NBDE Periodontics and Endodontics 5

Question 1

What is the function of EDTA in endodontic treatment?

Accepted Answer

Chelates calcium to remove the smear layer

Answer

EDTA (ethylenediaminetetraacetic acid) chelates calcium ions in dentin, removing the smear layer and opening dentinal tubules to improve sealer penetration and disinfection.

Question 2

Which periodontal surgery technique uses an envelope flap to access root surfaces without creating vertical releasing incisions?

Accepted Answer

Papilla preservation flap

Answer

The papilla preservation flap design maintains the interdental papilla intact, providing better esthetic outcomes and blood supply to the flap while accessing root surfaces.

Question 3

A tooth with a root canal-treated tooth develops a new periapical lesion 3 years post-treatment. What is the FIRST step in management?

Accepted Answer

Nonsurgical endodontic retreatment

Answer

Nonsurgical retreatment is the first-line approach for failed root canal therapy, as it addresses the most common cause of failure (inadequate debridement/seal) with less morbidity than surgery.

Question 4

Which microorganism is MOST commonly found in persistent/failed root canal infections?

Accepted Answer

Enterococcus faecalis

Answer

Enterococcus faecalis is the dominant organism in persistent endodontic infections due to its resistance to calcium hydroxide, ability to invade dentinal tubules, and survival in nutrient-poor environments.

Question 5

During a periodontal examination, 'bleeding on probing' (BOP) is MOST accurately described as an indicator of:

Accepted Answer

Gingival inflammation

Answer

Bleeding on probing (BOP) is primarily an indicator of gingival inflammation; its absence is more useful as a negative predictor of disease activity than its presence is as a positive predictor.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Periodontics and Endodontics 5