Dental Anatomy and Occlusion, Preparation for NBDE Part I, Vol 1

  • Category: General Dentistry, Dental Anatomy and Occlusion
  • Aim: Revising for NBDE Part I
  • Questions: 100
  • Hints: No
  • Mutiple Opportunites: No
  • Time Limit: No
  • Answer Explaining: Yes

Dental Anatomy and Occlusion

Congratulations - you have completed Dental Anatomy and Occlusion. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
Your answers are highlighted below.
Question 1
All posterior teeth have a height-of-contour located in which segment of the crown?
A
Occlusal 3rd of the lingual surface
B
Middle 3rd of the buccal surface
C
Middle 3rd of the lingual surface
D
Cervical 3rd of the lingual surface
Question 1 Explanation: 
The correct answer is C. All posterior teeth (premolars and molars) have a lingual HOC in the middle 3rd, and a buccal HOC in the cervical 3rd, when viewed from the proximal. Answer A is incorrect. No tooth has a buccal or lingual HOC in the occlusal 3rd of its crown. Remember, though, that the proximal HOC is located in the occlusal 3rd in most anterior teeth. Answer B is incorrect. The buccal HOC of posterior teeth is in the cervical 3rd. Answer D is incorrect. All anterior teeth (incisors and canines) have a lingual HOC in the cervical 3rd (at the cingulum).
Question 2
During mandibular movement, which aspect of a mandibular molar will never contact its maxillary antagonist, assuming all occlusal relationships are ideal?
A
Outer aspect of the buccal cusps
B
Inner aspect of the buccal cusps
C
Inner aspect of the lingual cusps
D
Outer aspect of the lingual cusps
Question 2 Explanation: 
The correct answer is D. The buccal cusps of the mandibular posterior teeth are supporting cusps, which mean that they contact the opposing dentition in areas called centric stops. Not only do these buccal cusps contact their maxillary antagonists in the intercuspal position, they also can contact their maxillary antagonist during working and nonworking lateral movements. The lingual cusps of the mandibular molar, on the other hand, are nonsupporting, and do not rest in a central fossa or marginal ridge area of a maxillary antagonist. However, the buccal incline of the lingual cusps can serve as a guiding incline for the maxillary lingual supporting cusps during mandibular movement. Answer A is incorrect. On the working side during lateral excursion, the outer aspect of the mandibular buccal (supporting) cusp can glide along the inner or lingual incline of the maxillary buccal guiding (nonsupporting) cusp. Answer B is incorrect. On the nonworking side, the lingual supporting cusps of the maxillary teeth can be guided along the inner aspect of the buccal cusps. Answer C is incorrect. The lingual aspect (nearest the cusp tip) of the lingual maxillary supporting cusps can be guided along the inner incline of the lingual mandibular cusps during excursive movements (working side).
Question 3
Which tooth has a mesial marginal ridge that is more cervically located than the distal marginal ridge?
A
Maxillary 1st premolar
B
Maxillary 2nd premolar
C
Mandibular 1st premolar
D
Mandibular 2nd premolar
Question 3 Explanation: 
The correct answer is C. Both the mesial contact and marginal ridge is more cervical than the distal, which is a feature that is unique to the mandibular 1st premolar. Answers A, B, and D are incorrect. These premolars have mesial marginal ridges located more occlusally than the distal marginal ridge. Recall that mesial marginal ridge grooves are almost always present on maxillary 1st premolars. Furthermore, the mesial marginal ridge of the mandibular 2nd premolar is more horizontal than the cervically sloping mesial marginal ridge of the mandibular 1st premolar.
Question 4
Which of the following teeth have a functional lingual surface? I. Maxillary incisors II. Maxillary canines III. Mandibular incisors IV. Mandibular canines
A
I only
B
I and IV
C
III and IV
D
I and II
E
None of the above
Question 4 Explanation: 
The correct answer is D. Both maxillary incisors and maxillary canines have a functional lingual surface. The maxillary canines are unique as the only cusped teeth with a functional lingual surface. The lingual surfaces, in part, help guide the mandible in excursive and protrusive movements. Answers: 23-31 213 Answers A, B, C, and E are incorrect. The incisofacial aspect of mandibular incisors and canines function against the lingual surfaces of maxillary incisors and canines, respectively. They aid in disarticulating the posterior teeth during protrusive and excursive movements (anterior guidance versus canine guidance).
Question 5
A 25-year-old patient presents with mamelons on the incisors. Which of the following is the most likely explanation for this finding?
A
Posterior crossbite
B
Anterior crossbite
C
Variation of normal
D
Anterior open bite
E
Nocturnal bruxism
Question 5 Explanation: 
The correct answer is D. Mamelons are small enamel tubercles on the incisal edges of anterior teeth formed from the three facial developmental lobes. They normally wear away when the tooth comes into functional contact with its opposing tooth. In an anterior open bite situation, there is no contact between the maxillary and mandibular anterior teeth. The age of the patient suggests that if the teeth were in contact, the mamelons would have been worn away. Answer A is incorrect. In a posterior crossbite, the anterior teeth would most likely remain in function during excursive movements, and the mamelons would have worn away. Answer B is incorrect. In an anterior crossbite, the anterior teeth would most likely remain in function during excursive movements, and the mamelons would have worn away. Answer C is incorrect. The presence of mamelons is considered normal only when they are present on newly erupted teeth that haven’t yet contacted their antagonists. Answer E in incorrect. Grinding of the teeth at night would lead to attrition, flattening the incisal edges or cusp tips, thus wearing mamelons away.
Question 6
Which of the following teeth contacts only one other tooth in the opposing arch in an ideal occlusion?
A
Maxillary central incisor
B
Maxillary lateral incisor
C
Mandibular central incisor
D
Maxillary 3rd molar
E
Both C and D
Question 6 Explanation: 
The correct answer is E. The narrow mandibular incisor opposes a relatively wide central incisor, and therefore only contacts this tooth. Also recall that the maxillary posteriors are positioned distally to their mandibular counterparts, so the maxillary 3rd molar can contact only the mandibular 3rd molar. The mandibular 3rd molar, on the other hand, can contact the distal marginal ridge of the maxillary 2nd molar, as well as the central fossa of the maxillary 3rd molar via its MB and DB cusps, respectively. Answer A is incorrect. The width of the maxillary central incisor allows it to be contacted by both the mandibular central and lateral incisors. Answer B is incorrect. The mandibular lateral incisor and canine can articulate with the maxillary lateral incisor.
Question 7
Which of the following premolars does not have a transverse ridge?
A
Maxillary 1st premolar
B
Maxillary 2nd premolar
C
Mandibular 1st premolar
D
Mandibular 2nd premolar (2-cusp type)
E
Mandibular 2nd premolar (3-cusp type)
Question 7 Explanation: 
The correct answer is E. On 2-cusped premolars, the triangular ridges of the buccal and lingual cusps converge at the central groove and join together to form a transverse ridge. However, the three triangular ridges of the 3-cusped mandibular 2nd premolar (one large buccal and two smaller lingual cusps resulting in a Y-shaped occlusal groove pattern) do not meet, and thus no transverse ridge is formed. Answers A, B, C, and D are incorrect. A transverse ridge crosses the occlusal surface of these premolars, running between the buccal and lingual cusps. Specifically, the triangular ridges of the buccal and lingual cusps unite to form the transverse ridge.
Question 8
Unique features of the primary mandibular 1st molar include all of the following EXCEPT
A
the mesial marginal ridge is overdeveloped and resembles a cusp.
B
the mesiolingual cusp is the largest.
C
the occlusal table distal to the transverse ridge is larger than the portion mesial to the transverse ridge.
D
there is no central fossa.
E
the crown is much wider mesiodistally than buccolingually.
Question 8 Explanation: 
The correct answer is B. The MB cusp is always the largest and longest cusp, occupying nearly two-thirds of the buccal surface. Answer A is incorrect. It has a very welldeveloped mesial marginal ridge. Answer C is incorrect. The occlusal table is much larger on the distal side of the transverse ridge compared to the mesial side. Answer D is incorrect. The occlusal table has a small mesial triangular fossa and a large distal fossa, but no central fossa due to the presence of a prominent transverse ridge extending between the MB and ML cusps. Answer E is incorrect. The mesiodistal length is greater than the buccolingual width.
Question 9
The horizontal distance between the labioincisal surfaces of mandibular incisors and the linguoincisal surfaces of maxillary teeth is referred to as
A
overjet.
B
overbite.
C
openbite.
D
crossbite.
Question 9 Explanation: 
The correct answer is A. Overjet is defined as horizontal overlap of the incisors, normally 2-3 mm. Answer B is incorrect. Overbite is defined as the vertical overlap of the incisors, normally 1-2 mm. Answer C is incorrect. There is no vertical overlap of the incisors in an openbite. Anterior openbite can result, for example, from a persistent thumb-sucking habit. Answer D is incorrect. Crossbite is a reversed horizontal overlap relationship of the teeth. If the lower incisors are anterior to the upper incisors in centric occlusion, the condition is called anterior crossbite or reverse overjet. Posterior crossbite exists when the maxillary posterior teeth are lingually positioned relative to the mandibular teeth in centric occlusion.
Question 10
The mandibular canine is most likely to occlude with the _____. A. B. C. D. E.
A
maxillary canine only
B
maxillary canine and 1st premolar
C
maxillary 1st premolar only
D
maxillary lateral incisor only
E
maxillary lateral incisor and
Question 10 Explanation: 
The correct answer is E. This arrangement is found in an ideal class I canine occlusion. Answer A is incorrect. In an ideal occlusion, the maxillary canine occludes with the mandibular canine and 1st premolar. Answer B is incorrect. This arrangement may be found in a class II occlusion. Answer C is incorrect. In an ideal occlusion, the maxillary 1st premolar occludes with the mandibular 1st and 2nd premolars. Answer D is incorrect. In an ideal occlusion, the maxillary lateral incisor articulates with the mandibular canine and lateral incisor.
Question 11
Which of the following points in the sagittal view of Posselt envelope of motion below is centric occlusion?
A
A
B
B
C
C
D
D
E
E
Question 11 Explanation: 
The correct answer is C. Centric occlusion is typically the most superior position, but retruded contact (D) is the most posterior. In some individuals, however, RC may coincide with CO, but it is never more anterior than CO. Answer A is incorrect. This is maximum protrusion. Answer B is incorrect. This is the anterior edge-to-edge position. Answer D is incorrect. This is retruded contact. Answer E is incorrect. This is maximum opening.
