NBDE Microbiology and Pathology 3

Question 1

Which hepatitis virus is transmitted parenterally and poses the greatest occupational risk to dental healthcare workers through needlestick injuries?

Accepted Answer

Hepatitis B virus (HBV)

Answer

HBV has the highest risk of transmission via needlestick (6–30%) compared to HCV (1.8%) or HIV (<0.3%), making vaccination essential for dental workers.

Question 2

A patient with recurrent herpetic labialis is under stress. Which statement best describes the pathogenesis of the recurrence?

Accepted Answer

HSV-1 reactivates from latency in the trigeminal ganglion

Answer

HSV-1 establishes latency in the trigeminal ganglion and reactivates due to triggers like stress, UV exposure, or immunosuppression.

Question 3

An ameloblastoma is best characterized histologically by which pattern?

Accepted Answer

Follicular islands with peripheral columnar cells and stellate reticulum

Answer

The follicular pattern of ameloblastoma shows islands of odontogenic epithelium with reverse-polarized columnar basal cells and a stellate reticulum core.

Question 4

Which organism is implicated as the primary etiologic agent of localized aggressive periodontitis (previously juvenile periodontitis)?

Accepted Answer

Aggregatibacter actinomycetemcomitans

Answer

Aggregatibacter actinomycetemcomitans produces leukotoxin and is the primary pathogen in localized aggressive periodontitis affecting first molars and incisors.

Question 5

A painless, slowly enlarging radiolucency at the angle of the mandible is found in a 25-year-old. Histology shows a parakeratinized stratified squamous epithelium lining. The diagnosis is:

Accepted Answer

Odontogenic keratocyst (OKC)

Answer

OKC is characterized by a thin, parakeratinized epithelium with a corrugated surface and high recurrence rate, often associated with Gorlin syndrome.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Microbiology and Pathology 3