INBDE Integrated National Board Dental Examination 2026
Latest Comprehensive Study Guide with Practice Questions
Clinical Dentistry Review, Verified Answers, Detailed
Rationales, Success Workbook
SECTION 1: DENTAL ANATOMY & OCCLUSION (Questions 1-15)
1. A 25-year-old patient presents with a completely impacted mandibular
third molar. Which tooth is the MOST frequently impacted tooth in the
permanent dentition?
A) Maxillary canine
B) Maxillary third molar
C) Mandibular second premolar
D) Mandibular third molar
Rationale: The correct answer is D) Mandibular third molar. Mandibular third
molars are the most frequently impacted teeth in the permanent dentition, followed
by maxillary third molars and maxillary canines. Impacted mandibular third molars
can lead to complications including pericoronitis, caries of the adjacent second
molar, root resorption, and cyst formation.
2. Which cranial nerve provides motor innervation to the muscles of
mastication?
A) Facial nerve (CN VII)
B) Hypoglossal nerve (CN XII)
C) Trigeminal nerve (CN V)
D) Glossopharyngeal nerve (CN IX)
Rationale: The correct answer is C) Trigeminal nerve (CN V) . The trigeminal
nerve is the largest cranial nerve and provides motor innervation to the muscles of
mastication (masseter, temporalis, medial pterygoid, lateral pterygoid) via the
mandibular division (V3). The facial nerve (CN VII) innervates the muscles of
facial expression.
,3. The periodontal ligament (PDL) primarily functions to:
A) Provide blood supply to the tooth
B) Cushion the tooth during mastication and transmit occlusal forces
C) Produce enamel
D) Anchor the tooth to the alveolar bone
Rationale: The correct answer is B) Cushion the tooth during mastication and
transmit occlusal forces. The periodontal ligament (PDL) is a specialized
connective tissue that connects the cementum of the tooth root to the alveolar bone.
Its primary functions include: (1) cushioning the tooth during mastication (shock
absorption), (2) transmitting occlusal forces to the bone, (3) providing sensory
feedback (proprioception), and (4) maintaining the tooth in its socket.
4. A patient presents with an inability to close their eyelids on the right side.
Which cranial nerve is MOST likely affected?
A) Trigeminal nerve (CN V)
B) Facial nerve (CN VII)
C) Oculomotor nerve (CN III)
D) Abducens nerve (CN VI)
Rationale: The correct answer is B) Facial nerve (CN VII) . The facial nerve
provides motor innervation to the muscles of facial expression, including the
orbicularis oculi muscle responsible for eyelid closure. Paralysis of this nerve
results in an inability to close the eyelid (lagophthalmos). This can occur in
conditions such as Bell's palsy or due to trauma.
5. Which of the following represents the correct dental formula for a
permanent adult human dentition?
A) 2-1-2--1-2-3
B) 2-1-2--1-2-3
C) 2-1-2--1-2-3
D) 2-1-2--1-2-3
Rationale: The correct answer is B) 2-1-2--1-2-3 . The dental formula for a
permanent adult human dentition is 2-1-2--1-2-3, representing two incisors,
,one canine, two premolars, and three molars in each quadrant. The primary
(deciduous) dentition formula is 2-1-0--1-0-2 (no premolars).
6. Which muscle is primarily responsible for protrusion of the mandible?
A) Masseter
B) Temporalis
C) Medial pterygoid
D) Lateral pterygoid
Rationale: The correct answer is D) Lateral pterygoid. The lateral pterygoid
muscle is the primary protrusive muscle of the mandible. When both lateral
pterygoid muscles contract simultaneously, the mandible is protruded forward. The
masseter and medial pterygoid are primary elevators (closing muscles), while the
temporalis is also an elevator with retrusive fibers.
7. A 45-year-old patient presents with a radiolucent lesion apical to tooth #21.
The most likely diagnosis for a well-defined, corticated radiolucency
associated with the apex of a non-vital tooth is:
A) Ameloblastoma
B) Radicular cyst (periapical cyst)
C) Dentigerous cyst
D) Odontoma
Rationale: The correct answer is B) Radicular cyst (periapical cyst) . A radicular
cyst (periapical cyst) is the most common odontogenic cyst and arises from
epithelial cell rests of Malassez in response to pulpal necrosis and inflammation. It
presents as a well-defined, corticated radiolucency at the apex of a non-vital tooth.
