lateral pterygoid is not part of the masseteric sling.
4. Which cusp on the primary mandibular first molar is highest and sharpest? A. Mesiobuccal B. Distobuccal C. Mesiolingual D. Distolingual
The correct answer is C. The primary first mandibular molar is a highly unusual tooth. It is molar-like
in form, with two roots (mesial and distal), but has a very pronounced mesial development of the
crown. The mesial section comprises two-thirds of the crown, and the distal portion is much reduced.
The mesiolingual cusp is the highest and sharpest, although the mesiobuccal is overall largest as
viewed from the occlusal. It is followed in size by the ML, DB, and DL cusps.
- Which of the following is NOT considered an important reason for restoring proximal
contact in dental restorations?
A. Contact protects the periodontal tissue
B. Contact prevents food impaction
C. Contact increases retention of the restorations
D. Contact prevents tooth drifting
The correct answer is C. Contact is re-established in proximal areas when Class II restorations are
completed. This restoration of contact at the correct contact level prevents food from wedging in
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between teeth and causing buildup of plaque and debris. This, in turn, protects the periodontal
ligament, because the chief etiology of periodontal bone loss is calculus and plaque accumulation.
Stability of the arch is maintained and tooth drifting is also minimized. Without contact, teeth may drift
mesially or distally into the space left by the faulty restoration. Proximal contact is NOT considered to
be related to filling material retention. This is because each restoration’s retention is supposed to
depend solely on the retentive properties of that individual tooth, tooth preparation, and material. In
other words, retention stands alone within the individual tooth. Adjacent teeth are never considered as
part of restoration retention.
6. The anterior tooth with the most pronounced lingual ridge is the: A. Maxillary central incisor B. Mandibular lateral incisor C. Maxillary canine D. Mandibular canine
The correct answer is C. A lingual ridge runs from the incisal edge down the center of the lingual
surface of the crown, toward the cervical end of the crown. It splits the lingual surface in half, and
usually has a depression on either side (lingual fossae) which separate the lingual ridge from the
mesial and distal marginal ridges. Lingual ridges are found on canines, but not on incisors (choices A
and B). The lingual ridge is more pronounced on the maxillary canine than on the mandibular (choice
D). This is in keeping with a general rule that the lingual anatomy of the maxillary canine is much
more pronounced than that of the mandibular.
- In centric occlusion, the mesiolingual cusp of the maxillary third molar will contact:
A. the central fossa of the mandibular second molar
B. the central fossa of the mandibular third molar
C. the distal marginal ridge of mandibular first molar and mesial marginal ridge of the second molar
D. the distal marginal ridge of mandibular second molar and mesial marginal ridge of the third molar
The correct answer is B. The mesiolingual cusp of a maxillary third molar is a holding cusp. The
general rule for maxillary holding cusps is as follows: a maxillary holding cusp contacts the distal
marginal ridge of its mandibular counterpart and the mesial marginal ridge of the mandibular tooth
distal to its counterpart, EXCEPT FOR THE MESIOLINGUAL CUSPS OF THE MOLARS, WHICH
CONTACT THE CENTRAL FOSSAE OF THEIR COUNTERPARTS. This should be the central fossa
of the counterpart, the mandibular third molar.
8. In comparison to those of permanent molars, the common root trunks of primary molars are proportionately: A. larger B. smaller C. relatively equal D. variable, depending on the tooth
The correct answer is B. The common root trunk refers to that area of root apical to the crown but
coronal to the bifurcation or trifurcation of the roots. It can be viewed as the combined root area from
which the individual roots emerge. It is characteristic of primary molars that they have little or no
common root trunk. That is, the roots appear to furcate almost immediately below the crown. This is
due to the fact that the primary molar roots must flare widely in order to leave room for the developing
crowns of the succedaneous premolars.
9. The attrition at the contact point between teeth is known to cause: A. Reduced embrasures interproximally B. Diastemas C. Longer clinical crowns D. Shorter clinical crowns
The correct answer is A. Over time, posterior teeth lose small amounts of enamel as the contact
points wear against each other during chewing. The contacts become slightly broader, the teeth
themselves become slightly closer, through drifting, and the embrasures between the teeth become
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slightly smaller. Diastemas (choice B) are not created, because the teeth drift to close any space
created by the attrition. The process is at a microscopic level; the wear is very gradual, as is the
accompanying drifting, so that contact is not lost. This process does not affect crown length (choices
C and D), which is occluso-cervical in direction. It only affects the mesio-distal dimension.
10. The epithelium of the mucous membrane of the mouth is: A. simple squamous B. stratified squamous C. simple columnar D. stratified columnar E. cuboidal
The correct answer is B. Squamous cells are flattened, pancake-like cells, and when in layers are
known as stratified. The stratified squamous cells lining the mucosa of the oral cavity are similar to
those lining the outer skin, although less keratinized. They do, however, flake off continuously into the
mouth. Simple squamous tissue would be too thin and not allow for the constant flaking and
replacement. Columnar epithelium is found in both the respiratory system and other organs of the
digestive system.
11. The glenoid (articular) fossa in which the mandibular condyle articulates is a depression within which cranial bone? A. Sphenoid B. Zygomatic C. Temporal D. Parietal E. A combination of more than one bone
The correct answer is C. The names for the fossa include mandibular, articular, glenoid, and
temporal. This is due to the location of the fossa wholly within the temporal bone. The anterior border
of the fossa is the articular eminence of the temporal bone, and the posterior border is the tympanic
section of the temporal bone. Slightly more posterior is the mastoid process and associated styloid
process. So the entire eminence is a temporal bone feature.
- The mesiobuccal cusp of the maxillary first molar occludes in:
A. the mesial marginal ridge of the mandibular second molar
B. the distal marginal ridge of the mandibular first molar
C. the central groove of the mandibular first molar
D. the facial embrasure between the mandibular first and second molars
E. the buccal groove of the first mandibular molar
The correct answer is E. Buccal cusps of maxillary teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for maxillary
buccal cusps is that they occlude in the facial embrasure between their mandibular counterpart and
the tooth distal to their counterpart, EXCEPT for the mesiobuccal cusps of the molars, which occlude
in the buccal grooves of their mandibular counterparts, and the distobuccal cusp of the first molar,
which opposes the distobuccal groove of the mandibular first molar. In this question we are dealing
with the exception of the mesiobuccal cusps of maxillary molars, which occlude with the buccal
groove of their mandibular counterpart. In this case, the maxillary first molar mesiobuccal cusp
contacts the mandibular first molar buccal groove.
13. In extraction of maxillary first premolars, the root anatomy guides the dentist to use a motion that is primarily: A. buccal-lingual luxation B. mesiodistal luxation C. rotation D. all of the above
The correct answer is A. One of the best reasons to know standard and unusual root shapes for the
various maxillary and mandibular teeth is to use the correct motion on the forceps when performing
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extractions. In general, rounded roots are primarily rotated, including the maxillary central incisors and
maxillary canines. All double- and triple-rooted teeth cannot be rotated and must be luxated in the
buccal and lingual directions. Mesial-distal motion is normally ruled out because of the existence of
adjacent teeth. It is used in rare cases where there is no mesial and distal adjacent tooth. The
maxillary first premolar is invariably double rooted with a buccal and lingual root, and can never be
rotated without breaking the crown off of the root.
14. How many teeth (out of 32) in the normal dentition oppose only ONE other tooth? A. None B. 1 C. 2 D. 4 E. 6
The correct answer is D. Because of the shift of the mandibular teeth in a mesial direction due to the
smaller size of the anterior teeth, most teeth have two opposing teeth. That is, they oppose their
counterpart in the other arch, and a tooth either mesial or distal to that counterpart. There are two
classes of exceptions. One of the exceptions is the mandibular central incisors. These two teeth (#24
and #25) oppose only the maxilary centrals (#8 and #9). The other exception is the maxillary third
molars (#1 and #16), which oppose only the mandibular third molars. Note that the mandibular third
molars oppose both the maxillary second and third molars.
