CRDTS LA EXAM Questions and answers 2025

1



CRDTS LA EXAM Questions and
answers 2025
When a nerve is in its resting state, the - (answers)A. K+ is concentrated outside the cell

B. Cell membrane is positive on the outside of the cell

C. Na+ is concentrated outside the cell Correct

D. Cell membrane is more positive on the inside of the cell



Which of the following maintains the resting potential of nerve fiber? - (answers)A. The K+
pump

B. The Na+ pump Correct

C. The concentration gradient

D. The electrical impulse



Select the following anesthetic(s) available in the US that is(are) formulated with epinephrine
1:200,000 - (answers)A. Lidocaine

B. Mepivacaine

C. Prilocaine

D. Articaine

E. Prilocaine and Articaine Correct



Which of the following anesthetics has the shortest duration when administering a local
anesthetic block? - (answers)A. Lidocaine 1:100,000

B. Mepivacaine 1:20,000

C. Mepivacaine 3% Correct

D. Prilocaine 4%

, 2


Levonordefrin has how many mg/mL of vasoconstrictor? - (answers)A. 0.05 mg/mL Correct

B. 0.01 mg/mL

C. 0.9 mg/mL

D. 0.005 mg/mL



How much epinephrine does a 1:200,000 dilution contain compared with a 1:100,000 dilution -
(answers)A. Half Correct

B. Twice

C. One quarter

D. One forth



What is the cardiac dose for epinephrine? - (answers)A. 0.2 mg

B. 0.04 mg Correct

C. 1.0 mg

D. 2.0 mg



How many cartridges could a cardiac patient safely receive if administering a 1:200,000
epinephrine dilution? - (answers)A. 1.1 cartridges

B. 4.4 cartridges Correct

C. 2.2 cartridges

D. 3.3 cartridges



What is the primary reason that catecholamines (epi) are added to local anesthetic solutions? -
(answers)A. Decrease the risk of toxicity Correct

B. Decrease the duration of action

C. Decrease the risk of postoperative pain

, 3


D. Decrease the risk of infection



Sodium bicarbonate is added to local anesthetic solutions: - (answers)A. Only when a
vasoconstrictor is added

B. To prevent the oxidation of the amide

C. To make the solution isotonic

D. To help increase the pH of the anesthetic. Correct



How many mg of epinephrine are in one cartridge of a 1:100,000 dilution? - (answers)A. 0.009
mg

B. 0.01 mg

C. 0.018 mg Correct

D. 0.02 mg



During the inferior alveolar block the patient feels a sudden electrical shock. This is due to: -
(answers)A. The needle touching the inferior alveolar nerve

B. The needle touching the lingual nerve Correct

C. The needle touching the buccal nerve

D. The needle touching the pterygomandibular raphe



Supraperiosteal injections are less successful on the mandible because of the: - (answers)A.
Porous bone of the mandible

B. Density of the bone of the mandible Correct

C. pH of the tissue on the mandible

D. Large nerve trunks of the mandible

, 4


Which of the following vasoconstrictor dilutions provides the greatest hemostasis? -
(answers)A. 1:20,000 levonordefrin

B. 1:50,000 epinephrine Correct

C. 1:100,000 epinephrine

D. 1:200,000 epinephrine



After the administration of a local anesthetic, what causes a droopy eyelid? - (answers)A.
Depositing the solution in the parotid gland Correct

B. Depositing the solution medial to the mandibular foramen

C. Depositing the solution above the infraorbital foramen

D. Depositing the solution at the anteromedial border of the neck of the mandibular condyle



Which anesthetic is primarily metabolized in the blood? - (answers)A. Lidocaine

B. Mepivacaine

C. Prilocaine

D. Articaine Correct



What is the recommended needle gauge for an inferior alveolar block? - (answers)A. 25 gauge
Correct

B. 27 gauge

C. 30 gauge

D. Any gauge is fine



The dental hygienist successfully administers an inferior alveolar block, but the patient does not
get numb. What is the possible reason why the patient does not get numb? - (answers)A.
Solution deposited superior to the mandibular foramen

B. Solution deposited inferior to the mandibular foramen Correct