Endodontics & Pulp Therapy for ORE Part 1
High-yield summary of root canal anatomy, irrigants (NaOCl, 17% EDTA), calcium hydroxide, and MTA obturation in ORE Part 1.
Key Syllabus Concepts Tested in Endodontics & Pulp Therapy
- Root canal morphology: MB2 canals in maxillary 1st molars (>70-80%) and Vertucci classifications
- Irrigants: NaOCl organic tissue dissolution, 17% EDTA smear layer chelation, and saline flushing
- Non-setting Calcium hydroxide (pH 12.5) inter-appointment medicament and MTA retro-fillings
- Symptomatic Irreversible Pulpitis lingering thermal pain (>30s) vs Reversible pulpitis
Sample SBA Practice Questions
Sample Question 1 (Paper A)
During endodontic preparation, which chemical irrigant is specifically used to chelate calcium and remove the inorganic component of the smear layer?
- Sodium hypochlorite solution (NaOCl) 2.5%
- Iodine potassium iodide solution (IKI) 2%
- Chlorhexidine digluconate solution (CHX) 2%
- Ethylenediaminetetraacetic acid (EDTA) solution 17%
✅ Correct Answer: Ethylenediaminetetraacetic acid (EDTA) solution 17%
Explanation: 17% EDTA chelates calcium ions to dissolve the inorganic component of the smear layer.
Clinical Pearl: Maximum safe Lidocaine dose is 4.4 mg/kg (up to 300mg total ~7 cartridges max in adults).
Sample Question 2 (Paper A)
Which microorganism is most frequently isolated from persistent, failed root canal treatments and is resistant to calcium hydroxide?
- Enterococcus faecalis
- Lactobacillus acidophilus
- Streptococcus mutans
- Actinomyces israelii
✅ Correct Answer: Enterococcus faecalis
Explanation: Enterococcus faecalis is a facultative anaerobic Gram-positive coccus capable of penetrating dentinal tubules and surviving alkaline environments.
Clinical Pearl: IV bisphosphonates (Zoledronic acid) carry high risk of osteonecrosis of jaw (MRONJ).
Sample Question 3 (Paper A)
What is the main biocompatible component of Mineral Trioxide Aggregate (MTA) responsible for setting in moist environments and promoting dentinal bridging?
- Tricalcium silicate
- Tricalcium aluminate
- Bismuth oxide
- Calcium sulphate dihydrate
✅ Correct Answer: Tricalcium silicate
Explanation: Tricalcium silicate hydrates in moisture to form calcium silicate hydrate gel and calcium hydroxide, releasing Ca2+ ions to induce dentinogenesis.
Clinical Pearl: 17% EDTA chelates calcium to remove the inorganic hydroxyapatite component of smear layer.
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