15. Which premolar is considered to be most molar-like in form? A. Maxillary first B. Maxillary second C. Mandibular first D. Mandibular second
The correct answer is D. The maxillary premolars are considered to be much more alike than are the
mandibular premolars. They are most premolar-like in form, with fairly similar sized buccal and lingual
cusps and greater overall symmetry. The mandibular premolars, by contrast, are significantly different
from each other. The first premolar is very canine-like with a small lingual cusp and relatively large
buccal cusp. The mandibular second premolar, while more premolar-like than the first, has attributes
of molars as well. The chief molar-like attribute of the mandibular second is the tendency toward three
cusps rather than two. The most common form of this tooth has a large buccal cusp with two smaller
lingual cusps making up the rest of the crown. The two lingual cusps are the mesiolingual and
distolingual and are separated by a lingual groove. There is a less common two-cusped variety which
is less molar-like in form.
- The distal inclination in roots of the permanent mandibular first molar is:
A. more pronounced in either root, depending on the tooth
B. usually more pronounced in the mesial root
C. usually more pronounced in the distal root
D. usually equal in both roots
The correct answer is B. In the mandibular first molar, one of the major distinctions between roots is
the greater distal curvature of the mesial root. The distal root, by contrast, is usually more straight,
without significant curvature. Another distinction is the deep root concavity seen running the length of
the mesial surface of the mesial root. The distal root, by comparison, will have no similar concavity or
a very slight depression. This concavity will sometimes express itself as a partial split (bifurcation) of
some small section of the apical end of the mesial root into two roots. This feature is rare to unknown
on the distal root.
17. The greatest curvature of the cervical line interproximally is found on the: A. Mesial of the maxillary central B. Mesial of the maxillary lateral C. Distal of the maxillary central D. Distal of the maxillary lateral
The correct answer is A. When viewed from the proximal, all incisors show a distinct curvature of the
cervical line as the line curves markedly upward (toward the incisal). It then returns to a much lower
(apical) level on both the facial and lingual. It is most noticeable on the mesial of the central incisor.
This is one of those most, biggest, longest, shortest type questions common in this section.
18. Which incisor commonly exhibits the most variety in anatomy in both crown form and root form? A. Maxillary central B. Maxillary lateral C. Mandibular central D. Mandibular lateral
The correct answer is B. It is commonly said that the third molars and the maxillary lateral incisor
are the most variable teeth in the mouth. The common forms of maxillary lateral variation include the
peg lateral, with an ice cream cone-shaped crown; the deep lingual pit, with a deep (often carious)
invagination; and the dens-in-dente, a deep lingual invagination giving a “tooth-within-a-tooth”
appearance on x-ray. By contrast, variations in the other incisors are minor and less pronounced.
- The mesiobuccal cusp of the maxillary third molar occludes in:
A. the mesial marginal ridge of the mandibular second molar
B. the distal marginal ridge of the mandibular second molar
C. the mesial marginal ridge of the mandibular third molar
D. the facial embrasure between the mandibular second and third molars
E. the buccal groove of the third mandibular molar
The correct answer is E. Buccal cusps of maxillary teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for maxillary
buccal cusps is that they occlude in the facial embrasure between their mandibular counterpart and
the tooth distal to their counterpart, EXCEPT for the mesiobuccal cusps of the molars, which occlude
in the buccal grooves of their mandibular counterparts, and the distobuccal cusp of the first molar,
which opposes the distobuccal groove of the mandibular first molar. In this question we are dealing
with the exception of the mesiobuccal cusps of maxillary molars, which occlude with the buccal
groove of their mandibular counterpart. In this case, the maxillary third molar mesiobuccal cusp
contacts the mandibular third molar buccal groove.
- The mesiobuccal cusp of the mandibular second molar occludes with which maxillary
tooth surfaces?
A. The mesial marginal ridge of the second molar and distal marginal ridge of the first molar
B. The distal marginal ridge of the second molar and mesial marginal ridge of the third molar
C. The embrasure between the first and second molars
D. The central fossa of the maxillary second molar
The correct answer is A. The mesiobuccal cusp of a mandibular molar is a holding (supporting)
cusp. The general rule of occlusion of mandibular holding cusps is as follows: the holding cusps of the
mandibular teeth occlude on the mesial marginal ridge of their maxillary counterpart, and the distal
marginal ridge of the maxillary tooth mesial to their counterpart, EXCEPT distobuccal cusps of
mandibular molars occlude with central fossae of their counterparts, the distal cusp of the mandibular
first molar occludes with the distal triangular fossa of its counterpart, and the first premolar occludes
only with the mesial marginal ridge of its counterpart (but not the canine). In this case, the maxillary
counterpart is the maxillary second molar, and the tooth immediately mesial to it is the maxillary first
molar.
21. The most prominent cingulum is found on which incisor? A. Maxillary central B. Maxillary lateral C. Mandibular central D. Mandibular lateral
The correct answer is B. The maxillary lateral is often the most distinct in almost any anatomical
form. Its cingulum is usually more notable relative to its size than that of the central. It should be noted
that maxillary cingula are almost always more prominent than their mandibular counterparts. In
addition to the prominent cingulum, the maxillary lateral often features a deep lingual fossa, deep
lingual pits, and tubercles on the cingulum.
22.Which premolar has a lingually inclined occlusal table? A. Maxillary first B. Maxillary second C. Mandibular first D. Mandibular second
The correct answer is C. The mandibular first premolar is very canine-like in form, with a much
reduced lingual cusp, almost resembling a cingulum. The occlusal table thus inclines apically from
buccal to lingual, as in a downward slope. This is important in operative dentistry, as the occlusal
preparation for this tooth also is slanted to the lingual. All other premolars are essentially flat in their
occlusal table, or possibly very slightly lingually leaning if the buccal cusp is slightly higher than the
lingual. However, only the mandibular first premolar has this trait so pronounced that it is very different
from the other three.
23. When viewed from the buccal, the tooth closest to vertical in the mesiodistal angulation of its main axis is the: A. maxillary central incisor B. maxillary lateral incisor C. maxillary canine D. maxillary first premolar
The correct answer is A. Another way of asking the question is: which tooth does not lean toward
the mesial or distal? The maxillary central incisor is almost straight vertically, estimated to be about 2
degrees from vertical. The lateral tends to lean slightly mesially, the canine even more in a distal
direction, and the first premolar slightly in a distal direction. Do not confuse this leaning with the
buccolingual leaning (when viewed from the mesial or distal). These measurements differ significantly
for the teeth listed, with the premolar being most vertical.
- The distobuccal cusp of the mandibular first molar occludes with which maxillary tooth
surfaces?
A. The mesial marginal ridge of the second molar and distal marginal ridge of the first molar
B. The central fossa of the first molar
C. The mesial marginal ridge of the first molar and the distal marginal ridge of the second premolar
D. The embrasure between the first and second molars
The correct answer is B. The distobuccal cusp of a mandibular molar is a holding (supporting) cusp.
The general rule of occlusion of mandibular holding cusps is as follows: the holding cusps of the
mandibular teeth occlude on the mesial marginal ridges of their maxillary counterparts, and the distal
marginal ridges of the maxillary tooth mesial to their counterparts, EXCEPT distobuccal cusps of
mandibular molars occlude with central fossae of their counterparts, the distal cusp of the mandibular
first molar occludes with the distal triangular fossa of its counterpart, and the first premolar occludes
only with the mesial marginal ridge of its counterpart (but not the canine). In this case, the maxillary
counterpart is the maxillary first molar, and the cusp should occlude in the central fossa of this tooth.
25. Canaliculi and Haversian systems: A. are found in acellular cementum B. are found in cellular cementum C. are found in both types of cementum D. are not found in cementum
The correct answer is D. Cementum is often described as the dental tissue which most resembles
bone. It has a similar mineral content, and has an organic matrix primarily composed of collagen
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fibers. However, the Haversian systems, concentric tissue layers, lacunae, canaliculi, etc., found in
bone are not found in cementum. Remember that these features are not always found in bone. Only
compact bone (rather than trabecular bone) has these features. Remember also that acellular
cementum could not have such features as Haversian systems, because Haversian systems contain
osteocytes (cells) within bony lacunae. However, neither acellular nor cellular cementum actually has
these features.
