Extraction Type	Incisor Retraction (mm)	Space Closure (% Anterior)	Anchorage Loss (Molar Advance mm)	Key Viva Point
4 Second Premolars	Max 3.3 / Man 2.9	50% Max / 46% Man	Max 3.2 / Man 3.4	Equal anterior-posterior split; reverse Spee controls tipping.
4 First Premolars	10.3 combined	66.5%	5.2	High retraction risk; reinforces Tweed’s 1/3 rule exceeded.
Upper 1st/Lower 2nd Premolar	9.3 combined	56.3%	7.2	Moderates over-retraction in borderline cases.
4 First Molars	6.3 combined	31%	13.9	Minimal anterior pull; boosts third molar eruption (90%).
Non-Extraction	1.7 Max / 0.8 Man forward	N/A	Minimal	Baseline for stability testing.

Mnemonic: “Second Less Pull” – Second premolars: Less incisor retraction than firsts; molars pull more via root area