EXTRACTION OR EXPAND?
2 MAJOR CIRCUMSTANCES for extraction
1)CL I crowding
extract? or e-x-p-a-n-d?
2)CL II post-adolescence
extraction for camouflage?
0-3 mm expand
10mm or more extract
4-9 mm expand? extract?
在1960年代为何增加?(why the increase in 1960s?)
→search for stability
introduction of begg technique~~full rather than partial banding
自1988年后为何下降(why the decrease more recently since 1988s)?
→concerns about stability
●severe extraction indications:
1)severe crowding >10 mm usually requires extraction~~if in doublt,don't!
2)good facial pattern~not skeletal CL II or CL III
3)fixed appliance treatment aviable in phase II treatment