- At the cervical line, a cross section of the maxillary canine would show:
A. a round shape
B. an oval shape wider on the lingual than the labial
C. a triangular shape with a distinctly wider labial surface
D. an oval shape with a slightly wider labial surface
The correct answer is D. The maxillary canine, at the cervix, will have a cross section which is oval
and flattened mesiodistally. It is generally slightly wider at the labial end than at the lingual. The pulp
cavity at this point is lens-shaped, double convex. It is similar in cross-sectional shape to the
mandibula canine.
27. An example of a guiding (nonsupporting) cusp is: A. distolingual of #30 B. mesiobuccal of #18 C. distolingual of #14 D. lingual of #5 E. palatal of #13
The correct answer is A. Note that the holding (supporting, occluding) cusps of the posterior
dentition are the lingual (palatal) cusps of the maxillary teeth and the buccal (facial) cusps of the
mandibular teeth. Buccals of maxillary teeth and linguals of mandibular teeth are guiding cusps.
Choice A is the lingual of a mandibular first molar, so it is not a holding cusp, and is a guiding cusp.
Choice B is a buccal of a mandibular molar and is a holding cusp. Choice C is a lingual cusp of a
maxillary molar and is a holding cusp. Choice D is the lingual of a maxillary premolar and is a holding
cusp. Choice E is the palatal (lingual) of a maxillary premolar and is a holding cusp.
28. Which incisor is most commonly congenitally missing? A. Maxillary central B. Maxillary lateral C. Mandibular central D. Mandibular lateral
The correct answer is B. The maxillary lateral and the third molars show more variability than any
other teeth. Besides a wide variety of unusual morphologies (peg lateral, etc.), the maxillary lateral
incisor is fairly commonly congenitally missing. In these patients, the canines drift mesially toward the
centrals. Also commonly congenitally missing are third molars and premolars.
- A patient is congenitally missing the maxillary lateral incisors and mandibular second
premolars. This individual is said to have the condition known as:
A. anodontia
B. oligodontia
C. hypodontia
D. hyperdontia
The correct answer is C. Anodontia (choice A) refers to the complete absence of tooth formation. In
oligodontia (choice B), most but not all teeth are missing. Both of these conditions are often
associated with ectodermal dysplasia. Hypodontia refers to a small number of congenitally missing
teeth. This is fairly common, and is not usually associated with a systemic disease or disturbance.
30. Cervical bulges are found on which surfaces of primary molar teeth? A. Mesial and distal B. Buccal and lingual C. Lingual only D. Buccal only
The correct answer is D. Cervical bulges are overhangs of the crown sticking out above the cervical
line of the primary teeth. In primary anteriors, the cervical bulge is found on both the buccal and
lingual surfaces. In the molars, it is found only on the buccal. The most conspicuous cervical bulge in
the primary molars is that of the primary mandibular first molar. It is often described as being potbelly
when seen from the proximal view. The other molars are not as exaggerated in this area, but still
show a pronounced buccal cervical bulge.
31. In rare cases, a permanent mandibular first molar may have a complete supernumerary third root. This root is usually: A. a second mesial root B. a second distal root C. a buccal root D. a lingual root
The correct answer is B. Despite the fact that the mandibular first molar has a distinct mesial root
concavity on the mesial side of the mesial root, and that this root sometimes furcates partially
upwards from the mesial, complete additional whole roots are usually second distal roots. Buccal
and/or lingual additional roots are not found.
- In centric occlusion, the distolingual cusp of the maxillary first molar will contact:
A. mesial marginal ridge of mandibular first premolar and distal marginal ridge of second premolar
B. the distal marginal ridge of mandibular second premolar and mesial marginal ridge of first molar
C. the distal marginal ridge of mandibular first molar and mesial marginal ridge of the second molar
D. the distal marginal ridge of the mandibular second molar and mesial marginal ridge of first molar
The correct answer is C. The distolingual cusp of a maxillary molar is a holding cusp. The general
rule for maxillary holding cusps is as follows: a maxillary holding cusp contacts the distal marginal
ridge of its mandibular counterpart and the mesial marginal ridge of the mandibular tooth distal to its
counterpart, EXCEPT FOR THE MESIOLINGUAL CUSPS OF THE MOLARS, WHICH CONTACT
THE CENTRAL FOSSAE OF THEIR COUNTERPARTS. This should be the distal marginal ridge of
the mandibular first molar and mesial marginal ridge of the second molar.
- The mesiolingual cusp of the mandibular second molar contacts:
A. the lingual embrasure between the maxillary first molar and second molar
B. the distal marginal ridge of the maxillary second molar
C. the central fossa of the maxillary second molar
D. the lingual groove of the maxillary second molar
E. the lingual embrasure between the maxillary second molar and third molar
The correct answer is A. Lingual cusps of mandibular teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for mandibular
lingual cusps is that they occlude in the lingual embrasures between their maxillary counterparts and
the teeth mesial to their counterparts, EXCEPT for the distolingual cusps of the mandibular molars,
which occlude in the lingual grooves of their maxillary counterparts. In this question we are not dealing
with the exception of the distolingual cusps of mandibular molars, so in this case, the mandibular
second molar mesiolingual cusp contacts the lingual embrasure between its counterpart (the maxillary
second molar) and the tooth mesial to it (the maxillary first molar).
- The epithelial root sheath of Hertwig is composed of:
A. inner enamel epithelium and stellate reticulum
B. stellate reticulum only
C. inner and outer enamel epithelium
D. all of the tissues listed above
E. none of the above
The correct answer is C. Only the original inner and outer enamel epithelium take part in root
formation. There is no stellate reticulum in between them, as would be found in the original enamel
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organ. The root form is originally outlined by the epithelial root sheath of Hertwig, which then induces
formation of odontoblasts, which then produce root dentin. Pieces of the root sheath, which do not
disappear, remain as the epithelial rests of Malassez. These small groups of tissue are ectodermal in
origin, as the original enamel epithelium is ectodermal.
- At the cervical line, a cross section of the maxillary lateral incisor would show:
A. a round shape
B. an oval shape wider on the lingual than the labial
C. a triangular shape with a distinctly wider labial surface
D. an oval shape with a slightly wider labial surface
E. mesiodistal flattening
The correct answer is A. The maxillary lateral incisor exhibits an almost round root cross section
shape at the cervical line. It is not flattened mesiodistally or labiolingually. The pulp chamber mimics
the root shape by being round at this point as well. It is very similar in both root shape and pulp shape
to those of the maxillary central. Note that as the pulp enters the coronal section, it will begin to widen
mesiodistally (flatten buccolingually) in keeping with the crown shape.
36. Because of the staining effect, tetracycline is not given to children younger than approximately what age? A. 2 years B. 5 years C. 8 years D. 11 years E. 14 years
The correct answer is C. This may not seem like dental anatomy, but it is actually a calcification
question. In order to avoid tetracycline staining or any other intrinsic stain of enamel, we must avoid
all ages where tooth crown calcification is occurring. The last tooth to calcify (and erupt) is the third
molar. Most third molars erupt at 17 to 21 years, but calcification of enamel occurs mostly at about
age 8. So pregnant mothers and children age 8 and younger are not given tetracycline.
37. Which structure is involved in pulling the disc of the TMJ forward? A. Stylomandibular ligament B. Medial pterygoid muscle C. Mandibular condyle D. TMJ meniscus E. Lateral pterygoid muscle
The correct answer is E. The lateral pterygoid connects from the greater wing of the sphenoid and
the lateral surface of the lateral pterygoid plate to the mandibular condyle, articular disc, and capsule.
