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TEST BANK FOR LOCAL ANESTHESIA FOR
DENTAL PROFESSIONALS
100 High-Yield Q&A with Verified Rationales
Updated for 2026-2027 Examinations
1. PHARMACOLOGY OF LOCAL ANESTHETICS
Question 1
A 45-year-old patient requires extraction of tooth #19. Which property
of a local anesthetic determines the duration of action?
A. Lipid solubility
B. Protein binding
C. pKa
D. Vasodilating activity
Answer: B. Protein binding
Rationale: The duration of action of a local anesthetic is primarily
determined by its protein-binding affinity. Agents with higher protein
binding (e.g., bupivacaine, 95% protein bound) remain in the tissue
longer, providing prolonged anesthesia. Lipid solubility (A) affects
potency, not duration. pKa (C) affects onset of action. Vasodilating
activity (D) affects duration indirectly but is not the primary
determinant.
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Exam Tip: Protein binding % = duration ranking:
• Bupivacaine (95%) → Long duration (3-8 hours)
• Ropivacaine (94%) → Long duration
• Lidocaine (65%) → Intermediate duration (1-2 hours)
• Mepivacaine (75%) → Intermediate duration
• Prilocaine (55%) → Intermediate duration
Question 2
Which physicochemical property most directly influences the onset
time of a local anesthetic?
A. Molecular weight
B. pKa relative to physiologic pH
C. Degree of vasodilation
D. Protein binding capacity
Answer: B. pKa relative to physiologic pH
Rationale: The pKa determines the proportion of drug that exists in the
un-ionized (lipid-soluble) form at tissue pH. Local anesthetics with pKa
closer to physiologic pH (7.4) have more un-ionized molecules available
to cross the nerve sheath and membrane. Lidocaine (pKa 7.7) has faster
onset than bupivacaine (pKa 8.1) or prilocaine (pKa 7.9).
Exam Tip: In inflamed tissue (acidic pH), onset is delayed because
more drug exists in the ionized (charged) form that cannot cross the
nerve membrane.
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Question 3
A dental hygienist is preparing to administer local anesthesia for scaling
and root planing. Which statement accurately describes the mechanism
of action of amide local anesthetics?
A. Blockade of sodium channels in the inactivated state
B. Inhibition of potassium efflux during repolarization
C. Antagonism of calcium channels at the presynaptic terminal
D. Enhancement of GABA-mediated chloride influx
Answer: A. Blockade of sodium channels in the inactivated state
Rationale: Amide local anesthetics bind to the intracellular portion of
voltage-gated sodium channels, preferentially in the inactivated state,
preventing sodium influx and subsequent depolarization. This raises the
threshold for excitation and blocks action potential propagation. Options
B, C, and D describe mechanisms of other drug classes.
Exam Tip: "Use-dependent blockade" means that rapidly firing nerves
(pain fibers) are more susceptible to local anesthetic blockade than
resting nerves.
Question 4
A patient with a history of methemoglobinemia requires local
anesthesia. Which local anesthetic should be avoided?
A. Lidocaine
B. Articaine
C. Prilocaine
D. Mepivacaine
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Answer: C. Prilocaine
Rationale: Prilocaine is metabolized to ortho-toluidine, which can
oxidize hemoglobin to methemoglobin. In patients with congenital or
acquired methemoglobinemia, or with high doses, this can precipitate
clinically significant methemoglobinemia (cyanosis, chocolate-brown
blood). Articaine (B) also has a slight risk but is less significant than
prilocaine.
Exam Tip: Maximum recommended dose of prilocaine is 8
mg/kg (lower than lidocaine's 7 mg/kg? Actually lidocaine is 7 mg/kg
with epi; prilocaine is 8 mg/kg). Monitor for cyanosis that does not
respond to oxygen.
Question 5
Which statement correctly compares ester and amide local anesthetics?
A. Esters are metabolized in the liver; amides are metabolized in plasma
B. Esters carry a higher risk of allergic reactions than amides
C. Amides contain a benzoyl ring; esters contain a benzene ring
D. Esters are more stable in solution than amides
Answer: B. Esters carry a higher risk of allergic reactions than
amides
Rationale: Ester local anesthetics (procaine, benzocaine, tetracaine) are
metabolized to para-aminobenzoic acid (PABA) , which is a common
allergen. True allergic reactions to amides (lidocaine, mepivacaine,
articaine) are extremely rare. Esters are metabolized in plasma by
TEST BANK FOR LOCAL ANESTHESIA FOR
DENTAL PROFESSIONALS
100 High-Yield Q&A with Verified Rationales
Updated for 2026-2027 Examinations
1. PHARMACOLOGY OF LOCAL ANESTHETICS
Question 1
A 45-year-old patient requires extraction of tooth #19. Which property
of a local anesthetic determines the duration of action?
