How can I fix darkened gums after a root canal and after getting a porcelain crown?

i am 22, i got a root canal done when i was much younger on one of my front tooth. After many years my dentist told me i would have to get a crown on that tooth because the tooth was dead and would turn a darker color. Even after getting an all porcelain crown my gums have still turned a noticeably darker color. I have read on internal bleaching, but is that only for natural teeth? How can i lighten my gums even after having an all porcelain crown? Do i have any options to fix this?