Modern Dental Assisting Chapter 37
Principles Test Bank Review 2025
Local Anesthesia - Method of Action
What is the primary method of action of local anesthesia?
A. By permanently damaging the nerve membrane
B. By numbing only the surface tissues
C. By reducing blood flow to the affected area
D. By injecting an anesthetic solution near a nerve, where treatment is to take place,
temporarily blocking the ability of the nerve membrane to generate an impulse
Rationale: Local anesthesia works by blocking sodium channels in the nerve membrane,
preventing nerve impulse transmission. It does not permanently damage nerves (A), only numb
the surface (B), or reduce blood flow (C).
Local Anesthesia - Ester
Which type of anesthetic solution is primarily used topically and metabolized in the plasma?
A. Amides
B. Esters
C. Nitrous oxide
D. Local infiltration agents
Rationale: Esters are mainly used as topical anesthetics and are hydrolyzed in the plasma.
Amides (A) are metabolized in the liver, nitrous oxide (C) is inhalation-based, and infiltration
agents (D) are techniques, not drug classes.
Local Anesthesia - Amides
Which statement best describes amides?
A. They are metabolized in the plasma.
B. They are primarily used as local anesthetics and metabolized by the liver.
C. They are only used as inhalation agents.
D. They are mainly used as sedatives.
Rationale: Amides are local anesthetics metabolized in the liver. Esters (A) are plasma
metabolized. Options C and D describe unrelated drug classes.
,Local Anesthesia - L/A drugs
What determines the choice of local anesthetic drugs?
A. Only the cost of the drug
B. The color of the cartridge
C. The procedure, patient’s health, and dentist’s preference
D. The size of the needle used
Rationale: Choice depends on clinical procedure, patient’s health, and the dentist’s judgment.
Cost (A) and cartridge color (B) are not primary factors, while needle size (D) relates to delivery,
not drug selection.
Local Anesthesia - Sodium chloride
Why is sodium chloride added to local anesthetic solutions?
A. To increase potency of the drug
B. To act as a preservative
C. To make the solution isotonic with body tissue
D. To reduce toxicity
Rationale: Sodium chloride ensures isotonicity, preventing irritation. It does not increase
potency (A), act as preservative (B), or reduce toxicity (D).
Local Anesthesia - Distilled water
What role does distilled water play in anesthetic solutions?
A. Enhances anesthesia duration
B. Reduces adverse effects
C. Provides an added volume of solution
D. Improves tissue penetration
Rationale: Distilled water is a diluent that increases volume. It doesn’t directly affect duration
(A), reduce side effects (B), or enhance penetration (D).
Local Anesthesia – Time span: Short acting
What is the typical duration of short-acting local anesthetics?
A. 30 to 90 minutes
B. 60 to 180 minutes
C. 240 to 540 minutes
D. 120 to 240 minutes
Rationale: Short-acting agents last 60–180 minutes. Option A underestimates duration, option C
describes long-acting, and option D describes intermediate-acting.
, Local Anesthesia – Time span: Intermediate acting
Intermediate-acting local anesthetics usually last:
A. 30 to 60 minutes
B. 120 to 240 minutes
C. 60 to 180 minutes
D. 240 to 540 minutes
Rationale: Intermediate agents last 120–240 minutes and are the most commonly used for
routine dental care. A is too short, C is short-acting, and D is long-acting.
Local Anesthesia – Time span: Long acting
How long do long-acting local anesthetics last?
A. 60 to 180 minutes
B. 120 to 240 minutes
C. 240 to 540 minutes
D. 30 to 60 minutes
Rationale: Long-acting agents provide anesthesia for 240–540 minutes. A and B are shorter
durations, and D is far too short.
Injection – Maxillary Arch
What are the three major types of anesthetic injections used in the maxillary arch?
A. Field block, mandibular block, general anesthesia
B. Local infiltration, general anesthesia, nerve block
C. Local infiltration, field block, nerve block
D. Buccal block, incisive block, infiltration
Rationale: Maxillary anesthesia is achieved through local infiltration, field block, or nerve
block. A and B incorrectly include general anesthesia. D lists mandibular injections.
Injection – Local Infiltration (Maxillary)
Which injection technique is used to anesthetize a small, isolated area in the maxillary arch?
A. Nerve block
B. Field block
C. Local infiltration
D. Buccal nerve block
Rationale: Local infiltration targets a small localized area. Field block (B) covers a larger
terminal nerve branch, nerve block (A) targets a main nerve trunk, and buccal block (D) is
mandibular.