It is the only muscle that attaches to these structures. The stylomandibular ligament, sometimes given
a vague protective function, extends from the styloid process to the lingula of the mandible. The
medial pterygoid muscle is an elevator with no direct attachment to the TMJ. The mandibular condyle
is separated from the glenoid (temporal) fossa by the articular (TMJ) disc. The condyle does not pull
the disc. The disc is also called the meniscus; they are the same thing.
38. The largest cusp of a maxillary first molar is the: A. mesiobuccal B. mesiolingual C. distobuccal D. distolingual E. Carabelli
The correct answer is B. The three largest cusps (trigon, or primitive cusp triangle) of the maxillary
first molar are the MB, ML, and DB cusps. The DL cusp is smallest, and is known as the talon cusp
(or talon). This cusp is also the one which is even less conspicuous as you go from first to second to
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third molar. Note also that the DB cusp decreases in relative size as you go from first to second and
third molar. The order of size of the cusps in this tooth, then, is from largest to smallest: ML, MB, DB,
DL, Carabelli.
39. Tooth #B is replaced by tooth #: A. 2 B. 3 C. 4 D. 5 E. 6
The correct answer is D. Remember that primary molars are succeeded by permanent premolars.
The permanent molars erupt distal to all primary teeth and do not replace them. So the maxillary
replacements are 4 for A, 5 for B, 6 for C, 7 for D, 8 for E, 9 for F, 10 for G, 11 for H, 12 for I, and 13
for J. 1, 2, 3, 14, 15, and 16 do not replace primary teeth.
40. Which two molars can be considered to be five-cusped teeth? A. Maxillary first and second B. Mandibular first and second C. Maxillary and mandibular first D. Maxillary and mandibular second
The correct answer is C. Most maxillary molars are considered four-cusped teeth. However, in some
cases, the Carabelli cusp (trait) can be large enough to be considered a fifth cusp on a maxillary first
molar. The maxillary second molar is usually four-cusped. The mandibular first molar is normally fivecusped
with an ML, MB, DL, and DB cusp and a fifth distal cusp. The mandibular second lacks the
distal cusp and is normally a four-cusp tooth.
41.The shape of the pulp chamber in cross section cut at the cervical line in the maxillary canine is: A. oval (flattened mesiodistally) B. oval (flattened bucco-lingually) C. round D. figure eight
The correct answer is A. Only maxillary incisors have roundish pulp chamber cross sections when
cut at the cervical line. This is true for both maxillary centrals and laterals. In general, mandibular
centrals and both arch canines will have ovalish pulp chambers, flattened mesiodistally. (Imagine
squashing a round pulp from both the mesial and distal sides at once, resulting in a squashed oval,
pointing to the buccal and lingual). Remember that the shape of a pulp chamber is usually related to
the shape of the surrounding root.
42. In the maxillary arch, the narrowest incisal or occlusal embrasure is located: A. between first premolar and canine B. between canine and lateral incisor C. between lateral incisor and central D. between central incisors
The correct answer is D. The best way to answer the question is to imagine contact points and
proximal-incisal angles for the anterior teeth. A small incisal embrasure will be located wherever the
contact points are high (incisal) and where proximal-incisal line angles are almost perpendicular. The
best example of this arrangement is the central incisors. Their mesial incisal line angles are very
square, and the contact is in the incisal third of the tooth. As you go further distally, the line angles
become more rounded, especially for canines. These rounded line angles at the incisal, as well as the
more apical contacts, dropping to the middle third as you reach the distal of the canine, ensure much
larger incisal embrasures
43. The inner enamel cuticle, found on the surface of enamel of an erupting tooth crown, is: A. also known as Nasmyth's membrane B. also known as the stratum intermedium C. cellular D. formed by odontoblasts
The correct answer is A. As the tooth crown nears eruption, the ameloblasts produce their final
product, known as the inner enamel cuticle. This material is acellular, and is firmly adherent to the
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enamel surface as the tooth erupts. Its older name is Nasmyth’s membrane. This cuticle has on its
outside a second acellular layer formed from the keratinized remnants of the dental sac. This
adherent double layer may persist for some time after the tooth erupts but is eventually worn away,
leaving the enamel exposed in the oral cavity.
44.. Which ligament of the temporomandibular joint originates from a thin, pointed extension of the temporal bone? A. Temporomandibular B. Stylomandibular C. Sphenomandibular D. Lateral
The correct answer is B. The bony origins of the three TMJ ligaments are primarily from three
different bones. The stylomandibular ligament originates from a thin, bony extension of the temporal
bone, known as the styloid process. The spine of the sphenoid bone is the major origin of the
sphenomandibular ligament. The lateral ligament (temporomandibular ligament) has its origin from the
zygomatic process. This process is a fusion of the temporal and zygomatic bones.
45. Which of the following is the most coronally located periodontal fiber group? A. Alveolar crestal B. Apical C. Horizontal D. Oblique
The correct answer is A. We can eliminate choice B, as the apex is at the opposite end from the
crown. The apical fibers are, of course, most apical, and run from the apex of the alveolar bone socket
to the root tip. The oblique fibers are slightly more coronal. They run from the cementum near the
apical end, obliquely coronally to alveolar bone. The horizontal fibers are more coronal and run
horizontally from cementum to alveolar bone around mid-root. The alveolar crestal fibers are most
coronal, and run from the most coronal part of the root to the alveolar crest of bone.
46. In a distal view of a permanent maxillary first molar, how many roots should be visible? A. 1 B. 2 C. 3 D. 4
The correct answer is C. This may not be as obvious as it seems. Rule out 4, as the molar only has
three roots: the palatal, mesiobuccal, and distobuccal. However, how should they look in a distal
view? The palatal root will clearly be visible as the only root on the palatal side. It is massive, and
often hooked. On the buccal end, a distal view should easily show the full length of the distobuccal
root, so we have two roots so far. What about the mesiobuccal? In this case we can see this root
mostly because it is larger than the distobuccal, so some, but not all, of the mesiobuccal root is
blocked by the distobuccal. We should, however, see some small sections of it outside of the profile of
the distobuccal root.
- The heights of contour of the mandibular first premolar, when viewed from the mesial, are
located within which third?
A. buccal in occlusal third, lingual in middle third
B. both in middle third
C. both in occlusal third
D. buccal in cervical third, lingual in occlusal third
E. both in cervical third
The correct answer is D. As a general rule, the buccal heights of contour of the premolars are
located within the cervical thirds. The lingual heights of contour will normally be more occlusal. On the
mandibular first premolar, it is especially occlusal, within the occlusal third.
48. Which of the following oral muscles is NOT innervated by CN V? A. Masseter B. Buccinator C. Medial pterygoid D. Lateral pterygoid E. Mylohyoid
The correct answer is B. The general rule for innervation by CN V (the trigeminal) is that it
innervates the muscles of mastication (temporalis, lateral pterygoid, medial pterygoid, masseter), the
mylohyoid, the anterior digastric, and the two tensors (tensor tympani and tensor veli palatini). Note
that the buccinator is not included. The buccinator is in the group of muscles of facial expression,
which are all innervated by CN VII (the facial nerve).
49. The contact of the permanent mandibular incisor with the canine occurs at which level of the lateral? A. Incisal third B. Junction of incisal and middle thirds C. Middle third D. Gingival third
The correct answer is A. Mandibular incisors are widest near the incisal tip, and their contacts (both
central and lateral) are always near the incisal edge. The mandibular canine contact with the lateral
incisor is thus in the incisal third. In the canine, the contact is also in the incisal third, but not as incisal
as in the lateral. The distal contact of the canine is also in the incisal third, but near the junction of the
incisal and middle thirds.
50. Dens-in-dente is most commonly noted in which tooth? A. Maxillary central B. Maxillary lateral C. Maxillary canine D. Mandibular central E. Mandibular lateral
The correct answer is B. The maxillary lateral is the most highly variable tooth in the mouth. It can
be normal incisor-shaped, peg-shaped, or congenitally missing, or have a wide variety of
invaginations, from small pits to deep pits to dens-in-dente, or tooth-within-a-tooth. This is the case
when the invagination is so deep that the radiographic appearance appears to show a small tooth
inside the maxillary lateral.
