Why is there a dark line at the gum edge of my veneer?
Most dark lines are optics or stain; a few are leakage. The distinction is quick to make in the chair.
A grey or dark line where veneer meets gum has several possible identities: root surface showing after mild recession, stained cement at the margin, the shadow of a darker underlying tooth through thin porcelain, or — least often but most important — a leaking margin.
Benign shadow or warning line?
A stable line that has looked the same for years and causes no symptoms is usually cosmetic. A line that is widening, paired with sensitivity, roughness, or floss snagging, moves into the warning category.
Treatment ranges from none at all to polishing, margin repair, or a new veneer with the margin placed differently. Gum position and tissue thickness differ from person to person, so have a dentist identify which kind of line yours is before considering cosmetic fixes.
MediIndex articles are for general information only and are not medical advice, diagnosis, or advertising. Outcomes vary by individual — consult a board-certified specialist for personal decisions.