Question 12
After preparing an ideal endodontic access for tooth No. 3, you notice a 4th canal. In which root is this 4th canal most likely located?
A
Mesiobuccal
B
Distobuccal
C
Palatal
D
Any of the above
Question 12 Explanation: 
The correct answer is A. A fourth canal may be found in the mesiobuccal (30% prevalence). The MB II canal is located about 1.8-mm lingual to the MB I canal.
Question 13
The primary maxillary 1st molar most closely resembles which permanent tooth?
A
Mandibular 1st molar
B
Mandibular 2nd molar
C
Maxillary 1st premolar
D
Maxillary 1st molar
E
Maxillary 2nd molar
Question 13 Explanation: 
The correct answer is C. Although they can resemble each other, there are enough differences that you will not confuse them. Even though the primary tooth has 4 cusps, the DB and DL cusps are inconspicuous, making the larger MB and ML cusps look like maxillary premolar cusps. The grooves form an “H” pattern, which is somewhat similar to a maxillary premolar. However, a distinct notch can be seen separating the large MB cusp from the diminutive DB cusp when viewed from the buccal. Answer A is incorrect. The primary mandibular 2nd molar most closely resembles the adult mandibular 1st molar. Answer B is incorrect. No primary tooth resembles the permanent mandibular 2nd molar. Answer D is incorrect. The primary maxillary 2nd molar most closely resembles the adult maxillary 1st molar. Answer E is incorrect. No primary tooth resembles the permanent maxillary 2nd molar.
Question 14
On a maxillary molar the palatal root is the longest of the three roots. Among all maxillary teeth, the palatal root of the maxillary 1st molar is the 3rd longest root.
A
Both statements are true.
B
Both statements are false.
C
The first statement is true; the second is false.
D
The first statement is false; the second is true.
Question 14 Explanation: 
The correct answer is A. The palatal root is the longest of the three roots in a maxillary molar, but 3rd longest among roots of maxillary teeth, after the maxillary canine and 2nd premolar roots.
Question 15
Molar crowns typically taper from buccal to lingual when viewed from the occlusal. Which tooth, as an exception, is most likely to taper from lingual to buccal?
A
Mandibular 1st molar
B
Mandibular 2nd molar
C
Maxillary 1st molar
D
Maxillary 2nd molar
Question 15 Explanation: 
The correct answer is C. Maxillary 1st molars can present with a wide, prominent DL cusp that results in a wider lingual half than buccal half. Keep in mind, though, that all molar crowns in general will taper from buccal to lingual, even maxillary 1st molars. It’s only those maxillary 1st molars with large distolingual cusps that serve as an exception to this rule. Answer A is incorrect. With three buccal cusps and two lingual cusps, the mandibular 1st molar clearly tapers to the lingual. Answer B is incorrect. Although this tooth exhibits less crown taper from buccal to lingual than the mandibular 1st molar, the lingual side is still narrower. Answer D is incorrect. Compared to maxillary 1st molars, 2nd molars taper more from the buccal to the lingual due to their smaller distolingual cusp.
Question 16
The maxillary buccal and mandibular lingual cusps function as supporting cusps in which of the following occlusal schemes?
A
Ideal intercuspal relationship
B
Nonworking side movement
C
Working-side movement
D
Posterior crossbite
Question 16 Explanation: 
The correct answer is D. In posterior crossbite situations, the supporting and guiding cusps are reversed. That is, the maxillary buccal and mandibular lingual cusps would be supporting, while the maxillary lingual and mandibular buccal cusps would function as guiding (nonsupporting) cusps. Answers A, B, and C are incorrect. In both working and nonworking movements of an ideal intercuspal relationship, the supporting cusps are the maxillary lingual cusps and the mandibular buccal cusps.
Question 17
The crowns of all primary teeth begin to calcify at what time?
A
2-4 months in utero
B
4-6 months in utero
C
6-8 months in utero
D
At birth
E
2-4 months postpartum
Question 17 Explanation: 
The correct answer is B. The incisors begin to calcify around 41/2 months, the canine and 1st molar around 5 months, and the 2nd molar around 6 months in utero. Answer A is incorrect. Although tooth development starts at about 6 weeks in utero, calcification has not yet started by 16 weeks. Answer C is incorrect. At 6-8 months in utero, all of the primary teeth are in a stage of calcification, but none of the permanent teeth have begun to calcify. Answer D is incorrect. The 1st permanent teeth start to calcify at birth. Answer E is incorrect. By 16 weeks postpartum, all of the primary central and lateral incisors have completed calcification, but none have erupted.
Question 18
In total, how many grooves can be found on the buccal and lingual surfaces of both mandibular 1st and 2nd molars?
A
2
B
3
C
4
D
5
E
6
Question 18 Explanation: 
The correct answer is D. The mandibular 1st molar has 3 grooves: buccal, distobuccal, and lingual. The 2nd molar has 2 grooves: buccal and lingual.
Question 19
Which tooth is likely to have root depressions on both the mesial and distal root surfaces?
A
Maxillary central incisor
B
Maxillary lateral incisor
C
Maxillary 2nd premolar
D
Mandibular 2nd premolar
Question 19 Explanation: 
The correct answer is C. Typically the maxillary 2nd premolar has only one root, and the shallow mesial developmental groove that exists on the root does not extend onto the crown, as it does on the maxillary 1st premolar. The root depression on the distal is often deeper than on the mesial. Answer A is incorrect. The cross-section of the root at the cervix of the maxillary central incisor is somewhat triangular in shape and there are no prominent root depressions. The distal root surface is convex; and at the very most, the mesial surface may be flattened or have a very slight longitudinal depression. Answer B is incorrect. A shallow longitudinal root depression is often found in the middle of the mesial root surface on a maxillary lateral, but not on the distal. Answer D is incorrect. Longitudinal depressions are not common on the mesial root surface, but are frequent on the distal surface. In contrast, the mandibular 1st premolar has root depressions present on both sides, deeper on the distal. Sometimes these depressions may be quite deep and end in a buccolingual apical bifurcation.
Question 20
In an ideal occlusion, the _____ cusp of the mandibular _____ contacts the central fossa of the maxillary 1st molar.
A
Buccal; 2nd premolar
B
Mesiobuccal; 1st molar
C
Distobuccal; 1st molar
D
Distal; 1st molar
E
Distobuccal; 2nd molar
Question 20 Explanation: 
The correct answer is C. Only the DB cusps of mandibular molars and ML cusps of maxillary molars reside in their counterpart’s central fossa in ideal intercuspation. The remaining supporting cusps reside in the mesial marginal ridge areas of their counterparts. Answer A is incorrect. The buccal cusp of the 2nd premolar resides in the mesial triangular fossa of the maxillary 2nd premolar. Answer B is incorrect. The MB cusp contacts the mesial marginal ridge of the maxillary 1st molar and the distal marginal ridge of the 2nd premolar. Answer D is incorrect. The DB cusp of the mandibular 1st molar resides in the central fossa of the maxillary 1st molar; the distal cusp of the mandibular 1st molar opposes the distal fossa of the maxillary 1st molar. Answer E is incorrect. The DB cusp contacts the central fossa of the maxillary 2nd (not the 1st) molar.
Question 21
The greatest contour of the cervical line (CEJ) can be found on the
A
mesial aspect of anterior teeth.
B
mesial aspect of posterior teeth.
C
distal aspect of anterior teeth.
D
distal aspect of posterior teeth.
Question 21 Explanation: 
The correct answer is A. Generally, teeth have a greater proximal cervical line curvature mesially than distally. The curvature is greatest on the incisors and decreases toward the last molar, in which there may be no curvature at all. Answer B is incorrect. The mesial and distal proximal cervical line contours of the anterior teeth have more curvature than on posterior teeth. Answer C is incorrect. The mesial surface generally has a greater curvature than the distal. Answer D is incorrect. The least amount of curvature (if any) can be expected on the distal aspects of posterior teeth.
Question 22
Which cusp is the longest and largest on a maxillary 1st molar?
A
Mesiolingual
B
Distolingual
C
Mesiobuccal
D
Distal
E
Distobuccal
Question 22 Explanation: 
The correct answer is A. Maxillary 1st molar: ML > MB > DB > DL > cusp of Carabelli. Answers B, C, and E are incorrect. See above. Answer D is incorrect. No distal cusp exists on this tooth. Instead, a distal cusp is found on the mandibular 1st molar.
Question 23
Which of the following teeth is most likely to be congenitally absent?
A
Maxillary lateral incisor
B
Maxillary canine
C
Mandibular canine
D
Mandibular 1st premolar
E
Mandibular 2nd premolar
Question 23 Explanation: 
The correct answer is A. The most frequently congenitally missing teeth: 3rd molars > Maxillary laterals > Mandibular 2nd premolars.
Question 24
A triangular outline form is present on which of the following teeth when viewed from the proximal aspect?
A
Mandibular 1st premolar
B
Maxillary 1st molar
C
Mandibular central incisor
D
Mandibular 1st molar
Question 24 Explanation: 
The correct answer is C. When viewed from the mesial or distal aspects, all anterior teeth (centrals, laterals, and canines) have a triangular or wedge-shaped outline. Answer A is incorrect. When viewed from the proximal aspect, all mandibular posterior teeth (premolars and molars) have a rhomboidal shape because the crowns tilt lingually from the cervix. Answer B is incorrect. All maxillary posterior have a trapezoidal crown outline when viewed from the mesial or distal, with longest uneven side at the base of the crown. Unlike mandibular posterior crowns which tilt lingually from the cervix, maxillary crowns are aligned directly over the roots from the proximal view. Answer D is incorrect. The outline form of this tooth from the proximal aspect is rhomboidal, as it is with all mandibular posterior teeth.
Question 25
The bud stage of tooth development starts at about
A
6 weeks in utero.
B
8 weeks in utero.
C
9 weeks in utero.
D
11 weeks in utero.
E
18 weeks in utero.
Question 25 Explanation: 
The correct answer is B. During the bud stage, epithelial cells from the primary epithelial band proliferate into the underlying ectomesenchyme. Answer A is incorrect. The primary epithelial band forms at about week 6 in utero. Answer C in incorrect. The cap stage, in which the bud splits into a caplike structure, and where the enamel organ, dental papilla, and dental follicle begin to take shape, starts at about week 9 in utero. Answer D is incorrect. The bell stage of tooth development, in which cells differentiate in preparation for the formation of hard tissues, starts at about week 11 in utero. Answer E is incorrect. At approximately 18 weeks in utero, the tooth enters the crown stage in which enamel and dentin are actively synthesized.
