RDH National Board Dental Hygiene Examination 2026
Latest Comprehensive Study Guide with Practice Questions
Clinical Dental Hygiene Review, Verified Answers, Detailed
Rationales, Success Workbook
QUESTION 1
The dental pulp is primarily composed of which type of connective tissue?
A) Dense regular connective tissue
B) Loose areolar connective tissue
C) Specialized loose connective tissue
D) Adipose tissue
ANSWER: C) Specialized loose connective tissue
RATIONALE: The dental pulp is composed of specialized loose connective tissue
that contains nerves, blood vessels, lymphatics, fibroblasts, and odontoblasts. It is
unique in that it is enclosed within the rigid dentin walls of the pulp chamber.
Dense regular connective tissue (A) is found in tendons and ligaments. Loose
areolar connective tissue (B) is found throughout the body but lacks the specialized
cellular components of pulp. Adipose tissue (D) is fat tissue.
QUESTION 2
What is the primary mechanism of action of local anesthetics?
A) Blocking sodium channels in the neuronal membrane
B) Blocking calcium channels in the neuronal membrane
C) Blocking potassium channels in the neuronal membrane
D) Blocking neurotransmitter release from the presynaptic terminal
ANSWER: A) Blocking sodium channels in the neuronal membrane
RATIONALE: Local anesthetics (e.g., lidocaine, bupivacaine) work by reversibly
blocking voltage-gated sodium channels in the neuronal membrane. This prevents
the influx of sodium ions required for depolarization, thereby blocking the
generation and propagation of action potentials. Calcium channels (B) are blocked
,by other drug classes. Potassium channels (C) are not the primary target.
Neurotransmitter release (D) is blocked by different mechanisms.
QUESTION 3
The cell type responsible for bone resorption is the:
A) Osteoblast
B) Osteocyte
C) Osteoclast
D) Chondrocyte
ANSWER: C) Osteoclast
RATIONALE: Osteoclasts are multinucleated cells responsible for bone
resorption (breakdown). They secrete acids and enzymes that dissolve bone
mineral and degrade the organic matrix. Osteoblasts (A) are responsible for bone
formation. Osteocytes (B) are mature bone cells that maintain bone tissue.
Chondrocytes (D) are cartilage cells.
QUESTION 4
Which of the following organisms is the most common cause of infective
endocarditis following dental procedures?
A) Staphylococcus aureus
B) Viridans group streptococci
C) Pseudomonas aeruginosa
D) Candida albicans
ANSWER: B) Viridans group streptococci
RATIONALE: Viridans group streptococci (particularly S. mutans and S.
sanguinis) are the most common cause of infective endocarditis following dental
procedures. These organisms are normal flora of the oral cavity and can enter the
bloodstream during dental procedures, adhering to damaged heart
valves. Staphylococcus aureus (A) is more commonly associated with skin
infections.
,QUESTION 5
The antibiotic of choice for prophylaxis against infective endocarditis in patients
allergic to penicillin is:
A) Amoxicillin
B) Cephalexin
C) Clindamycin
D) Tetracycline
ANSWER: C) Clindamycin
RATIONALE: For patients allergic to penicillin, the American Heart Association
recommends clindamycin (600 mg) as an alternative antibiotic for infective
endocarditis prophylaxis prior to dental procedures. Amoxicillin (A) is the first-
line choice for non-allergic patients but is contraindicated in penicillin-allergic
patients. Cephalexin (B) has cross-reactivity with penicillin in some patients.
QUESTION 6
Which cranial nerve provides motor innervation to the muscles of mastication?
A) Cranial nerve V (Trigeminal)
B) Cranial nerve VII (Facial)
C) Cranial nerve IX (Glossopharyngeal)
D) Cranial nerve XII (Hypoglossal)
ANSWER: A) Cranial nerve V (Trigeminal)
RATIONALE: The mandibular branch (V3) of the trigeminal nerve (cranial nerve
V) provides motor innervation to the muscles of mastication (masseter, temporalis,
medial pterygoid, lateral pterygoid). Cranial nerve VII (B) innervates the muscles
of facial expression. Cranial nerve IX (C) innervates the stylopharyngeus muscle.
QUESTION 7
Which of the following vitamins is essential for blood coagulation?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
, ANSWER: D) Vitamin K
RATIONALE: Vitamin K is essential for the synthesis of several clotting factors
(Factors II, VII, IX, X) in the liver. Vitamin A (A) is important for vision and
epithelial health. Vitamin C (B) is important for collagen synthesis. Vitamin D (C)
is important for calcium metabolism and bone health.
QUESTION 8
The normal resting pH of saliva is approximately:
A) 5.0-5.5
B) 6.2-7.6
C) 7.8-8.2
D) 4.0-4.5
ANSWER: B) 6.2-7.6
RATIONALE: The normal resting pH of saliva ranges from approximately 6.2 to
7.6, with an average around 6.8. This slightly acidic to neutral pH provides optimal
conditions for oral health. Saliva's buffering capacity helps maintain this pH. A pH
below 5.5 (A) would be associated with enamel demineralization. Alkaline pH (C)
is not typical for resting saliva.
QUESTION 9
Which of the following is a dental anomaly characterized by incomplete
development of enamel, resulting in pits and grooves?
A) Amelogenesis imperfecta
B) Dentinogenesis imperfecta
C) Fluorosis
D) Enamel hypoplasia
ANSWER: D) Enamel hypoplasia
RATIONALE: Enamel hypoplasia is a defect in enamel formation resulting in
incomplete development of enamel, characterized by pits, grooves, or missing
enamel. Amelogenesis imperfecta (A) is a genetic disorder affecting enamel
formation. Dentinogenesis imperfecta (B) affects dentin formation. Fluorosis (C)
results from excessive fluoride intake.
