NBDE Part II 4

Question 1

During endodontic treatment of a maxillary first molar, which root canal is MOST likely to have a second canal?

Accepted Answer

Mesiobuccal root

Answer

The mesiobuccal root of the maxillary first molar has a second canal (MB2) in approximately 60–95% of cases and is clinically the most commonly missed canal.

Question 2

Which material is contraindicated as a base under composite resin restorations due to inhibition of polymerization?

Accepted Answer

Zinc oxide eugenol (ZOE)

Answer

Eugenol from ZOE inhibits the free-radical polymerization of composite resins, leading to a soft, unset surface layer at the interface.

Question 3

A patient presents with a chief complaint of pain in the upper left quadrant. On examination, tooth #14 is non-vital, has a sinus tract, and shows a periapical radiolucency. The sinus tract most likely originates from:

Accepted Answer

Cannot be determined without a GP trace

Answer

Placing a gutta-percha point into the sinus tract and tracing it radiographically is the definitive method to identify the exact origin of the sinus tract.

Question 4

The maximum recommended dose of lidocaine with epinephrine for a healthy 70 kg adult patient is approximately:

Accepted Answer

500 mg

Answer

The maximum dose of lidocaine with epinephrine is 7 mg/kg with an absolute maximum of 500 mg in a healthy adult.

Question 5

Which of the following is the primary reason for placing a rubber dam during endodontic treatment?

Accepted Answer

To prevent salivary contamination of the root canal system

Answer

Rubber dam isolation is mandatory in endodontics primarily to prevent microbial contamination of the canal from saliva, which would compromise treatment outcomes.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Part II 4