ABSTRACT
OBJECTIVE: The aim of this study was to compare the differences in closing extraction spaces between maxillary first premolar and second premolar extractions using 3-dimensional finite element analysis (FEA). METHODS: Maxillary artificial teeth were selected according to Wheeler's dental anatomy. The size and shape of each tooth, bracket and archwire were made from captured real images by a 3D laser scanner and FEA was performed with a 10-noded tetrahedron. A 10 degrees gable bend was placed behind the bull loop on a 0.017" x 0.025" archwire. The extraction space was then closed through 12 repeated activating processes for each 2 mm of space. RESULTS AND CONCLUSIONS: The study demonstrated that the retraction of anterior teeth was less for the second premolar extraction than for the first premolar extraction. The anterior teeth showed a controlled tipping movement with slight extrusion, and the posterior teeth showed a mesial-in rotational movement. For the second premolar extraction, buccal movement of posterior teeth was highly increased.