Case: a bump above tooth F

Correct answer: D. A sinus tract from a necrotic pulp

• A. A mucocele results from a severed minor salivary gland duct and occurs mostly on the lower lip; it is not associated with a discoloured tooth.
• B. An eruption cyst is a bluish, fluctuant swelling directly over an erupting tooth crown, not over the root of an already-erupted, discoloured tooth.
• C. A pyogenic granuloma is a red, friable, easily bleeding overgrowth driven by local irritation, without a necrotic pulp behind it.
• D. Correct. Trauma, discoloration and then a gingival swelling over the root is a parulis — the opening of a sinus tract draining a necrotic pulp. The dark crown is the trauma-induced pulpal change that preceded it.

Correct answer: D. Extraction of the affected primary tooth

• A. Fluoride treats caries risk. It does nothing for pulpal necrosis and an established infection.
• B. Occlusal reduction relieves traumatic occlusion, which is not the problem here.
• C. Monitoring leaves an active infection sitting over a developing tooth germ, risking enamel defects or Turner hypoplasia in the successor.
• D. Correct. An infected primary tooth with an active draining sinus threatens the developing permanent successor. Extraction — or pulpectomy where the tooth is restorable and the infection is contained — resolves the source; with a draining tract and a nearby succedaneous tooth bud, extraction is the safe choice.

Note: Track space after extraction. Tooth F is a primary canine, so loss before eruption of the permanent successor may warrant space maintenance.