Hello, some years back I had a trauma on my front tooth. It got darker, and I’ve made an internal bleaching at the time. Some years passed and on that tooth I put a ceramic crown. At the time looked great, but now, after 3 years I notice that my tooth is darker again. It’s noticeable a darker color inside the crown. My question is, can I do an internal bleaching again on this tooth that has a ceramic crown?