Objectives: This study aimed to investigate the effect of varying edentulous space on canine distal bodily movement during space closure following maxillary first premolar extraction, using finite element method (FEM) analysis of clear aligner (CA).
Methods: The FEM was used to simulate distal canine bodily movement following maxillary first premolar extraction with clear aligners. Four CA designs for the edentulous space were compared: no-pontic, full pontic, half-pontic, and beam designs. Three-dimensional models of the tooth components and CA were created. The target was set at a 0.25 mm distal canine movement. Longterm tooth movement was simulated using an iterative calculation method.
Results: All the groups initially showed crown displacement, distal tipping, and distal rotation. Over time, the movement patterns differed according to the design. The no-pontic design exhibits the greatest displacement and tipping. The beam design exhibited the largest initial displacement, but the lowest displacement and tipping thereafter. Full- and half- pontic designs yielded intermediate results. The force reduction was significant immediately after CA application, followed by a gradual decrease. The mean tooth movement achievement rate was approximately 76.7%.
Conclusion: The edentulous space design of the CA significantly affected the tooth movement behavior. An iterative simulation is necessary to evaluate the long-term tooth movement patterns. The beam design demonstrated optimal suitability for bodily movements with the least tipping. For optimal results, additional setup or overcorrection may be necessary.

Keywords: FEM, extraction space, clear aligner design