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Pediatric Dentistry · patient case with 3 questions

Child with lower lip swelling the day after a stainless steel crown

Patient: Child, 7 years old

Chief complaint: Brought by his father with swelling of the lower lip.

Background: A stainless steel crown was placed the day before under local anaesthesia.

Current findings: Swelling of the lower lip at the level of the mandibular occlusal plane.

Question 1

What is the most likely cause?

  1. Infection tracking from the crowned tooth
  2. An immunological reaction to the nickel in the crown
  3. An allergic reaction to the local anaesthetic
  4. Trauma — self-inflicted lip biting while the lip was anaesthetised
Show answer and explanation

Correct answer: D. Trauma — self-inflicted lip biting while the lip was anaesthetised

  • A. Infection appearing within 24 hours of crown placement, localised to the lip rather than the vestibule or face, does not fit.
  • B. Nickel allergy from a stainless steel crown is rare and would not present as isolated lip swelling at the occlusal line.
  • C. Anaesthetic allergy manifests immediately as urticaria, angio-oedema or anaphylaxis, not as delayed lip swelling the following day.
  • D. CORRECT. This is the classic paediatric post-anaesthetic complication. Following an inferior alveolar nerve block the lip is numb, and children chew, bite or suck the insensate tissue, producing a traumatic ulcer and swelling that appears hours later, once sensation returns. The timing and location at the occlusal plane are diagnostic.

Note: Prevention is the exam point: warn the child AND the caregiver before they leave, and consider a cotton roll or a warning sticker.

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Question 2

What is your conduct?

  1. Prescribe a systemic antibiotic
  2. Prescribe a corticosteroid cream
  3. Refer urgently to a paediatric hospital
  4. Reassure the father and ask him to monitor it at home
Show answer and explanation

Correct answer: D. Reassure the father and ask him to monitor it at home

  • A. There is no infection to treat; antibiotics are unnecessary.
  • B. Topical corticosteroid is not indicated for a traumatic ulcer and may impair healing.
  • C. This is a benign, self-limiting injury requiring no urgent referral.
  • D. CORRECT. A traumatic lip lesion of this kind heals spontaneously within one to two weeks. Management is reassurance, a soft diet, gentle cleaning, analgesia if needed and observation, with instructions to return if it worsens or shows signs of secondary infection.

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Question 3

The mother asks whether anything can shorten the numbness after future appointments. Which agent reverses soft tissue anaesthesia?

  1. Naloxone
  2. Atropine
  3. Phentolamine mesylate
  4. Flumazenil
Show answer and explanation

Correct answer: C. Phentolamine mesylate

  • A. Naloxone reverses OPIOIDS.
  • B. Atropine is an antimuscarinic used for bradycardia and to reduce secretions.
  • C. CORRECT. PHENTOLAMINE MESYLATE (OraVerse®) is an alpha-adrenergic ANTAGONIST. Injected into the same site, it reverses the vasoconstriction produced by the epinephrine in the anaesthetic, increasing local blood flow and accelerating clearance of the anaesthetic — roughly halving the duration of soft tissue numbness. It directly reduces the risk of exactly the self-inflicted lip trauma this child sustained.
  • D. Flumazenil reverses BENZODIAZEPINES.

Note: Learn the reversal set: phentolamine for soft tissue anaesthesia, flumazenil for benzodiazepines, naloxone for opioids.

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