The effects of height and width in L-loop characteristics: 3D analysis using finite element method

Desirable tooth movements need optimal force systems. Loops are employed to move teeth properly. Lloop is used frequently due to its ease of fabrication. The aim of this study is to assess the expected forces and moments when a definite length of wire is bent to form L-loop. In other words, the effect of loop height and width on the produced force and moment is evaluated by the finite element method (FEM).
Six 3D finite element models were designed of an L-loop without pre-activation bends keeping the total lengths of wire equal to 24.34 0.5 mm. The cross section of wire was 0.016”× 0.022”. The force produced by activation in a 0.1 millimeter increment was recorded.
In model L1, the findings start with 0.086 N in 0.1 mm of activation and increased to 0.88 N in 1 mm of loop opening. The pattern of findings was almost the same for other loop designs (L2 through L6) with an increase in findings. M/F ratios were almost constant in a loop design along its activation starting with 3 in L1 and reaching about 1.9-2 in L6.
Moment to force ratios were almost constant in a loop design along its activation. increasing width and decreasing height with almost the same length of loop wire can increase force and therefor reduce M/F ratio.