NBDE Endodontics 5 — Questions and Answers
Question 1: A patient reports pain on biting specifically to one tooth. Cold and heat tests are normal. Percussion is painful. No periapical pathology on radiograph. What is the most likely diagnosis?
- Reversible pulpitis
- Cracked tooth syndrome (Correct answer)
- Chronic apical periodontitis
- Acute apical abscess
Correct answer: Cracked tooth syndrome
Cracked tooth syndrome presents with pain on biting (especially release), normal thermal responses, and no radiographic changes — a classic diagnostic challenge.
Question 2: Which classification describes a non-vital tooth with a periapical lesion that has no signs or symptoms?
- Symptomatic apical periodontitis
- Asymptomatic apical periodontitis (Correct answer)
- Chronic suppurative apical periodontitis
- Condensing osteitis
Correct answer: Asymptomatic apical periodontitis
Asymptomatic apical periodontitis is diagnosed in a non-vital tooth with periapical bone loss but no clinical symptoms, confirmed by pulp sensibility testing.
Question 3: The concept of 'apical patency' during root canal instrumentation refers to:
- Achieving a smooth glide path to working length
- Passing a small file 0.5–1mm through the apical foramen to prevent debris blockage (Correct answer)
- Enlarging the apical preparation to at least a #40 file
- Confirming canal length with an electronic apex locator
Correct answer: Passing a small file 0.5–1mm through the apical foramen to prevent debris blockage
Apical patency is maintained by passing a small (#10) patency file slightly through the foramen periodically to prevent dentinal debris from packing at the apex.
Question 4: Condensing osteitis (focal sclerosing osteomyelitis) radiographically appears as:
- Periapical radiolucency with a corticated border
- Diffuse periapical radiopacity around the apex of a tooth with pulpal pathology (Correct answer)
- Well-defined radiolucency with corticated borders resembling a cyst
- Loss of lamina dura
Correct answer: Diffuse periapical radiopacity around the apex of a tooth with pulpal pathology
Condensing osteitis is a diffuse periapical radiopacity representing a low-grade inflammatory bone reaction to mild pulpal irritation.
Question 5: Which factor most increases the risk of sodium hypochlorite accident (injection beyond the apex)?
- Use of 2.5% vs 5.25% concentration
- Use of a side-vented needle without binding in the canal
- Large apical foramen size in immature or resorbed teeth (Correct answer)
- Rubber dam isolation
Correct answer: Large apical foramen size in immature or resorbed teeth
A large or irregular apical foramen (as in immature teeth or external resorption) allows irrigant to escape the canal and contact periapical tissues, causing a severe hypochlorite accident.
Question 6: In the AAE classification system, which diagnosis applies to a tooth with vital inflamed pulp tissue causing moderate-to-severe pain that does NOT subside after stimulus removal?
- Normal pulp
- Reversible pulpitis
- Symptomatic irreversible pulpitis (Correct answer)
- Pulp necrosis
Correct answer: Symptomatic irreversible pulpitis
Symptomatic irreversible pulpitis is characterized by spontaneous or provoked pain that lingers >30 seconds after stimulus removal, indicating irreversible pulpal damage requiring root canal treatment.
Question 7: Which post-endodontic restoration provides the best long-term prognosis for a maxillary first premolar after root canal treatment?
- Direct composite resin restoration with cuspal coverage
- Full-coverage crown (Correct answer)
- Amalgam restoration without cuspal coverage
- Resin-bonded cast metal post and core only
Correct answer: Full-coverage crown
Maxillary first premolars are highly susceptible to vertical fracture after root canal treatment; a full-coverage crown provides the essential cuspal protection to prevent fracture.
NBDE Endodontics 5
A patient reports pain on biting specifically to one tooth.
Cold and heat tests are normal.
Percussion is painful.
No periapical pathology on radiograph.
What is the most likely diagnosis?