NDEB Assessment of Fundamental Knowledge
(AFK) & Clinical Decision Making National Dental
Examining Board of Canada (NDEB) 150 Original
Practice Questions with Rationales
DOMAIN 1: Oral Anatomy & Histology (Questions 1-15)
1. Which tooth in the permanent dentition most commonly exhibits a C-shaped root canal
morphology?
A) Maxillary first molar
B) Mandibular first molar
C) Mandibular second molar
D) Maxillary second premolar
Answer: C) Mandibular second molar
Rationale: C-shaped root canals are most frequently found in mandibular second molars,
particularly in certain ethnic populations.
2. The cementoenamel junction (CEJ) of a tooth typically overlaps the cementum over enamel
in what percentage of cases?
A) 10%
B) 30%
C) 60%
D) 90%
Answer: C) 60%
Rationale: The CEJ has three relationships: cementum over enamel (~60%), edge-to-edge
(~30%), and gap with exposed dentin (~10%).
3. Which papilla on the tongue is responsible for the majority of taste sensation?
A) Filiform papillae
B) Fungiform papillae
C) Circumvallate papillae
D) Foliate papillae
Answer: B) Fungiform papillae
, Rationale: Fungiform papillae contain taste buds on their superior surface. Filiform papillae
are mechanical (no taste).
4. The maxillary first molar has how many roots?
A) Two
B) Three
C) Four
D) One
Answer: B) Three
Rationale: Maxillary first molars typically have three roots (mesiobuccal, distobuccal, palatal).
5. Which muscle is the primary protractor of the mandible?
A) Temporalis
B) Masseter
C) Lateral pterygoid
D) Medial pterygoid
Answer: C) Lateral pterygoid
Rationale: The lateral pterygoid attaches to the condyle and disc; bilateral contraction
protrudes the mandible.
6. The parotid gland's duct (Stensen's duct) opens into the oral cavity opposite which tooth?
A) Maxillary first premolar
B) Maxillary second molar
C) Mandibular first molar
D) Mandibular second premolar
Answer: B) Maxillary second molar
Rationale: Stensen's duct opens on the buccal mucosa near the maxillary second molar.
7. Which nerve provides sensory innervation to the maxillary posterior teeth?
A) Anterior superior alveolar nerve
B) Middle superior alveolar nerve
C) Posterior superior alveolar nerve
D) Inferior alveolar nerve
Answer: C) Posterior superior alveolar nerve
, Rationale: The PSA nerve branches from the maxillary nerve (V2) before entering the
infraorbital canal.
8. The mandibular foramen is located on which surface of the mandible?
A) Lateral surface of the ramus
B) Medial surface of the ramus
C) Anterior surface of the body
D) Posterior surface of the body
Answer: B) Medial surface of the ramus
Rationale: The mandibular foramen is on the medial surface of the ramus, transmitting the
inferior alveolar nerve.
9. Which tooth in the primary dentition is the last to erupt?
A) Primary maxillary central incisor
B) Primary mandibular first molar
C) Primary maxillary second molar
D) Primary mandibular second molar
Answer: D) Primary mandibular second molar
Rationale: The primary mandibular second molar erupts around 24-30 months, last of the
primary dentition.
10. The junction between the crown and root of a tooth is called the:
A) Cervical line
B) Apical foramen
C) Pulp chamber
D) Furcation
Answer: A) Cervical line
Rationale: The cervical line (CEJ) demarcates the anatomical crown from the root.
11. Which of the following is NOT a muscle of mastication?
A) Masseter
B) Temporalis
C) Buccinator
D) Medial pterygoid
Answer: C) Buccinator
Rationale: The buccinator is a facial muscle (cheek), not a primary masticatory muscle.
, 12. The incisive papilla is located:
A) On the buccal mucosa
B) On the hard palate behind the maxillary central incisors
C) On the ventral tongue
D) On the soft palate
Answer: B) On the hard palate behind the maxillary central incisors
Rationale: The incisive papilla overlies the nasopalatine foramen and is a landmark for the
nasopalatine nerve block.
13. The permanent mandibular first molar typically has how many cusps?
A) Three
B) Four
C) Five
D) Six
Answer: C) Five
Rationale: The mandibular first molar has five cusps: mesiobuccal, mesiolingual, distobuccal,
distolingual, and distal.
14. Which structure forms the roof of the infratemporal fossa?
A) Maxilla
B) Sphenoid bone (greater wing)
C) Temporal bone
D) Zygomatic bone
Answer: B) Sphenoid bone (greater wing)
Rationale: The greater wing of the sphenoid forms the superior boundary of the infratemporal
fossa.
15. The lingual nerve carries which type of fibers?
A) Only motor fibers
B) General sensation (touch, pain, temperature) from anterior 2/3 of tongue
C) Only taste fibers
D) Sympathetic fibers only
Answer: B) General sensation (touch, pain, temperature) from anterior 2/3 of tongue
Rationale: The lingual nerve (branch of mandibular V3) carries general sensation; taste is
carried by chorda tympani.
