Generally there are a few methods to create space to align teeth. The main ways are:
1. Extraction
2. File the teeth (IPR)
3. Push the teeth forward (buccal expansion)
4. Push the back teeth back (distalization)
There are pros and cons of each options. You are right to point out that excessive filing may lead to sensitive teeth.
Most of our enamel at the area where filing is done are about 0.6-1.5mm thick. Based on my experience, if the filing of enamel is done is a meticulous and measured way, it is very rare for patients to experience sensitivity.
Hope that helps, and have a great journey to a nicer smile ahead!
