Gingivitis (inflammation of the gingiva) and oxydated free crown margins in the area of the front teeth. This is probably caused by the palladium-containing composition used as crown scaffold. Metal ions can infiltrate the gingiva and bones and color them dark gray or black. The only therapeutic option is removal of the metal-ceramic crowns and their replacement by metal-free crowns made of pure ceramic (e.g. zircon)