51. Dentinal tubules which enter into enamel are known as: A. enamel spindles B. enamel tufts C. enamel lamellae D. none of the above
The correct answer is A. There are a number of somewhat confusing anomalies at the
dentinoenamel junction. Enamel spindles are odontoblastic processes and dentinal tubules which
extend a short way into enamel. Enamel lamellae, on the other hand, extend from enamel into dentin.
They are pieces of uncalcified organic enamel material. Enamel tufts are hypocalcified enamel rods.
They are individual entities; however, they appear as groups (tufts) when a group of them are viewed
laterally.
52. Guiding cusps normally contact: A. mesial marginal ridges B. distal marginal ridges C. central fossae D. embrasures
The correct answer is D. In occlusion, cusps are defined as either holding (supporting) cusps or
guiding cusps. Holding cusps, in central occlusion, make contact with the opposing arch, establish
vertical dimension of occlusion, and support the forces of occlusion. They are the lingual cusps of the
maxillary arch and buccal cusps of the mandibular. When the teeth are in centric occlusion, these
cusps are in contact. The other cusps (guiding) are not. The other cusps are either lingual to the
contact (lingual cusps of the mandibular arch) or buccal to the contact (buccal cusps of the maxillary
arch). Holding cusps generally occlude in the marginal ridge and central fossa areas of the opposing
arch. Guiding cusps generally lie in embrasures between teeth, or between cusps of the lingual or
buccal surfaces of the opposing arch.
53. Which premolar, when viewed from the facial, has a longer mesial cusp ridge than distal cusp ridge? A. Maxillary first B. Maxillary second C. Mandibular first D. Mandibular second
The correct answer is A. The question depends on the fact that the maxillary first premolar has an
asymmetric positioning of its two cusps. Rather than having the buccal and lingual cusps in a straight
line, the buccal cusp is displaced slightly distally, and the lingual cusp is displaced slightly mesially.
This gives the occlusal view of the tooth a slightly twisted appearance. Cusp ridges run from the cusp
tip to the proximal edge of the tooth at the marginal ridge. Therefore, if you look facially at the
maxillary first premolar, you will see the buccal cusp shifted toward the distal. This makes the cusp tip
farther from the mesial, and thus there will be a longer mesial cusp ridge on this tooth.
- In centric occlusion, the distolingual cusp of the maxillary second molar will contact:
A. the central fossa of the mandibular second molar
B. the distal marginal ridge of the mandibular first molar and mesial marginal ridge of second molar
C. the distal marginal ridge of the mandibular second molar and mesial marginal ridge of first molar
D. the distal marginal ridge of the mandibular second molar and mesial marginal ridge of third molar
The correct answer is D. The distolingual cusp of a maxillary second molar is a holding cusp. The
general rule for maxillary holding cusps is as follows: a maxillary holding cusp contacts the distal
marginal ridge of its mandibular counterpart and the mesial marginal ridge of the mandibular tooth
distal to its counterpart, EXCEPT FOR THE MESIOLINGUAL CUSPS OF THE MOLARS, WHICH
CONTACT THE CENTRAL FOSSAE OF THEIR COUNTERPARTS. This should be the distal
marginal ridge of the mandibular second molar and mesial marginal ridge of the third molar.
55. Of the following premolars, the one which can never be rotated during extraction is the: A. maxillary first B. maxillary second C. mandibular first D. mandibular second
The correct answer is A. For the most part, rotation of a tooth during extraction works best on teeth
with rounded roots, such as the maxillary central incisor and maxillary canine. It can be used in
conjunction with buccal-lingual luxation on teeth with single ovalish roots. It can never be used on
double-rooted teeth. Of the premolars above, the maxillary first is always double rooted. Of the others,
the maxillary second is sometimes double rooted and sometimes single. For the mandibular
premolars, the mandibular first is the most likely to have a single ovalish, but close to round, root. It is
theMOST likely premolar on which rotation may be part of the extraction.
- In centric occlusion, the lingual cusp of the maxillary second premolar contacts:
A. mesial marginal ridge of mandibular first premolar and distal marginal ridge of second premolar
B. distal marginal ridge of mandibular first premolar and mesial marginal ridge of second premolar
C. mesial marginal ridge of the mandibular first molar and distal marginal ridge of second premolar
D. distal marginal ridge of the mandibular second premolar and mesial marginal ridge of first molar
The correct answer is D. The mesiolingual cusp of a maxillary second premolar is a holding cusp.
The general rule for maxillary holding cusps is as follows: a maxillary holding cusp contacts the distal
marginal ridge of its mandibular counterpart and the mesial marginal ridge of the mandibular tooth
distal to its counterpart, EXCEPT FOR THE MESIOLINGUAL CUSPS OF THE MOLARS, WHICH
CONTACT THE CENTRAL FOSSAE OF THEIR COUNTERPARTS. This should be the distal
marginal ridge of the mandibular second premolar and mesial marginal ridge of the first molar.
- The maxillary molar most likely to have fused roots is the:
A. first
B. second
C. third
D. fused roots are rare for all three molars
The correct answer is C. While all three maxillary molars commonly have three roots, the roots and
their arrangement differ distinctively from one to the other. Most notable in the first molar is the plierslike
appearance of the two buccal roots. The mesiobuccal hooks distally and the distobuccal hooks
mesially. The second molar does not have this curvature, and the two buccal roots are more parallel,
with both roots inclined distally. The third molar often has three fused roots forming a cone-like
structure, or sometimes all distally inclined. These factors are important in exodontia of maxillary
molars. Maxillary third molars, in particular, can sometimes be elevated out distally in a rotating
manner because of the fused cone-like distally facing roots.
58.The distobuccal cusp of the mandibular second molar occludes with which maxillary tooth
surfaces?
A. The mesial marginal ridge of the second molar and distal marginal ridge of the first molar
B. The distal marginal ridge of the second molar and mesial marginal ridge of the third molar
C. The embrasure between the first and second molars
D. The central fossa of the maxillary second molar
The correct answer is D. The distobuccal cusp of a mandibular molar is a holding (supporting) cusp.
The general rule of occlusion of mandibular holding cusps is as follows: the holding cusps of the
mandibular teeth occlude on the mesial marginal ridge of their maxillary counterpart, and the distal
marginal ridge of the maxillary tooth mesial to their counterpart, EXCEPT distobuccal cusps of
mandibular molars occlude with central fossae of their counterparts, the distal cusp of the mandibular
first molar occludes with the distal triangular fossa of its counterpart, and the first premolar occludes
only with the mesial marginal ridge of its counterpart (but not the canine). In this case, the maxillary
counterpart is the maxillary second molar, and the mandibular cusp will occlude in its central fossa.
59. The major blood supply of the PDL is from: A. pulpal vessels B. gingival vessels C. periosteal vessels D. periapical vessels
The correct answer is C. All of the vessels listed supply blood to the PDL, as all of them are in the
vicinity of the PDL and all anastomose or send branches there. Out of this group, however, the
MAJOR source is vessels branching from the periosteum surrounding the alveolar bone. Note that
both lymphatics and nerves follow the path of the blood vessels in the PDL.
60. Which tooth below is MOST likely to be caries-resistant? A. Maxillary first premolar B. Mandibular second premolar C. Mandibular lateral incisor D. Mandibular second molar E. Maxillary central incisor
The correct answer is C. Look for a mandibular anterior tooth to be your answer here. You will often
notice clinically that partially edentulous patients often retain mandibular anteriors despite loss of most
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other teeth. This is due to the following three factors: 1) they have few significant pits or fissures; 2)
they are bathed in saliva most of the time, which resists plaque buildup; and 3) they are cleaned by
the normal movements of the tongue. Other teeth cannot fit all three of these categories. Note that
mandibular canines are often the last teeth left. This is because, although the mandibular incisors are
rarely lost to caries, they are often lost to periodontal disease, partially due to their short roots and
easy calculus buildup.
