They can. When I got mine, the orthodontist inserted these itty bitty green washers between my teef. This was to create space for the braces. Then a couple weeks later the green thingies came out and the braces went on, then the wires. He used this tool that sounded like a ratchet wrench to tighten the wires. It did hurt a little bit, but the pain went away after a couple days, and I was fine. Until...... my next appointment, when he did the ratchet thing again. This was pretty much the way it went from that appointment on. You get used to it, only to go back in and get tortured again at your next appointment, over and over. But the end result is nice. I have a nicethhh thet of teef now.