NBDE Endodontics 5

Question 1

A patient reports pain on biting specifically to one tooth. Cold and heat tests are normal. Percussion is painful. No periapical pathology on radiograph. What is the most likely diagnosis?

Accepted Answer

Cracked tooth syndrome

Answer

Cracked tooth syndrome presents with pain on biting (especially release), normal thermal responses, and no radiographic changes — a classic diagnostic challenge.

Question 2

Which classification describes a non-vital tooth with a periapical lesion that has no signs or symptoms?

Accepted Answer

Asymptomatic apical periodontitis

Answer

Asymptomatic apical periodontitis is diagnosed in a non-vital tooth with periapical bone loss but no clinical symptoms, confirmed by pulp sensibility testing.

Question 3

The concept of 'apical patency' during root canal instrumentation refers to:

Accepted Answer

Passing a small file 0.5–1mm through the apical foramen to prevent debris blockage

Answer

Apical patency is maintained by passing a small (#10) patency file slightly through the foramen periodically to prevent dentinal debris from packing at the apex.

Question 4

Condensing osteitis (focal sclerosing osteomyelitis) radiographically appears as:

Accepted Answer

Diffuse periapical radiopacity around the apex of a tooth with pulpal pathology

Answer

Condensing osteitis is a diffuse periapical radiopacity representing a low-grade inflammatory bone reaction to mild pulpal irritation.

Question 5

Which factor most increases the risk of sodium hypochlorite accident (injection beyond the apex)?

Accepted Answer

Large apical foramen size in immature or resorbed teeth

Answer

A large or irregular apical foramen (as in immature teeth or external resorption) allows irrigant to escape the canal and contact periapical tissues, causing a severe hypochlorite accident.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Endodontics 5