Latest Comprehensive Study Guide with Practice Questions
Clinical Dental Hygiene Review, Verified Answers, Detailed
Rationales, Success Workbook
QUESTION 1
The dental pulp is primarily composed of which type of connective tissue?
A) Dense regular connective tissue
B) Loose areolar connective tissue
C) Specialized loose connective tissue
D) Adipose tissue
ANSWER: C) Specialized loose connective tissue
RATIONALE: The dental pulp is composed of specialized loose connective tissue
that contains nerves, blood vessels, lymphatics, fibroblasts, and odontoblasts. It is
unique in that it is enclosed within the rigid dentin walls of the pulp chamber.
Dense regular connective tissue (A) is found in tendons and ligaments. Loose
areolar connective tissue (B) is found throughout the body but lacks the specialized
cellular components of pulp. Adipose tissue (D) is fat tissue.
QUESTION 2
What is the primary mechanism of action of local anesthetics?
A) Blocking sodium channels in the neuronal membrane
B) Blocking calcium channels in the neuronal membrane
C) Blocking potassium channels in the neuronal membrane
D) Blocking neurotransmitter release from the presynaptic terminal
ANSWER: A) Blocking sodium channels in the neuronal membrane
RATIONALE: Local anesthetics (e.g., lidocaine, bupivacaine) work by reversibly
blocking voltage-gated sodium channels in the neuronal membrane. This prevents
the influx of sodium ions required for depolarization, thereby blocking the
generation and propagation of action potentials. Calcium channels (B) are blocked
,by other drug classes. Potassium channels (C) are not the primary target.
Neurotransmitter release (D) is blocked by different mechanisms.
QUESTION 3
The cell type responsible for bone resorption is the:
A) Osteoblast
B) Osteocyte
C) Osteoclast
D) Chondrocyte
ANSWER: C) Osteoclast
RATIONALE: Osteoclasts are multinucleated cells responsible for bone
resorption (breakdown). They secrete acids and enzymes that dissolve bone
mineral and degrade the organic matrix. Osteoblasts (A) are responsible for bone
formation. Osteocytes (B) are mature bone cells that maintain bone tissue.
Chondrocytes (D) are cartilage cells.
QUESTION 4
Which of the following organisms is the most common cause of infective
endocarditis following dental procedures?
A) Staphylococcus aureus
B) Viridans group streptococci
C) Pseudomonas aeruginosa
D) Candida albicans
ANSWER: B) Viridans group streptococci
RATIONALE: Viridans group streptococci (particularly S. mutans and S.
sanguinis) are the most common cause of infective endocarditis following dental
procedures. These organisms are normal flora of the oral cavity and can enter the
bloodstream during dental procedures, adhering to damaged heart
valves. Staphylococcus aureus (A) is more commonly associated with skin
infections.
,QUESTION 5
The antibiotic of choice for prophylaxis against infective endocarditis in patients
allergic to penicillin is:
A) Amoxicillin
B) Cephalexin
C) Clindamycin
D) Tetracycline
ANSWER: C) Clindamycin
RATIONALE: For patients allergic to penicillin, the American Heart Association
recommends clindamycin (600 mg) as an alternative antibiotic for infective
endocarditis prophylaxis prior to dental procedures. Amoxicillin (A) is the first-
line choice for non-allergic patients but is contraindicated in penicillin-allergic
patients. Cephalexin (B) has cross-reactivity with penicillin in some patients.
QUESTION 6
Which cranial nerve provides motor innervation to the muscles of mastication?
A) Cranial nerve V (Trigeminal)
B) Cranial nerve VII (Facial)
C) Cranial nerve IX (Glossopharyngeal)
D) Cranial nerve XII (Hypoglossal)
ANSWER: A) Cranial nerve V (Trigeminal)
RATIONALE: The mandibular branch (V3) of the trigeminal nerve (cranial nerve
V) provides motor innervation to the muscles of mastication (masseter, temporalis,
medial pterygoid, lateral pterygoid). Cranial nerve VII (B) innervates the muscles
of facial expression. Cranial nerve IX (C) innervates the stylopharyngeus muscle.
QUESTION 7
Which of the following vitamins is essential for blood coagulation?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
, ANSWER: D) Vitamin K
RATIONALE: Vitamin K is essential for the synthesis of several clotting factors
(Factors II, VII, IX, X) in the liver. Vitamin A (A) is important for vision and
epithelial health. Vitamin C (B) is important for collagen synthesis. Vitamin D (C)
is important for calcium metabolism and bone health.
QUESTION 8
The normal resting pH of saliva is approximately:
A) 5.0-5.5
B) 6.2-7.6
C) 7.8-8.2
D) 4.0-4.5
ANSWER: B) 6.2-7.6
RATIONALE: The normal resting pH of saliva ranges from approximately 6.2 to
7.6, with an average around 6.8. This slightly acidic to neutral pH provides optimal
conditions for oral health. Saliva's buffering capacity helps maintain this pH. A pH
below 5.5 (A) would be associated with enamel demineralization. Alkaline pH (C)
is not typical for resting saliva.
QUESTION 9
Which of the following is a dental anomaly characterized by incomplete
development of enamel, resulting in pits and grooves?
A) Amelogenesis imperfecta
B) Dentinogenesis imperfecta
C) Fluorosis
D) Enamel hypoplasia
ANSWER: D) Enamel hypoplasia
RATIONALE: Enamel hypoplasia is a defect in enamel formation resulting in
incomplete development of enamel, characterized by pits, grooves, or missing
enamel. Amelogenesis imperfecta (A) is a genetic disorder affecting enamel
formation. Dentinogenesis imperfecta (B) affects dentin formation. Fluorosis (C)
results from excessive fluoride intake.