61.A patient presents for examination with both mandibular first molars distal to the maxillary
first molars. This occlusion is known as:
A. Class I, distocclusion
B. Class II, mesiocclusion
C. Class II, distocclusion
D. Class III, mesiocclusion
E. Class III, distocclusion
The correct answer is C. The normal (Class I) jaw relationship will result in the mandibular first molar
being located one cusp (one-half tooth) mesial to the maxillary first molar. If the mandibular molar is
located distal to the maxillary, it indicates a small mandible (micrognathy) or another problem causing
the maxillary teeth to be too far mesial and the mandibular too far distal. This is distocclusion is
Angles Class II. Mesiocclusion is Angles Class III, where the mandibular first molar is more than onehalf
tooth mesial to the maxillary first molar.
62. Which of the following is NOT a periodontal fiber? A. Oblique B. Transseptal C. Apical D. Horizontal
The correct answer is B. Periodontal fibers must run from the cementum of the tooth into alveolar
bone. The main periodontal fiber types are alveolar crestal, horizontal, oblique, and apical, named for
either their position or alignment. The transseptal fiber is classified with the gingival group, as it does
not enter alveolar bone. Instead, as the name suggests, it travels from one tooth to another tooth,
crossing over the alveolar crest. It attaches directly from the cementum of one tooth into the
cementum of another, but does not attach to bone.
63. The anterior tooth with the most pronounced lingual ridge is the: A. Maxillary central incisor B. Mandibular lateral incisor C. Maxillary canine D. Mandibular canine
The correct answer is C. A lingual ridge runs from the incisal edge down the center of the lingual
surface of the crown, toward the cervical end of the crown. It splits the lingual surface in half, and
usually has a depression on either side (lingual fossae) which separate the lingual ridge from the
mesial and distal marginal ridges. Lingual ridges are found on canines, but not on incisors (choices A
and B). The lingual ridge is more pronounced on the maxillary canine than on the mandibular (choice
D). This is in keeping with a general rule that the lingual anatomy of the maxillary canine is much
more pronounced than that of the mandibular.
- Oblique ridges are found on which molar teeth?
A. Maxillary first and second
B. Mandibular first and second
C. Maxillary and mandibular first
D. Maxilary and mandibular second
E. First and second molars in both arches
The correct answer is A. Oblique ridges are characteristic of maxillary molar teeth. They connect the
mesiolingual and distobuccal cusps. The oblique ridge is also considered to be the distal end of the
trigon, the major cusp area of the maxillary molar, composed of the ML, MB, and DB cusps. The DL
15
cusp is often reduced and is referred to as the talon (as opposed to the trigon). The trigon is
evolutionarily the primitive cusp triangle of the molar crown. Oblique ridges are not found on
mandibular molars or on any other teeth.
65. The most highly mineralized oral or dental tissue is: A. enamel B. dentin C. bone D. cementum
The correct answer is A. Enamel is the most mineralized and hardest tissue in the human body.
Most estimates place the mineral content of enamel at about 95 to 98%. Dentin, though highly
mineralized, still has more organic content than does enamel. Most estimates place the mineral
content of dentin at about 80%. Cementum is least mineralized, and is most similar to bone. There are
varying estimates of its mineral content, but most place it at about 60 to 65%.
66. The embrasures which surround the contact points of anterior teeth are: A. mesial, distal, lingual, buccal B. mesial and distal only C. buccal and lingual only D. buccal, lingual, cervical, gingival E. incisal, cervical, buccal, lingual
The correct answer is E. The best way to answer the question is to imagine that the embrasures are
spaces surrounding a small point of contact between two incisors. This small contact point will have
space above it, below it, in front of it, and in back of it. These spaces in dental anatomy will be,
respectively, incisal, cervical (gingival), buccal (facial), and lingual (palatal). Note that there is no
space mesial or distal to the contact point. Immediately mesial or distal to the contact would be tooth
structure.
- The distolingual cusp of the mandibular second molar contacts:
A. the lingual embrasure between the maxillary first molar and second molar
B. the lingual groove of the maxillary second molar
C. the central fossa of the maxillary second molar
D. the lingual groove of the maxillary first molar
E. the lingual embrasure between the maxillary second molar and third molar
The correct answer is B. Lingual cusps of mandibular teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for mandibular
lingual cusps is that they occlude in the lingual embrasures between their maxillary counterparts and
the teeth mesial to their counterparts, EXCEPT for the distolingual cusps of the mandibular molars,
which occlude in the lingual grooves of their maxillary counterparts. In this question we are dealing
with the exception of the distolingual cusps of mandibular molars, so in this case, the mandibular
second molar distolingual cusp contacts the lingual groove of its counterpart (the maxillary second
molar).
- The distobuccal cusp of the maxillary second molar occludes in:
A. the mesial marginal ridge of the mandibular second molar
B. the buccal groove of the mandibular second molar
C. the central groove of the mandibular third molar
D. the facial embrasure between the mandibular first and second molars
E. the facial embrasure between the mandibular second and third molars
The correct answer is E. Buccal cusps of maxillary teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for maxillary
buccal cusps is that they occlude in the facial embrasures between their mandibular counterparts and
the teeth distal to their counterparts, EXCEPT for the mesiobuccal cusps of the molars, which occlude
in the buccal grooves of their mandibular counterparts, and the distobuccal cusp of the first molar,
16
which opposes the distobuccal groove of the mandibular first molar. In this question, we are NOT
dealing with the exception of the mesiobuccal cusps of the maxillary molars or the distobuccal cusp of
the maxillary first molar, so this cusp should follow the general rule and occlude with the facial
embrasure between its mandibular counterpart (the mandibular second molar) and the mandibular
molar distal to it (the mandibular third molar).
- The mandibular incisors of a patient are worn down so that dentin is visible on the incisal
edge. This is due to grinding of these edges against the natural maxillary incisors. This loss of
tooth structure can be termed:
A. attrition
B. abrasion
C. erosion
D. internal resorption
The correct answer is A. Attrition is the mechanical wearing of teeth due to physiologic processes,
including chewing and bruxism. Abrasion (choice B) is the mechanical wearing away of tooth structure
due to some outside object, such as toothbrush abrasion at the cervical lines of teeth due to hard
sideways brushing, or from habitually holding bobby pins or nails with the teeth. Erosion (choice C) is
the chemical dissolving of tooth structure. It can be caused by a number of factors, including sucking
on lemons and other acidic fruit, excessive intake of acidic beverages (cola), or excessive vomiting,
as in bulimia. Bulimics often exhibit normal facial surfaces with severely eroded lingual surfaces.
- In centric occlusion, the lingual cusp of the maxillary first premolar contacts:
A. mesial marginal ridge of mandibular first premolar and distal marginal ridge of second premolar
B. distal marginal ridge of mandibular first premolar and mesial marginal ridge of second premolar
C. mesial marginal ridge of the mandibular first molar and distal marginal ridge of second premolar
D. distal marginal ridge of the mandibular second premolar and mesial marginal ridge of first molar
The correct answer is B. The lingual cusp of a maxillary premolar is a holding cusp. The general rule
for maxillary holding cusps is as follows: a maxillary holding cusp contacts the distal marginal ridge of
its mandibular counterpart and the mesial marginal ridge of the mandibular tooth distal to its
counterpart, EXCEPT FOR THE MESIOLINGUAL CUSPS OF THE MOLARS, WHICH CONTACT
THE CENTRAL FOSSAE OF THEIR COUNTERPARTS. This should be the distal marginal ridge of
the mandibular first premolar and mesial marginal ridge of the second premolar.
71. When a fourth canal is found in the permanent maxillary first molar, it is found in the: A. mesiobuccal root B. distobuccal root C. palatal root D. mesiolingual root
The correct answer is A. Note that the three-rooted maxillary first molar does not have a
mesiolingual root. The maxillary first molar most often has three roots: mesiobuccal, distobuccal, and
palatal. The palatal root is largest, and its canal is largest and widest. In the case of a fourth canal, it
is invariably found in the mesiobuccal root. The distobuccal and palatal roots are invariably onecanalled.
