Dark lines around dental crowns and veneers can be very off-putting. After all, porcelain is selected for dental restorations, at least in part, due to its aesthetic abilities.
The good news is, black lines around porcelain veneers or crowns poses no physical dangers. The bad news is, unless replaced, black lines cannot be removed from dental restorations.
Porcelain is an incredibly strong and functionally reliable material. Used for plates, bathroom fixtures, and other items that must be strong enough for frequent use but should also look and feel appealing.