NBDE Endodontics 3

Question 1

Which obturation technique involves heating gutta-percha and compacting it into the canal using a carrier?

Accepted Answer

Carrier-based obturation (Thermafil)

Answer

Carrier-based systems like Thermafil use a plastic or metal carrier coated with alpha-phase gutta-percha that is heated and inserted to fill the canal.

Question 2

A patient develops paresthesia of the lower lip after root canal treatment of a mandibular second molar. What is the most likely cause?

Accepted Answer

Over-instrumentation beyond the apex compressing the inferior alveolar nerve

Answer

Overfilling or aggressive instrumentation beyond the apex of mandibular molars can impinge on or chemically injure the inferior alveolar nerve, causing paresthesia.

Question 3

What distinguishes a Type IV canal configuration (Weine classification) from Type III?

Accepted Answer

One canal that divides into two at the apex with two foramina

Answer

Weine Type IV begins as one canal and divides near the apex into two separate canals with two distinct apical foramina.

Question 4

Which condition is an absolute contraindication to performing a pulpotomy on a primary molar?

Accepted Answer

Pathologic internal root resorption

Answer

Pathologic internal root resorption indicates the radicular pulp is irreversibly inflamed and infected, making pulpotomy (which preserves the radicular pulp) contraindicated.

Question 5

The zone of coagulation necrosis seen after MTA or calcium hydroxide apexification therapy heals primarily by which process?

Accepted Answer

Cementum deposition over the apex (cementogenesis)

Answer

Calcium hydroxide and MTA promote apical closure primarily through cementogenesis, with cementum-like hard tissue deposited over the open apex.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Endodontics 3