NATIONAL BOARD DENTAL HYGIENE EXAMINATION
(NBDHE) EXAM PRACTICE QUESTIONS AND
CORRECT ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALE 2026 Q&A| INSTANT DOWNLOAD PDF
1. Which type of epithelium lines the gingival sulcus?
A. Keratinized stratified squamous epithelium
B. Junctional epithelium
C. Nonkeratinized stratified squamous epithelium
D. Simple squamous epithelium
Rationale: The gingival sulcus is lined by nonkeratinized
stratified squamous epithelium. This tissue allows flexibility and
provides protection while lacking the keratinized surface layer
found in the outer gingiva. Understanding gingival histology is
essential for assessing periodontal health and disease.
2. Which cranial nerve provides sensory innervation to the
maxillary teeth?
A. Facial nerve (CN VII)
B. Glossopharyngeal nerve (CN IX)
C. Trigeminal nerve (CN V) – maxillary division
D. Hypoglossal nerve (CN XII)
Rationale: The maxillary division (V2) of the trigeminal nerve
supplies sensory innervation to the maxillary teeth and
associated structures. Knowledge of cranial nerve anatomy is
critical for pain assessment and local anesthesia administration.
, 3. Which microorganism is most strongly associated with
dental caries initiation?
A. Porphyromonas gingivalis
B. Streptococcus mutans
C. Actinobacillus actinomycetemcomitans
D. Fusobacterium nucleatum
Rationale: Streptococcus mutans is highly cariogenic because it
metabolizes sugars into acids and thrives in low-pH
environments. It is considered a primary pathogen in caries
initiation.
4. What is the normal pH range of saliva?
A. 4.0–5.0
B. 5.0–6.0
C. 6.2–7.6
D. 8.0–9.0
Rationale: Normal saliva typically ranges from slightly acidic to
slightly alkaline. This buffering capacity helps neutralize acids
and protect against demineralization.
5. Which tooth usually erupts first in the permanent
dentition?
A. Maxillary central incisor
B. Mandibular first molar
C. Maxillary canine
D. Mandibular second premolar
Rationale: The mandibular first molar commonly erupts around
age six and is often referred to as the "six-year molar." It usually
erupts before any permanent incisors.
, 6. Which periodontal fiber group attaches cementum to
alveolar bone?
A. Transseptal fibers
B. Circular fibers
C. Alveolar crest fibers
D. Dentogingival fibers
Rationale: Alveolar crest fibers extend from cementum to the
alveolar crest and help resist lateral tooth movement while
supporting periodontal attachment.
7. Which vitamin deficiency is associated with scurvy?
A. Vitamin A
B. Vitamin D
C. Vitamin C
D. Vitamin K
Rationale: Vitamin C is essential for collagen synthesis.
Deficiency results in scurvy, characterized by bleeding gums,
delayed wound healing, and connective tissue weakness.
8. The primary inorganic component of enamel is:
A. Calcium carbonate
B. Fluorapatite
C. Hydroxyapatite
D. Calcium phosphate
Rationale: Enamel is composed primarily of hydroxyapatite
crystals, which provide hardness and resistance to wear.
Fluoride can convert hydroxyapatite into more acid-resistant
fluorapatite.
, 9. Which index measures oral hygiene by evaluating debris
and calculus?
A. CPITN
B. Gingival Index
C. OHI-S
D. Plaque Index
Rationale: The Simplified Oral Hygiene Index (OHI-S) evaluates
oral cleanliness by measuring debris and calculus accumulation
on selected tooth surfaces.
10. Which type of bone is most commonly found
between maxillary anterior teeth?
A. Dense cortical bone
B. Thin cortical plate with cancellous bone
C. Compact bone only
D. Trabecular bone only
Rationale: Maxillary anterior bone is generally thin and
composed of cortical plates surrounding cancellous bone. This
anatomy influences periodontal disease progression and
radiographic interpretation.