Principles Test Bank Review 2025
Local Anesthesia - Method of Action
What is the primary method of action of local anesthesia?
A. By permanently damaging the nerve membrane
B. By numbing only the surface tissues
C. By reducing blood flow to the affected area
D. By injecting an anesthetic solution near a nerve, where treatment is to take place,
temporarily blocking the ability of the nerve membrane to generate an impulse
Rationale: Local anesthesia works by blocking sodium channels in the nerve membrane,
preventing nerve impulse transmission. It does not permanently damage nerves (A), only numb
the surface (B), or reduce blood flow (C).
Local Anesthesia - Ester
Which type of anesthetic solution is primarily used topically and metabolized in the plasma?
A. Amides
B. Esters
C. Nitrous oxide
D. Local infiltration agents
Rationale: Esters are mainly used as topical anesthetics and are hydrolyzed in the plasma.
Amides (A) are metabolized in the liver, nitrous oxide (C) is inhalation-based, and infiltration
agents (D) are techniques, not drug classes.
Local Anesthesia - Amides
Which statement best describes amides?
A. They are metabolized in the plasma.
B. They are primarily used as local anesthetics and metabolized by the liver.
C. They are only used as inhalation agents.
D. They are mainly used as sedatives.
Rationale: Amides are local anesthetics metabolized in the liver. Esters (A) are plasma
metabolized. Options C and D describe unrelated drug classes.
,Local Anesthesia - L/A drugs
What determines the choice of local anesthetic drugs?
A. Only the cost of the drug
B. The color of the cartridge
C. The procedure, patient’s health, and dentist’s preference
D. The size of the needle used
Rationale: Choice depends on clinical procedure, patient’s health, and the dentist’s judgment.
Cost (A) and cartridge color (B) are not primary factors, while needle size (D) relates to delivery,
not drug selection.
Local Anesthesia - Sodium chloride
Why is sodium chloride added to local anesthetic solutions?
A. To increase potency of the drug
B. To act as a preservative
C. To make the solution isotonic with body tissue
D. To reduce toxicity
Rationale: Sodium chloride ensures isotonicity, preventing irritation. It does not increase
potency (A), act as preservative (B), or reduce toxicity (D).
Local Anesthesia - Distilled water
What role does distilled water play in anesthetic solutions?
A. Enhances anesthesia duration
B. Reduces adverse effects
C. Provides an added volume of solution
D. Improves tissue penetration
Rationale: Distilled water is a diluent that increases volume. It doesn’t directly affect duration
(A), reduce side effects (B), or enhance penetration (D).
Local Anesthesia – Time span: Short acting
What is the typical duration of short-acting local anesthetics?
A. 30 to 90 minutes
B. 60 to 180 minutes
C. 240 to 540 minutes
D. 120 to 240 minutes
Rationale: Short-acting agents last 60–180 minutes. Option A underestimates duration, option C
describes long-acting, and option D describes intermediate-acting.
, Local Anesthesia – Time span: Intermediate acting
Intermediate-acting local anesthetics usually last:
A. 30 to 60 minutes
B. 120 to 240 minutes
C. 60 to 180 minutes
D. 240 to 540 minutes
Rationale: Intermediate agents last 120–240 minutes and are the most commonly used for
routine dental care. A is too short, C is short-acting, and D is long-acting.
Local Anesthesia – Time span: Long acting
How long do long-acting local anesthetics last?
A. 60 to 180 minutes
B. 120 to 240 minutes
C. 240 to 540 minutes
D. 30 to 60 minutes
Rationale: Long-acting agents provide anesthesia for 240–540 minutes. A and B are shorter
durations, and D is far too short.
Injection – Maxillary Arch
What are the three major types of anesthetic injections used in the maxillary arch?
A. Field block, mandibular block, general anesthesia
B. Local infiltration, general anesthesia, nerve block
C. Local infiltration, field block, nerve block
D. Buccal block, incisive block, infiltration
Rationale: Maxillary anesthesia is achieved through local infiltration, field block, or nerve
block. A and B incorrectly include general anesthesia. D lists mandibular injections.
Injection – Local Infiltration (Maxillary)
Which injection technique is used to anesthetize a small, isolated area in the maxillary arch?
A. Nerve block
B. Field block
C. Local infiltration
D. Buccal nerve block
Rationale: Local infiltration targets a small localized area. Field block (B) covers a larger
terminal nerve branch, nerve block (A) targets a main nerve trunk, and buccal block (D) is
mandibular.
