Hello everyone, I hope some of my fellow ortho residents can comment upon the following treatment plan and critique it. Case: 32 year old female with complaint of increased overjet Overjet 6mm U1/MxPl 109 L1/MnPl 91 High MPA Class II Half unit malocclusion Upper arch well algined Lower arch has 6mm posterior crowding (3mm per quadrant) Lower first bicuspids are endodontically involved. Gingiva and bone overlying lower incisors are thin My treatment plan...(please critique!!!!) is to extract all first bicuspids Each bicuspid is 8mm in mesiodistal width. The treatment objectives are to reduce the overjet to 2mm and maintain lower incisor position. This has been agreed upon by my supervisor but i have some problem with the space management....... My questions are 1) what is my upper anchorage demand??? and 2) what is my lower anchorage demand??? My dilemma stems from this Some of my tutors advocate treating the upper arch maximum anchorage and the lower arch minimum anchorage. I agree with the lower arch demand. Now to retract the upper anteriors to an ideal overjet of 2mm will require 4mm of space per quadrant which is 50% of the space....this should just be moderate anchorage demand no? Some seniors have told me that when i attempt to drag the lower 2nd premolar and then the 1st molar forward the lower anteriors will retract. So that means even if they retract 2mm i will need to retract the upper anterior teeth 6mm. This is 75% of the extraction space so this amount of retraction will require maximum anchorage in the upper arch e.g...nance, band 7s etc But my thinking is as follows...... I can place lingual root torque on the lower incisors and tie the lower 6 anterior teeth together and then pull the lower 2nd premolars forward. I can now fit a lingual arch across the 8 teeth in the anterior segment and pull the lower molar forward. Now since there was 3mm of posterior crowding per quadrant in the lower arch and the extraction space is 8mm per quadrant...i need to protact the lower 2nd premolar and lower first molar 5mm....so lets say i end up retracting the lower anteriors 40% of the space which is 2mm. Hopefully with all the precautions i shouldnt retract the lower anteriors more than that. Now lets say i have retracted the upper anteriors with reciprocal space closure in the upper and retracted the upper anteriors 4mm. Since we started with an overjet of 6mm and the lower incisors retracted a bit (lets say 2mm as discussed above) we will end up with an overjet of 4mm. Now i can ask the patient to wear some class II elastics to mesialise the lower incisors 2mm to achieve and ideal overjet of 2mm...in other words..."regain the anchorage" i lost from the lower anterior segment as it retracted while i closed the lower space. Now some may feel this is round tripping....but i disagree as i have tried everything to prevent the lower anteriors from moving back and the alternative is to leave them in a retracted position. So "it is what it is" so to speak! I feel the advantage of my plan is that i will finish with my lower incisors and upper incisors at the position we aimed for. I know this is a high angle case so i can place a step down bend on the wire mesial to the lower 6 to prevent the lower molar from extruding with the class II elastics. Plus the elastics shouldnt be in place more than a few months so i dont think the vertical effects will be too bad...do you agree? My critique of the other treatment plan that called from maximum anchorage in the upper arch is that it takes into account that the lower anteriors will retract while closing the lower space. So this treatment will finish with lower incisors posterior to their original starting position and upper incisors retracted to this posterior lower incisor position. We thus fail to meet our objectives. I would love to know what you all think of my logic and whether you feel i am correct in my thinking? Thanks, Peter.