Fig. 2
From: Mechanical force system of double key loop with finite element analysis
Meshing and preactivation of DKL. a Meshing of DKL model with refined elements. b Archwire with key loops was fixed on the mesial end, and the distal end was free. Simulative preactivation of DKL with a spring generated curvature between the mesial and distal archwires. The angle between the distal archwire and horizontal line was named as the preactivation angle (θ)