Question:
In cases where both arches are narrow and the incisors are severely crowded, I understand that it is possible to expand the upper arch with a midline Expander or a Fanscrew Appliance. But how about the lower arch? Can you use the same appliances to expand the lower?

Answer:
You can definitely expand the lower arch with a midline or Fanscrew Expander. But this is normally done simultaneously with the expansion of the upper arch in cases with very narrow occlusion. I often use an Inman Aligner with a combined expander on the lower like the attached photo. You can only expand by 2.5mm, otherwise you are bound to get occlusal interferences, unless it is an open bite case. You also need to let the patient turn the screw more progressively, i.e. 1/8th turn every 2-3 days, otherwise they get soreness due to a thinner mucosa. It does work well though. I use them about 20% of the time in lower cases.

Tags: Severe Lower Crowding, Expansion, Midline Expansion, Fanscrew Appliance