ORE Part 2 Endodontics 1 — Questions and Answers
Question 1: Which irrigant is considered the gold standard for root canal disinfection due to its ability to dissolve organic tissue?
- Chlorhexidine 2%
- Sodium hypochlorite 2.5–5.25% (Correct answer)
- EDTA 17%
- Normal saline
Correct answer: Sodium hypochlorite 2.5–5.25%
Sodium hypochlorite is the gold standard root canal irrigant because it has broad antimicrobial activity and is the only irrigant capable of dissolving necrotic pulp tissue.
Question 2: What is the primary reason for using a rubber dam during endodontic treatment?
- To improve visibility of the operating field
- To prevent instrument aspiration and maintain asepsis (Correct answer)
- To retract soft tissues away from the tooth
- To reduce patient anxiety during the procedure
Correct answer: To prevent instrument aspiration and maintain asepsis
The rubber dam isolates the tooth from oral flora to maintain asepsis and prevents potentially fatal aspiration of endodontic instruments.
Question 3: Which feature best distinguishes symptomatic irreversible pulpitis from reversible pulpitis?
- Sharp pain on cold stimulation
- Spontaneous pain and lingering pain after stimulus removal (Correct answer)
- Mild aching aggravated by biting
- Sensitivity to sweet foods only
Correct answer: Spontaneous pain and lingering pain after stimulus removal
Symptomatic irreversible pulpitis is characterised by spontaneous pain and pain that lingers for 30 seconds or more after removal of the stimulus, indicating irreversible pulpal damage.
Question 4: How does an electronic apex locator determine the working length of a root canal?
- By measuring impedance between the file tip and oral mucosa (Correct answer)
- By calculating the tooth length from a digital radiograph
- By detecting temperature changes at the canal terminus
- By measuring the resistance of dentin to file penetration
Correct answer: By measuring impedance between the file tip and oral mucosa
Electronic apex locators measure the electrical impedance between an instrument tip in the canal and an electrode placed on the oral mucosa, which changes predictably at the apical constriction.
Question 5: What is the primary function of EDTA in root canal treatment?
- To kill anaerobic bacteria within the root canal
- To remove the smear layer by chelating calcium ions from dentine (Correct answer)
- To dissolve necrotic organic tissue
- To bleach discoloured dentine tubules
Correct answer: To remove the smear layer by chelating calcium ions from dentine
EDTA is a chelating agent that removes the smear layer produced during instrumentation by binding calcium ions from the inorganic dentine component.
Question 6: Which cells are responsible for producing reactionary (secondary) dentine in response to pulpal irritation?
- Cementoblasts
- Ameloblasts
- Odontoblasts (Correct answer)
- Fibroblasts
Correct answer: Odontoblasts
Odontoblasts, which line the pulp-dentine junction, are responsible for continued dentine formation throughout life and produce reactionary dentine in response to injury.
Question 7: What is the most appropriate immediate management for an acute apical abscess with spreading cellulitis and systemic signs of infection?
- Definitive root canal treatment in a single visit
- Analgesics only and review in 48 hours
- Drainage, systemic antibiotics, and definitive endodontic treatment or extraction (Correct answer)
- Prescribe antibiotics alone without intraoral intervention
Correct answer: Drainage, systemic antibiotics, and definitive endodontic treatment or extraction
Spreading infection with systemic involvement requires both surgical drainage and systemic antibiotics; antibiotics alone are insufficient without addressing the source, and definitive treatment follows once acute symptoms resolve.
ORE Part 2 Endodontics 1
Which irrigant is considered the gold standard for root canal disinfection due to its ability to dissolve organic tissue?