11. What is the principal cause of gingivitis?
A. Trauma from occlusion
B. Calculus alone
C. Dental plaque biofilm
D. Genetic disorders
(NBDHE) EXAM PRACTICE QUESTIONS AND
CORRECT ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALE 2026 Q&A| INSTANT DOWNLOAD PDF
1. Which type of epithelium lines the gingival sulcus?
A. Keratinized stratified squamous epithelium
B. Junctional epithelium
C. Nonkeratinized stratified squamous epithelium
D. Simple squamous epithelium
Rationale: The gingival sulcus is lined by nonkeratinized
stratified squamous epithelium. This tissue allows flexibility and
provides protection while lacking the keratinized surface layer
found in the outer gingiva. Understanding gingival histology is
essential for assessing periodontal health and disease.
2. Which cranial nerve provides sensory innervation to the
maxillary teeth?
A. Facial nerve (CN VII)
B. Glossopharyngeal nerve (CN IX)
C. Trigeminal nerve (CN V) – maxillary division
D. Hypoglossal nerve (CN XII)
Rationale: The maxillary division (V2) of the trigeminal nerve
supplies sensory innervation to the maxillary teeth and
associated structures. Knowledge of cranial nerve anatomy is
critical for pain assessment and local anesthesia administration.
, 3. Which microorganism is most strongly associated with
dental caries initiation?
A. Porphyromonas gingivalis
B. Streptococcus mutans
C. Actinobacillus actinomycetemcomitans
D. Fusobacterium nucleatum
Rationale: Streptococcus mutans is highly cariogenic because it
metabolizes sugars into acids and thrives in low-pH
environments. It is considered a primary pathogen in caries
initiation.
4. What is the normal pH range of saliva?
A. 4.0–5.0
B. 5.0–6.0
C. 6.2–7.6
D. 8.0–9.0
Rationale: Normal saliva typically ranges from slightly acidic to
slightly alkaline. This buffering capacity helps neutralize acids
and protect against demineralization.
5. Which tooth usually erupts first in the permanent
dentition?
A. Maxillary central incisor
B. Mandibular first molar
C. Maxillary canine
D. Mandibular second premolar
Rationale: The mandibular first molar commonly erupts around
age six and is often referred to as the "six-year molar." It usually
erupts before any permanent incisors.
, 6. Which periodontal fiber group attaches cementum to
alveolar bone?
A. Transseptal fibers
B. Circular fibers
C. Alveolar crest fibers
D. Dentogingival fibers
Rationale: Alveolar crest fibers extend from cementum to the
alveolar crest and help resist lateral tooth movement while
supporting periodontal attachment.
7. Which vitamin deficiency is associated with scurvy?
A. Vitamin A
B. Vitamin D
C. Vitamin C
D. Vitamin K
Rationale: Vitamin C is essential for collagen synthesis.
Deficiency results in scurvy, characterized by bleeding gums,
delayed wound healing, and connective tissue weakness.
8. The primary inorganic component of enamel is:
A. Calcium carbonate
B. Fluorapatite
C. Hydroxyapatite
D. Calcium phosphate
Rationale: Enamel is composed primarily of hydroxyapatite
crystals, which provide hardness and resistance to wear.
Fluoride can convert hydroxyapatite into more acid-resistant
fluorapatite.
, 9. Which index measures oral hygiene by evaluating debris
and calculus?
A. CPITN
B. Gingival Index
C. OHI-S
D. Plaque Index
Rationale: The Simplified Oral Hygiene Index (OHI-S) evaluates
oral cleanliness by measuring debris and calculus accumulation
on selected tooth surfaces.
10. Which type of bone is most commonly found
between maxillary anterior teeth?
A. Dense cortical bone
B. Thin cortical plate with cancellous bone
C. Compact bone only
D. Trabecular bone only
Rationale: Maxillary anterior bone is generally thin and
composed of cortical plates surrounding cancellous bone. This
anatomy influences periodontal disease progression and
radiographic interpretation.
11. What is the principal cause of gingivitis?
A. Trauma from occlusion
B. Calculus alone
C. Dental plaque biofilm
D. Genetic disorders
