The first time I got my archwire put on my braces there was one black little center mark on it... I was able to scrape it off with my fingernail. This time there are 3 black marks, and I've been trying to get rid of them for the past 2 days but they're still visible.

Is there an easy way to get the center mark off of my archwire?
Is the center mark important after the archwire is in place?