(AFK) & Clinical Decision Making National Dental
Examining Board of Canada (NDEB) 150 Original
Practice Questions with Rationales
DOMAIN 1: Oral Anatomy & Histology (Questions 1-15)
1. Which tooth in the permanent dentition most commonly exhibits a C-shaped root canal
morphology?
A) Maxillary first molar
B) Mandibular first molar
C) Mandibular second molar
D) Maxillary second premolar
Answer: C) Mandibular second molar
Rationale: C-shaped root canals are most frequently found in mandibular second molars,
particularly in certain ethnic populations.
2. The cementoenamel junction (CEJ) of a tooth typically overlaps the cementum over enamel
in what percentage of cases?
A) 10%
B) 30%
C) 60%
D) 90%
Answer: C) 60%
Rationale: The CEJ has three relationships: cementum over enamel (~60%), edge-to-edge
(~30%), and gap with exposed dentin (~10%).
3. Which papilla on the tongue is responsible for the majority of taste sensation?
A) Filiform papillae
B) Fungiform papillae
C) Circumvallate papillae
D) Foliate papillae
Answer: B) Fungiform papillae
, Rationale: Fungiform papillae contain taste buds on their superior surface. Filiform papillae
are mechanical (no taste).
4. The maxillary first molar has how many roots?
A) Two
B) Three
C) Four
D) One
Answer: B) Three
Rationale: Maxillary first molars typically have three roots (mesiobuccal, distobuccal, palatal).
5. Which muscle is the primary protractor of the mandible?
A) Temporalis
B) Masseter
C) Lateral pterygoid
D) Medial pterygoid
Answer: C) Lateral pterygoid
Rationale: The lateral pterygoid attaches to the condyle and disc; bilateral contraction
protrudes the mandible.
6. The parotid gland's duct (Stensen's duct) opens into the oral cavity opposite which tooth?
A) Maxillary first premolar
B) Maxillary second molar
C) Mandibular first molar
D) Mandibular second premolar
Answer: B) Maxillary second molar
Rationale: Stensen's duct opens on the buccal mucosa near the maxillary second molar.
7. Which nerve provides sensory innervation to the maxillary posterior teeth?
A) Anterior superior alveolar nerve
B) Middle superior alveolar nerve
C) Posterior superior alveolar nerve
D) Inferior alveolar nerve
Answer: C) Posterior superior alveolar nerve
, Rationale: The PSA nerve branches from the maxillary nerve (V2) before entering the
infraorbital canal.
8. The mandibular foramen is located on which surface of the mandible?
A) Lateral surface of the ramus
B) Medial surface of the ramus
C) Anterior surface of the body
D) Posterior surface of the body
Answer: B) Medial surface of the ramus
Rationale: The mandibular foramen is on the medial surface of the ramus, transmitting the
inferior alveolar nerve.
9. Which tooth in the primary dentition is the last to erupt?
A) Primary maxillary central incisor
B) Primary mandibular first molar
C) Primary maxillary second molar
D) Primary mandibular second molar
Answer: D) Primary mandibular second molar
Rationale: The primary mandibular second molar erupts around 24-30 months, last of the
primary dentition.
10. The junction between the crown and root of a tooth is called the:
A) Cervical line
B) Apical foramen
C) Pulp chamber
D) Furcation
Answer: A) Cervical line
Rationale: The cervical line (CEJ) demarcates the anatomical crown from the root.
11. Which of the following is NOT a muscle of mastication?
A) Masseter
B) Temporalis
C) Buccinator
D) Medial pterygoid
Answer: C) Buccinator
Rationale: The buccinator is a facial muscle (cheek), not a primary masticatory muscle.
, 12. The incisive papilla is located:
A) On the buccal mucosa
B) On the hard palate behind the maxillary central incisors
C) On the ventral tongue
D) On the soft palate
Answer: B) On the hard palate behind the maxillary central incisors
Rationale: The incisive papilla overlies the nasopalatine foramen and is a landmark for the
nasopalatine nerve block.
13. The permanent mandibular first molar typically has how many cusps?
A) Three
B) Four
C) Five
D) Six
Answer: C) Five
Rationale: The mandibular first molar has five cusps: mesiobuccal, mesiolingual, distobuccal,
distolingual, and distal.
14. Which structure forms the roof of the infratemporal fossa?
A) Maxilla
B) Sphenoid bone (greater wing)
C) Temporal bone
D) Zygomatic bone
Answer: B) Sphenoid bone (greater wing)
Rationale: The greater wing of the sphenoid forms the superior boundary of the infratemporal
fossa.
15. The lingual nerve carries which type of fibers?
A) Only motor fibers
B) General sensation (touch, pain, temperature) from anterior 2/3 of tongue
C) Only taste fibers
D) Sympathetic fibers only
Answer: B) General sensation (touch, pain, temperature) from anterior 2/3 of tongue
Rationale: The lingual nerve (branch of mandibular V3) carries general sensation; taste is
carried by chorda tympani.
