A vital tooth has a fracture with carious exposure extending about 4 mm below the alveolar crest on the lingual aspect. What is the treatment?

Correct answer: C. Extraction

• A. Endodontics addresses the pulp but does nothing about a margin sitting 4 mm subcrestally, and the tooth is vital in any case.
• B. A crown placed over a margin this deep violates the biologic width and guarantees chronic inflammation and bone loss.
• C. Correct. At 4 mm below the crest, crown lengthening cannot re-establish the biologic width and an adequate ferrule without removing so much bone that the tooth — and its neighbours — are compromised. Extraction is the realistic answer.
• D. Crown lengthening works for margins at or just below the crest, roughly 1 to 2 mm. Four mm below the crest is beyond its reach on the lingual of a posterior tooth.

Note: ⚑ The recall does not mark a key for this item. The reasoning above follows the biologic width principle — roughly 3 mm of sound structure is needed coronal to the bone (2 mm biologic width plus 1 mm ferrule). Orthodontic extrusion is the alternative worth raising in the group if the tooth is strategically important.