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Endodontics Flashcards

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

Read the first 7 Endodontics flashcards as text

  1. Which microorganism is most commonly isolated from teeth with failed root canal treatment (persistent infection)?

    Answer: Enterococcus faecalis

    Enterococcus faecalis dominates persistent endodontic infections due to its ability to survive in nutrient-poor, alkaline environments and resist calcium hydroxide treatment.

  2. A patient presents with a draining sinus tract on the attached gingiva near tooth #30. The tract is traced with a gutta-percha cone. Where does the cone most likely terminate?

    Answer: Periapical region of the offending tooth

    Sinus tracts from endodontic origin typically track through bone and soft tissue to terminate at the periapical area of the causative tooth.

  3. Which sealer type is considered the current gold standard for biocompatibility and bond strength in root canal obturation?

    Answer: Epoxy resin-based sealers (AH Plus)

    Epoxy resin-based sealers like AH Plus demonstrate superior bond strength to dentin, low solubility, and excellent long-term clinical performance.

  4. During access preparation of a mandibular second premolar, the clinician should anticipate which unusual canal configuration?

    Answer: Possible two canals that may or may not merge

    Mandibular premolars have notoriously variable canal anatomy, with two canals present in a significant percentage that may merge or remain separate — a major source of treatment failure.

  5. When calcium hydroxide is used as an intracanal medicament, its primary antimicrobial mechanism is:

    Answer: Disruption of bacterial membranes by hydroxyl ions raising pH above 11

    The high pH (>11) generated by hydroxyl ion release denatures bacterial proteins and enzymes, disrupts membrane integrity, and damages bacterial DNA.

  6. A 9-year-old patient has an immature permanent incisor with a necrotic pulp. Which treatment option is most appropriate?

    Answer: Apexification with MTA or regenerative endodontic procedure

    Immature necrotic teeth require apexification (MTA barrier) or regenerative endodontic procedures to promote apical closure before or instead of conventional obturation.

  7. Which CBCT finding is most useful in identifying a missed MB2 canal in a maxillary first molar before retreatment?

    Answer: Separate radiolucent channel in the mesiobuccal root distinct from MB1

    CBCT axial slices through the mesiobuccal root clearly reveal a separate MB2 canal as a distinct radiolucent channel, guiding retreatment access.