Dental mcqs

7/22/2019 Dental mcqs

1/198

The crowns of the incisors when viewed from the incisal

A. are wider mesiodistally than buccolingually in both arches

B. are wider buccolingually than mesiodistally in both arches

C. are wider mesiodistally in the maxilla, and wider buccolingually in the mandible

D. are wider mesiodistally in the mandible and wider mesiodistally in the maxilla

The correct answer is C. This is known as an arch trait, as it is true for both incisors of each

arch. Both incisors of the maxilla are wider mesiodistally. Both incisors of the mandible are

wider buccolingually. The maxillary central, in particular, is known for the greatest

assymetry in this regard. It is much wider mesiodistally than buccolingually, and that

difference, expressed as a ratio, is greatest for that incisor. It is also the largest incisor, in

both dimensions, in absolute size.


2/198

A rule regarding congenitally missing teeth is:

A. A mandibular tooth is more likely to be missing than its maxillary counterpart

B.

A distal tooth of a type is more likely to be missing than the mesial tooth of the

same type

C.

A mesial tooth of a type is more likely to be missing than a distal tooth of the

same type

D. None of the above is true

The correct answer is B. In any set of teeth (incisor, premolar, molar), the distal tooth is

more likely to be congenitally missing than the mesial. So lateral incisors are missing more

than centrals, second premolars are missing more than first premolars, and third molars

are more commonly missing than first or second. Of all of these, the MOST commonly

missing is the maxillary lateral incisor. Note that choice A is therefore incorrect.


3/198

In centric occlusion, the mesiolingual cusp of the maxillary first molar will contact:

A.

the mesial marginal ridge of the mandibular first premolar and distal marginal

ridge of the second premolar

B.

the distal marginal ridge of the mandibular first molar and distal marginal ridge of

the second molar

C.

the distal marginal ridge of the mandibular second premolar and mesial marginal

ridge of the first molar

D. the central fossa of the mandibular first molar

The correct answer is D. The mesiolingual 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 central fossa of the counterpart, the mandibular first molar.


4/198

The premolar which is most often double rooted is the:

A. maxillary first

B. maxillary second

C. mandibular first

D. mandibular second

The correct answer is A. Maxillary first premolars are almost always double rooted. When

single rooted, they always have two separate root canals. The level of division of the two

roots varies, from complete division up to the crown, to only a small separation apically.

The mandibular first premolar is most often singlerooted, and the mandibular second

premolar is almost always single rooted (double roots are rarer than in the mandibular

first). The maxillary second premolar is most often single rooted. The extreme likelihood

that the maxillary first premolar will have two roots has implications for both endodontics

and exodontia of this tooth. It is also reported that some small percentage (5% in one

study) are actually triple rooted.


5/198

The central fossa of a maxillary first molar is NOT bordered by which cusp?

A. Mesiobuccal

B. Mesiolingual

C. Distobuccal

D. Distolingual

The correct answer is D. The central fossa, containing a central pit, is located within the

main cusp triangle (trigon) of the maxillary first molar. The three major cusps: MB, ML, and

DB, surround the fossa and form the trigon, or primitive cusp triangle. The DL cusp (talon)

is not part of the trigon, does not surround the central fossa, and is the smallest cusp of

the tooth (excluding the Carabelli cusp or trait).


6/198

In the primary mandibular first molar, the most noticeable cusps are:

A. MB and DB

B. MB and ML

C. DB and DL

D. MB and DL

The correct answer is B. The primary mandibular first molar is a highly unusual tooth.

Although it technically contains four cusps, in typical molar fashion it has a great variety in

the prominence of those cusps. The MB and ML cusp are most prominent, and the mesial

section of the crown comprises two-thirds of the crown area. Both the DB and DL cusps are

much reduced. The range of cusp size, in decreasing order is: MB, ML, DB, DL. The ML cusp

is notable for a pointy, cone-like shape.


7/198

The mesiobuccal 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 distal marginal ridge of the third molar and mesial marginal ridge of thesecond molar

C. The mesial marginal ridge of the third molar only

D. The central fossa of the maxillary third 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 mesialmarginal ridge of its counterpart (but not the canine). In this case, the maxillary

counterpart is the maxillary third molar, and the tooth immediately mesial to it is the

maxillary second molar.


8/198

Tooth #23 replaces which primary tooth?

A. K

B. L

C. M

D. N

E. O

The correct answer is D. Both 23 and N are mandibular left incisors. Remember that A

through J are maxillary, while K through T are mandibular. The mandibular replacements

are 20 for K, 21 for L, 22 for M, 23 for N, 24 for O, 25 for P, 26 for Q, 27 for R, 28 for S, and

29 for T. Remember that permanent molars 17, 18, 19, 30, 31, and 32 do not replace

primary teeth.


9/198

Which cusp of the maxillary molar is NOT part of the trigon (primitive cusp triangle)?

A. Mesiolingual

B. Mesiobuccal

C. Distolingual

D. Distobuccal

The correct answer is C. In evolution, three cusps of the maxillary molar are considered to

be the primary cusp triangle, and the original three cusps of the evolving molar. They form

the trigon, and are the MB, ML, and DB cusps. The fourth cusp, the DL, is the smallest, is

considered to be a minor cusp, and is known evolutionarily as the talon, or talon cusp. This

cusp is less conspicuous as you go from first to second to third maxillary molar.


10/198

Which is the most common supernumerary tooth?

A. Mesiodens

B. Second lateral incisor

C. Third mandibular

D. Fourth maxillary molar

The correct answer is A. A mesiodens is a supernumerary located midline in the maxilla. It

has a wide variety in morphology and is usually extracted. It is the most common and

frequently causes a diastema between the central incisors. The other relatively common

supernumeraries are the second maxillary lateral incisor, third mandibular premolar, and

fourth maxillary molar.


11/198

The mesiobuccal 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 premolar

B.The distal marginal ridge of the first molar and mesial marginal ridge of thesecond molar

C. The embrasure between the first and second molars

D. The distal triangular fossa of the first 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 THEFIRST 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 tooth mesial to it is the second premolar.


12/198

Extreme bruxism over time may cause masseteric hypertrophy. It can be noted on the face

as:

A. Swelling in the area of the temporal fossa

B. Swelling in the lateral mandibular ramus area

C. Swelling on the medial surface of the jaw

D. Loss of muscle substance near the ramus

E. Loss of muscle mass above and below the lips

The correct answer is B. Masseteric hypertrophy means gain in muscle substance of the

masseter muscle. The masseter is located on the lateral part of the ramus and angle, and

its growth in thickness can be seen as a squareness of the lower face on frontal view.

People who brux (express tension by clenching their teeth) often develop this larger-than-

normal size masseter. It can sometimes be confused with parotid swelling, although the

parotids are slightly higher in location. Remember that the medial pterygoid is medial, not

lateral, to the ramus. Loss of muscle substance would be atrophy rather than hypertrophy.


13/198

The mucosa found on the surface of the dorsum of the tongue is known as:

A. lining mucosa

B. masticatory mucosa

C. specialized mucosa

D. none of the above

The correct answer is C. Specialized mucosa is found on the dorsum of the tongue and

contains taste buds and various papillae, including circumvallate, foliate, fungiform, and

filiform. Masticatory mucosa consists of the gingiva and covering of the hard palate. Most

of the other areas of the oral cavity are lined by lining mucosa. The characteristics of

masticatory mucosa are keratinization, thin or absent submucosa, and tight binding of the

lamina propria to underlying periosteum. Lining mucosa is generally nonkeratinized, with a

thin lamina propria. Near the teeth, the gingiva and lining mucosa (alveolar mucosa) meet

at the mucogingival junction.


