A thin gingiva and a fractured incisal edge

Correct answer: B. Thin scalloped — higher risk of recession after surgery, restoration or implant placement

• A. Thick flat tissue does not preferentially recede. Dense, fibrotic, abundant keratinised tissue over thicker bone is the resilient pattern.
• B. CORRECT. The THIN SCALLOPED phenotype is characterised by delicate translucent tissue, a narrow band of keratinised gingiva, a highly scalloped gingival margin, slender triangular crowns with contact points near the incisal edge, and thin underlying bone prone to dehiscence and fenestration. Its clinical significance is that it responds to inflammation, surgery, restorative margins and implant placement by RECEDING rather than pocketing. It also SHOWS THROUGH — a metal crown margin or a grey implant abutment is visible beneath it — and interdental papillae are considerably harder to preserve or regenerate.
• C. This reverses the association. It is the THICK phenotype that tends to respond to inflammation by pocketing, while the thin phenotype recedes.
• D. Thick flat is the opposite phenotype, and it is the one that RESISTS recession. Pairing it with a high recession risk inverts both halves.

Note: Current terminology prefers PHENOTYPE over biotype, because the tissue characteristics can be modified — by connective tissue grafting, for instance — whereas ‘biotype’ implied something genetically fixed. Practical consequences for this patient: keep restorative margins SUPRAGINGIVAL wherever possible, handle the tissue minimally, and if an implant is ever contemplated in this aesthetic zone, plan soft tissue augmentation from the outset. Note too that triangular crowns in a thin phenotype are the anatomy that produces black triangles.

Correct answer: A. On the facial ENAMEL surrounding the preparation, as a long chamfer or bevel

• A. CORRECT. The bevel is cut in ENAMEL on the FACIAL surface, extending roughly 1 to 2 mm around the periphery of the preparation — often described as a long chamfer or a scalloped bevel. It serves three purposes, all of which matter in an anterior restoration. It exposes the ENDS of the enamel rods rather than their sides, which markedly improves the etch pattern and bond strength. It increases the SURFACE AREA available for bonding. And it creates a gradual, blended transition in restoration thickness that optically HIDES the margin — the aesthetic reason an unbevelled Class IV shows a visible line.
• B. The axiopulpal line angle is bevelled in AMALGAM preparations, notably Class II, in order to reduce stress concentration within a brittle material. It is a different material serving a different purpose and has no application to a bonded anterior composite.
• C. Bevelling only the incisal edge leaves the remainder of the margin as a butt joint, which is inferior both adhesively and aesthetically at precisely the visible margins that matter.
• D. A bevel placed in dentine achieves nothing. The rod-geometry argument applies only to ENAMEL, and bevelled dentine simply thins the restoration at its margin without improving the bond.

Note: This appears frequently as an EXCEPT item, so note what a bevel does NOT do: it does not prevent marginal fracture. If anything, a very thin feather-edged composite margin is MORE prone to chipping. Its three genuine purposes are bond strength, surface area and aesthetic blending. Note also the favourable geometry here — a Class IV has a low configuration factor, so polymerisation shrinkage stress is much less of a problem than in a Class V or Class I.