The Mechanics of Maxillary Molar Distal Movement Using Class II Carriere Motion Appliance: A Finite Element Study

To clarify the mechanics of tooth movement produced by a unique distalizer, Class II Carriere Motion appliance (CMA), in which the maxillary canine is connected to the maxillary first molar with a stiff bar, long-term tooth movement was simulated by the finite element method (FEM). The FEM models of the maxillary canine, premolars, and first molar were made based on a dental study model. The periodontal ligament (PDL) was constructed on the root and assumed to be a nonlinear elastic material. The teeth and the alveolar bone were assumed to be rigid bodies. The tooth moved by accumulating the initial movement produced by the elastic deformation of the PDL. When retraction force was applied to the canine from the mandibular dentition, the canine tipped or rotated clockwise and extruded due to the vertical component of the retraction force. The molar and premolars also tipped and moved distally, but hardly extruded because the vertical force did not act on them. As a result of these tooth movements, the canine protruded from the dentition. An interproximal space was created between the canine and the lateral incisor. These movement patterns were similar to those in other clinical studies using the CMA.