Question 26
The incisal edge or cusp tip of which tooth ideally lies in the facial embrasure between the mandibular canine and mandibular 1st premolar?
A
Maxillary lateral incisor
B
Maxillary canine
C
Maxillary 1st premolar
D
Maxillary 2nd premolar
Question 26 Explanation: 
The correct answer is B. In an ideal occlusion, the cusp tip of the maxillary canine sits between the mandibular canine and 1st premolar. Answer A is incorrect. The incisal edge of the maxillary lateral incisor opposes the mandibular lateral incisor and canine. Answer C is incorrect. The cusp tip of the maxillary 1st premolar resides between the mandibular 1st and 2nd premolars. Answer D is incorrect. The cusp tip of the maxillary 2nd premolar lies in the facial embrasure between the mandibular 2nd premolar and 1st molar.
Question 27
A 30-year-old patient presents with shallow, cup-shaped depressions on the cervicofacial surface of the maxillary anterior teeth. The posterior teeth also exhibit extensive loss of the occlusal surface, including numerous noncarious class VI lesions. Tooth No. 30 has an amalgam restoration that extends about 1 mm above the level of the tooth structure. Which of the following is the most likely cause of this wear?
A
Abfraction
B
Attrition
C
Erosion
D
Abrasion
Question 27 Explanation: 
The correct answer is C. Erosion is the loss of tooth structure from chemical means, such as acids. It typically affects smooth surfaces, including lingual and occlusal surfaces, resulting in cup-shaped defects. Erosion limited to the facial surfaces of the maxillary anterior teeth is often associated with dietary sources of acid (eg, sucking on lemons); whereas palatal erosion is often associated with regurgitation of gastric acids (eg, GERD or bulimia). The amalgam restoration extending above the remaining occlusal surface of No. 30 suggests that an erosive process is at play, rather than attrition. Answer A is incorrect. Abfraction is the loss of tooth structure resulting from abnormal occlusal stresses. As a tooth flexes under stress, enamel rods fracture just coronal to the CEJ, leading to V-shaped cervical-facial lesions. Answer B is incorrect. Attrition is wear caused by tooth-tooth contact. Large, flat, smooth, and shiny wear facets are the typical presentation. Answer D is incorrect. Abrasion is wear caused by abnormal mechanical means (often overzealous oral hygiene or other factitious habits). Toothbrush abrasion typically presents as a V-shaped notch in the cervical region, frequently in the canine-premolar area.
Question 28
After a difficult extraction of tooth No. 31, you notice that your patient’s jaw cannot close. You diagnose the problem as a right-side TMJ dislocation. What is the initial direction that you should redirect the mandible to treat the problem?
A
Push the ramus superiorly
B
Push the ramus posteriorly
C
Push the ramus downward
D
Slide the ramus mesially
E
Slide the ramus laterally
Question 28 Explanation: 
The correct answer is C. A TMJ dislocation occurs when the condyle translates anteriorly, in front of the articular eminence. To correct, you should apply firm downward pressure on the posterior mandible and ramus, with concomitant upward pressure on the chin. This motion, coupled with natural TMJ muscular guidance, will allow the condyle to move back over the articular eminence into its original position within the glenoid fossa. Reduction attempts should be made as soon as possible to prevent severe pain and/or muscle spasm.
Question 29
How many point angles are found on tooth No. 12?
A
1
B
2
C
3
D
4
E
5
Question 29 Explanation: 
The correct answer is D. Remember that a point angle is formed by the junction of 3 surfaces. All teeth have 4 point angles. In the example in question, tooth No. 11 is the maxillary left 1st premolar, which has mesiofacial- occlusal, disto-facial-occlusal, mesiolingual- occlusal, and disto-lingual-occlusal point angles. Answers A, B, C, and E are incorrect. See above.
Question 30
In an ideal occlusion, the mesiobuccal cusp of the permanent maxillary 2nd molar opposes which of the following?
A
The buccal groove of the mandibular 2nd molar
B
The distobuccal groove of the mandibular 1st molar
C
The mesiobuccal groove of the mandibular 2nd molar
D
The buccal embrasure between the mandibular 1st and 2nd molars
Question 30 Explanation: 
The correct answer is A. Just like an ideal 1st molar relationship, the MB cusp of the maxillary 2nd molar opposes the buccal groove of its counterpart, the mandibular 2nd molar. Answer B is incorrect. The DB cusp of the maxillary 2nd molar opposes this groove in ideal intercuspation. Answer C is incorrect. An MB groove does not exist on the mandibular 2nd molar which has only 2 buccal cusps and a single buccal groove (opposed by the MB cusp of the maxillary 2nd molar). Answer D is incorrect. This relationship could exist in a class II malocclusion in which the buccal groove of the mandibular 1st permanent molar is distal to the MB cusp of the maxillary 1st permanent molar. However, the question asks for the molar relationship in the ideal intercuspal position.
Question 31
Ordinarily, a 7-year-old child would have what teeth clinically visible in the mouth?
A
All 20 primary teeth and 4 permanent 1st molars
B
18 primary teeth and 2 permanent teeth
C
16 primary teeth and 8 permanent teeth
D
12 primary teeth and 12 permanent teeth
Question 31 Explanation: 
The correct answer is C. The 8 permanent teeth include 4 permanent central incisors and 4 permanent 1st molars. All of the primary teeth are present except the four primary central incisors (20 4 = 16), which exfoliated when the permanent central incisors erupted at approximately age 6-7. Answer A is incorrect. This is likely a 6-yearold child with permanent 1st molars that hasn’t yet exfoliated any primary central incisors. Answer B is incorrect. This is an unlikely scenario in which the permanent mandibular central incisors erupted prior to the permanent 1st molars, for example. Answer D is incorrect. This is an older child (about 8 years old) with permanent 1st molars (4), central incisors (4), lateral incisors (4), and primary canines (4) and molars (8). In a couple of years (ages 10-12), the child should expect the eruption of the permanent mandibular canine and permanent mandibular and maxillary premolars, followed by the permanent maxillary canine.
Question 32
At what age is a child expected to have 12 primary teeth and 12 permanent teeth?
A
6.5 years
B
7.5 years
C
8.5 years
D
10.5 years
E
12.5 years
Question 32 Explanation: 
The correct answer is C. Follow the eruption sequence of permanent teeth until you get to 12 permanent teeth: 4 first molars + 4 central incisors + 4 lateral incisors = 12 permanent teeth. Eight primary incisors were replaced by the 8 permanent incisors (20 −8 = 12 primary teeth remaining). The child described above is at the end of the early mixed dentition phase and is most likely 8.5 years old. Answer A is incorrect. At most, only 8 permanent teeth (4 first molars and 4 [upper and lower] central incisors) would be expected at this age. All primary teeth except the lower and upper central incisors would remain (20 −4 = 16 primary teeth). Answer B is incorrect. It is likely that the permanent maxillary lateral incisors would not have erupted by this age (usually around age 8-9). Answer D is incorrect. At the very least, one would expect the mandibular canine and/or the maxillary 1st premolar to have erupted at this age, yielding 14-16 permanent teeth and 8-10 primary teeth. Answer E is incorrect. By this age, no primary teeth should remain. The permanent 2nd molars likely would have erupted (at about age 11-13).
Question 33
All of the following are true of the articular disc EXCEPT
A
it is biconcave, with a central avascular intermediate zone.
B
it is composed of dense hyaline cartilage.
C
it consists of thick anterior and posterior bands.
D
fibers of the lateral pterygoid attach to its most anterior portion.
E
it divides the area between the glenoid fossa and the condyle into two compartments: superior and inferior.
Question 33 Explanation: 
The correct answer is B. Remember that the articular disc (meniscus) is composed of dense fibrocartilage, providing the most protection against compression and tension. Answers A and C are incorrect. The disc is elliptical and biconcave, consisting of thick anterior and posterior bands. The central intermediate zone is much thinner and completely avascular. Answer D is incorrect. The superior insertion areas of the lateral pterygoid muscle are the anterior portion of the articular disc and capsule. Its inferior insertion site is the anterior condylar neck. Answer E is incorrect. Because it is biconcave, the disc has two reciprocal articular surfaces: one between its superior aspect and the glenoid fossa and articular eminence; the other between the inferior aspect and the condyle. The spaces between these structures create superior and anterior compartments.
Question 34
Which of the following is the most reproducible mandibular position?
A
Centric occlusion
B
Functional occlusion
C
Postural position
D
Centric relation
Question 34 Explanation: 
The correct answer is D. Centric relation (CR) is the intercuspation of the teeth when the condyles are located in the most anterior and superior position of the glenoid fossae. Because the condylar position of CR is anatomically defined, it is relatively easy for dentists to consistently position the mandible there when changing a patient’s VDO. Answers A and B are incorrect. These mandibular positions may present challenges in reproducibility because occlusal interferences or tooth-to-tooth contacts may shift the mandible slightly in another direction. Answer C is incorrect. Any variation is muscle contractility can alter the postural position dimension.
Question 35
How many transverse ridges exist on a maxillary molar?
A
0
B
1
C
2
D
3
E
4
Question 35 Explanation: 
The correct answer is B. Each maxillary molar has one transverse ridge, which runs between the MB and ML cusps. Answers A, C, D, and E are incorrect. See above.
Question 36
Which of the following is the best description of where primate spaces are located?
A
Between all the primary anterior teeth
B
Between the canine and 1st premolar in the mandible
C
Distal to the primary canines in the maxilla
D
Between the canine and 1st and 2nd primary molars
E
Distal to primary canines in the mandible
Question 36 Explanation: 
The correct answer is E. Primate spaces are located mesial to the primary canines in the maxilla (between the lateral incisors and canines), and distal to primary canines in the mandible (between the primary canines and primary 1st molars). The primate spaces (so named because most subhuman primates have these spaces throughout life) are normally present from the time the primary teeth erupt, and close with the eruption of the permanent 1st molars (early mesial shift). Answer A is incorrect. Spacing is normal throughout the anterior part of the primary dentition, but is most notable in the primate spaces mentioned above. Answer B is incorrect. Careful! Primate spaces are found only in the primary dentition (premolars are only found in the permanent dentition). Answer C is incorrect. The primate space is mesial to the primary canines in the maxilla. Answer D is incorrect. This answer choice most closely resembles the definition of leeway space, which is the difference between the sum of the mesiodistal widths of the primary canine, 1st and 2nd molars, and the succeeding permanent canine, 1st and 2nd premolars.