14/198

The premolar with a root cross section and pulp chamber shape at the cervical line which is

most similar to that of a canine is the:

A. mandibular first

B. mandibular second

C. maxillary first

D. maxillary second

The correct answer is A. You could answer this on general principal, that the mandibular

first premolar is the most canine-like premolar tooth in almost every way. However, in

detail, the mandibular first premolar has a round root cross section and a roundish pulp

chamber at the cervix. The second premolar has a generally more flattened shape in the

mesiodistal direction and a correspondingly oval pulp chamber. It may be constricted at

the center with a corresponding hourglass shape. The maxillary first premolar root is

flatttened mesiodistally, as is the pulp chamber. It is usually constricted at the center,

indicating the two roots and two canals found in the tooth. The second maxilllary

premolar, with one root, is less likely to be constricted into an hourglass shape.


15/198

Which ligament of the temporomandibular joint inserts into the ramus and angle of the

mandible?

A. Temporomandibular

B. Stylomandibular

C. Sphenomandibular

D. Lateral

The correct answer is B. The origins and insertions of the TMJ ligaments are as follows: The

stylomandibular ligament arises from the spine of the temporal bone known as the styloid

process and inserts on the lower ramus and angle of the mandible. The sphenomandibular

ligament arises from a spine on the sphenoid bone and runs forward and downward to

insert on the lingula and deep ramus of the mandible. The lateral ligament is also known as

the temporomandibular ligament. It descends from the lower border and tubercle of the

zygoma to the posterior lateral condyle. Its fibers merge with those of the articular

capsule.


16/198

The tissue located between the inner and outer enamel epithelium is known as:

A. stellate reticulum

B. dental sac

C. dental papilla

D. enamel organ

The correct answer is A. The stellate reticulum is an ectodermal tissue located between

the inner and outer enamel epithelium. The stellate, or star-like, appearance of the tissue

is caused by the arrangement of few cells within a network, separated by intracellular fluid.

The inner enamel epithelium will differentiate into ameloblasts and form enamel. The

outer enamel epithelium eventually merges with the gingiva as the tooth erupts. A small

cell layer between the inner enamel epithelium and stellate reticulum is referred to as the

stratum intermedium. Its presence is necessary for proper ameloblast function. The dental

sac is mesodermal and forms cementum and the periodontal ligament. The dental papilla is

mesodermal and forms pulp and dentin. The enamel organ consists of inner and outer

enamel epithelium, stellate reticulum and stratum intermedium and forms enamel. It isectodermal in origin.


17/198

The central portion of the articular disc of the TMJ is best described as:

A. convex and avascular

B. convex and vascular

C. concave and avascular

D. concave and vascular

The correct answer is C. The articular disc of the TMJ is composed of fibrous connective

tissue. Some sources state that chondrocytes are found within it, so it is sometimes

referred to as fibrous connective tissue with an underlying base of fibrocartilage. Its shape

is biconcave, somewhat like that of an erythrocyte, with a raised outer portion and

depressed middle. The central portion is avascular, and only the periphery, especially the

posterior periphery is vascularized.


18/198

Which ligament of the temporomandibular joint merges with the fibers of the articular

capsule?

A. Lateral

B. Stylomandibular

C. Sphenomandibular

D. None of the above

The correct answer is A. The lateral ligament, also known as the temporomandibular

ligament, is found extending downward from the lateral surface of the zygoma. The

zygoma is formed from the contact of the zygomatic section of the temporal bone and the

temporal portion of the zygomatic bone. The ligament is roughly triangular in shape, and

on its medial side is found the articular capsule and joint. Fibrous connective tissue

composes both the ligament and capsule, and there is a fibrous connection between them.


19/198

Which characteristic is NOT typical of lining mucosa?

A. Nonkeratinized

B. Lines the surface of the hard palate

C. Freely moveable

D. Contains a well developed submucosa

E. Epithelium thin

The correct answer is B. Lining mucosa covers most of the oral cavity except for the hard

palate and gingival areas. It is usually loose, freely movable, and has a well-developed

submucosa. The lamina propria is often highly glandular. The epithelium is thin and

nonkeratinized. Epithelial ridges and rete pegs are uncommon and short.


20/198

Severing the left lateral pterygoid will cause the mandible to move in what direction if the

patient attempts to protrude?

A. Posteriorly

B. Closure (elevation)

C. Right

D. Left

E. Downward (depression)

The correct answer is D. If you like rules, the rule is that if a lateral pterygoid is injured, the

mandible moves toward the injured side. If you wish to understand this rule better,

imagine two intact lateral pterygoids protruding the mandible normally. Now cut the left

lateral pterygoid, and imagine that the left side stays in place but the right side continues

to protrude. In effect, the mandible will rotate around the axis of the left side. The left side

stays in place while the right side rotates left. Lateral pterygoids have little effect on

closing.


21/198

Incisal contact between the maxillary and mandibular incisors is seen normally:

A. in centric occlusion

B. in working movements

C. in protrusive movements

D. in retrusive movements

E. never

The correct answer is C. Posterior contact is normal during centric occlusion and maintains

the vertical dimension of occlusion. In a normal dentition, however, the incisors are slightly

out of contact during centric occlusion. When the mandible moves forward (protrusion),

the incisal edges of the mandibular anteriors meet the lingual surfaces of their maxillary

counterparts as the teeth separate during opening. (Try it in your mouth!). Note that

during retrusion (moving the mandible from centric occlusion to a more distal position), no

such contact occurs. During working (lateral) movements, only posterior teeth and canines

contact (group function), or canines contact alone (canine/cuspid protected guidance).


22/198

As you go from mandibular first to second to third molars, overall root length:

A. increases, then decreases

B. increases

C. decreases

D. decreases, then increases

The correct answer is C. While the mandibular third molar is often so variable that it is

hard to make useful predictions about it, these generalities apply to mandibular first,

second, and third molars as you move distally in the arch: 1) they decrease in mesiodistal

length, and 2) their roots decrease in length. Third-molar roots may resemble normal

molars or may be missing roots or have additional roots. Roots are often partially or totally

fused. In some cases they form a cone-like, fused mass, making exodontia much simpler in

these cases. In all cases, however, their roots are shorter than those of their second-molar

counterparts, which are always smaller than those of the first molars.


23/198

The most common number of mammelons on an incisor is:

A. 1

B. 2

C. 3

D. 4

The correct answer is C. Mammelons are bumps on the incisal edge of incisors. They are

most commonly found on central incisors of both arches, and if found on the laterals, they

are less prominent than those found on the centrals. There are normally three, but this is

variable. The three are termed mesial, central, and distal. They are often worn off on adult

teeth through years of occlusion.


24/198

In extraction of maxillary central incisors, the root anatomy guides the dentist to use a

motion that is primarily:

A. buccal-lingual luxation

B. mesio-distal luxation

C. rotation

D. all of the above

The correct answer is C. 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 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 central is

invariably single rooted with a rounded root, and can almost always be rotated without

breaking the crown off of the root.


