Integrated National Board Dental Examination
(INBDE) — Advanced Practice Question Bank
v2.0 a well detailed exam 2025/2026 graded
A+ upgraded !!! Comprehensive 150-Question
Simulated Examination Covering Foundation
Knowledge Areas and Clinical Content
Domains with Detailed Rationales
SECTION 1: DENTAL ANATOMY AND OCCLUSION
Question 1
Which permanent tooth most commonly exhibits a C-shaped root canal configuration?
A. Maxillary first molar
B. Mandibular second molar
C. Mandibular first premolar
D. Maxillary second premolar
Correct Answer: B
Rationale: The mandibular second molar most commonly exhibits a C-shaped root canal
configuration, particularly in Asian populations. This anatomical variation features a single,
ribbon-shaped canal with a C-shaped cross-section. The maxillary first molar typically has three
to four canals, while mandibular first premolars and maxillary second premolars may have two
canals but rarely C-shaped.
,Question 2
The lingual inclination of the maxillary posterior teeth is referred to as:
A. Curve of Spee
B. Curve of Wilson
C. Sphere of Monson
D. Balkwill angle
Correct Answer: B
Rationale: The Curve of Wilson describes the mediolateral curvature of the occlusal plane when
viewed from the frontal aspect. It represents the lingual inclination of the maxillary posterior
teeth and the buccal inclination of the mandibular posterior teeth, creating a transverse curve.
The Curve of Spee is the anteroposterior curve, and the Sphere of Monson describes the
theoretical spherical arrangement of occlusal surfaces.
Question 3
The occlusal contact pattern in centric occlusion for a Class I occlusion with normal overbite and
overjet shows:
A. All maxillary cusps contacting all mandibular cusps
B. Supporting cusps contacting opposing marginal ridges and fossae
C. Supporting cusps contacting opposing supporting cusps
D. No posterior tooth contacts
Correct Answer: B
Rationale: In centric occlusion, the supporting cusps (maxillary palatal and mandibular buccal
cusps) contact the opposing marginal ridges, fossae, and occlusal surfaces. This is described as
"cusps to fossae" contacts, which provides stable occlusion. The non-supporting (guiding) cusps
(maxillary buccal and mandibular lingual) do not contact in centric occlusion.
Question 4
The dental formula for the permanent dentition is:
A. 2-1-2-3
B. 2-1-2-2
C. 2-1-3-3
D. 2-2-2-3
,Correct Answer: A
Rationale: The dental formula for the permanent dentition is 2-1-2-3, indicating 2 incisors, 1
canine, 2 premolars, and 3 molars per quadrant. The primary dentition formula is 2-1-0-2 (2
incisors, 1 canine, 0 premolars, 2 molars). This formula represents the typical dentition pattern
for humans.
Question 5
Which of the following teeth has the greatest mesiodistal dimension of any tooth in the
permanent dentition?
A. Maxillary central incisor
B. Maxillary first molar
C. Mandibular first molar
D. Maxillary canine
Correct Answer: C
Rationale: The mandibular first molar has the greatest mesiodistal dimension of any tooth in
the permanent dentition, measuring approximately 11–12 mm. The maxillary central incisor is
the largest incisor, and the maxillary first molar is broad but not the widest. The mandibular first
molar's large mesiodistal dimension contributes to its function as a primary grinding tooth.
Question 6
The primary function of the articular eminence of the temporomandibular joint is to:
A. Provide attachment for the lateral pterygoid muscle
B. Guide the condylar movement during mouth opening and closing
C. Serve as the site of muscle attachment for the temporalis
D. Protect the joint from excessive loading
Correct Answer: B
Rationale: The articular eminence is a bony prominence anterior to the glenoid fossa that
guides the condylar movement during mandibular opening and closing. The condyle moves
down and forward along the articular eminence during opening. This guidance is essential for
normal jaw function and helps prevent dislocation.
, Question 7
The primary supporting cusp of the maxillary first molar is the:
A. Mesiobuccal cusp
B. Distobuccal cusp
C. Mesiolingual cusp
D. Distolingual cusp
Correct Answer: C
Rationale: The mesiolingual cusp is the primary supporting (functional) cusp of the maxillary
first molar. It is the largest cusp and occludes with the central fossa of the mandibular first
molar. Supporting cusps are the palatal cusps of maxillary teeth and the buccal cusps of
mandibular teeth, which maintain vertical dimension and support chewing forces.
Question 8
The pulp chamber of the mandibular first molar typically contains how many pulp horns?
A. Three
B. Four
C. Five
D. Two
Correct Answer: B
Rationale: The pulp chamber of the mandibular first molar typically contains four pulp horns—
one for each of the four major cusps (mesiobuccal, distobuccal, mesiolingual, distolingual). This
reflects the external morphology and the presence of four major cusps. The mandibular first
molar may have five cusps in some cases but usually has four pulp horns.
