Preclinics of Conservative Dental Medicine · MU Sofia

45. Difficulties and complications during and after irrigation.

Explains the hypochlorite accident, where sodium hypochlorite is forced beyond the apex, covering its causes, signs and step-by-step management, followed by prevention. Also sets out other complications such as eye and skin exposure, allergy, air emphysema and instrument breakage in a summary table, the NaOCl and chlorhexidine precipitate, and difficulties in reaching the apical third, including vapour lock and debris packing.

Inside: 5 sections · 1 labelled picture · 1 table · 17 flashcards · 7 min

Topic 45 of 53 in the MU Sofia syllabus for Preclinics of Conservative Dental Medicine (Dental Medicine, Year 3). The free AceMed note covers it in 5 sections, about 812 words (7 min of reading), with 17 flashcards.

In this note

  1. Introduction
  2. The hypochlorite accident
  3. Other complications during and after irrigation
  4. Difficulties during irrigation
  5. Key points

Introduction

Mistakes in irrigation can harm the patient, not only the tooth, because sodium hypochlorite (NaOCl) dissolves vital tissue as readily as necrotic pulp. This note covers the hypochlorite accident, the other complications during and after irrigation, and the difficulty of getting irrigant into the apical third. The irrigants and the technique themselves are topic 44.

The hypochlorite accident

A hypochlorite accident is the extrusion of NaOCl beyond the apex or through a perforation into the periapical tissues, where it causes a chemical burn: haemolysis, tissue necrosis and acute inflammation. Damage grows with the concentration and the volume forced out. Most reported cases involve maxillary teeth.

Causes

  • Needle wedged (bound) in the canal: the irrigant cannot flow back coronally, so all of it is driven apically.
  • Forceful injection, especially through a narrow or blocked needle.
  • Needle at or beyond the working length, or an overestimated working length.
  • A wide foramen: open apex of an immature tooth, apical resorption, an over-instrumented foramen.
  • Perforation of the root or the pulp chamber floor.

Signs

  • Immediate severe pain, even under local anaesthesia.
  • Rapid swelling of the lip, cheek or infraorbital region within minutes.
  • Haemorrhage through the canal.
  • Ecchymosis (bruising) of skin and mucosa over the following hours to days.
  • Later: paraesthesia or anaesthesia of a nearby nerve, secondary infection; a chlorine taste and throat irritation if NaOCl entered the maxillary sinus.

Management, step by step

  1. Stop irrigating and remove the needle. Stay calm, tell the patient what happened and reassure them.
  2. Let the canal bleed (it flushes the irrigant out), aspirate at the access cavity and irrigate gently with sterile saline to dilute the rest.
  3. Control pain: local anaesthetic (often a long-acting block) and analgesics.
  4. Cold compresses on the first day to limit swelling, then warm compresses and warm mouth rinses to improve local circulation.
  5. Antibiotics only when there is a risk of secondary infection (extensive necrosis, spreading swelling); corticosteroids and antihistamines according to local protocol.
  6. Dry and seal the canal temporarily, record the event and review the patient the next day and over the following weeks; finish the treatment later with saline or chlorhexidine as irrigant. Refer urgently to hospital if the airway is threatened, the swelling spreads to the neck, eye or floor of the mouth, or the reaction is severe.

Prevention

  • Keep the needle loose and 1–2 mm short of the working length, and inject slowly with light pressure while moving it up and down.

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