25/198

As the tooth bud develops into a tooth, the ameloblasts and odontoblasts:

A. become farther apart

B. become closer together

C. stay approximately the same distance apart

D. are always immediately next to each other

The correct answer is A. Early in tooth bud formation, the tissues of the enamel organ-

outer enamel epithelium, stellate reticulum, stratum intermedium, and inner enamel

epithelium-form adjacent to the dentin-forming tissues of the dental papilla. In fact, at this

stage, the ameloblasts and future odontoblasts are in contact along the length of the tooth

bud. The dentin production begins first, and predentin is laid down by odontoblasts. This

predentin production induces the ameloblasts to begin enamel production by cells of the

inner enamel epithelium. Thus, dentin is produced above the odontoblasts while enamel is

formed below the inner enamel epithelium. Both dentin and enamel are deposited

between these two layers, and the former site of the junction of the two layers becomes

the DEJ, or dento-enamel junction. By tooth completion, the enamel organ is at the surfaceof the gingiva while the odontoblasts are producing dentin for the tooth root. Thus, these

cell layers are very far apart at this point.


26/198

The major function of contact points in the dentition is to:

A. protect the incisal surface

B. protect the periodontium

C. protect the alveolar mucosa

D. protect restorations from poor retention

E. none of the above

The correct answer is B. Contacts ensure that food does not get lodged between teeth and

into the sulcus. Food, debris, and plaque in that area will lead to inflammation, tissue

destruction, and bone loss. Contacts do not protect the incisal surface, as they are below

(cervical to) that area. They do protect the gingiva (see above), but not especially the

alveolar mucosa, which is more cervical and basically below the tooth region. The alveolar

mucosa begins at the mucogingival junction. Contact is not involved in restoration

retention. All restorations must be retained by retention within the individual tooth itself.


27/198

The premolar most likely to have a three-cusped appearance when viewed from the

occlusal is the:

A. maxillary first

B. maxillary second

C. mandibular first


The correct answer is D. The premolars are usually considered to be two-cusped teeth

(bicuspids). The exception to the rule, to a small extent, is the mandibular second

premolar. Often, the lingual cusp area is divided into a mesiolingual cusp and a distolingual

cusp. This gives the tooth a three-cusped appearance. A two-cusped variety also exists,

with a large lingual cusp instead of the two smaller ones. In the three-cusped variety, a

lingual groove separates the two lingual cusps. Note that the two-cusped and three-cusped

varieties are not grossly different in size, as the single lingual cusp is about the same size as

a mesioloingual and distolingual combined. The other premolars exist primarily in double-

cusped varieties only.


28/198

At the cervical line, a cross section of the mandibular 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 mandibular and maxillary canines exhibit similar cross

sectional shapes at the cervical line. The mandibular canine cross section 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.


29/198

In performing a left working movement:

A. Only the left lateral pterygoid contracts

B. Only the right lateral pteyrgoid contracts

C. Both lateral pterygoids contract

D. Neither lateral pterygoid contracts

The correct answer is B. In a left working movement, the mandible moves toward the left.

The left side is then known as the working side and the right side as the nonworking

(balancing) side. The lateral pterygoids pull the mandibular condyles forward, so the pull of

both together results in protrusion. For only a left-sided movement, the left lateral

pterygoid does not contract and the left condyle stays in a relatively unchanging position (it

does rotate slightly). The right lateral pterygoid contracts and pulls the right side of the

mandible outward, and then it turns left, as the left side of the mandible is stationary.

Remember that the right lateral pterygoid moves the mandible left, and the left lateral

pterygoid moves the mandible right.


30/198

Which is the first primary tooth to erupt?

A. Mandibular central

B. Mandibular lateral

C. Maxillary central

D. Maxillary lateral

The correct answer is A. If you see enough small children in your practice, you'll often

notice that a 6-month-old child will have only two teeth: the two mandibular centrals.

These are commonly the first teeth to erupt, and most commonly do so at 6 months.

Mandibular laterals are often seen at about 9 months. Maxillary centrals and maxillary

laterals average about 8 months. First molars then precede canines in both arches, and

second molars are last in both arches. The last primary is usually the maxillary second

molar at about 24 months. These times may vary considerably. Know the most common

order: central, lateral, first molar, canine, second molar.


31/198

Which pair of angles of a maxillary first molar are acute when the tooth is viewed from the

occlusal?

A. MB and ML

B. DB and DL

C. MB and DB

D. ML and DL

E. None of the above

The correct answer is E. If you view the maxillary first molar from the occlusal, its shape is

that of a rhombus, or equal-sided parallelogram. In any parallelogram, one pair of opposite

corners will be obtuse, while the other pair of opposite corners will be acute. In the

maxillary first molar, the opposite pair of MB and DL are acute, while the pair ML and DB

are obtuse.


32/198

Of the following anterior teeth, the one most likely to be double rooted is the:

A. Maxillary lateral

B. Mandibular lateral

C. Maxillary canine

D. Mandibular canine

The correct answer is D. Although none of the teeth listed is commonly double rooted, the

mandibular canine is the most likely of this group. Maxillary laterals (choice A) are highly

variable and are often the most variable teeth in the mouth. However, their variability

does not usually include double-rooted appearance. Mandibular centrals and laterals

(choice B) often have proximal root grooves. If these grooves are deep, there may be an

appearance of becoming double rooted, but they rarely are. Maxillary canines (choice C)

are invariably single rooted. Mandibular canines are occasionally double rooted. The point

of separation into two roots may be toward the cervical of the root, or almost at the apex.

This double-rooted possibility is significant for both exodontia and endodontics.


33/198

When extracting maxillary teeth, the root tip most likely to be forced into the maxillary

sinus is that of a:

A. canine

B. first premolar

C. second premolar

D. first molar

E. second molar

The correct answer is D. Anatomically, roots of the maxillary first molar are closest to the

sinus, which dips downward in this area. Periapical x-rays of the area sometimes reveal

that the roots of the first molar border right on the sinus margin. Although the first molar

is the MOST likely tooth to have a root enter the sinus, roots of the second premolar and

second molar can occasionally end up there as well.


34/198

Which cell type of the enamel organ is widely separated by liquid between the cells?

A. Outer enamel epithelium

B. Stellate reticulum

C. Stratum intermedium

D. Inner enamel epithelium

The correct answer is B. Both the inner and outer enamel epithelium are solid lines of cells

with no space between the cells in each line. Between these two layers of cells we find the

stratum intermedium, close to the inner enamel epithelium; and the stellate reticulum,

filling the space between the stratum intermedium and outer enamel epithelium. The

stratum intermedium is generally a few layers of squamous epithelium. The stellate

reticulum is a reticulum (net-like network) of widely separated cells (think of stars in the

sky). These cells are surrounded by a clear liquid matrix and are connected by cell

processes.


35/198

The premolar with the buccal cusp most distally placed relative to the lingual is the:

A. maxillary first

B. maxillary second

C. mandibular first


The correct answer is A. An unusual aspect of the maxillary first premolar is the mesial-

distal placement of the cusps. The buccal cusp is off center toward the distal, while the

lingual cusp is off center toward the mesial. If you look at the tooth from the lingual,

therefore, you will always see two distinct cusp tips, one slightly to the mesial or distal of

the other. This placement, when viewed occlusally, is said to give the tooth a twisted

appearance. This situation is not found in the second premolar, where the cusps are almost

equal in size and straight in alignment.


36/198

Alveolar bone is composed of:

A. compact bone

B. spongy bone

C. bundle bone

D. all of the above


The correct answer is D. 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. Collagen fibers of the periodontal ligament insert into the outer cortical compact

layer, and are known as Sharpey's fibers. Compact bone with Sharpey's fibers is also known

as bundle bone.