Ameloblastoma is a benign odontogenic tumor, dentigerous cyst surrounds the
crown of an unerupted tooth, and odontoma is a hamartomatous lesion.
8. The maxillary sinus is innervated by branches of which nerve?
A) Maxillary division of the trigeminal nerve (V2)
B) Mandibular division of the trigeminal nerve (V3)
, C) Facial nerve (CN VII)
D) Glossopharyngeal nerve (CN IX)
Rationale: The correct answer is A) Maxillary division of the trigeminal nerve
(V2) . The maxillary sinus is innervated by the posterior superior alveolar nerve,
middle superior alveolar nerve, and anterior superior alveolar nerve—all branches
of the maxillary division of the trigeminal nerve (V2). This innervation is clinically
relevant for diagnosing sinus pathology and for anesthesia considerations during
dental procedures in the maxillary posterior region.
9. The permanent maxillary first molar typically has how many roots?
A) One
B) Two
C) Three
D) Four
Rationale: The correct answer is C) Three. The permanent maxillary first molar
typically has three roots: two buccal (mesiobuccal and distobuccal) and one palatal
root. The mesiobuccal root is the most commonly affected by procedural errors due
to its curvature. The maxillary second molar typically has three roots fused, while
maxillary third molars show significant variation.
10. Which of the following represents Angle's Class I occlusion?
A) The mesiobuccal cusp of the maxillary first molar occludes in the buccal groove
of the mandibular first molar
B) The mesiobuccal cusp of the maxillary first molar occludes in the buccal
groove of the mandibular first molar
C) The mesiobuccal cusp of the maxillary first molar occludes distal to the buccal
groove of the mandibular first molar
D) The maxillary central incisors are in edge-to-edge relationship with the
mandibular incisors
Rationale: The correct answer is B) The mesiobuccal cusp of the maxillary first
molar occludes in the buccal groove of the mandibular first molar. Angle's
Class I occlusion (neutrocclusion) is defined as the mesiobuccal cusp of the
maxillary first molar occluding in the buccal groove of the mandibular first molar.
Latest Comprehensive Study Guide with Practice Questions
Clinical Dentistry Review, Verified Answers, Detailed
Rationales, Success Workbook
SECTION 1: DENTAL ANATOMY & OCCLUSION (Questions 1-15)
1. A 25-year-old patient presents with a completely impacted mandibular
third molar. Which tooth is the MOST frequently impacted tooth in the
permanent dentition?
A) Maxillary canine
B) Maxillary third molar
C) Mandibular second premolar
D) Mandibular third molar
Rationale: The correct answer is D) Mandibular third molar. Mandibular third
molars are the most frequently impacted teeth in the permanent dentition, followed
by maxillary third molars and maxillary canines. Impacted mandibular third molars
can lead to complications including pericoronitis, caries of the adjacent second
molar, root resorption, and cyst formation.
2. Which cranial nerve provides motor innervation to the muscles of
mastication?
A) Facial nerve (CN VII)
B) Hypoglossal nerve (CN XII)
C) Trigeminal nerve (CN V)
D) Glossopharyngeal nerve (CN IX)
Rationale: The correct answer is C) Trigeminal nerve (CN V) . The trigeminal
nerve is the largest cranial nerve and provides motor innervation to the muscles of
mastication (masseter, temporalis, medial pterygoid, lateral pterygoid) via the
mandibular division (V3). The facial nerve (CN VII) innervates the muscles of
facial expression.
,3. The periodontal ligament (PDL) primarily functions to:
A) Provide blood supply to the tooth
B) Cushion the tooth during mastication and transmit occlusal forces
C) Produce enamel
D) Anchor the tooth to the alveolar bone
Rationale: The correct answer is B) Cushion the tooth during mastication and
transmit occlusal forces. The periodontal ligament (PDL) is a specialized
connective tissue that connects the cementum of the tooth root to the alveolar bone.
Its primary functions include: (1) cushioning the tooth during mastication (shock
absorption), (2) transmitting occlusal forces to the bone, (3) providing sensory
feedback (proprioception), and (4) maintaining the tooth in its socket.
4. A patient presents with an inability to close their eyelids on the right side.
Which cranial nerve is MOST likely affected?