Question 37
How many cusp tips can be seen on a mandibular 1st molar when viewed directly from the buccal?
A
2
B
3
C
4
D
5
Question 37 Explanation: 
The correct answer is D. All 5 cusp tips can be seen from the buccal. The somewhat staggered arrangement of the 3 buccal and 2 lingual cusps allow the tips of the lingual cusps to peak above the buccal and distobuccal grooves. Answers A, B, and C are incorrect. Minimally, the 3 buccal cusps would be visible.
Question 38
Maxillary 1st molars are wider mesiodistally on the buccal than the lingual. Mandibular 1st molars are wider on the lingual than buccal.
A
Both statements are true.
B
Both statements are false.
C
The first statement is true; the second is false.
D
The first statement is false; the second is true.
Question 38 Explanation: 
The correct answer is B. Maxillary 1st molars are typically rhomboidal in shape when viewed from the occlusal, and often a prominent distolingual cusp exists such as the lingual portion of the occlusal surface is in fact wider than the buccal portion. Mandibular 1st molars have a somewhat trapezoidal occlusal outline, with the shortest side (mesiodistally) on the lingual. In general, maxillary 1st molars are wider on the lingual, and mandibular molars are wider on the buccal. Answers A, C, and D are incorrect. See above.
Question 39
As a dentist, how many determinants of occlusion can you directly control?
A
0
B
1
C
2
D
3
E
4
Question 39 Explanation: 
The correct answer is B. Remember the four determinants of occlusion: the right and left TMJs, the neuromusculature, and the teeth. As a dentist, the only one that can be directly controlled is the teeth (by restorations, orthodontics, and equilibration).
Question 40
In which age range would one normally expect to see all 20 primary teeth present, but no permanent teeth yet visible?
A
0.5-1 years
B
1-1.5 years
C
1-2 years
D
2.5-5.5 years
E
3.5-6.5 years
Question 40 Explanation: 
The correct answer is D. The 1st primary teeth to erupt are the mandibular central incisors at about 6 months of age; the last are the 2nd molars at about age 2. The 1st permanent teeth to erupt are the 1st molars around age 6. Therefore, the answer to this question must be between ages 2 and 6 years. Answer A is incorrect. By age 1, all of the primary 1st molars may not have erupted. Answer B is incorrect. By age 1,5, all of the primary canines may not have erupted. Answer C is incorrect. By age 2, all of the primary 2nd molars may not have erupted.Answer E is incorrect. By age 6,5, the permanent 1st molars have most likely erupted.
Question 41
When viewed from the occlusal, the proximal contact between mandibular 1st and 2nd molars is located
A
slightly lingual to the middle 3rd.
B
in the middle 3rd.
C
slightly buccal to the middle 3rd.
D
in the cervical 3rd.
Question 41 Explanation: 
The correct answer is C. All posterior teeth, when viewed from the occlusal, have proximal contacts that are slightly buccal to the middle 3rd. Answer A is incorrect. No tooth in an ideal dentition has a proximal contact that is lingual to the middle 3rd when viewed from the occlusal. Answer B is incorrect. If the question asked you to evaluate the proximal contact from the buccal or lingual views, then this answer would have been correct. Answer D is incorrect. The occlusocervical position of a proximal contact cannot be evaluated when viewing a tooth from the occlusal. Rather, one would have to look from the buccal or lingual views. Nonetheless, when viewed from the buccal or lingual, the contact described in the question above would be in the middle 3rd (as it is for all posterior teeth).
Question 42
Which cusp on permanent maxillary molars generally gets progressively smaller from the 1st to the 3rd molar?
A
Mesiolingual
B
Distolingual
C
Mesiobuccal
D
Distobuccal
Question 42 Explanation: 
The correct answer is B. This is one of the most obvious characteristics that distinguishes 1st, 2nd, and 3rd molars from each other. In fact, the smaller DL cusp of the maxillary 2nd molar, compared to the wider, prominent DL cusp of 1st molars, gives the appearance of more taper (narrowing) from buccal to lingual on 2nd molars.
Question 43
Which one of the following normally singlerooted teeth is most likely to have a bifurcated root?
A
Maxillary central incisor
B
Maxillary lateral incisor
C
Maxillary canine
D
Mandibular canine
E
Maxillary 1st premolar
Question 43 Explanation: 
The correct answer is D. Longitudinal root depressions exist on both sides of the mandibular canine root, and when deep enough, clearly bifurcate the root labiolingually. Answers A, B, and C are incorrect. Maxillary central incisors, laterals incisors, and canines almost always have one canal and are invariably single rooted. Answer E is incorrect. Careful! This tooth is not normally single rooted; rather, it typically has two roots and a bifurcation.
Question 44
All of the following are true regarding primary molars in comparison to permanent molars EXCEPT
A
primary teeth have roots that are longer, more slender, and highly divergent.
B
primary molars have a much more pronounced buccal cervical ridge.
C
deciduous enamel is thinner, and has a more consistent depth throughout the crown.
D
primary molars have shorter root trunks.
E
primary molars have well-defined occlusal anatomy with pronounced ridges and deep fossae.
Question 44 Explanation: 
The correct answer is E. Primary molars have a shallow occlusal anatomy relative to their permanent counterparts. Cusps are short, ridges are not as pronounced, and the fossae are not as deep. Answer A is incorrect. The roots of primary molars are very divergent, which allows for the eruption of the permanent premolars. They are also much less curved, and there is little to no root trunk. Answer B is incorrect. The mesial cervical ridge of primary molars is very prominent, and the cervical lines course more apically on the mesial half due to this prominence. Recall that all primary anterior teeth also have prominent cervical ridges. Answer C is incorrect. Enamel is approximately 1 mm thick and of relatively uniform thickness in primary molars as opposed to that of permanent molars, which is 2.5 mm thick on the occlusal surface. Answer D is incorrect. Primary molars have much shorter root trunks than their permanent counterparts. This allows their roots to diverge at a more coronal level, accommodating the size of the underlying permanent tooth.
Question 45
A working interference is a premature contact of the posterior teeth on the same side as the direction of the mandibular movement. A protrusive interference is a premature contact between the mesial aspects of maxillary posterior teeth and the distal aspects of mandibular posterior teeth.
A
Both statements are true.
B
Both statements are false.
C
The first statement is true; the second statement is false.
D
The first statement is false; the second statement is true.
Question 45 Explanation: 
The correct answer is C. Working interferences are premature contacts of posterior teeth on the working side during lateral excursive movement. Recall that nonworking interferences occur on the nonworking side. Protrusive interferences occur between the distal aspects of maxillary posterior teeth and mesial aspects of mandibular posterior teeth.
Question 46
The primary teeth erupt in which of the following sequences?
A
ABCDE
B
BACDE
C
ABDCE
D
ACBDE
Question 46 Explanation: 
The correct answer is C. Central incisors (A) erupt around 6 months of age, lateral incisors (B) at 9 months, primary 1st molars (D) at 12 months, primary canines (C) at 18 months, and primary 2nd molars (E) at 24 months. Mandibular primary teeth typically erupt before the maxillary primary teeth with the exception of the primary lateral incisors. Remember: ABDCE at 6,9,12,18,24.
Question 47
All of the following are true of the functional outer aspect (FOA) in ideal occlusions EXCEPT
A
it is located on the outer aspect of supporting cusps.
B
it may contact the inner incline of supporting cusps.
C
in the mandibular arch, it is a continuous ribbon which runs from the buccal of one 3rd molar to the other, covering the incisal edges of the lower anterior teeth.
D
it does not exist on maxillary anterior teeth.
E
it is no more than 1 mm wide.
Question 47 Explanation: 
The correct answer is B. The FOA has the potential to make contact with the inner incline of guiding cusps. Answers A, C, D, and E are incorrect. The lingual inclines of the maxillary anterior teeth are guiding inclines.
Question 48
In an ideal occlusion, the lingual cusp of the permanent maxillary 1st premolar occludes where?
A
Mesial triangular fossa of the mandibular 1st premolar
B
Distal triangular fossa of the mandibular 1st premolar
C
Distal marginal ridge of the mandibular 1st premolar
D
Mesial marginal ridge of the mandibular 2nd premolar
E
Mesial triangular fossa of the mandibular 2nd premolar
Question 48 Explanation: 
The correct answer is B. The lingual cusps of the maxillary premolars tilt mesially and, Answers: 12-22 211 therefore, will articulate with the distal triangular fossae of their mandibular premolar counterparts. Recall that mandibular teeth are situated mesially and lingually to their counterparts in the maxilla. Therefore, as a general rule, a maxillary tooth will articulate with its mandibular counterpart and the tooth distal to it; likewise, a mandibular tooth will articulate with its maxillary counterpart and the tooth mesial to it. Accordingly, the maxillary 1st premolar will occlude with the mandibular 1st premolar (counterpart) and the mandibular 2nd premolar (the tooth distal to the counterpart). Answers A, C, D, and E are incorrect. Nothing rests in these fossae in ideal intercuspation.
Question 49
Which of the following is the term for a supernumerary tooth in the maxillary anterior region?
A
Mesiodens
B
Distodens
C
Dens-in-dente
D
Paramolar
E
Talon cusp
Question 49 Explanation: 
The correct answer is A. A mesiodens is a small supernumerary tooth that typically forms between maxillary central incisors. It has a cone-shaped crown with a short root, and may remain unerupted. Answer B is incorrect. A supernumerary 4th molar is often called a distodens, or distomolar. Answer C is incorrect. Dens-in-dente (toothwithin- a-tooth) is a deep surface invagination of the crown or root that is lined by enamel. In order of decreasing frequency, the permanent teeth most commonly affected are the following: Lateral incisors > Central incisors > Premolars > Canines > Molars. Answer D is incorrect. A supernumerary tooth situated lingually or buccally to a molar tooth is termed a paramolar. Answer E is incorrect. A talon cusp (dens evaginatus of an anterior tooth) is a welldelineated additional cusp (not an additional tooth) that is located on the surface of an anterior tooth. These cusps occur most commonly on maxillary lateral and central incisors, projecting from the lingual surface, and forming a three-pronged pattern resembling an eagle’s talon.
Question 50
The primary sensory innervation of the TMJ arises from what cranial nerve?