37/198

The class of teeth considered to have a long axis which is most vertical in a buccolingual

direction (as viewed from the mesial or distal) is the:

A. incisors

B. canines

C. premolars

D. molars

The correct answer is C. Premolars do not vary far from a vertical line when viewed from

the mesial or distal. Both maxillary and mandibular incisors tip their roots greatly toward

the lingual, and canines less so. Mandibular molar roots lean buccally while maxillary molar

roots lean palatally.


38/198

When assigning types of mandibular motion to the compartments of the TMJ, it is

generally agreed that which compartment is associated with which motion type?

A. Anterior: rotation, posterior: translation

B. Anterior: translation, posterior: rotation

C. Superior: rotation, inferior: translation

D. Superior: translation, inferior: rotation

The correct answer is D. First, eliminate choices A and B, as the disc divides the joint

compartment into upper (superior) and lower (inferior) compartments only. In the upper

compartment, the upper surface of the disc acts as a cushion as the mandibular condyle

slides forward. This cushion slides against the articular eminence in the movement of the

condyle in a forward and downward direction. When rotating about an axis during

opening, the condyle slides against the lower surface of the disc which conforms to the

shape of the condylar head. So we say that translation occurs in the upper compartment

and rotation in the lower.


39/198

Osteons, Haversian systems, and concentric bone layers:

A. are not found in alveolar socket bone

B. are found in the outer layer of alveolar bone

C. are found in the inner layer of alveolar bone

D. are found throughout alveolar bone

The correct answer is B. 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. Haversian systems, with concentric rings of bone with osteocytes and canaliculi,

which surround a canal with artery, vein, and nerve, are found only in compact (lamellar)

bone. These systems do not exist within the inner spongy layers of bone, whether we are

looking at alveolar bone or any other bone in the body.


40/198

If vertical dimension of occlusion is VDO, and vertical dimension of rest is VDR, and

freeway space is FS, then:

A. VDO + VDR = FS

B. VDO + FS = VDR

C. VDR + FS = VDO


The correct answer is B. The vertical dimension of occlusion (VDO) is a vertical

measurement on the front of the face when the teeth are in full occlusion (centric

occlusion). When the face is at rest, the teeth are slightly apart, and the vertical dimension

of the front of the face is slightly longer. This is the vertical dimension of rest (VDR). The

distance between the teeth at this point is the freeway space (FS). So when we take the

smaller VDO and add the few millimeters of the FS, we get the slightly longer VDR. VDR is

generally 2 to 5 mm more than VDO.


41/198

The primary mandibular central incisor usually exfoliates between which ages?

A. 4-5 years

B. 6-7 years

C. 8-9 years

D. 10-11 years

E. 12-13 years

The correct answer is B. Eruption and exfoliation questions are common in this section. The

mandibular primary centrals are often the first teeth lost, most commonly at age 6. Often

they exfoliate as the permanent first molars are erupting. For mandibular primaries, the

centrals exfoliate at year 6-7, the laterals at year 7-8, the canine at year 9-10, the first molar

at year 10-11, and the second molar at age11-12. Remember that all exfoliation questions

are approximations of average ages. The wrong answers must be fairly far off the mark.


42/198

Which incisor is most commonly found doubled (supernumerary)?

A. Maxillary central

B. Maxillary lateral

C. Mandibular central

D. Mandibular lateral

The correct answer is B. As is often the case, the maxillary lateral incisor is the answer for

weirdest or most variable tooth. In this case, it is the most common supernumerary (doubled

incisor), as it is also the most common missing, oversized, or undersized incisor. Note that the

most distal tooth (lateral incisor, second premolar, third molar) in a set is always more likely

to be missing or have a supernumerary. Note also that the most common supernumerary is

the mesiodens. This tooth is found in the maxillary midline. It is not, however, considered an

additional central. It has a morphology unique to itself and different from centrals.


43/198

Alveolar bone is composed of:

A. cortical bone only

B. cancellous bone only

C. cortical bone surrounding cancellous bone

D. cancellous bone surrounding cortical bone

The correct answer is C. Alveolar bone is a combination of cortical (compact) bone and

trabecular (spongy) bone. The cortical bone is on the outside surface, both next to the tooth

root and also continuous with the cortical bone of the maxilla and mandible. The cortical

bone adjacent to the tooth root is sometimes referred to as lamina dura. Nerves and blood

vessels travel primarily through the more porous cancellous bone between the two cortical

plates. Note that alveolar bone can be lost rapidly either in periodontal disease or following

tooth extraction.


44/198

Which muscle of mastication both strongly elevates and strongly retrudes the mandible?

A. Masseter

B. Medial pterygoid

C. Lateral pterygoid

D. Temporalis

E. Anterior digastric

The correct answer is D. The temporalis is a strong, broad, flat muscle which can both

elevate (close) and retrude (pull back) the mandible. This is due to the fact that it contains

both vertical and nearly horizontal muscle fibers. The vertical fibers pull the mandible straight

upward (elevation), while the horizontal fibers pull straight backward (retrusion). The most

anterior fibers of the temporalis are the vertical. As you move posteriorly, they become first

diagonal, and then horizontal. NBDE questions in the past have referred to this muscle as

being an elevator in the anterior and an elevator/retruder in the posterior.


45/198

The primary crown most UNLIKE any permanent tooth is the:

A. central incisor

B. lateral incisor

C. canine

D. first molar

E. second molar

The correct answer is D. The primary first molars, both maxillary and mandibular, are unique

in morphology and bear little resemblance to any permanent teeth. Primary incisors and

canines resemble their permanent counterparts closely, except in certain proportional ways.

Likewise, primary second molars are notable for closely resembling their permanent FIRST

molar counterparts. The primary maxillary first molar is a little like a premolar in shape, but

generally has one minor and two major cusps. It is both small and squat in appearance. The

mandibular primary first molar is four-cusped but has a distinctly larger development of the

mesial end. The MB and ML cusps generally comprise two-thirds of the area of the crown.


46/198

In a noncarious, unrestored, and fully erupted tooth, dentin continues to form at the border

of the pulp and dentin. This dentin is known as:

A. primary dentin

B. secondary dentin

C. tertiary dentin

D. reparative dentin


The correct answer is B. Dentin forms the bulk of both the crown and root of the tooth. In

the crown, it underlies the outer enamel. In the root, it underlies a thin layer of cementum.

The original dentin of the crown and root is primary dentin and is the most regular in

structure. The pulp continues to form dentin later in life at the dentin-pulp border. This

results in smaller pulp chambers with age. This dentin is secondary dentin, and is less regular

in structure than is primary dentin. Reparative dentin is formed as a defense against caries,

irritation, deep restorations, etc. It is the least regular in structure, and is alo known as

sclerotic dentin. There is no tertiary dentin.


47/198

Enamel is formed from which embryonic germ layer?

A. Endoderm

B. Mesoderm

C. Ectoderm


The correct answer is C. Of the tissues comprising the tooth structure, only enamel is formed

from ectoderm. It is made by ameloblasts, which are ectodermal derivatives. Cementum,

produced by cementoblasts, and dentin, produced by odontoblasts, are both mesodermal

derivatives (choice B). Note also that pulpal tissue is mesodermal. No tooth structural tissue

is endodermal (choice A).


