Irrigants and dressings inside the canal
- Dental material
Sodium hypochlorite is the main root canal irrigant because it dissolves tissue and kills bacteria. Pushed past the root tip, it causes a painful tissue injury.
See it in 3D: Maxillary sinus
What it is
Irrigants flush, dissolve and disinfect the parts of the canal system files cannot reach. Sodium hypochlorite dissolves organic tissue and kills bacteria; a chelating agent such as EDTA removes the mineral smear layer left by files; chlorhexidine is antibacterial but does not dissolve tissue. Between visits a calcium hydroxide dressing keeps the canals disinfected.
Composition and properties
- Sodium hypochlorite: the only common irrigant that dissolves pulp tissue; strongly antibacterial.
- EDTA (a chelator): removes the smear layer so irrigants and sealer reach the tubules.
- Chlorhexidine: antibacterial and long-acting, but mixed with hypochlorite it forms a brown precipitate, so the canal is rinsed between them.
- Calcium hydroxide paste: the standard dressing between visits; strongly alkaline and antibacterial.
- Antibiotic pastes are used mainly in regenerative endodontics; some contain minocycline, which stains teeth.
Uses, limits and safety
- Hypochlorite accident: sudden severe pain, rapid swelling, bruising and bleeding from the canal when irrigant goes past the apex or through a perforation.
- Prevent it with rubber dam, a side-vented needle that does not bind in the canal, gentle pressure and staying short of working length.
- Hypochlorite also bleaches clothes and burns eyes: patient bib and eye protection are routine.
Next step / Initial management
- Suspected hypochlorite accident: stop, irrigate the canal with saline, control pain, apply cold compresses and reassure the patient.
- Swelling spreading to the neck or floor of the mouth, or breathing difficulty: airway first and emergency referral; otherwise refer to the oral surgeon for review the same day.
- Eye splash: irrigate with plenty of water at once and refer to ophthalmology.
Test yourself
Think of the answer, then tap the question to see it.
Which root canal irrigant dissolves pulp tissue?
Sodium hypochlorite.
Why are chlorhexidine and sodium hypochlorite not mixed in the canal?
Together they form a brown precipitate that can block tubules and stain the tooth.
What are the signs of a hypochlorite accident?
Sudden severe pain, rapid swelling, bruising and bleeding from the canal during irrigation.
Connections
See it in 3D1
The structures of Durgical's 3D anatomy where it is found.
In Pharmacology1
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Irrigants and irrigation activation systems in Endodontics (Brazilian Dental Journal (PMC open access), 2023); Factors influencing the occurrence and progress of sodium hypochlorite accident: A narrative and update review (Journal of Conservative Dentistry (PMC open access), 2023); Endodontic Materials Used To Fill Root Canals (StatPearls Publishing (NCBI Bookshelf), 2023).
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Representative model, for educational purposes only.