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Pediatric Dentistry · patient case with 2 questions

5-year-old — bump on tooth F after trauma

Scenario: A 5-year-old fell and lost tooth E last month. She now has a bump on tooth F that appeared 3 days ago. The tooth is DARKER than the adjacent teeth and has some mobility. Radiographs show LESS THAN 1/3 of the root remaining.

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Question 1

What does she have?

  1. A mucocele of the labial mucosa
  2. A sinus tract (fistula) from a necrotic primary tooth
  3. An eruption cyst over the succedaneous tooth
  4. A parulis from a periodontal abscess of the permanent incisor
Show answer and explanation

Correct answer: B. A sinus tract (fistula) from a necrotic primary tooth

  • A. A mucocele is a painless bluish fluid-filled swelling of minor salivary gland origin, most often on the lower lip, unrelated to a necrotic tooth.
  • B. Correct. The triad of a DISCOLOURED (dark) tooth, MOBILITY, and a soft-tissue 'bump' appearing 3 days ago is a parulis/sinus tract draining a necrotic primary incisor after trauma. Pulp necrosis following luxation injury is the underlying event.
  • C. An eruption cyst is a bluish, fluctuant, dome-shaped swelling directly OVER an erupting tooth crown and is not associated with a darkened, mobile, previously traumatised tooth.
  • D. The permanent incisor has not erupted at this age, and the picture is of primary-tooth pathology.

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Question 2

What is the treatment?

  1. Extraction of the primary tooth
  2. Incision and drainage only, then observe
  3. Antibiotics alone and re-evaluate in 2 weeks
  4. Pulpectomy and zinc oxide–eugenol obturation
Show answer and explanation

Correct answer: A. Extraction of the primary tooth

  • A. Correct. With LESS THAN ONE THIRD of the root remaining, the tooth is close to exfoliation and has inadequate root structure to support pulp therapy. A necrotic primary tooth with an active sinus tract and advanced resorption is extracted to protect the developing permanent successor.
  • B. Incision and drainage manages an acute swelling but leaves the source of infection — the necrotic pulp — in place.
  • C. Antibiotics do not address the necrotic pulp and are not indicated for a localised, drainable odontogenic infection in a healthy child.
  • D. Pulpectomy requires adequate remaining root length and a restorable tooth; with under 1/3 of root left, obturation is not feasible and would risk damaging the permanent tooth germ.

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