ORE Part 2 Endodontics 2 — Questions and Answers
Question 1: What is considered the most common biological cause of post-treatment endodontic failure?
- Inadequate coronal seal allowing recontamination
- Overfilling of the root canal system
- Residual bacteria persisting within the root canal system (Correct answer)
- Procedural errors during canal instrumentation
Correct answer: Residual bacteria persisting within the root canal system
Residual bacteria surviving within the complex root canal anatomy after treatment is the primary biological cause of persistent periapical pathology and endodontic failure.
Question 2: Which obturation material remains the gold standard for filling root canals in conventional endodontic treatment?
- Zinc oxide eugenol paste alone
- Gutta-percha with a root canal sealer (Correct answer)
- Mineral trioxide aggregate (MTA)
- Calcium hydroxide paste
Correct answer: Gutta-percha with a root canal sealer
Gutta-percha combined with a root canal sealer is the gold standard obturation material due to its biocompatibility, dimensional stability, radiopacity, and ease of removal if retreatment is required.
Question 3: What is a 'ledge' as a complication in endodontic treatment?
- A perforation through the root canal wall into the periodontium
- An artificial step created in the canal wall preventing further instrument progress (Correct answer)
- A fractured instrument segment lodged within the canal
- An area of external cervical root resorption
Correct answer: An artificial step created in the canal wall preventing further instrument progress
A ledge is an iatrogenic shelf or false pathway created on the canal wall, most often in curved canals, which prevents instruments from reaching the established working length.
Question 4: If a sodium hypochlorite injection accident occurs with extrusion beyond the apex, what is the most appropriate immediate management?
- Increase irrigation pressure to dilute the extruded material
- Stop irrigation immediately and manage pain and swelling conservatively (Correct answer)
- Prescribe antibiotics and discharge without further intervention
- Immediately refer to hospital for surgical debridement
Correct answer: Stop irrigation immediately and manage pain and swelling conservatively
Immediate management involves stopping irrigation, providing pain relief, applying ice to reduce swelling, and monitoring; most cases resolve with conservative management, with hospital referral reserved for severe or progressive cases.
Question 5: What is the principle behind the step-back technique in root canal preparation?
- Preparing the coronal flaring before beginning apical instrumentation
- Preparing the apex first then using progressively larger files coronally to create a taper (Correct answer)
- Using ultrasonic instruments to clean the apical third
- Removing the smear layer in a coronal-to-apical direction
Correct answer: Preparing the apex first then using progressively larger files coronally to create a taper
The step-back technique involves establishing the working length and preparing the apical third first, then 'stepping back' with successively larger files coronally to develop a funnel-shaped taper.
Question 6: Which microorganism is most strongly associated with persistent and treatment-resistant endodontic infections?
- Streptococcus mutans
- Enterococcus faecalis (Correct answer)
- Porphyromonas gingivalis
- Fusobacterium nucleatum
Correct answer: Enterococcus faecalis
Enterococcus faecalis is associated with persistent endodontic infections because it resists calcium hydroxide medicaments, survives in nutrient-poor environments, and adheres strongly to dentinal walls.
Question 7: Which radiographic appearance is most characteristic of a chronic apical periodontitis lesion?
- Widening of the periodontal ligament space alone
- Well-defined radiolucency at the root apex (Correct answer)
- Diffuse periapical radiopacity with loss of lamina dura
- Round radiolucent defect within the root canal space
Correct answer: Well-defined radiolucency at the root apex
Chronic apical periodontitis presents as a well-defined (or sometimes ill-defined) periapical radiolucency representing bone destruction secondary to chronic infection from a necrotic pulp.
ORE Part 2 Endodontics 2
What is considered the most common biological cause of post-treatment endodontic failure?