ABE Clinical Endodontics 2 — Questions and Answers
Question 1: A patient presents with a maxillary first molar requiring retreatment. CBCT reveals a separated instrument in the apical third of the MB2 canal. What is the most appropriate initial management?
- Immediate surgical removal via apicoectomy
- Bypass the fragment and obturate around it if periapical healing is present (Correct answer)
- Extract the tooth without attempting retrieval
- Place calcium hydroxide and re-evaluate in 3 months without attempting bypass
Correct answer: Bypass the fragment and obturate around it if periapical healing is present
When periapical pathology is absent and bypassing a separated instrument is possible, obturation around it is a viable and often successful approach.
Question 2: Which irrigant is most effective at dissolving necrotic pulp tissue remnants in the root canal system?
- Chlorhexidine 2%
- EDTA 17%
- Sodium hypochlorite 5.25% (Correct answer)
- Saline
Correct answer: Sodium hypochlorite 5.25%
Sodium hypochlorite is the only endodontic irrigant capable of dissolving organic tissue, making it the gold standard for pulp tissue dissolution.
Question 3: A patient has a sinus tract traced to a maxillary lateral incisor with a normal periodontal probing depth but a non-vital pulp. What is the most likely diagnosis?
- Periodontal abscess
- Pulp necrosis with chronic apical abscess (Correct answer)
- Dens invaginatus with secondary infection
- Vertical root fracture
Correct answer: Pulp necrosis with chronic apical abscess
A sinus tract traced to a tooth with pulp necrosis and normal periodontal probing indicates a chronic apical abscess of endodontic origin.
Question 4: During instrumentation of a mandibular molar, the working length suddenly increases by 3 mm. This most likely indicates:
- Canal transportation
- Ledge formation
- Apical perforation (Correct answer)
- Instrument binding in the coronal third
Correct answer: Apical perforation
A sudden increase in working length during instrumentation is the classic sign of an apical perforation.
Question 5: Which pulp capping material is considered the current gold standard for direct pulp capping in a mature permanent tooth?
- Zinc oxide-eugenol cement
- Glass ionomer cement
- Mineral trioxide aggregate (MTA) (Correct answer)
- Calcium hydroxide paste
Correct answer: Mineral trioxide aggregate (MTA)
MTA is considered the current gold standard for direct pulp capping due to its superior biocompatibility, sealing ability, and dentinal bridge formation.
Question 6: A patient reports pain upon biting down on a mandibular premolar. The tooth has a full-coverage crown, tests vital with cold, and has no periapical pathology on radiograph. The most likely diagnosis is:
- Irreversible pulpitis
- Symptomatic apical periodontitis
- Cracked tooth syndrome (Correct answer)
- Reversible pulpitis
Correct answer: Cracked tooth syndrome
Sharp pain on biting with a vital tooth, full crown, and no radiographic changes is characteristic of cracked tooth syndrome.
Question 7: The phenomenon of 'phoenix abscess' refers to:
- An acute exacerbation of a chronic periapical lesion (Correct answer)
- A periapical abscess that forms immediately after pulp necrosis
- An abscess that develops after endodontic therapy is completed
- A chronic suppurative process unrelated to pulpal disease
Correct answer: An acute exacerbation of a chronic periapical lesion
A phoenix abscess is an acute exacerbation of a pre-existing chronic periapical lesion, often triggered by mechanical disturbance during treatment.
ABE Clinical Endodontics 2
A patient presents with a maxillary first molar requiring retreatment.
CBCT reveals a separated instrument in the apical third of the MB2 canal.
What is the most appropriate initial management?