ABE Endodontic Microbiology and Pathology 4

Question 1

Which species of Actinomyces is most frequently implicated in extra-radicular actinomycosis, a cause of refractory periapical pathology?

Accepted Answer

Actinomyces israelii

Answer

A. israelii is the most common cause of actinomycosis, including periapical actinomycosis, and forms characteristic 'sulfur granules' in tissue.

Question 2

The Malassez epithelial cell rests in the periodontal ligament are significant in endodontic pathology because they:

Accepted Answer

Can proliferate to form the epithelial lining of a radicular cyst

Answer

The rests of Malassez can proliferate when stimulated by inflammatory mediators and form the epithelial lining characteristic of radicular cysts.

Question 3

Which pattern of periapical cyst behavior has been proposed to explain why some cysts do NOT heal after successful root canal treatment?

Accepted Answer

True cyst — completely enclosed epithelial cavity independent of the canal

Answer

True cysts have a completely enclosed epithelial lining and are self-sustaining independent of the root canal, potentially not resolving with root canal treatment alone.

Question 4

A patient presents with a draining sinus tract traced to the apex of tooth #30. The most likely microbial etiology of this chronic presentation is:

Accepted Answer

Mixed anaerobic consortium dominated by gram-negative anaerobes

Answer

Chronic periapical abscesses with sinus tracts typically harbor a mixed anaerobic consortium dominated by gram-negative anaerobes such as Fusobacterium and Prevotella species.

Question 5

Leukotrienes (LTB4) contribute to periapical pathology primarily by:

Accepted Answer

Promoting chemoattraction of neutrophils to the infection site

Answer

LTB4 is a potent chemoattractant for neutrophils, driving their migration into periapical tissues during acute inflammatory episodes.

(ABE) American Board of Endodontics Practice Test

(ABE) American Board of Endodontics Practice Test

ABE Endodontic Microbiology and Pathology 4