A few days after receiving a Class II restoration, a patient returns with interproximal inflammation and reports that dental floss shreds when passed through the contact. What is the MOST likely cause?

Correct answer: B. An overhang or void at the gingival margin of the restoration

• A. A premature occlusal contact causes percussion sensitivity, not interproximal floss shredding.
• B. Correct. Shredding floss is the classic sign of a rough, ledged or voided GINGIVAL MARGIN. An overhang or a marginal void leaves a sharp edge that catches and tears floss fibres, while simultaneously acting as a plaque trap that produces the localised papillary inflammation described. The correct management is to finish and smooth the margin, or replace the restoration.
• C. Under-cured composite causes a soft surface and post-operative sensitivity, but shredding specifically localises the problem to a marginal irregularity.
• D. A proximal concavity (under-contour) produces food impaction and open contacts, but it does not shred floss — there is no sharp ledge to catch fibres.