Fig. 2From: Different biomechanical effects of clear aligners in bimaxillary space closure under two strong anchorages: finite element analysisTwo coordinate systems were used to evaluate the tooth displacements. A Global coordinate system was set based on the occlusal plane and used to evaluate the vertical displacements of teeth. B Local coordinate system was set on the body center of the clinical crown and root apex of every tooth: x (mesiodistal direction), y (labial lingual direction), and z (tooth long-axis direction). Local coordinates were used to analyze the labial/lingual and mesial/distal displacements of teethBack to article page