A
CN V
B
CN VII
C
CN VIII
D
CN IX
E
CN XI
Question 50 Explanation: 
The correct answer is A. The auriculotemporal nerve conducts the primary innervation to the TMJ. It transmits pain within the capsule, and also provides parasympathetics to the parotid gland. The auriculotemporal nerve is a branch of CN V3. Two other nerves also supply sensory fibers to the TMJ: the nerve to the masseter and the posterior deep temporal nerve, both of which are innervated by CN V3. Remember that the TMJ only receives sensory innervation, not motor.
Question 51
Primary teeth are more constricted at the cervical 3rd than their permanent counterparts. Pulp chambers are comparatively smaller in primary teeth.
A
Both statements are true.
B
Both statements are false.
C
The first statement is true; the second is false.
D
The first statement is false; the second is true.
Question 51 Explanation: 
The correct answer is C. Primary teeth are more constricted at the cervical 3rd than permanent teeth. Pulp chambers are comparatively larger in primary teeth, especially in the mesial horns. Therefore, great care must be taken when preparing class I and class II cavity preps, especially on the mesial half.
Question 52
In an Angle class III malocclusion, the cusp tip of the maxillary canine is located
A
distal to the buccal embrasure created by the mandibular canine and 1st premolar.
B
centered in the embrasure created by the mandibular canine and 1st premolar.
C
mesial to the buccal embrasure created by the mandibular canine and 1st premolar.
D
none of the above.
Question 52 Explanation: 
The correct answer is A. A class III canine relationship occurs when the maxillary canine occludes distal to the distal cusp ridge of the mandibular canine. Answer B is incorrect. This defines an Angle class I occlusion. Answer C is incorrect. This defines an Angle class II occlusion. Answer D is incorrect. See above.
Question 53
Which of the following is correct?
A
VDR = VDO – FS
B
VDO = CO – FS
C
VDR = VDO + FS
D
VDO = CO + CR
E
VDR = VDO + CO
Question 53 Explanation: 
The correct answer is C. The vertical dimension of rest (VDR) is the vertical dimension of the face with the mandible in the postural (rest) position. The vertical dimension of occlusion (VDO) is the vertical dimension of the face when the teeth contact in centric occlusion (CO). For a dentate patient, then, VDR > VDO. The difference between the two is the freeway space (FS), the distance the teeth are separated when the mandible is in the postural position (typically 1-3 mm). Thus, VDR = VDO + FS. Answers A, B, D, and E are incorrect. Another way to state it is VDO = VDR – FS.
Question 54
Which muscle inserts in the articular disc and condylar neck?
A
Masseter
B
Medial pterygoid
C
Lateral pterygoid
D
Temporalis
Question 54 Explanation: 
The correct answer is C. The superior fibers of the lateral pterygoid originate at the roof of the infratemporal fossa, and insert in the articular capsule and disc. Its inferior fibers originate on the lateral side of the lateral pterygoid plate, and insert on the anterior condylar neck. Functions of the lateral pterygoid muscle include mandibular protrusion, depression, and contralateral excursion. Answer A is incorrect. The superior fibers of the lateral pterygoid originate at the roof of the infratemporal fossa, and insert in the articular capsule and disc. Its inferior fibers originate on the lateral side of the lateral pterygoid plate, and insert on the anterior condylar neck. Functions of the lateral pterygoid muscle include mandibular protrusion, depression, and contralateral excursion. Answer B is incorrect. The medial pterygoid originates at the medial side of the lateral pterygoid plate, and inserts on the medial side of the mandibular angle. Functions of the medial pterygoid muscle include mandibular elevation, protrusion, and contralateral excursion. Answer D is incorrect. The temporalis originates at the lower temporal line, temporal fossa, and temporal fascia, and inserts on the medial coronoid process and anterior ramus. Functions of the temporalis muscle include mandibular elevation, retrusion, and ipsilateral excursion.
Question 55
The crown of the primary maxillary central incisor
A
has a longer length incisocervically and is smaller mesiodistally than the permanent maxillary central incisor.
B
has a longer length incisocervically and is larger mesiodistally than the permanent maxillary central incisor.
C
has a shorter length incisocervically and is smaller mesiodistally than the permanent maxillary central incisor.
D
has a shorter length incisocervically and is larger mesiodistally than the permanent maxillary central incisor.
Question 55 Explanation: 
The correct answer is D. In general, the crowns of primary anterior teeth are wider mesiodistally compared to their incisocervical height. Hence, primary teeth appear “short and squat” relative to their permanent counterparts.
Question 56
Which of the following teeth has the roundest pulp chamber (at the level of the CEJ)?
A
Maxillary central incisor
B
Maxillary lateral incisor
C
Maxillary canine
D
Mandibular central incisor
E
Mandibular lateral incisor
Question 56 Explanation: 
The correct answer is A. The maxillary central incisor has the roundest pulp chamber (although it is not perfectly round). It is slightly egg shaped with the widest portion buccally. Answer B is incorrect. The maxillary lateral incisor has an egg-shaped pulp chamber with the widest portion buccally. Answer C is incorrect. The maxillary canine has an oval-shaped pulp chamber, flattened mesiodistally (hourglass shaped). Answer D is incorrect. The mandibular central incisor has an oval-shaped pulp chamber, flattened mesiodistally (hourglass shaped). Answer E is incorrect. The mandibular lateral incisor has an oval-shaped pulp chamber, flattened mesiodistally (hourglass shaped).
Question 57
Which tooth is most likely to have two canals in a single root?
A
Mandibular lateral incisor
B
Mandibular canine
C
Mandibular 2nd premolar
D
Maxillary central incisor
E
Maxillary canine
Question 57 Explanation: 
The correct answer is A. Mandibular lateral incisors, which are single rooted, frequently have two canals (up to 40%). Answer B is incorrect. The mandibular canine is typically single rooted with one canal. Although a two-rooted (buccal and lingual), two-canal variant exists (4%-20%), the question asks for the tooth that has 2 canals within a single root. Answer C is incorrect. The mandibular 2nd premolar will have a single canal within a single root 97.5% of the time. Answer D is incorrect. Invariably, the maxillary central incisor has 1 root and 1 canal. Answer E is incorrect. Like the maxillary central incisor, expect a single root with 1 canal in the maxillary canine.
Question 58
Which of the following muscles is/are most active in maintaining centric occlusion? I. Masseter II. Medial pterygoid III. Lateral pterygoid IV. Temporalis
A
I only
B
I and II
C
I and IV
D
II and III
E
I, II, and IV
Question 58 Explanation: 
The correct answer is E. When the mandible is at rest, the teeth generally do not contact each other. In order for the teeth to touch in centric occlusion, muscles that elevate the mandible must contract. The major elevators of the mandible are the masseter, medial pterygoid, and temporalis muscles.
Question 59
The 2nd largest cusp on a mandibular 2nd molar is the
A
mesiolingual.
B
distolingual.
C
mesiobuccal.
D
distobuccal.
E
distal.
Question 59 Explanation: 
The correct answer is B. For a mandibular 2nd molar, the order from largest to smallest cusps is ML > DL > MB > DB. The same is true for the four major cusps of the mandibular 1st molar; the minor 5th distal cusp is the smallest of all (ML > DL > MB > DB > D).
Question 60
Of the mandibular premolars, the 1st premolar has the longest and sharpest buccal cusp. Among maxillary premolars, the 2nd premolar has the longest and sharpest buccal cusp.
A
Both statements are true.
B
Both statements are false.
C
The first statement is true; the second is false.
D
The first statement is false; the second is true.
Question 60 Explanation: 
The correct answer is C. The 1st premolars in both arches have the longest and sharpest buccal cusps relative to the 2nd premolars. Remember that all premolars except the mandibular 1st premolar have a longer buccal cusp than lingual cusp.
Question 61
Mandibular molars usually have how many roots?
A
1
B
2
C
3
D
4
E
5
Question 61 Explanation: 
The correct answer is B. Mandibular molars have a larger mesial root and a smaller distal root. Answer A is incorrect. All anterior teeth, as well as mandibular premolars and maxillary 2nd premolars, are typically single rooted. Answer C is incorrect. Maxillary molars have three roots. Answer D is incorrect. No tooth typically has four roots. Answer E in incorrect. Come on—are you kidding me!
Question 62
A cervical ridge is found on the facial surface of how many primary teeth?
A
4
B
8
C
12
D
16
E
20
Question 62 Explanation: 
The correct answer is E. The cervical ridge runs mesiodistally in the cervical 3rd of the buccal surface of all primary teeth (as well as all permanent molars). The cervical ridge is prominent in primary anterior teeth, and is best seen when viewed from the proximal. The cervical ridge of primary molars is most prominent on the mesial-facial aspect.
Question 63
How many premolars are found in each quadrant of a normal deciduous dentition?
A
0
B
1
C
2
D
3
E
4
Question 63 Explanation: 
The correct answer is A. There are no premolars in the deciduous (primary) dentition. Premolars are only found in the adult permanent dentition, and succeed the primary molars. Answer B is incorrect. In the permanent (not the primary) dentition, there are 2 premolars per quadrant, 4 premolars per arch, for a total of 8 premolars in both arches (maxilla and mandible).
Question 64
Which cusp has two triangular ridges on the maxillary 1st molar?
A
Mesiolingual
B
Distolingual
C
Cusp of Carabelli
D
Mesiobuccal
E
Distobuccal
Question 64 Explanation: 
The correct answer is A. The large ML cusp has one triangular ridge that meets the MB triangular ridge to form a transverse ridge. Its 2nd triangular ridge extends toward the DB cusp and forms part of the oblique ridge. Answer B is incorrect. The DL cusp has only one, inconspicuous triangular ridge that abuts with the oblique ridge at a roughly perpendicular angle. Answer C is incorrect. The cusp of Carabelli does not have a triangular ridge. Answer D is incorrect. The MB cusp has only one triangular ridge (forming a transverse ridge with ML cusp). Answer E is incorrect. The DB cusp has only one triangular ridge, which joins with one from the ML cusp to form part of the oblique ridge.
Question 65
Which succedaneous tooth erupts beneath tooth J?
A
1
B
10
C
13
D
20
E
21
Question 65 Explanation: 
The correct answer is C. Tooth J is the primary left maxillary 2nd molar, which is replaced by the maxillary left 2nd premolar, No. 13. Answer A is incorrect. The maxillary right permanent 3rd molar is not a succedaneous tooth. Answer B is incorrect. Tooth No. 10, the maxillary left lateral incisor, replaces the primary left lateral incisor, G. Answer D is incorrect. Tooth No. 20, the mandibular left 2nd premolar, replaces the primary left mandibular 2nd molar, K. Answer E is incorrect. Tooth No. 21, the mandibular left 1st premolar, replaces the primary left mandibular 1st molar, L.
