We also use Functional Expansion Appliances, which are used to create space in crowded conditions.  They are adjusted systematically, and are removable.  If functional appliances are needed, this is usually the first phase of orthodontics (often called the orthopedic phase to develop bone growth and space).  Once the needed space is created, Fastbraces(R) or Invisalign(R) is used to complete treatment to obtain the desired result.