48/198

The shape of the pulp chamber in cross section cut at the cervical line in the mandibular

central incisor 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 incisors 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.


49/198

The Carabelli cusp (trait) is found attached to which cusp?

A. Mesiobuccal

B. Mesiolingual

C. Distobucal

D. Distolingual

The correct answer is B. The Carabelli cusp (trait) is a variable cusp or extension of the

mesiolingual cusp of the maxillary first molar. Its expression varies from that of a full cusp, at

its largest, to a small protuberance at its smallest. Its expression varies among various races

and ethnic groups. Some anatomists describe it as a cusp, making the maxillary first molar a

five-cusped tooth. Others consider it a variety or trait of a four-cusped tooth. It is sometimes

missing, and a groove or pit is found in the normal Carabelli cusp region of the mesiolingual

cusp.


50/198

Which periodontal fibers are most in line with the long axis of the root?

A. Alveolar crestal

B. Apical

C. Horizontal

D. Oblique

The correct answer is B. If we arbitrarily call the long axis of the root vertical, only the apical

periodontal fibers are nearly parallel (vertical). The apical fibers run vertically from the apex

of the alveolar bone socket to the root apex cementum. More coronally, the next fibers, the

oblique, run obliquely (slanted) from near apical cementum to more coronal alveolar bone.

Horizontal fibers run horizontally from cementum to bone, which is thus perpendicular to the

root axis. The most coronal alveolar fibers run obliquely from coronal cementum, apically

slanted toward the alveolar crest of bone.


51/198

Which of the following permanent teeth is NOT succedaneous?

A. Maxillary lateral incisor

B. Mandibular first molar

C. Maxillary second premolar

D. Mandibular canine

E. Maxillary canine

The correct answer is B. Succedaneous refers to a tooth that succeeds another tooth; that is,

a tooth that replaces a previous tooth. Remember that permanent incisors and canines

replace primary incisors and canines (choices A, D, and E). Permanent premolars replace

primary molars (choice C). Thus, all the permanent teeth mentioned so far are succedaneous.

Permanent molars are not succedaneous as they do not replace primary teeth. The

permanent first molar develops distal to all primary teeth, and later the second and third

molars do likewise. Molars do not replace any primary teeth and are therefore not

succedaneous.


52/198

Which premolar exhibits H, Y, and U occlusal patterns?

A. Maxillary first

B. Maxillary second

C. Mandibular first

D. Mandibular second

The correct answer is D. The mandibular second premolar has a variety of occlusal

appearances due mostly to its two-cusped or three-cusped nature. There is a slightly larger

buccal cusp area, and then either an approximately equal-sized lingual cusp, or a pair of

lingual cusps, known as the mesiolingual and distolingual cusps. Together, these two form an

area slightly smaller than the buccal cusp. In the event of the three cusps, an occlusal Y

groove pattern is common. On the two-cusped variety, either an H (more common) or U (less

common) pattern may be found.


53/198

The inclinations of the root tips of the mesiobuccal and distobuccal roots of the maxillary first

molar are, respectively:

A. mesial, mesial

B. mesial, distal

C. distal, mesial

D. distal, distal

E. straight, straight

The correct answer is C. 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.


54/198

Which muscle of mastication controls movement of the articular disc of the TMJ?

A. Medial pterygoid

B. Lateral pterygoid

C. Temporalis

D. Masseter

The correct answer is B. The lateral pterygoid muscle has two heads. The superior head

arises from the greater wing of the sphenoid bone, and the inferior head from the lateral

plate of the lateral pterygoid bone. They extend posteriorly to the mandibular condyle, TMJ

capsule, and TMJ disc. Fibers from the upper head enter the capsule and merge with the

fibrous connective tissue of both the capsule and disc. This is related to the function of the

muscle in protruding the mandible, and pulling the disc with the condyle during protrusion,

depressing (opening), and lateral movements. No other muscle enters the TMJ.


55/198

The mesiolingual cusp of the mandibular first molar contacts:

A. the lingual embrasure between the maxillary first molar and second premolar

B. the distal marginal ridge of the maxillary second molar

C. the central fossa of the maxillary first molar

D. the lingual groove of the maxillary first molar

E. the lingual embrasure between the maxillary first molar and second 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 first molar mesiolingual cusp contacts

the lingual embrasure between its counterpart (the maxillary first molar) and the tooth

mesial to it (the maxillary second premolar).


56/198

In a mandibular canine, which surface is usually most parallel to the long axis of the tooth?

A. Buccal

B. Lingual

C. Mesial

D. Distal

The correct answer is C. Reviewing the surfaces, the lingual surface of the canine contains

the bulbous cingulum. The surface of the lingual is thus slanted at roughly 45 degrees from

the long axis (as represented by the root). Likewise, the facial surface slants inward as you go

from cervical to incisal. The distal surface slants lingually as the tooth narrows coronally. Our

answer is mesial. The mesial surface is vertical overall, with no large bulge. Notice that the

distal is always more rounded and bulbous than the mesial, which is relatively straight and, if

extended, would roughly parallel the root.


57/198

Mesial-occlusal-distal (MOD) cavity preparations are most difficult in which of the following

teeth?

A. Permanent mandibular first premolar

B. Permanent maxillary second molar

C. Primary mandibular second molar

D. Primary mandibular first molar

The correct answer is D. MOD preparations can be difficult because tooth structure must be

removed from three tooth surfaces. The remaining tooth structure can be weak, and pulp

horns may be exposed. They are especially hard in small teeth with large pulp horns. The

primary mandibular first molar is a good example. It has a very narrow distal end, is small

overall, and has very high mesial pulp horns. Additionally, little tooth structure remains after

the MOD is cut. Permanent mandibular first premolars are small, but not like the primaries.

They should have a slanted occlusal floor, but an MOD is possible. Permanent maxillary

second molars are generally large and would be the best of this group for making an MOD

preparation. The primary mandibular second molar, while small, is larger than the first molar,and has the same shape as a permanent first molar, making it not as difficult to perform an

MOD preparation.


58/198

The primary maxillary first molar is often said to have a premolar shaped crown. This tooth

will invariably have how many roots?

A. One

B. Two

C. Three

D. Four

The correct answer is C. Despite a somewhat premolar-shaped crown, the primary maxillary

first molar is consistent in root form with all maxillary molars, primary or permanent, in

having three roots. They are the mesiobuccal, distobuccal, and palatal. Premolars will

routinely have either one or two roots. Primary molars lack a common root trunk, and have

widespread roots which allow space for the developing premolar crown underneath.


59/198

Synovial fluid-producing tissue in the TMJ:

A. is found throughout all surfaces

B. is not found within the joint

C. is found only on articular surfaces

D. is found only on non-articular surfaces

The correct answer is D. The TMJ is a synovial joint, similar to most other movable joints. It is

different in having a fibrous articular disc. The surface of the disc is fibrous connective tissue,

and the surface of the articulating surfaces of the glenoid fossa are fibrous connective tissue

overlying hyaline cartilage. These surfaces are not covered with synovial tissue; however,

their smooth functioning is dependent on the production of synovial fluid elsewhere in the

joint. This production occurs in all non-articulating surfaces of the joint, which are lined with

synovial tissue.


60/198

Which teeth exhibit isomorphy with each other?