Question 66
The mandibular condyle and its associated disc slide against which surface in normal mandibular opening?
A
Posterior one-fourth of mandibular fossa
B
Anterior portion of articular eminence
C
Posterior portion of articular eminence
D
Articular (glenoid) fossa
Question 66 Explanation: 
The correct answer is C. The articular eminence is located just anterior and inferior to the articular (glenoid) fossa. The functional portion is on the posterior inferior aspect of articular eminence where the mandibular condyle (and intervening articular disc) rubs against during mandibular movement. 214 Answer A is incorrect. This portion of mandibular fossa does not articulate with any part of the condyle or disc. Answer B is incorrect. Only when the condyle and disc slip past the articular eminence, can the anterior aspect of the articular eminence be engaged. However, this is a pathologic, painful condition resulting in an open-locked jaw. Answer D is incorrect. The anterior threefourths of the mandibular fossa, also called the articular (glenoid) fossa, is considered nonfunctioning because, when the teeth are in tight centric occlusion, there is no contact among the condylar head, disc, and this part of the temporal bone.
Question 67
Which cusp is most likely to be absent on a maxillary 2nd molar?
A
Mesiolingual
B
Distolingual
C
Cusp of Carabelli
D
Mesiobuccal
E
Distobuccal
Question 67 Explanation: 
The correct answer is C. Maxillary 2nd molars rarely have a cusp of Carabelli. It is also noteworthy to mention that the DL cusp is absent in more than one-third of these teeth!
Question 68
Which tooth is most likely to have a cervical enamel projection?
A
Maxillary central incisor
B
Maxillary canine
C
Mandibular 1st premolar
D
Mandibular 2nd premolar
E
Mandibular 2nd molar
Question 68 Explanation: 
The correct answer is E. Cervical enamel projections (CEPs) are apical extensions of enamel located at furcation entrances on molar teeth (28% mandibular, 17% maxillary). CEP size can vary greatly from small projections at the CEJ to larger extensions into the furcation proper. They are most commonly found on buccal surfaces. In decreasing order of incidence: Mandibular 2nd molars > Maxillary 2nd molars > Mandibular 1st molars > Maxillary 1st molars. Like enamel pearls, CEPs can predispose a tooth to periodontal attachment loss since connective tissue does not attach to the enamel (where cementum would normally be located).
Question 69
How many teeth in the primary dentition normally have a cingulum?
A
6
B
8
C
10
D
12
E
14
Question 69 Explanation: 
The correct answer is D. All anterior teeth (incisors and canines) in both the permanent and primary dentitions have a cingulum, or bulge, on the cervical 3rd of the lingual surface. 4 central incisors + 4 lateral incisors + 4 canines = 12 teeth.
Question 70
Which tooth has the most prominent lingual ridge with mesial and distal fossae?
A
Maxillary central incisor
B
Mandibular lateral incisor
C
Maxillary lateral incisor
D
Mandibular canine
E
Maxillary canine
Question 70 Explanation: 
The correct answer is E. Both maxillary and mandibular canines have characteristic labial and lingual ridges, but those on maxillary canines are more prominent. The vertical lingual ridge extends to the cingulum of the canines, creating mesial and distal fossae on either side of the lingual ridge. Answers A, B, and C are incorrect. None of these teeth have labial or lingual ridges. Instead, these teeth have a single concave lingual fossa bounded by mesial and distal marginal ridges, and a convex cingulum on the lingual surface. Answer D is incorrect. The question asks for the tooth with the most prominent lingual ridge. The lingual ridge on the maxillary canine is more prominent.
Question 71
Which of the following has both mesial and distal contact areas located at the same height in the incisal 3rd?
A
Maxillary central incisor
B
Maxillary lateral incisor
C
Mandibular central incisor
D
Mandibular lateral incisor
E
Mandibular canine
Question 71 Explanation: 
The correct answer is C. In general, mesial contact areas of anterior teeth are located in the incisal 3rd, and distal contact areas are positioned more cervically. The only exception is the mandibular central incisors. Due to the highly symmetric nature of the mandibular centrals about their root-axis line, both mesial and distal contacts exist at the same level (the incisal 3rd). Answer A is incorrect. Although the mesial contact is in the incisal 3rd, the distal contact is located at the junction of the incisal and middle 3rds. Answer B is incorrect. Both maxillary lateral incisor and maxillary canine have mesial contact areas at the junction of the incisal and middle 3rds, and distal contacts located in the middle 3rd. Answer D is incorrect. Although both mesial and distal contacts are located in the incisal 3rd of the mandibular lateral incisor, the distal contact is located slightly more cervically than the mesial (ie, they are not at the same height occlusocervically). Answer E is incorrect. With a mesial contact in the incisal 3rd and a distal contact area in the middle 3rd, the mandibular canine has the greatest difference in height between its proximal contacts than any other tooth.
Question 72
Which of the following cusp tips passes through the buccal groove of mandibular 1st molar during a working-side movement?
A
MB of maxillary 1st molar
B
DB of maxillary 1st molar
C
ML of maxillary 1st molar
D
DL of maxillary 1st molar
E
Buccal of maxillary 2nd premolar
Question 72 Explanation: 
The correct answer is A. Recall that, in an ideal occlusion, the MB cusp of the maxillary 1st molar opposes the buccal groove of the mandibular 1st molar. As the mandible moves to laterally to the working side, the MB cusp tip slides through the buccal groove. Answers B, C, D, and E are incorrect. See above.
Question 73
A maxillary molar has _____ fossae; and the mandibular molar has _____ fossae on the occlusal surface.
A
3; 3
B
3; 4
C
4; 3
D
4; 4
Question 73 Explanation: 
The correct answer is C. Each maxillary molar has 4 fossae: mesial triangular, central(bounded by the mesial transverse ridge and the oblique ridge), distal triangular, and distal (within the distal oblique groove, and between the oblique ridge and DL cusp). Each mandibular molar has 3 fossae: mesial, central, and distal.
Question 74
Which is the principal muscle that protrudes the mandible?
A
Masseter
B
Medial pterygoid
C
Lateral pterygoid
D
Temporalis
Question 74 Explanation: 
The correct answer is C. The lateral pterygoids are the primary protractors of the mandible. It also functions in mandibular depression and contralateral excursion. Answer A is incorrect. The masseter functions in mandibular elevation (primary function), retrusion, and ipsilateral excursion. Answer B is incorrect. The medial pterygoid functions in mandibular elevation, protrusion, and contralateral excursion. Answer D is incorrect. The temporalis functions in mandibular elevation, retrusion, ipsilateral excursion, and maintaining its rest position.
Question 75
Which posterior tooth is most symmetrical from an occlusal view?
A
Maxillary 1st premolar
B
Maxillary 2nd premolar
C
Maxillary 1st molar
D
Mandibular 1st premolar
E
Mandibular 1st molar
Question 75 Explanation: 
The correct answer is B. The maxillary 2nd premolar, with its oval occlusal outline, is typically much more symmetrical than the 1st premolar, which has a decidedly more asymmetric, hexagonal occlusal outline. In fact, the only part of the occlusal outline of the maxillary 1st premolar that appears symmetrical is the buccal surface, with its rounded, inverted V-shape due to the prominent buccal ridge. The remaining lingual three-fourths of the 1st premolar, on the other hand, appears bent to the mesial. Answer A is incorrect. An asymmetric occlusal outline is a distinguishing feature of the maxillary 1st premolar that is not present on the 2nd premolars. The mesial outline appears straight or concave, and is bisected by a mesial marginal ridge groove not present on the distal. Moreover, the mesial marginal ridge is shorter buccolingually than the more convex distal marginal ridge such as the lingual three-fourths of the crown appear bent to the mesial. Lastly, the lingual cusp tip is positioned more to the mesial and the buccal cusp tip more to the distal, versus 2nd premolars which are more symmetrical overall. Answer C is incorrect. With its prominent mesiolingual cusp and oblique ridge connecting to the distobuccal cusp, it’s quite evident that the occlusal outline is asymmetric. Answer D is incorrect. The mesiolingual groove that separates the mesial marginal ridge from the lingual cusp renders this tooth relatively asymmetric when viewed from the occlusal. There is more bulk on the distal half, and the mesial side of the crown appears pushed in on the mesiolingual corner. Answer E is incorrect. The presence of a minor fifth cusp (distal cusp) on the buccal creates an asymmetric occlusal outline. Overall, there are 3 buccal cusps (MB, DB, distal) and 2 lingual cusps (ML, DL).
Question 76
All of the following cusp tips occlude in the central fossa of an opposing tooth during ideal intercuspation EXCEPT
A
mesiobuccal of mandibular 1st molar.
B
distobuccal of mandibular 1st molar.
C
mesiolingual of maxillary 2nd molar.
D
distobuccal of mandibular 2nd molar.
Question 76 Explanation: 
The correct answer is A. The MB cusp tip of the mandibular 1st molar contacts the interproximal marginal ridges of the maxillary 1st molar and 2nd premolar. Answers B, C, and D are incorrect. Remember: the DB cusps of mandibular molars and ML cusps of maxillary molars occlude in the central fossae of their opposing counterparts in ideal intercuspation.
Question 77
The primary mandibular 2nd molar most closely resembles which permanent tooth?
A
Mandibular 1st molar
B
Mandibular 2nd molar
C
Maxillary 1st molar
D
Maxillary 2nd molar
Question 77 Explanation: 
The correct answer is A. The primary mandibular 2nd molar resembles the mandibular 1st molar; however, the three buccal cusps of the primary tooth are nearly equal in size, whereas the permanent 1st molar bears a distal cusp which is typically considerably smaller. Answer B is incorrect. No primary tooth resembles the permanent mandibular 2nd molar. Answer C is incorrect. The primary maxillary 2nd molar resembles the permanent maxillary 1st molar. They are similar in most respects (albeit the primary 2nd molar is smaller), with an oblique ridge and fossae (and sometimes even a cusp of Carabelli) corresponding to those of the permanent maxillary 1st molar. Answer D is incorrect. No primary tooth resembles the permanent maxillary 2nd molar.
Question 78
Which of the following are supporting cusps?
