I have a spring similar to what manna22, Jenp and victor36 describes and shows.
It hurts plain and simple. The pressure on the two teeth is immense and I'm pretty good with pain. The pressure on the canine is more than the tooth on the other side.
This is my second spring and it is much thicker than the one I had before. This is my second month with a spring; so about 6 weeks so far. I'm pretty sure I'll have it for another 6 weeks at least as there is lots more work to be done to make enough room for that tooth that is sitting back there.
On my visit yesterday, Ortho ordered a crimp on the end of the spring to increase the pressure and increase it did! The canine is very tender to teh touch today and I've eaten soup and soft foods today.
The pressure on the tooth after the second spring lasted about a week. With all that said, I'll do whatever it takes to get that tooth forward. It is working.

