A proximal (Class II) carious lesion typically begins at what location?

Correct answer: B. Just apical (cervical) to the proximal contact point

• A. The contact point is subject to physiological wear during function and is not where the lesion begins.
• B. CORRECT. The lesion starts immediately APICAL to the contact area — in the zone between the contact point and the free gingival margin. The contact itself is self-cleansing because the teeth burnish one another during function, but the area just below it is protected from the toothbrush, sheltered from salivary flow, and ideal for plaque stagnation.
• C. The cementoenamel junction is the site of ROOT caries in patients with recession — a different lesion in a different population.
• D. The area occlusal to the contact is accessible to the toothbrush and to salivary clearance.

Note: This anatomy dictates operative design: the gingival floor of a Class II box must be extended apically past the lesion, which is why the wedge and matrix band must adapt tightly at that level to avoid an overhang.