A. Lipid solubility
B. Protein binding
C. pKa
D. Vasodilating activity
Answer: B. Protein binding
Rationale: The duration of action of a local anesthetic is primarily
determined by its protein-binding affinity. Agents with higher protein
binding (e.g., bupivacaine, 95% protein bound) remain in the tissue
longer, providing prolonged anesthesia. Lipid solubility (A) affects
potency, not duration. pKa (C) affects onset of action. Vasodilating
activity (D) affects duration indirectly but is not the primary
determinant.
,2|Page
Exam Tip: Protein binding % = duration ranking:
• Bupivacaine (95%) → Long duration (3-8 hours)
• Ropivacaine (94%) → Long duration
• Lidocaine (65%) → Intermediate duration (1-2 hours)
• Mepivacaine (75%) → Intermediate duration
• Prilocaine (55%) → Intermediate duration
Question 2
Which physicochemical property most directly influences the onset
time of a local anesthetic?
A. Molecular weight
B. pKa relative to physiologic pH
C. Degree of vasodilation
D. Protein binding capacity
Answer: B. pKa relative to physiologic pH
Rationale: The pKa determines the proportion of drug that exists in the
un-ionized (lipid-soluble) form at tissue pH. Local anesthetics with pKa
closer to physiologic pH (7.4) have more un-ionized molecules available
to cross the nerve sheath and membrane. Lidocaine (pKa 7.7) has faster
onset than bupivacaine (pKa 8.1) or prilocaine (pKa 7.9).
Exam Tip: In inflamed tissue (acidic pH), onset is delayed because
more drug exists in the ionized (charged) form that cannot cross the
nerve membrane.
,3|Page
Question 3
A dental hygienist is preparing to administer local anesthesia for scaling
and root planing. Which statement accurately describes the mechanism
of action of amide local anesthetics?
A. Blockade of sodium channels in the inactivated state
B. Inhibition of potassium efflux during repolarization
C. Antagonism of calcium channels at the presynaptic terminal
D. Enhancement of GABA-mediated chloride influx
Answer: A. Blockade of sodium channels in the inactivated state
Rationale: Amide local anesthetics bind to the intracellular portion of
voltage-gated sodium channels, preferentially in the inactivated state,
preventing sodium influx and subsequent depolarization. This raises the
threshold for excitation and blocks action potential propagation. Options
B, C, and D describe mechanisms of other drug classes.
Exam Tip: "Use-dependent blockade" means that rapidly firing nerves
(pain fibers) are more susceptible to local anesthetic blockade than
resting nerves.
Question 4
A patient with a history of methemoglobinemia requires local
anesthesia. Which local anesthetic should be avoided?
A. Lidocaine
B. Articaine
C. Prilocaine
D. Mepivacaine
, 4|Page
Answer: C. Prilocaine
Rationale: Prilocaine is metabolized to ortho-toluidine, which can
oxidize hemoglobin to methemoglobin. In patients with congenital or
acquired methemoglobinemia, or with high doses, this can precipitate
clinically significant methemoglobinemia (cyanosis, chocolate-brown
blood). Articaine (B) also has a slight risk but is less significant than
prilocaine.
Exam Tip: Maximum recommended dose of prilocaine is 8
mg/kg (lower than lidocaine's 7 mg/kg? Actually lidocaine is 7 mg/kg
with epi; prilocaine is 8 mg/kg). Monitor for cyanosis that does not
respond to oxygen.
Question 5
Which statement correctly compares ester and amide local anesthetics?
A. Esters are metabolized in the liver; amides are metabolized in plasma
B. Esters carry a higher risk of allergic reactions than amides
C. Amides contain a benzoyl ring; esters contain a benzene ring
D. Esters are more stable in solution than amides
Answer: B. Esters carry a higher risk of allergic reactions than
amides
Rationale: Ester local anesthetics (procaine, benzocaine, tetracaine) are
metabolized to para-aminobenzoic acid (PABA) , which is a common
allergen. True allergic reactions to amides (lidocaine, mepivacaine,
articaine) are extremely rare. Esters are metabolized in plasma by
