I've got braces and my dentist placed a spring on the bottom section of my teeth what is it for? I've noticed a tooth is separating is that meant to happen?
He is creating space. Either for a tooth that has not come in yet, a tooth that is set back behind others, or for an eventual implant. Also, he could be using it to push a tooth in the direction he wants it to go. If you have a power chain pulling on either of those teeth at the end of your spring, then the chain is pulling the tooth over while the spring is pushing it over. It's like a double force.
Yes, it's what is meant to happen. It's a coiled spring wire which works by placing a slight but constant pressure, to open an area creating extra space for the teeth to be pulled into their correct alignment or position. Hope I've been of some help and good luck with your ortho!