Sodium Hypochlorite Extrusion During Emergency Treatment of an Acute Abscess
Ahmed, 29, presents to a government dental emergency clinic at 8 pm with a 2-day history of severe throbbing pain and swelling of the left cheek. Tooth 37 is grossly carious, non-vital, tender to percussion, with a 5 mm fluctuant buccal swelling and temperature 37.8°C; he has trismus of 25 mm. The on-call dentist begins root canal treatment. After enlarging to 25/.04 and delivering 5.25% sodium hypochlorite with a side-vented needle wedged to resistance, the patient suddenly cries out, reports a burning taste and severe pain; within minutes there is rapid swelling of the buccal vestibule and a diffuse swelling extending toward the mandibular border. The dentist stops. He has no allergies, takes no medication, and is otherwise fit.
1. What is your immediate diagnosis and how do you manage the patient in the first hour?
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This is a sodium hypochlorite extrusion, not an allergic reaction and not local anaesthetic toxicity. The sudden severe pain, burning taste and rapid swelling during irrigation are the giveaway. The priorities are to stop, assess the airway, and limit further tissue damage.
I would stop irrigation immediately, remove the needle, and aspirate any residual solution from the canal without flushing more. I would reassure the patient, examine the swelling and the airway, check that the eye is not involved on that side, and give cold compresses extraorally. Analgesia should be arranged; paracetamol and appropriate opioid-sparing measures are preferable, and NSAIDs may be considered if there is no contraindication.
I would monitor for increasing swelling, trismus, difficulty swallowing, and voice change. If there is airway compromise or rapidly spreading swelling, I would arrange urgent hospital referral. Antibiotics are not automatically indicated for the chemical injury itself, but this patient already has an acute apical abscess with a fluctuant swelling and mild fever, so incision and drainage and antibiotics may be needed for the infection. I would document the event, the volume and concentration used, the time, and the findings, and review within 24 hours. Corticosteroids are not routine and should not replace airway assessment.
2. Which technique errors most likely contributed, and what irrigation protocol should have been used for this canal?
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The key error was wedging the needle to resistance. A side-vented needle becomes a pressure device when it binds in the canal; the side vent does not protect against extrusion if the needle is snug and the operator keeps pushing. Delivering 5.25% hypochlorite near the apex in a tooth with a large periapical lesion and an open or resorbed apical foramen further increases risk.
The safe protocol is to use a side-vented needle that is loose in the canal, placed 2–3 mm short of the working length, with slow delivery and continuous back-and-forth movement. I would confirm patency and apical size first, use a smaller gauge needle in a narrow canal, and never force against resistance. I would irrigate with gentle pressure, allow the solution to return, and use ultrasonic activation or apical negative pressure where appropriate rather than increasing delivery pressure. The concentration and volume should be the minimum needed for disinfection, and the patient should be warned to signal any burning immediately.
Good technique also includes checking the needle depth on a radiograph when anatomy is unclear and avoiding over-instrumentation of the apical foramen before irrigation.
3. Does this event change your diagnosis and definitive treatment plan for 37? Explain how you would complete the case.
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The diagnosis remains acute apical abscess with a fluctuant buccal swelling, but the chemical injury adds a new problem. I would not continue instrumenting and irrigating that canal at the same visit. The tooth needs drainage and a temporary dressing, not more hypochlorite.
I would incise and drain the fluctuant swelling, obtain pus for culture if available, and prescribe antibiotics if there are systemic signs. The canal would be gently cleaned at a safe length, dried, and dressed with calcium hydroxide, with a good temporary seal. I would review in 24–48 hours and again in one week to assess the chemical injury and the infection.
The definitive root canal treatment should be completed once the soft tissue has settled. At that stage I would re-establish working length, use the safe irrigation protocol, and obturate with a coronal seal. If the tooth is restorable, the long-term prognosis depends more on the original periodontal and periapical condition than on the extrusion, but I would tell the patient that tissue necrosis and scarring can occur and that review is needed. I would also complete an incident report and review the clinic's emergency irrigation protocol.