A patient has marked localized gingival recession on a mandibular anterior tooth immediately adjacent to the labial frenum. What is the MOST likely cause?

Correct answer: C. A high frenal attachment pulling on the marginal gingiva

• A. Gingivitis is generalized and reversible; it produces inflammation and edema rather than isolated recession at a single frenal site.
• B. Occlusal trauma widens the PDL and can cause mobility, but it does not by itself cause gingival recession.
• C. CORRECT. A frenum that inserts at or near the free gingival margin transmits muscle pull directly to the marginal tissue during lip movement. This retracts the margin, opens the sulcus, impedes plaque control, and produces LOCALIZED recession confined to that site. Treatment is a frenectomy/frenotomy, usually combined with a graft if root coverage is desired.
• D. Abrasion typically produces recession across several adjacent teeth on the side the patient favors, with a wedge-shaped cervical notch — not a single tooth at the frenum.

Note: Key clue = 'localized' + 'adjacent to the frenum'. Frenal pull is the anatomic answer.