72. Odontoblasts laying down dentin matrix would be expected to contain large numbers of well-developed: A. nuclei B. lysosomes C. rough ER D. smooth ER E. mitochondria
The correct answer is C. This is a case of a best answer with a reasonable second-best answer.
The best answer is rough endoplasmic reticulum. The rough ER contains numerous ribosomes, and is
known for producing proteins for export. Collagen fibers of the dentin matrix would be good examples
17
of protein made for export (outside of the cell). The second-best answer is probably mitochondria, in
that the synthesis of collagen would be energy-consuming. Odontoblasts are single nuclei cells (unlike
osteoclasts, which are multinucleated). Note that smooth ER lacks ribosomes, and that the digestive
enzyme activity of lysosomes would not be needed for this process.
73. A mandibular permanent first molar is likely to have a deep root concavity running apically down: A. both roots B. the mesial root C. the distal root D. neither root
The correct answer is B. One of the distinctions between the mandibular first-molar mesial and distal
roots is the deep root concavity seen running the length of the mesial surface of the mesial root. The
distal root, by comparison, will have no similar concavity or a very slight depression. Other differences
include the greater likelihood of the mesial root having a distal curvature, and the greater likelihood of
the mesial root being partly split by a partial furcation running partway up from the apical end.
- The distobuccal cusp of the mandibular third molar occludes with which maxillary tooth
surfaces?
A. The mesial marginal ridge of the third molar and distal marginal ridge of the second molar
B. The central fossa of the third molar
C. The mesial marginal ridge of the third molar only
D. The distal marginal ridge of the third molar only
The correct answer is B. The distobuccal cusp of a mandibular molar is a holding (supporting) cusp.
The general rule of occlusion of mandibular holding cusps is as follows: the holding cusps of the
mandibular teeth occlude on the mesial marginal ridge of their maxillary counterpart, and the distal
marginal ridge of the maxillary tooth mesial to their counterpart, EXCEPT distobuccal cusps of
mandibular molars occlude with central fossae of their counterparts, the distal cusp of the mandibular
first molar occludes with the distal triangular fossa of its counterpart, and the first premolar occludes
only with the mesial marginal ridge of its counterpart (but not the canine). In this case, the maxillary
counterpart is the maxillary third molar, and the cusp should occlude in the central fossa of this tooth.
Remember that the mandibular third molar is located one-half tooth mesial to the maxillary.
- Damage to the right lateral pterygoid results in:
A. the mandible turning right on protrusion
B. inability to elevate the mandible
C. the mandible turning left on protrusion
D. none of the above
The correct answer is A. As a rule, the mandible will move toward the side of injury when the lateral
pterygoid is damaged. In this case, the right condyle will not move because of the muscle damage.
The left condyle moves forward, but because there is no movement on the right side, the left condyle
moves out and rotates to the right, with the nonmoving right condyle acting as a pivot point. Damage
to the lateral pterygoid will not affect elevation (closing), because the lateral pterygoid is not an
elevator. The elevators are the temporalis, medial pterygoid, and masseter.
- The distal cusp of the mandibular first molar occludes with which maxillary tooth
surfaces?
A. The mesial marginal ridge of the first molar and distal marginal ridge of the second molar
B. The distal marginal ridge of the second molar and mesial marginal ridge of the first molar
C. The embrasure between the first and second molars
D. The distal triangular fossa of the first molar
The correct answer is D. The distal cusp of the mandibular first molar is a holding cusp. The general
rule of occlusion of mandibular holding cusps is as follows: the holding cusps of the mandibular teeth
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occlude on the mesial marginal ridge of their maxillary counterpart, and the distal marginal ridge of the
maxillary tooth mesial to their counterpart, EXCEPT DISTOBUCCAL CUSPS OF MANDIBULAR
MOLARS OCCLUDE WITH CENTRAL FOSSAE OF THEIR COUNTERPARTS, THE DISTAL CUSP
OF THE MANDIBULAR FIRST MOLAR OCCLUDES WITH THE DISTAL TRIANGULAR FOSSA OF
ITS COUNTERPART, AND THE FIRST PREMOLAR OCCLUDES ONLY WITH THE MESIAL
MARGINAL RIDGE OF ITS COUNTERPART (BUT NOT THE CANINE). Note that mesiobuccal cusps
of mandibular molars and buccal cusps of premolars contact marginal ridges.
77. Hypocalcified enamel rods which enter into enamel from the DEJ are known as: A. enamel spindles B. enamel tufts C. enamel lamellae D. none of the above
The correct answer is B. There are a number of somewhat confusing anomalies at the
dentinoenamel junction. Enamel spindles are odontoblastic processes and dentinal tubules which
extend a short way into enamel. Enamel lamellae, on the other hand, extend from enamel into dentin.
They are pieces of uncalcified organic enamel material. Enamel tufts are hypocalcified enamel rods.
They are individual entities; however, they appear as groups (tufts) when a group of them are viewed
laterally.
- The mesiolingual cusp of the mandibular third molar contacts:
A. the lingual embrasure between the maxillary second molar and third molar
B. the distal marginal ridge of the maxillary second molar
C. the central fossa of the maxillary second molar
D. the lingual groove of the maxillary third molar
E. the buccal embrasure between the maxillary second molar and third molar
The correct answer is A. Lingual cusps of mandibular teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for mandibular
lingual cusps is that they occlude in the lingual embrasures between their maxillary counterparts and
the teeth mesial to their counterparts, EXCEPT for the distolingual cusps of the mandibular molars,
which occlude in the lingual grooves of their maxillary counterparts. In this question we are not dealing
with the exception of the distolingual cusps of mandibular molars, so in this case, the mandibular third
molar mesiolingual cusp contacts the lingual embrasure between its counterpart (the maxillary third
molar) and the tooth mesial to it (the maxillary second molar).
79. Based on root morphology, the tooth most likely to be successfully rotated during exodontia is the: A. Maxillary central B. Mandibular central C. Mandibular lateral D. Mandibular canine
The correct answer is A. During extraction, rotation can be used on teeth with rounded conical roots.
Two primary examples are maxillary centrals (especially) and maxillary laterals. Rotation may also be
used somewhat with maxillary canines. If roots are flattened mesiodistally, then buccal-lingual
movement is used instead of rotation, as rotation may cause crown fracture. Mandibular centrals,
laterals, and canines (choices B, C, and D) are all flattened mesiodistally, and therefore are usually
not rotated during extraction. Mandibular canines also may occasionally have two roots (buccal and
lingual), which will prohibit rotation.
- As compared to the cross section of the maxillary central incisor at the cervical line, the
cross section of the mandibular central is:
A. more flattened mesiodistally
B. more flattened faciolingually
C. rounder
D. almost identical
The correct answer is A. As a general rule, maxillary incisors have round root sections and round
pulp chamber cross sections. Mandibular incisors have more oval ones, and are flattened
mesiodistally. This is in keeping with the general root shape of each. Maxillary incisor roots are round,
and mandibular ones are flattened to a greater degree. Note that in both arches, as the pulp moves
coronally it will flatten buccolingually, in keeping with the coronal shape of all incisors.
81.The marrow space inside alveolar bone surrounding teeth: A. does not exist B. is usually red marrow C. is usually hematopoietic marrow D. is usually yellow marrow
The correct answer is D. Two types of marrow space are found within bone, red (hematopoietic),
which is the source of blood cells; and yellow (fatty), which does not produce blood cells. The alveloar
bone is similar to most bone in the body in having a compact outer layer of lamellar bone and an inner
layer of spongy bone. This spongy bone contains marrow space, usually of the yellow (fatty) type,
although some red marrow exists, especially in the ramus and condyle of the mandible.