A. Primary maxillary first and second molars

B. Primary maxillary second and primary mandibular second molars

C. Primary mandibular first molars and primary maxillary first molars

D. Primary maxillary second molars and permanent maxillary first molars


The correct answer is D. Isomorphy refers to a close similarity in morphology and crown

shape between two teeth. The most notable examples of isomorphy are the primary second

molars with the permanent first molars IN BOTH ARCHES. Thus, by looking at a primary

second molar in either arch, you can very accurately predict the morphology of the

permanent first molar in that same arch. Isomorphy does not exist between primary first and

second molars, as both first molars are very unusual in shape and both second molars closely

resemble permanent first molars.


61/198

The distobuccal 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 distobuccal 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 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 distobuccal cusps of the

maxillary first molar, which occludes with the distobuccal groove of its mandibular

counterpart, the mandibular first molar.


62/198

The distal contact point and height of contour of the maxillary lateral incisor is located:

A. at the incisal edge

B. in the incisal third

C. in the middle third

D. in the cervical third

The correct answer is C. As is generally the case, the distal contact of this tooth is more

cervical than is the mesial contact. On the mesial side, where it contacts the central incisor,

the contact will be near the junction of incisal and middle thirds. However, on the distal side,

it is slightly more cervical, usually around the middle of the middle third. This is the contact

with the maxillary canine. On the canine, this height of contour is at the junction of the incisal

and middle third.


63/198

The buccal cusp of the maxillary first 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 first premolar and canine

The correct answer is D. 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 groove of their mandibular counterpart, 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 first and second

mandibular premolars.


64/198

The most common arrangement of canals in the roots of a permanent mandibular first molar

is:

A. two mesial, two distal

B. two mesial, one distal

C. one mesial, two distal

D. one mesial, one distal


The correct answer is B. Although some variation exists, the most common arrangement of

canals in the mandibular first molar is two canals in the mesial root (MB and ML), and one in

the distal. The largest is normally the distal, followed by the MB, then the ML. Approximately

25% of mandibular first molars will have four canals: MB, ML, DB, and DL.


65/198

The lingual fossa is normally deepest on which incisor?

A. Maxillary central

B. Maxillary lateral

C. Mandibular central

D. Mandibular lateral

The correct answer is B. The maxillary lateral is noted for its variability, and one area of great

variety is the lingual fossa. It is normally more pronounced than that of any other incisor and

often contains a pit, from narrow and shallow to deep and extensive. Extremely deep pits

may give a dens-in-dente appearance. In operative dentistry the maxillary lateral is the only

incisor in which you will occasionally see lingual pit amalgams. The lingual surface is often

marked by a lingual marginal groove and tubercles on the cingulum. In general, expect any

type of unusual variety to be most commonly found on maxillary laterals.


66/198

Sharpey's fibers in the periodontal ligament:

A. enter only alveolar bone

B. enter only cementum

C. are collagenous in composition

D. enter cancellous bone to form bundle bone

The correct answer is C. Sharpey's fibers is an older name for the collagenous bundles of the

periodontal ligament which connect the tooth to the tooth socket. The two tissues entered

by these fibers are cementum on the tooth, and the cortical bone plate of the alveolar bone.

When they enter the cortical plate, the resulting bone, when viewed under the microscope, is

termed bundle bone. The fibers do not penetrate the bone enough to reach the cancellous

inner layers of the alveolar bone.


67/198

The mesial and distal heights of contour of the maxillary canine are, respectively:

A. incisal third, incisal third

B. junction of incisal/ middle third, junction of incisal/middle third

C. junction of incisal/middle third, middle third

D. middle third, middle third

E. middle third, cervical third

The correct answer is C. One way to eliminate answers is to note that the labial view of the

maxillary canine is not symmetrical. The mesial cusp ridge is shorter than the distal cusp

ridge. This means that the distance from the cusp tip to the mesial contact is shorter than

that from the cusp tip to the distal contact. Another way to look at it is that the distal cusp

ridge dips lower (more cervical). Therefore, the distal height of contour will be more cervical

than the mesial. The mesial height of contour is at about the junction of incisal and middle

thirds, while the distal is at the middle of the middle third. Do not consider choice E, even

though it follows the pattern discussed above. These contacts (middle, cervical) are too

cervical for an anterior tooth.


68/198

A mandibular permanent first molar is more likely to have a partially bifurcated:

A. mesial root

B. distal root

C. both roots are equally likely to be bifurcated

D. neither root is bifurcated

The correct answer is A. 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. 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. Other differences include the greater likelihood of the mesial

root having a pronounced distal curvature.


69/198

In a left working movement:

A. the left side moves laterally, and the right side medially

B. the left side moves medially, and the right side laterally

C. both sides move medially

D. both sides move laterally

The correct answer is A. In a left working movement, the mandible shifts to the left. From a

central position, the left side of the mandible is moving away from center (laterally). The right

side of the mandible, although also moving left, is moving toward the center (medially). The

left TMJ purely rotates when the right is rotating and translating mechanically.

Note that it is impossible for both sides of the mandible to move either laterally or medially

at the same time.


70/198

The faciolingual dimension of a mandibular first molar, when compared to the mesiodistal

dimension, is:

A. smaller

B. larger

C. the same

D. larger or smaller, depending on the tooth

The correct answer is A. Mandibular first molars are the largest teeth in the mouth, in

mesiodistal dimension. While they are also large buccolingually, they are invariably larger

mesiodistally by about 0.5 to 1.0 mm. This is in contrast to the maxillary first molar, which is

slightly larger buccolingually than mesiodistally, usually by about 1.0 mm. The mandibular

second molar is about equal in both directions and is thus more symmetrical than the first

molar.


71/198


72/198

The earliest succedaneous tooth in the mouth to erupt is the:

A. Primary mandibular central incisor

B. Primary mandibular lateral incisor

C. Permanent mandibular first molar

D. Permanent maxillary first molar

E. Permanent mandibular central incisor

The correct answer is E. The question depends entirely on the definition of succedaneous. A

succedaneous tooth succeeds (replaces) another tooth. So only permanent teeth can be

succedaneous. Note, however, that permanent molars are never succedaneous, as they

erupt distal to all primary teeth (choices C and D). Only permanent incisors, canines, and

premolars can be succedaneous (refer to choices A and B). Of all succedaneous teeth, the

permanent mandibular central incisor is usually first, appearing at about age 6, close to the

eruption of the nonsuccedaneous permanent mandibular first molar.


73/198

In the permanent mandibular third molar, when viewed from the occlusal:

A. the mesial end is larger than the distal

B. the distal end is larger than the mesial

C. the mesial and distal ends are the same size

D. it is impossible to generalize about mandibular third molars

The correct answer is A. Beware of choice D. Although mandibular third molars are

notoriously variable in both crown and root form, there are some good generalizations.

Almost invariably, the mesial (trigonid) end of the crown is wider, larger, and more distinct

than the distal (talonid). The most common pattern is a four-cusp tooth, with MB and ML

being the largest cusps and the whole occlusal surface tapering toward the distal.


74/198

The lamina propria is:

A. epithelial tissue

B. connective tissue

C. adipose tissue

D. muscle tissue

The correct answer is B. The lamina propria is a loose connective tissue located within the

mucosal layer, just underneath the epithelium. In the oral cavity, it will be found below the

outer layer of stratified squamous epithelium. The lamina propria in the oral cavity often

forms wedge-like extensions into concavities in the epithelium, known as connective tissue

papillae. The corresponding epithelial extensions into the connective tissue are known as

rete pegs.


