Question:
Why would I use a midline expander if I have less than 3m of crowding? If there's less than 2.5mm of crowding, can you use an expander to do the whole case non-IPR? For a 3mm case, can you use a midline expansion for 2.5mm of the crowding and IPR for the other 0.5mm? Would you turn the expander twice a week? When wouldn't you use it? Can you use it inappropriately or mess up a case by using one unnecessarily?

Answer:
I often use an expander to move the teeth out and expand the curve, unless it is a really mild case. You can do the whole case non-IPR if crowding is less than 2.5mm, but you should still do a little IPR to free up the contact. For a 3mm case you can use any combination of the two methods. But obviously your next course of action will be dependent on what you see at each follow-up appointment. For example, if the desired movement and overall goal is achieved after four weeks with only four turns and two sessions of IPR, then stop. You can turn the expander twice a week, but that can sometimes cause soreness for the patient. I rarely use expansion on the lower arch. The lowers normally move a little quicker and compliance is much better with the normal IA. In addition, the lingual mucosa gets a little more sore with expansion. You can only mess up a case with an expander if you let the patient over expand, i.e. they fail to return for a long period of time during which they continue to turn the screw. If this happens, you need to instruct them to slowly unwind it and this will help pull the arch back in.

Tags: Expansion, Tips on Expansion, Combined Inman and Expander, Fanscrew Expander, Troubleshooting, Problem Solving, FAQ's, Over Expansion