Endodontics · patient case question
What is the principal reason sodium hypochlorite is used as an endodontic irrigant?
Patient case: The tooth that bled during shaping
demo: 38-year-old male
chief: Referred for root canal treatment of a mandibular molar with a necrotic pulp.
history: Unremarkable. No allergies.
meds: None.
findings: Tooth 19 fails to respond to cold and is tender to percussion. Access is completed and the canals are irrigated. Partway through cleaning and shaping the patient reports sudden severe pain and the operator notices brisk bleeding from the canal along with rapid swelling of the cheek. Separately, tooth 4 in the same patient shows a narrow radiolucency running along the lateral root surface and joining an apical radiolucency.
Show answer and explanation
Correct answer: A. It is bactericidal and dissolves organic pulp tissue
- A. Correct. Hypochlorite is a strong oxidising agent that kills bacteria and dissolves necrotic and vital organic tissue, including the pulp remnants and biofilm in the areas of the canal system that instruments cannot reach. That combination is what makes it irreplaceable.
- B. Substantivity, meaning sustained antimicrobial action after application, is a property of chlorhexidine, not hypochlorite.
- C. Lubrication is a secondary benefit of any irrigant and is not the reason hypochlorite is chosen.
- D. The inorganic component of the smear layer is removed by a chelator, EDTA, which is why the two are used in sequence rather than as alternatives.