AGD Endodontics and Pulpal Therapy 5 — Questions and Answers
Question 1: Which microorganism is most commonly associated with persistent endodontic infections and is resistant to standard irrigation protocols?
- Streptococcus mutans
- Enterococcus faecalis (Correct answer)
- Porphyromonas gingivalis
- Fusobacterium nucleatum
Correct answer: Enterococcus faecalis
Enterococcus faecalis is highly resistant to calcium hydroxide and commonly colonizes filled canals, making it the leading cause of treatment failure.
Question 2: During root canal treatment, a separated instrument is found in the middle third of a curved canal. What is the FIRST recommended action?
- Immediately refer to an endodontist for surgical retrieval
- Attempt to bypass the fragment and obturate around it
- Assess retrievability with magnification and consider bypass before removal attempts (Correct answer)
- Extract the tooth without further attempts
Correct answer: Assess retrievability with magnification and consider bypass before removal attempts
The recommended initial approach is to assess the fragment's position and retrievability under magnification, then attempt bypass if removal carries high risk.
Question 3: What is the purpose of placing calcium hydroxide as an inter-appointment medicament?
- Lubricate canals between appointments
- Provide antimicrobial action and stimulate periapical healing (Correct answer)
- Seal the access cavity temporarily
- Dissolve remaining pulp tissue
Correct answer: Provide antimicrobial action and stimulate periapical healing
Calcium hydroxide raises intracanal pH to ~12, killing residual bacteria and promoting periapical tissue repair between appointments.
Question 4: A mandibular second premolar is known for its challenging anatomy. What variant most commonly causes missed canals?
- Three separate roots
- A C-shaped canal configuration
- Two canals that merge into one (Type II Vertucci) (Correct answer)
- A single very wide ribbon-shaped canal
Correct answer: Two canals that merge into one (Type II Vertucci)
Mandibular second premolars frequently have two canals (Vertucci Type II) that join apically, with the second canal easily missed if access is inadequate.
Question 5: The 'apical vapor lock' phenomenon during irrigation refers to:
- NaOCl vapor irritating the periapex when extruded
- Trapped air at the apex preventing irrigant from reaching the last few millimeters (Correct answer)
- Vaporization of irrigant under ultrasonic activation
- Steam produced by heated gutta-percha near the apex
Correct answer: Trapped air at the apex preventing irrigant from reaching the last few millimeters
Air trapped apically creates a vapor lock that blocks irrigant penetration; this can be countered with sonic/ultrasonic agitation or negative pressure techniques.
Question 6: Which pulp capping material has shown superior long-term outcomes in randomized clinical trials compared to calcium hydroxide?
- Zinc phosphate cement
- MTA and Biodentine (calcium silicate cements) (Correct answer)
- Glass ionomer cement
- Intermediate restorative material (IRM)
Correct answer: MTA and Biodentine (calcium silicate cements)
Calcium silicate cements like MTA and Biodentine consistently outperform calcium hydroxide in direct pulp capping due to superior biocompatibility and dentinal bridge formation.
Question 7: Regenerative endodontic procedures (REPs) for immature necrotic teeth primarily aim to achieve which outcome?
- Complete obturation with gutta-percha
- Continued root development (apexogenesis) and possible pulp tissue regeneration (Correct answer)
- Rapid elimination of pain within 24 hours
- Immediate crown placement to restore function
Correct answer: Continued root development (apexogenesis) and possible pulp tissue regeneration
REPs use disinfection and blood clot scaffolding to allow stem cells from the apical papilla to promote continued root maturation.
AGD Endodontics and Pulpal Therapy 5
Which microorganism is most commonly associated with persistent endodontic infections and is resistant to standard irrigation protocols?