- In the Posselt envelope of motion, protruded contact position (PCP) is:
A. achieved with the posterior teeth in occlusion
B. an extreme border position
C. the same as edge-to-edge
D. the same as an Angle Class II relationship
The correct answer is B. The Posselt envelope of motion is a tracing of the extreme border
movements of the mandible. It shows how far the mandible can protrude, retrude, open, and close,
and all motions connecting these points. Protruded contact position is caused by protruding the
mandible as far as possible. This will normally push the mandible past edge-to-edge, until the
mandible appears to be in a Class III relationship. As the mandible protrudes, anterior tooth contact
causes separation of the teeth out of occlusion.
83. Rests of Malassez are composed of: A. ectodermal derivatives B. former enamel epithelium cells C. former root sheath of Hertwig cells D. all of the above
The correct answer is D. The epithelial rests of Malassez are found in the periodontal ligament and
are leftovers from the root formation process. The root is originally outlined by the epithelial root
sheath of Hertwig, which is composed of the inner and outer enamel epithelium tissues, without a
stellate reticulum in between. The root sheath induces formation of odontoblasts, which then produce
root dentin. Pieces of the root sheath, which do not disappear, remain as the epithelial rests of
Malassez. These small groups of tissue are ectodermal in origin, as the original enamel epithelium is
ectodermal.
- When compared to the buccal roots of the maxillary first molar, the buccal roots of the
maxillary second molar are:
A. more parallel, with a pliers-like appearance
B. less parallel, lacking a pliers-like appearance
C. more parallel, with both having a mesial tip orientation
D. more parallel, with both having a distal tip orientation
The correct answer is D. A characteristic curve of the two buccal root tips of the maxillary first molar
toward each other is sometimes referred to as a pliers-handled appearance or pincer appearance. In
effect, the roots grow apically and then turn toward each other, forming a U shape. This shape helps
explain the stability of the tooth, especially when combined with the tripod-like arrangement of the
palatal root. Note that the same roots of the second maxillary molar often both point distally,
distinguishing one molar from the other. These roots in the second molar are also more parallel than
those in the first molar. In buccal view they seem to sway distally, with the palatal root in the midline
and slightly mesially tilted.
85. Which of the following permanent teeth is MOST likely to be missing a distolingual cusp? A. Mandibular first molar B. Maxillary first molar C. Mandibular second premolar D. Maxillary second molar
The correct answer is C. The mandibular first molar is invariably a five-cusped tooth, with MB, ML,
DB, DL, and distal cusps. Maxillary first and second molars are normally four-cusped teeth. The
distolingual cusp is usually less pronounced on the second molar. It is often absent on the maxillary
third molar, but that answer is not listed. The mandibular second premolar is either a two- or threecusped
tooth. The two-cusped variety has a single buccal cusp and a single lingual cusp, while the
three-cusped version has a buccal cusp and paired mesiolingual and distolingual cusps. However,
both varieties are common, so it is common to find this tooth lacking the distolingual cusp.
- The buccal cusp of the maxillary second premolar occludes in:
A. the mesial marginal ridge of the mandibular first premolar
B. the distal marginal ridge of the mandibular second premolar
C. the mesial marginal ridge of the mandibular second premolar
D. the facial embrasure between the mandibular first and second premolars
E. the facial embrasure between the mandibular second premolar and first molar
The correct answer is E. Buccal cusps of maxillary teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for maxillary
buccal cusps is that they occlude in the facial embrasure between their mandibular counterpart and
the tooth distal to their counterpart, EXCEPT for the mesiobuccal cusps of the molars, which occlude
in the buccal grooves of their mandibular counterparts, and the distobuccal cusp of the first molar,
which opposes the distobuccal groove of the mandibular first molar. In this question, the contact is the
embrasure between second mandibular premolar (the counterpart) and the first molar (the tooth distal
to the counterpart).
- In occlusion, guiding cusps are defined as:
A. lingual cusps of maxillary and mandibular arches
B. bucccal cusps of maxillary and mandibular arches
C. buccal cusps of the maxillary arch and lingual cusps of the mandibular arch
D. lingual cusps of the maxillary arch and buccal cusps of the mandibular arch
The correct answer is C. In occlusion, cusps are defined as either holding (supporting) cusps or
guiding cusps. Holding cusps, in central occlusion, make contact with the opposing arch, establish
vertical dimension of occlusion, and support the forces of occlusion. They are the lingual cusps of the
maxillary arch and buccal cusps of the mandibular. When the teeth are in centric occlusion, these
cusps are in contact. The other cusps (guiding) are not. The other cusps are either lingual to the
contact (lingual cusps of the mandibular arch) or buccal to the contact (buccal cusps of the maxillary
arch).
88. Protrusive movement causes the condyle of the mandible to move: A. backward and downward B. backward and upward C. forward and downward D. forward and upward
The correct answer is C. Protrusive movement is defined as moving the mandible outward, away
from the head. If you are in centric occlusion, you will protrude to move toward an edge-to-edge
position. The lateral pterygoid moves both condyles forward when it contracts, so the initial protrusive
movement is forward. When the condyle contacts the articular eminence in the glenoid fossa, it
cannot move directly forward anymore and begins to glide downward along the surface of the fossa.
- As compared to those of the permanent mandibular first molar, the roots of the second
molar are:
A. more mesially inclined
B. straighter
C. more distally inclined
D. very similar in inclination to the first molar
The correct answer is C. In the permanent mandibular first molar, the mesial root is usually slightly
curved distally, and the distal root is straighter but pointing toward the distal. In the second molar, both
roots are usually significantly inclined toward the distal and curved distally at the end. They tend to
resemble each other more than the two roots of the first molar do. They are also closer together. The
roots in the first molar are more widely spread.
90. Which of the following fiber sets does NOT attach to cementum? A. Alveolar crestal B. Dento-gingival C. Circular D. Oblique
The correct answer is C. The attachment fibers are usually divided into two groups, the gingival
group and the periodontal group. Gingival fibers attach tissues, not including alveolar bone. For
example, circular fibers run only within gingiva, encircling the tooth. Dento-gingival fibers run from
cementum to gingiva. Dento-periosteal fibers run from cementum to periosteum. Periodontal fibers
run from alveolar bone to cementum, and include alveolar crestal, oblique, horizontal, and apical.
- The mesiobuccal cusp of the maxillary second molar occludes in:
A. the buccal groove of the second mandibular molar
B. the facial embrasure between the mandibular first and second molars
C. the central groove of the mandibular second molar
D. the distal marginal ridge of the mandibular first molar
E. the buccal groove of the mandibular third molar
The correct answer is A. Buccal cusps of maxillary teeth are guiding cusps, not holding cusps.
Therefore, they do not occlude on marginal ridges or central fossae. The general rule for maxillary
buccal cusps is that they occlude in the facial embrasures between their mandibular counterparts and
the teeth distal to their counterparts, EXCEPT for the mesiobuccal cusps of the molars, which occlude
in the buccal grooves of their mandibular counterparts, and the distobuccal cusp of the first molar,
which opposes the distobuccal groove of the mandibular first molar. In this question we are dealing
with the exception of the mesiobuccal cusps of maxillary molars, which occlude with the buccal
grooves of their mandibular counterparts. In this case, the maxillary second molar mesiobuccal cusp
contacts the mandibular second molar buccal groove (its counterpart).
92. The shape of the pulp chamber in cross section cut at the cervical line in the maxillary central incisor is: A. oval (flattened mesiodistally) B. oval (flattened bucco-lingually) C. round D. figure eight
The correct answer is C. Only maxillary incisors have roundish pulp chamber cross sections when
cut at the cervical line. Laterals are egg-shaped with the widest portion labial, not round. This is true
for both maxillary centrals and laterals, which are egg-shaped with the widest portion of the labial not
round. In general, mandibular incisors and both arch canines will have oval-shaped pulp chambers,
flattened mesiodistally. (Imagine squashing a round pulp from both the mesial and distal sides at
once, resulting in a squashed oval, pointing to the buccal and lingual). Remember that the shape of a
pulp chamber is usually related to the shape of the surrounding root.