75/198

In a left lateral (working movement):

A. the left mandibular teeth are the working side and move to the left

B. the left mandibular teeth are the working side and move to the right

C. the left mandibular teeth are the balancing side and move to the left

D. the left mandibular teeth are the balancing side and move to the right

The correct answer is A. By definition, a working movement occurs when the mandibular

teeth on one side move laterally across the surfaces of the maxillary teeth toward their own

side. In other words, in a left working movement, left mandibular cusps move laterally left

across the cusps of the maxillary left teeth. The other side is known as the nonworking

(balancing) side. In this case, the balancing side is the right side. In a left working movement,

the balancing side also moves left, as the mandible cannot move both left and right at the

same time.


76/198

The buccal cusp of the mandibular canine occludes with which maxillary tooth surfaces?

A.

The mesial marginal ridge of the first premolar and distal marginal ridge of the

canine

B.

The mesial marginal ridge of the canine and distal marginal ridge of the lateral

incisor

C. The embrasure between the canine and first premolar


The correct answer is D. The buccal cusp of a mandibular canine is not considered to be a

holding (supporting) cusp. Therefore, the general rule of occlusion of mandibular holding

cusps does not apply. The canine, as an anterior tooth, will normally be slightly out of contact

between its maxillary counterpart and the tooth immediately mesial to it. In this case, the

maxillary counterpart is the maxillary canine, and the tooth mesial to it is the lateral incisor.


77/198

The buccal cusp of the mandibular first premolar contacts which surfaces on maxillary teeth?

A.

The mesial marginal ridge of the first premolar and distal marginal ridge of the

canine

B.

The mesial marginal ridge of the second premolar and distal marginal ridge of the

first premolar

C.

The distal marginal ridge of the first premolar and the mesial marginal ridge of the

canine


The correct answer is D. While theoretically it may appear that the correct answer is choice

A, most authors state that there is no contact with the maxillary canine distal marginal ridge,

and the canine remains slightly out of contact but near the area of the buccal cusp of the

mandibular first premolar. 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 WITHCENTRAL 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).


78/198

The Carabelli cusp (trait) is found on which molar tooth?

A. Maxillary first

B. Mandibular first

C. Maxillary second

D. Mandibular second

The correct answer is A. The Carabelli cusp (trait) is a variable cusp or extension of the

mesiolingual cusp of the maxillary first molar. Its expression varies from that of a full cusp, at

its largest, to a small protuberance at its smallest. Its expression varies among various races

and ethnic groups, including an increased incidence in people of Asian descent. Some

anatomists describe it as a cusp, making the maxillary first molar a five-cusped tooth. Others

consider it a variety or trait of a four-cusped tooth. It is sometimes missing, and a groove or

pit is found in the normal Carabelli cusp region of the mesiolingual cusp.


79/198

Which permanent mandibular molar is most likely to be marked by supplemental occlusal

grooves, crenulations, and unpredictable placement of pits?

A. First molar

B. Second molar

C. Third molar

D. All molars about equally

The correct answer is C. The question may be answered on general principle, in that the third

molars are often the most unpredictable teeth in either arch. The specific patterns referred

to here are the pit-groove patterns. In third molars, you will often find supplemental grooves

at right angles to the main grooves, and additional pits and fissures not normally seen in first

and second molars. The crenulated pattern refers to a highly grooved overall occlusal surface

with grooves running in all directions, leaving a lacy, nook-and-cranny occlusal surface.


80/198

Functions attributed to the ligaments of the temporomandibular joint include all of the

following EXCEPT:

A. increasing stability of the joint

B. aiding in forward movement of the condyle

C. increasing the strength of the joint

D. limiting extreme motion of the joint

E. All of the above are ligament functions

The correct answer is B. The ligaments, being fibrous connective tissue in composition, play

no role in movement of the condyle. Muscular tissue is necessary for this movement,

specifically fibers from the upper head of the lateral pterygoid muscle. There is disagreement

among anatomy sources as to the function or role of the ligaments. None give the ligaments

an extremely important function, but most claim that they help limit motion of the mandible

beyond a certain point, or act as barriers to excessive forward or downward motion. Others

give the ligaments a general strengthening function which adds stability to the joint. Most

importantly, the Dental Boards usually agree with the general notion of adding strength,

stability, and limits of movement to the joint.


81/198

Which of the following is a function of pulpal tissue?

A. Sensory

B. Formation of dentin

C. Nutritive

D. Defensive

E. All of the above

The correct answer is E. It should be noted that the MAJOR function of pulp is the production

of dentin, as dentin is the major structural tissue of both crown and root. Any question on

the dental boards that asks for the "most important" function will have dentin formation as

the answer. However, the pulp is also sensory (clearly). All sensory fibers in the pulp carry

pain sensation, regardless of whether the original stimulus is hot, cold, or touch. The nutritive

function of pulp consists of providing materials to the dentin through the odontoblastic

processes. The defensive function of the pulp consists of a limited ability to produce a

defensive inflammatory response, and the formation of reparative dentin when the tooth is

damaged.


82/198

Cervical bulges are found on which surfaces of primary anterior teeth?

A. Mesial and distal

B. Buccal and lingual

C. Lingual only

D. Buccal only

The correct answer is B. Primary teeth are notable for cervical bulges; that is, extension of

the crown at the cervical line. In the primary anteriors, these bulges extend over both the

buccal and lingual surfaces, as though the cervical line was a tightened belt and was

tightened further to make the crown overhang in both front and back. In the primary molars,

by contrast, the cervical bulge is buccal only.


83/198

Which of the following permanent teeth is MOST likely to be missing a distolingual cusp?

A. Mandibular first molar

B. Maxillary first molar

C. Maxillary third molar

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. This is an arch trait: the gradual diminishment in size of the

distolingual cusp as you go posteriorly in the maxilla. In the lower arch, the mandibular

second premolar can also be viewed as possibly lacking a distolingual cusp. This tooth is

either two- or three-cusped. 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 as well, although that answer is not listed here.


84/198

As you go from mandibular first to second to third molars, mesiodistal crown length:

A. increases, then decreases

B. increases

C. decreases

D. decreases, then increases

The correct answer is C. While the mandibular third molar is often so variable that it is hard

to make useful predictions about it, these generalities apply to mandibular first, second, and

third molars as you move distal in the arch: 1) they decrease in mesiodistal length, and 2)

their roots decrease in length. Third-molar crowns may resemble normal molars or may be

missing whole cusps. In rare cases they are roundish or ovoid, but they are always smaller

than their second-molar counterparts, which are always smaller than the first molars. Note

that buccolingual length is always shortest in the third molar but about equal in the first and

second.


85/198

When compared to that of permanent teeth, primary teeth color tends to be:

A. whiter

B. darker

C. similar in shade

D. variable, depending on the individual tooth

The correct answer is A. As a general rule, primary teeth are whiter than their permanent

counterparts. This shade difference is often noticed by parents. It is common for parents to

notice, for example, that newly erupted permanent mandibular incisors are a few shades

darker or more yellowish than the primary maxillary incisors that may remain as the

mandibular permanent incisors erupt. In the mixed dentition (normal, unstained, not heavily

carious, and no tetracycline effects), you can often pick out the primary versus permanent

teeth by color alone.