Question 9
In a normal occlusion, the mesiobuccal cusp of the maxillary first molar occludes in the:
A. Central fossa of the mandibular first molar
B. Mesial marginal ridge of the mandibular first molar
C. Buccal groove of the mandibular first molar
D. Distal fossa of the mandibular first molar
Correct Answer: A
(INBDE) — Advanced Practice Question Bank
v2.0 a well detailed exam 2025/2026 graded
A+ upgraded !!! Comprehensive 150-Question
Simulated Examination Covering Foundation
Knowledge Areas and Clinical Content
Domains with Detailed Rationales
SECTION 1: DENTAL ANATOMY AND OCCLUSION
Question 1
Which permanent tooth most commonly exhibits a C-shaped root canal configuration?
A. Maxillary first molar
B. Mandibular second molar
C. Mandibular first premolar
D. Maxillary second premolar
Correct Answer: B
Rationale: The mandibular second molar most commonly exhibits a C-shaped root canal
configuration, particularly in Asian populations. This anatomical variation features a single,
ribbon-shaped canal with a C-shaped cross-section. The maxillary first molar typically has three
to four canals, while mandibular first premolars and maxillary second premolars may have two
canals but rarely C-shaped.
,Question 2
The lingual inclination of the maxillary posterior teeth is referred to as:
A. Curve of Spee
B. Curve of Wilson
C. Sphere of Monson
D. Balkwill angle
Correct Answer: B
Rationale: The Curve of Wilson describes the mediolateral curvature of the occlusal plane when
viewed from the frontal aspect. It represents the lingual inclination of the maxillary posterior
teeth and the buccal inclination of the mandibular posterior teeth, creating a transverse curve.
The Curve of Spee is the anteroposterior curve, and the Sphere of Monson describes the
theoretical spherical arrangement of occlusal surfaces.
Question 3
The occlusal contact pattern in centric occlusion for a Class I occlusion with normal overbite and
overjet shows:
A. All maxillary cusps contacting all mandibular cusps
B. Supporting cusps contacting opposing marginal ridges and fossae
C. Supporting cusps contacting opposing supporting cusps
D. No posterior tooth contacts
Correct Answer: B
Rationale: In centric occlusion, the supporting cusps (maxillary palatal and mandibular buccal
cusps) contact the opposing marginal ridges, fossae, and occlusal surfaces. This is described as
"cusps to fossae" contacts, which provides stable occlusion. The non-supporting (guiding) cusps
(maxillary buccal and mandibular lingual) do not contact in centric occlusion.
Question 4
The dental formula for the permanent dentition is:
A. 2-1-2-3
B. 2-1-2-2
C. 2-1-3-3
D. 2-2-2-3
,Correct Answer: A
Rationale: The dental formula for the permanent dentition is 2-1-2-3, indicating 2 incisors, 1
canine, 2 premolars, and 3 molars per quadrant. The primary dentition formula is 2-1-0-2 (2
incisors, 1 canine, 0 premolars, 2 molars). This formula represents the typical dentition pattern
for humans.
Question 5
Which of the following teeth has the greatest mesiodistal dimension of any tooth in the
permanent dentition?
A. Maxillary central incisor
B. Maxillary first molar
C. Mandibular first molar
D. Maxillary canine
Correct Answer: C
Rationale: The mandibular first molar has the greatest mesiodistal dimension of any tooth in
the permanent dentition, measuring approximately 11–12 mm. The maxillary central incisor is
the largest incisor, and the maxillary first molar is broad but not the widest. The mandibular first
molar's large mesiodistal dimension contributes to its function as a primary grinding tooth.
Question 6
The primary function of the articular eminence of the temporomandibular joint is to:
A. Provide attachment for the lateral pterygoid muscle
B. Guide the condylar movement during mouth opening and closing
C. Serve as the site of muscle attachment for the temporalis
D. Protect the joint from excessive loading
Correct Answer: B
Rationale: The articular eminence is a bony prominence anterior to the glenoid fossa that
guides the condylar movement during mandibular opening and closing. The condyle moves
down and forward along the articular eminence during opening. This guidance is essential for
normal jaw function and helps prevent dislocation.
, Question 7
The primary supporting cusp of the maxillary first molar is the:
A. Mesiobuccal cusp
B. Distobuccal cusp
C. Mesiolingual cusp
D. Distolingual cusp
Correct Answer: C
Rationale: The mesiolingual cusp is the primary supporting (functional) cusp of the maxillary
first molar. It is the largest cusp and occludes with the central fossa of the mandibular first
molar. Supporting cusps are the palatal cusps of maxillary teeth and the buccal cusps of
mandibular teeth, which maintain vertical dimension and support chewing forces.
Question 8
The pulp chamber of the mandibular first molar typically contains how many pulp horns?
A. Three
B. Four
C. Five
D. Two
Correct Answer: B
Rationale: The pulp chamber of the mandibular first molar typically contains four pulp horns—
one for each of the four major cusps (mesiobuccal, distobuccal, mesiolingual, distolingual). This
reflects the external morphology and the presence of four major cusps. The mandibular first
molar may have five cusps in some cases but usually has four pulp horns.
Question 9
In a normal occlusion, the mesiobuccal cusp of the maxillary first molar occludes in the:
A. Central fossa of the mandibular first molar
B. Mesial marginal ridge of the mandibular first molar
C. Buccal groove of the mandibular first molar
D. Distal fossa of the mandibular first molar
Correct Answer: A