A) Trigeminal nerve (CN V)
B) Facial nerve (CN VII)
C) Oculomotor nerve (CN III)
D) Abducens nerve (CN VI)
Rationale: The correct answer is B) Facial nerve (CN VII) . The facial nerve
provides motor innervation to the muscles of facial expression, including the
orbicularis oculi muscle responsible for eyelid closure. Paralysis of this nerve
results in an inability to close the eyelid (lagophthalmos). This can occur in
conditions such as Bell's palsy or due to trauma.
5. Which of the following represents the correct dental formula for a
permanent adult human dentition?
A) 2-1-2--1-2-3
B) 2-1-2--1-2-3
C) 2-1-2--1-2-3
D) 2-1-2--1-2-3
Rationale: The correct answer is B) 2-1-2--1-2-3 . The dental formula for a
permanent adult human dentition is 2-1-2--1-2-3, representing two incisors,
,one canine, two premolars, and three molars in each quadrant. The primary
(deciduous) dentition formula is 2-1-0--1-0-2 (no premolars).
6. Which muscle is primarily responsible for protrusion of the mandible?
A) Masseter
B) Temporalis
C) Medial pterygoid
D) Lateral pterygoid
Rationale: The correct answer is D) Lateral pterygoid. The lateral pterygoid
muscle is the primary protrusive muscle of the mandible. When both lateral
pterygoid muscles contract simultaneously, the mandible is protruded forward. The
masseter and medial pterygoid are primary elevators (closing muscles), while the
temporalis is also an elevator with retrusive fibers.
7. A 45-year-old patient presents with a radiolucent lesion apical to tooth #21.
The most likely diagnosis for a well-defined, corticated radiolucency
associated with the apex of a non-vital tooth is:
A) Ameloblastoma
B) Radicular cyst (periapical cyst)
C) Dentigerous cyst
D) Odontoma
Rationale: The correct answer is B) Radicular cyst (periapical cyst) . A radicular
cyst (periapical cyst) is the most common odontogenic cyst and arises from
epithelial cell rests of Malassez in response to pulpal necrosis and inflammation. It
presents as a well-defined, corticated radiolucency at the apex of a non-vital tooth.
Ameloblastoma is a benign odontogenic tumor, dentigerous cyst surrounds the
crown of an unerupted tooth, and odontoma is a hamartomatous lesion.
8. The maxillary sinus is innervated by branches of which nerve?
A) Maxillary division of the trigeminal nerve (V2)
B) Mandibular division of the trigeminal nerve (V3)
, C) Facial nerve (CN VII)
D) Glossopharyngeal nerve (CN IX)
Rationale: The correct answer is A) Maxillary division of the trigeminal nerve
(V2) . The maxillary sinus is innervated by the posterior superior alveolar nerve,
middle superior alveolar nerve, and anterior superior alveolar nerve—all branches
of the maxillary division of the trigeminal nerve (V2). This innervation is clinically
relevant for diagnosing sinus pathology and for anesthesia considerations during
dental procedures in the maxillary posterior region.
9. The permanent maxillary first molar typically has how many roots?
A) One
B) Two
C) Three
D) Four
Rationale: The correct answer is C) Three. The permanent maxillary first molar
typically has three roots: two buccal (mesiobuccal and distobuccal) and one palatal
root. The mesiobuccal root is the most commonly affected by procedural errors due
to its curvature. The maxillary second molar typically has three roots fused, while
maxillary third molars show significant variation.
10. Which of the following represents Angle's Class I occlusion?
A) The mesiobuccal cusp of the maxillary first molar occludes in the buccal groove
of the mandibular first molar
B) The mesiobuccal cusp of the maxillary first molar occludes in the buccal
groove of the mandibular first molar
C) The mesiobuccal cusp of the maxillary first molar occludes distal to the buccal
groove of the mandibular first molar
D) The maxillary central incisors are in edge-to-edge relationship with the
mandibular incisors
Rationale: The correct answer is B) The mesiobuccal cusp of the maxillary first
molar occludes in the buccal groove of the mandibular first molar. Angle's
Class I occlusion (neutrocclusion) is defined as the mesiobuccal cusp of the
maxillary first molar occluding in the buccal groove of the mandibular first molar.
