My son just had his first permanent molar cavity filled. It was a big cavity on a bottom molar so the dentist did a silver filling which covers most of the chewing surface. Since it's big, the dentist offered to polish it in a week so it would not look as bad. However, my son refuses to have it polished, since the silver will be visible either way, so he doesn't want to spend more time at the dentist fo no reason, so he's willing to let his filling get dark. Should I listen to him, and let him skip the polishing, since he did at least get the cavity filled?