A
Distobuccal cusp of maxillary 1st molars
B
Lingual cusp of mandibular 2nd premolars
C
Mesiolingual cusp of maxillary 1st molars
D
Distolingual cusp of mandibular 1st molars
Question 78 Explanation: 
The correct answer is C. Remember that supporting cusps are the maxillary lingual and mandibular buccal cusps. These cusps (also called working cusps) function by grinding against the opposing teeth. Supporting cusps tend to be rounder and located than nonsupporting cusps. The tips of the supporting cusps rest in the opposing marginal ridge areas with the exception of the ML cusp of maxillary molars and DB cusps of mandibular molars which rest in the opposing central fossa. Answers A, B, and D are incorrect. All mandibular lingual and maxillary buccal cusps are nonsupporting cusps. These cusps tend to be taller and sharper than supporting cusps, and their function is to help disarticulate the teeth during excursive jaw movements. Note that nonsupporting cusps do not occlude in any fossae or marginal ridge areas, but they do oppose grooves and embrasure areas.
Question 79
Using the Universal Numbering System, which of the following represents the four permanent adult canines?
A
13, 23, 33, 43
B
6, 11, 22, 27
C
C, H, R, M
D
6, 12, 22, 27
E
53, 63, 73, 83
Question 79 Explanation: 
The correct answer is B. The Universal Number System numbers the permanent dentition 1 through 32 starting with the maxillary right 3rd molar as No. 1 and the mandibular right 3rd molar as No. 32. Answer A is incorrect. If the question had asked you to use the Federation Dentaire Internationale (FDI) system, then this answer choice would be correct. In the FDI numbering system, the 1st digit represents the quadrant and arch in which the tooth is found, as well as whether or not the tooth is primary or permanent; the 2nd number denotes the tooth position relative to the midline, from closest to farthest away. Answer C is incorrect. The primary, not the permanent, canines are identified with the Universal Numbering System in this answer.Recall that the primary teeth are identified by letter rather than number in this system, starting with the primary maxillary right 2nd molar as A, lettering across the maxillary arch to J (primary maxillary left 2nd molar), dropping down to K (primary mandibular left 2nd molar), and ending at T (mandibular right 2nd molar). Answer D is incorrect. Tooth No. 12 identifies the permanent maxillary left 1st premolar using the Universal Numbering System; however, tooth No. 12 in the FDI system identifies the permanent maxillary right lateral incisor. Answer E is incorrect. This choice identifies the primary canines according to the FDI System. In the primary dentition, the upper right (UR) quadrant is designated “5”, the UL is “6”, LL is “7”, and LR is “8”, and the canine is the 3rd (“3”) tooth from the midline, numbering distally.
Question 80
How many teeth contact both anterior and posterior segments of the opposing arch in ideal intercuspation?
A
0
B
2
C
4
D
6
E
8
Question 80 Explanation: 
The correct answer is C. The maxillary canines contact mandibular canines (anterior segment) and mandibular 1st premolars (posterior segment). Likewise, the mandibular 1st premolar contacts the opposing maxillary canine (anterior) and 1st premolar (posterior). Thus, 2 maxillary canines + 2 mandibular 1st premolars = 4 total teeth. Remember: Maxillary teeth contact their opposing counterpart and the tooth distal to it. Mandibular teeth contact their opposing counterpart and the tooth mesial to it.
Question 81
In an ideal dentition, which of the following teeth occludes with only one other tooth in the opposing arch during the full range of mandibular movements?
A
Mandibular 1st molar
B
Mandibular lateral incisor
C
Mandibular central incisor
D
Maxillary lateral incisor
E
Maxillary central incisor
Question 81 Explanation: 
The correct answer is C. In centric relation, lateral excursions, and mandibular protrusion, the mandibular central incisor will only articulate with the lingual or incisal aspect of the maxillary central incisor. Answer A is incorrect. The mandibular 1st molar articulates with the maxillary 1st molar and 2nd premolar in maximum intercuspation and during lateral excursive and protrusive movements. Answer B is incorrect. The mandibular lateral incisor can articulate with the maxillary lateral and central incisors. Answer D is incorrect. The maxillary lateral incisor can articulate with the mandibular lateral incisor and canine. Answer E is incorrect. Both the mandibular central and lateral incisors can contact the lingual surface of the maxillary central incisor.
Question 82
The maxillary 1st premolar typically has a pulp chamber of what shape (at the level of the CEJ)?
A
Round
B
Egg shaped
C
Oval (flattened mesiodistally)
D
Oval (flattened buccolingually)
E
Rectangular
Question 82 Explanation: 
The correct answer is C. The maxillary 1st premolar has an oval-shaped pulp chamber, flattened mesiodistally (like an hourglass). Remember that it generally has two roots. Mandibular incisors also have pronounced hourglass-shaped pulp chambers. The mesiodistal constriction of the oval is less pronounced in the canines and other premolars. Answer A is incorrect. Although no tooth has a perfectly round pulp chamber (at the level of the CEJ), the maxillary central incisor has the roundest. Answer B is incorrect. The maxillary lateral incisor has an egg-shaped pulp chamber. Answer D is incorrect. No teeth have an oval-shaped pulp chamber that is flattened buccolingually. Answer E is incorrect. The mandibular 1st molar has a rectangular-shaped pulp chamber.
Question 83
The facial height-of-contour of the maxillary 2nd premolar is in what segment of the crown?
A
Incisal 3rd
B
Junction of the incisal and middle 3rds
C
Middle 3rd
D
Junction of the middle and cervical 3rds
E
Cervical 3rd
Question 83 Explanation: 
The correct answer is E. Remember that the buccal/facial HOC of all permanent teeth is located in the cervical 3rd of the crown. The lingual HOC of all anterior teeth is also located in the cervical 3rd (at the cingulum). Answer C is incorrect. The lingual HOC of all posterior teeth (premolars and molars) is located in the middle 3rd of the crown.
Question 84
Which feature allows one to distinguish between the permanent mandibular lateral incisor and the permanent mandibular central incisor from an occlusal view?
A
A decreased mesiodistal length of the lateral incisor.
B
The cingulum location is slightly distal of center on the central incisor.
C
The distolingual twist of the lateral incisor’s incisal edge.
D
The incisal edge of central incisor is lingual to the root axis line.
Question 84 Explanation: 
The correct answer is C. From an occlusal view, the major feature distinguishing the mandibular lateral incisor from the mandibular central incisor is the presence of a distolingual twist found in the distal half of the lateral’s incisal edge. This distolingual twist follows the natural arch shape of the mandible and, therefore, also allows one to easily distinguish right from left mandibular lateral incisors. The mandibular central incisor, on the other hand, is bilaterally symmetrical with a centered cingulum, making it very difficult to determine right from left. Answer A is incorrect. Unlike maxillary incisor crowns, where the central is larger than the lateral, the mandibular lateral incisor crown is slightly larger in all dimensions. Answer B is incorrect. The cingulum of the mandibular lateral incisor is slightly distal of center (similar to the maxillary central incisor and mandibular canine). Anterior teeth that have a centered cingulum on the lingual surface include the mandibular central incisor, maxillary canine, and maxillary lateral incisor. Answer D is incorrect. Both the mandibular central and lateral incisors have incisal edges that are lingual to the root-axis line, and therefore is not a distinguishing feature.
Question 85
All of the following are true regarding the curve of Spee EXCEPT
A
the curve in the lower arch is concave.
B
the curve in the upper arch is convex.
C
the curve is formed by the lingual inclination of the mandibular molars.
D
the curve is directed anteroposteriorly.
Question 85 Explanation: 
The correct answer is C. The lingual inclination of the crowns of mandibular posterior teeth helps define the curve of Wilson, not the curve of Spee. When viewed from the anterior, the lingual cusps of the posterior teeth in both arches are aligned at a more inferior levelthan the buccal cusps, thus giving rise to the curve of Wilson, or mediolateral curve. Answers A, B, and D are incorrect. When viewed from the buccal, the cusp tips of posterior teeth follow a gradual curve that is convex in the maxillary arch and concave in the mandibular arch (relative to a flat plane of occlusion between the two arches). The curve of Spee runs anteroposteriorly, and is sometimes referred to as the anteroposterior curve.
Question 86
Which of the following primary teeth has the longest root? A. B. C. D. E.
A
Maxillary central incisor
B
Maxillary canine
C
Maxillary 2nd molar
D
Mandibular canine
E
Mandibular 2nd molar
Question 86 Explanation: 
The correct answer is B. Just like its permanent counterpart, the primary maxillary canine has the longest root of all deciduous teeth, averaging 13.5 mm in length. Answer A is incorrect. The primary maxillary central incisor has one of the shorter roots, measuring about 10 mm in length. Remember that the mandibular central incisor has the shortest primary root (9 mm in length). Answer C is incorrect. The primary maxillary 2nd molar roots average 11.7 mm in length. Answer D is incorrect. The primary mandibular canine root averages 11.5 mm in length. Answer E is incorrect. The primary mandibular 2nd molar roots average 11.3 mm in length.
Question 87
Which of these surfaces is a proximal surface?
A
Facial
B
Lingual
C
Incisal
D
Buccal
E
Mesial
Question 87 Explanation: 
The correct answer is E. The proximal surfaces are the sides of a tooth generally next to an adjacent tooth. The mesial surface is closer to the midline, whereas the distal surface is farther from the midline. Answer A is incorrect. The facial surface rests against the lip or cheek. Answer B is incorrect. The lingual surface is nearest the tongue. Answer C is incorrect. The incisal surface is the cutting edge of an anterior tooth. Answer D is incorrect. The buccal surface is the same as the facial surface, but more commonly used for posterior teeth.
Question 88
The mandible functions as what type of lever?
A
Class I
B
Class II
C
Class III
D
Class IV
Question 88 Explanation: 
The correct answer is C. A class III lever is comparable to “tweezers” in which the effort is between the fulcrum and the load. In the case of the mandible, the fulcrum is the TMJ. The effort is supplied by the masseter, medial pterygoid, and temporalis muscles which attach at locations anteroinferiorly to the TMJ (ie, coronoid process, inferior border of mandible, lateral and medial aspects of the ramus, etc), and the load is imparted upon incising food. Answer A is incorrect. A class I lever is a “see-saw” in which the fulcrum is between the effort and the load. Answer B is incorrect. A class II lever is a “wheelbarrel” in which the load is between the fulcrum and effort. Answer D is incorrect. This is not a simple lever classification type.
Question 89
Which tooth has the greatest root-to-crown ratio?
