Gum Nodule Behind Last Tooth in a 5-Year-Old: Differential Diagnosis

A gingival nodule posterior to the last molar in a young child may represent several entities:

1. Eruption cyst: Fluid-filled sac over erupting permanent molar; bluish/whitish, painless, resolves spontaneously.
2. Fibroma: Benign fibrous hyperplasia; firm, pink, smooth; usually asymptomatic.
3. Peripheral ossifying fibroma: Rare, may contain bone; firm, reddish/bluish; may require excision.
4. Canker sore (aphthous ulcer): Typically ulcerated, painful; rarely nodular.
5. Abscess: Painful, fluctuant, purulent; associated with caries or trauma.
6. Rare tumors: Odontogenic or salivary gland neoplasms (very uncommon).

Clinical and radiographic evaluation by a pediatric dentist is necessary for definitive diagnosis and management.