86/198

When compared to that of permanent teeth, the ratio of mesio-distal diameter to crown

height of primary teeth is:

A. greater

B. less

C. the same

D. variable, depending on the individual tooth

The correct answer is A. Primary teeth are often said to have a short or squat appearance of

their crowns compared to those of permanent teeth. This is because these teeth are often

relatively wide mesiodistally and short incisocervically. This results in a LARGE ratio of

mesiodistal diameter to incisocervical crown height. This ratio is smaller in the permanent

teeth, which lack the short, squat appearance of primaries. One example: for maxillary

central incisors, the primary tooth ratio is 1.083 (the tooth is just slightly bigger mesioincisally

than in crown height), while for the corresponding permanent incisor it is .809 (the

mesiodistal diameter is only 80% of the crown height).


87/198

When primary mandibular incisors are retained too long and the permanent incisors erupt

with the primaries still in place, the permanents usually erupt in what position relative to the

primaries?

A. Mesially

B. Distally

C. Lingually

D. Buccally

The correct answer is C. This is a fairly common occurrence. A child of about 6 years will

often present to the dental clinic with a parent, and the parent will be concerned about a

double row of teeth. In these cases, the permanent mandibular incisors are erupting before

the primaries have completely exfoliated. An x-ray usually confirms partial resorption of the

primary roots, and the primaries are allowed to exfoliate. No further treatment is usually

indicated. In rare cases where the permanents erupt buccally, extraction of the primaries and

tooth movement of the permanents is in order, however this is highly unusual.


88/198

The mesial height of contour of the mandibular central incisor is:

A. near the incisal edge

B. at the junction of the incisal and middle thirds

C. in the middle third

D. at the junction of the middle and cervical thirds

The correct answer is A. Mandibular central incisors contact at the most incisal point found

on any tooth. The contact is located just below the incisal edge. On the distal surface, it is still

incisal and near the edge, but is slightly more cervical than the contact found on the mesial

side of the tooth.


89/198

The TMJ structure consists of:

A. One synovial compartment

B. An upper synovial and lower nonsynovial compartment

C. Two synovial compartments

D. Two nonsynovial compartments

The correct answer is C. The TMJ has an upper and lower compartment, separated by the

articular disc, which is composed of fibrous connective tissue. Both the upper and lower

compartments are synovial; that is, they produce synovial fluid. Synovial fluid aids in

lubricating the articular surfaces of the joint, and is found in many movable joints. Note that

the synovial membrane lines the inside of the joint but not the actual articulating surfaces.

These surfaces are fibrous connective tissue over hyaline cartilage.


90/198

The lingual cusp of the mandibular first premolar contacts:

A. the mesial marginal ridge of the maxillary first premolar

B. the distal marginal ridge of the maxillary second premolar

C. the central fossa of the maxillary second premolar

D. the lingual embrasure between the maxillary first and second premolars

E. the lingual embrasure between the maxillary first premolar and canine

The correct answer is E. 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 first premolar lingual cusp contacts the

lingual embrasure between its counterpart (the maxillary first premolar) and the tooth mesial

to it (the maxillary canine).


91/198

Which characteristic most distinguishes permanent mandibular central incisors from lateral

incisors?

A. Mesiodistal length

B. Buccolingual length

C. Root length

D. Rotation of the crown around the root axis


The correct answer is D. The mandibular central and lateral incisors can be viewed as almost

twins. They are similar in dimension both mesiodistally and buccolingually. (The lateral may

be slightly, but not significantly, larger). Their roots are similar in length, although the lateral

may have a more pronounced distal inclination. The crowns are of similar anatomy. However,

the lateral has a twisted or rotated crown, as if you took a central and then slightly rotated

the crown around the long axis of the root. The root may appear to face forward, while the

incisal edge is curved in keeping with the normal curve of cusp tips of the mandibular arch.


92/198

The formation of dual teeth with combined enamel and dentin crowns but with only one root

is known as:

A. gemination

B. dilaceration

C. concrescence

D. dens-in-dente

E. taurodont

The correct answer is A. Gemination is a form of fusion, where a single root attempts to form

two crowns, and these crowns share dentin and enamel. A dilaceration is a sharply bent root,

especially near the apex. Concrescence is joining of two teeth by cementum union.

Taurodonts are teeth, usually molars, with short roots relative to crown size, and large pulpal

chambers, giving rise to a bull-like appearance. Dens-in-dente refers to a tooth-within-a-

tooth appearance and is due to invagination, usually in a maxillary lateral incisor.


93/198

The lingual surfaces of most maxillary teeth of a patient are worn down so that dentin is

visible through the remaining enamel on the lingual side. This is due to the dissolving of the

mineral of the enamel by strong acid. This loss of tooth structure can be termed:

A. attrition

B. abrasion

C. erosion

D. internal resorption

The correct answer is C. Erosion 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. This is due to the effect of strong

mineral acid from the stomach (hydrochloric acid at pH 2). Attrition (choice A) 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 sidewaysbrushing, or from habitually holding bobby pins or nails with the teeth. Internal resorption

(choice D) is the loss of dentin from pathologic dissolving by processes inside the pulp

chamber. It can follow tooth trauma.


94/198

The Golgi apparatus in odontoblasts producing dentin can be expected to be:

A. absent

B. less developed than in an average cell

C. developed to the same degree as that of an average cell

D. more highly developed than that of an average cell

The correct answer is D. Remember that the function of Golgi apparatus is to modify and

package proteins produced for export by the cell. In this way, an odontoblast would be

similar to any other protein-producing secretory cell. Proteins produced by ribosomes on the

rough ER will enter the ER and travel to the Golgi apparatus. Here, within the flattened sacs

of the Golgi, the collagen and other fibers will be modified and packaged to be sent to the

edge of the cell for secretion as dentin matrix. So the large production demands of producing

collagen and other proteins for predentin should result in odontoblasts having large,

numerous, and active Golgi bodies.


95/198

When you move the mandible from centric occlusion (maximum intercuspation) to protruded

contact (edge-to-edge) position:

A. vertical dimension decreases

B. horizontal overlap increases

C. vertical overlap increases


The correct answer is D. As you move from centric occlusion to edge-to-edge position, the

mandibular teeth separate from the maxillary and a space is created between the two

arches. Try this yourself, as you protrude and slide the mandible forward. The anterior teeth

act as a guide as you slowly separate from occlusal contact until only incisal edges of incisors

contact. At this point, the increased space between the arches adds to vertical dimension.

There is no vertical overlap (overbite; choice C) nor is there any horizontal overlap (overjet;

choice B) at this point. So protrusion to edge-to-edge increases vertical dimension while

decreasing both vertical and horizontal overlap.


96/198

In centric occlusion, the mesiolingual cusp of the maxillary second molar will contact:

A. the central fossa of the mandibular second molar

B. the central fossa of the mandibular first molar

C.

the distal marginal ridge of the mandibular first molar and mesial marginal ridge of

the second molar

D.

the distal marginal ridge of the mandibular second premolar and mesial marginal

ridge of the first molar

The correct answer is A. The mesiolingual 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 central fossa of the

counterpart, the mandibular second molar.


97/198

The most common arrangement of canals in the roots of a permanent maxillary first molar is:

A. ML, MB, DL, DB

B. ML, MB, and DB only

C. ML, MB, and palatal

D. MB, DB, and palatal


The correct answer is D. Most often, the maxillary first molar has three canals: a

mesiobuccal, a distobuccal, and a palatal.

Date post:	10-Feb-2018
Category:	Documents
Upload:	pinpointq
View:	312 times
Download:	6 times

Dental mcqs

Documents