Periodontics · patient case question
Tooth #3 is restorable but the mesial margin lies 2 mm subgingivally, invading the biologic width. What should be done FIRST?
Patient case: Rampant caries on a full-mouth series
Patient: Female, 29 years old
Chief complaint: “A piece of my back tooth broke off.”
History: No systemic disease. Frequent sugared energy drinks. Last dental visit six years ago. Brushes once daily, no floss.
Findings: Full-mouth series shows occlusal and proximal caries in 14 teeth. Tooth #3 has gross coronal destruction extending 2 mm subgingivally on the mesial. No periapical radiolucencies. Salivary flow is normal.
Show answer and explanation
Correct answer: B. Crown lengthening
- A. The tooth is described as restorable. Extraction is premature when a predictable periodontal solution exists.
- B. CORRECT. Restoring into the biologic width — roughly 2 mm of connective tissue attachment plus junctional epithelium above the crest, needing about 3 mm total from crest to margin — produces chronic inflammation, bleeding, unpredictable recession and bone loss. CROWN LENGTHENING, by osseous resection with an apically positioned flap, re-establishes that dimension and gives a supragingival margin with adequate ferrule. Allow six to eight weeks of healing, and up to six months in the aesthetic zone, before definitive impressions.
- C. Placing a margin into the attachment guarantees persistent inflammation and eventual failure of an otherwise well-made crown.
- D. Orthodontic EXTRUSION of the affected tooth, not the adjacent teeth, is the legitimate alternative to surgical crown lengthening — particularly in the aesthetic zone where bone removal on neighbours would be costly. Extruding the neighbours achieves nothing.
Note: The two routes to a restorable margin: surgical crown lengthening, which sacrifices attachment on adjacent teeth, or forced orthodontic eruption with fibrotomy, which preserves it. Choose by aesthetic demand and crown-to-root ratio.