A
Maxillary central incisor
B
Maxillary canine
C
Mandibular canine
D
Mandibular 1st molar
Question 89 Explanation: 
The correct answer is D. Don’t be troubled if you missed this question since it’s unlikely that anyone would get it correct unless you like to memorize random tables. If anything, this question is an exercise in reading a question carefully and thinking about it before answering. Many may have chosen the maxillary canine, since it has the longest root in the permanent dentition. However, it also has a relatively long crown length (only the mandibular canine and maxillary central incisor are longer), making the root-to-crown ratio less than thought. The answer is a tooth with a relatively squat crown and reasonably long roots. The mandibular 1st molar fits this bill: its rootto- crown ratio is 1.87. The maxillary 1st molar is a close 2nd with a 1.78 root-to-crown ratio. Answer A is incorrect. Root-to-crown ratio = 1.24 (the lowest of all teeth). Answer B is incorrect. Root-to-crown ratio = 1.70. Answer C is incorrect. Root-to-crown ratio = 1.45.
Question 90
All anterior teeth develop from how many lobes?
A
2
B
3
C
4
D
5
E
6
Question 90 Explanation: 
The correct answer is C. Three facial lobes and one lingual lobe (cingulum) comprise the four developmental lobes of anterior teeth. Canines and most premolars also develop from four lobes (three of which comprise the facial aspect). The only exception is the three-cusped mandibular 2nd premolar which develops from five lobes (three facial lobes of the buccal cusp and two lobes for each of the two lingual cusps). Answers A and B are incorrect. No tooth develops from only 2 or 3 lobes. Four lobes is the minimum. Answer D is incorrect. As a general rule, each molar cusp forms from one lobe. Therefore, the mandibular 1st molar develops from five lobes (three buccal and two lingual). Answer E is incorrect. A variant of the mandibular 1st molar bears six cusps (a 3rd lingual cusp called tuberculum intermedium), each of which is developed from a single lobe.
Question 91
When the mandible shifts to the left, the right condylar head moves in which direction relative to articular eminence?
A
Anteriorly, downward, laterally
B
Anteriorly, downward, medially
C
Anteriorly, upward, laterally
D
Anteriorly, upward, medially
E
Posteriorly, upward, laterally
Question 91 Explanation: 
The correct answer is B. During left working movement, the right (nonworking) condyle rotates and translates anteriorly, downward along the articular eminence, and medially to the left. The left (working) condyle rotates forward and typically translates slightly laterally to the left (a Bennett shift).
Question 92
Angle classification of occlusion is based primarily on
A
the relationship between the maxillary and mandibular anterior teeth.
B
the position of the maxillary canines.
C
the relationship between the maxillary and mandibular 1st molars.
D
the amount of anterior overjet.
Question 92 Explanation: 
The correct answer is C. Angle classification is primarily based on molar relationships. For example, a class I molar relationship is one in which the MB cusp of the maxillary 1st molar opposes the buccal groove of the mandibular 1st molar. If the maxillary 1st molar is mesial to this position, a class II molar relationship exists. If it is distal, a class III molar relationship exists. Answer A is incorrect. This has no bearing on Angle classification of occlusion. Answer B is incorrect. Although the canine relationship can be classified as class I (ie, maxillary canine tip falls between the mandibular canine and 1st premolar), class II, or III, it is the molar relationship that primarily defines Angle classification of occlusion. Answer D is incorrect. This has no bearing on Angle classification; however, excessive overjet may be seen as a sequela of class II, division I occlusion.
Question 93
In a maxillary 1st molar, a depression associated with a furcation might be detectable on all of the following surfaces EXCEPT
A
buccal.
B
palatal.
C
mesial.
D
distal.
Question 93 Explanation: 
The correct answer is B. The large palatal root spans the entire width of the lingual surface, tapering from the CEJ to a blunted or rounded apex. No furcation can be detected on this surface. Remember: palatal roots are wider in the mesiodistal than in the buccopalatal direction. Answer A is incorrect. The buccal furcation entrance may be detected between the MB and DB roots an average of 4.2 mm from the CEJ. Answer C is incorrect. The mesial furcation entrance may be detected between the MB and palatal roots an average of 3.6 mm from the CEJ. This furcation is most easily accessed from the palatal given the relatively large breadth of the MB root buccolingually. Answer D is incorrect. The distal furcation entrance may be detected between the DB and palatal roots an average of 4.8 mm from the CEJ. Since the DB root is not as wide as the MB root buccolingually, this furcation is centered buccolingually.
Question 94
A “zig-zag” occlusal pattern can be found on which of the following teeth?
A
Mandibular 2nd molar
B
Mandibular 1st molar
C
Maxillary 2nd molar
D
Maxillary 1st molar
E
Maxillary 2nd premolar
Question 94 Explanation: 
The correct answer is B. The central groove of the mandibular 1st molar zigzags mesiodistally between the three buccal cusps and two lingual cusps. Answer A is incorrect. The mandibular 2nd molar has buccal and lingual grooves that align to intersect with the central groove to form a “plus-sign” occlusal pattern. Answers C and D are incorrect. Maxillary molars have an oblique ridge running diagonally across the occlusal surface separating the DL cusp from the other cusps, and creates a discontinuous occlusal pattern. Answer E is incorrect. The maxillary 2nd premolar has a short central groove with multiple supplemental grooves.
Question 95
A patient presents to your office with what appears to be five mandibular incisors. However,upon radiographic examination, you count four roots. The most likely explanation for this finding is
A
concrescence.
B
hypercementosis.
C
fusion.
D
gemination.
E
fibrous dysplasia.
Question 95 Explanation: 
The correct answer is D. Both gemination and fusion can be described as conditions in which “double teeth” occur. They occur most often in the maxillary and anterior regions and are differentiated by counting the number of teeth in the dentition. In gemination (or twinning), one tooth bud splits to form what appears to be two teeth (1 root, 2 teeth). The single root is not split and has a common pulp canal. Both twinned and fused crowns typically appear double in width compared to a single tooth but notched since the division is incomplete. Answer A is incorrect. Concrescence occurs when the roots of two or more unique teeth are united by cementum. Answer B is incorrect. Hypercementosis is the nonneoplastic deposition of excessive cementum. Blunting of the roots is frequently seen upon radiographic examination. Answer C is incorrect. In fusion, two adjacent tooth germs fuse during development (2 roots, 2 teeth). Unlike gemination, radiographs usually reveal two separate but fused roots with separate pulp chambers. Answer E is incorrect. Fibrous dysplasia is a developmental condition in which bone is progressively replaced by fibrous tissue. The key radiographic appearance of fibrous dysplasia is described as “ground glass.” There is no association between any of the above conditions and fibrous dysplasia.
Question 96
Mandibular molar crowns tilt lingually at the cervix. Maxillary molar crowns are aligned directly over the roots.
A
Both statements are true.
B
Both statements are false.
C
The first statement is true; the second is false.
D
The first statement is false; the second is true.
Question 96 Explanation: 
The correct answer is A. Both mandibular premolar and molar crowns tilt toward the lingual (relative to the root-axis line) when viewed from the proximal. Moreover, the cusp tips of the mandibular canines, as well as the incisal edges of the mandibular incisors, are typically positioned lingual to the root-axis line. The opposite is true of the maxillary incisors and canines, which typically have incisal edges/cusp tips that are positioned slightly labial to the root-axis line. Maxillary molar and premolar crowns do not tip noticeably in any direction, and appear aligned directly over the roots.
Question 97
All of the following muscles involved in mastication are innervated by the mandibular branch of trigeminal nerve EXCEPT
A
temporalis.
B
masseter.
C
buccinator.
D
medial pterygoid.
E
lateral pterygoid.
Question 97 Explanation: 
The correct answer is C. The buccinator muscle assists in mastication by compressing the cheek against molar teeth, thus holding food under the teeth. It originates from the pterygomandibular raphe and maxillary and mandibular buccal alveolar processes. Its upper and lower fibers crisscross to insert into the lower and upper lip, respectively. The buccinator receives its innervation from the facial nerve (CN VII, buccal branch). Answers A, B, D, and E are incorrect. These are the four muscles of mastication, all innervated by CN V3.
Question 98
Which of the following is TRUE of individuals with anodontia?
A
They have additional or supernumerary teeth.
B
They have congenitally missing teeth.
C
They have additional maxillary and mandibular incisors.
D
They have all teeth shaped as incisors.
E
None of the above.
Question 98 Explanation: 
The correct answer is B. Anodontia refers to the total lack of tooth development. These individuals do form any teeth. Someone with partial anodontia is congenitally missing one or more teeth. Remember that an edentulous patient does not necessarily suffer from anodontia. 212 Answer A is incorrect. Hyperdontia is the development of an increased number of teeth, which may be associated with conditions such as cleidocranial dysplasia, Down syndrome, Gardner syndrome, and Sturge- Weber angiomatosis.
Question 99
What TMJ ligament is derived from the 1st branchial arch?
A
Temporomandibular
B
Sphenomandibular
C
Stylomandibular
D
Lateral
Question 99 Explanation: 
The correct answer is B. The sphenomandibular ligament is a remnant of Meckel cartilage, originally derived from the 1st branchial arch. It extends from the spine of the sphenoid bone to the mandibular lingula. Answers A and D are incorrect. The temporomandibular ligament (also called the lateral ligament) does not directly derive from one of the branchial arches. Answer C is incorrect. The stylomandibular ligament is not originally derived from one of the branchial arches. It extends from the styloid process to the mandibular angle.
Question 100
Which of the following has the highest frequency of impaction?
A
Maxillary lateral incisor
B
Maxillary canine
C
Maxillary 1st molar
D
Mandibular canine
E
Mandibular 2nd premolar
Question 100 Explanation: 
The correct answer is B. An impacted tooth is one that does not erupt within the expected time. Although 3rd molars are the most commonly impacted teeth in the adult dentition, it is not represented as a choice. Maxillary canines are the 2nd most common impacted teeth, followed by mandibular premolars. Recall that maxillary canines are the last nonmolar teeth to erupt in the maxillary arch, emerging after all the incisors and premolars have erupted. Given their long path of eruption, and the possibility of insufficient arch space, they may become impacted, typically to the palatal. Answer A is incorrect. Although impaction of these teeth is not unheard of, the frequency is less than that of 3rd molars and maxillary canines. Answers C, D, and E are incorrect. See above.
Once you are finished, click the button below. Any items you have not completed will be marked incorrect. Get Results
There are 100 questions to complete.
List
Return
Shaded items are complete.
12345
678910
1112131415
1617181920
2122232425
2627282930
3132333435
3637383940
4142434445
4647484950
5152535455
5657585960
6162636465
6667686970
7172737475
7677787980
8182838485
8687888990
9192939495
96979899100
End
Return

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>