Fig. 8From: A comparison of three-dimensional stress distribution and displacement of naso-maxillary complex on application of forces using quad-helix and nickel titanium palatal expander 2 (NPE2): a FEM studyStress distribution after activation of the quad-helix and NPE2 models in the cross-sectional view at the first deciduous molar (a, b), second deciduous molar (c, d), and first permanent molar (e, f)Back to article page