Practice Test Geeks(ABE) American Board of Endodontics Practice Test
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Endodontic Microbiology and Pathology Flashcards

7 cards from real ABE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which anaerobic species is considered a 'keystone pathogen' capable of restructuring the entire microbial community in endodontic infections despite low abundance?

    Answer: Porphyromonas endodontalis

    P. endodontalis, like P. gingivalis, can modulate the local microbiome and immune response disproportionate to its numbers, fitting the keystone pathogen model.

  2. Condensing osteitis (focal sclerosing osteomyelitis) is best characterized as:

    Answer: A reactive bone formation response to low-grade pulpal inflammation

    Condensing osteitis represents reactive periapical bone sclerosis in response to chronic, low-grade pulpal infection or irritation.

  3. Which component of gram-negative bacterial cell walls is most responsible for stimulating macrophages to release IL-1β and TNF-α in periapical tissues?

    Answer: Lipopolysaccharide (LPS)

    LPS (endotoxin) from gram-negative bacteria is a potent stimulator of macrophage-derived pro-inflammatory cytokines via TLR4 signaling.

  4. During the transition from pulp necrosis to periapical abscess formation, which process represents the earliest response at the periapex?

    Answer: Vascular dilation and neutrophil emigration

    The earliest periapical response involves vascular dilation and neutrophil emigration as the acute inflammatory response begins.

  5. Extra-radicular infection most commonly involves which microbial structure adherent to the external root surface?

    Answer: Bacterial biofilm on the root apex (apical biofilm)

    Extra-radicular infection often manifests as an apical biofilm on the external root surface, which may explain persistent periapical pathology after adequate root canal treatment.

  6. Which histological finding is MOST characteristic of a periapical abscess as opposed to a periapical granuloma?

    Answer: Central area of liquefactive necrosis with neutrophils

    A periapical abscess is characterized by central liquefactive necrosis with a predominance of neutrophils (pus formation).

  7. Sodium hypochlorite's antimicrobial efficacy in the root canal is primarily attributed to its:

    Answer: Release of free chlorine and oxidation of bacterial proteins

    NaOCl releases free chlorine (hypochlorous acid) which oxidizes and denatures bacterial proteins, destroying cell membranes and inactivating enzymes.