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A dark line has appeared beside the crown on a root canal tooth
How much does the position of a dark line at a crown’s edge tell a dentist about what it is? Could it be staining at the margin, or might it point to decay underneath, a gap, or damage to the crown?
I’m also wondering what changes the urgency of getting it checked. Would a loose crown, food catching at the edge, or pain make a difference, and can an exam usually distinguish these possibilities or is imaging often needed? I know the line alone wouldn’t prove the root canal has failed, but I’d like to understand what a dentist looks for next.
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2 replies
The line’s position can offer a clue, but I wouldn’t treat “right at the edge” as proof that it’s only stain. A mark confined to the crown margin may be surface staining; one that continues onto the tooth, or an edge that looks visibly open, gives the dentist a different concern to assess. They’ll examine the margin directly, and decay under a crown may not be visible from the surface, so imaging can be needed to evaluate it.
The urgency changes if the crown becomes loose, food keeps catching at its edge, or there’s pain: those are reasons to arrange a prompt dental assessment rather than just keep an eye on an unchanged, painless line. Swelling or fever calls for urgent care. None of those signs tells you what the line is, but they do change how quickly it should be checked.