## 3 Results
### CBCT Superimposition  
Pre- and post-treatment CBCT images and 3D superimposition of the maxilla from the CBCT images are shown in Figures 13 and 14, respectively. The pretreatment CBCT indicated that the roots of the maxillary premolars and molars protruded into the maxillary sinus (Figure 13 FJ; Figure 14B,F,J,N). The post-treatment CBCT showed that these maxillary  
Figure 12: Lateral cephalometric, cephalometric tracing, and panoramic radiographs after 2 years of retention. roots had moved without inducing any root resorption (Figure 13G,K; Figure 14C,G,K,O). CBCT superimposition showed that the crowns and roots of the maxillary teeth had distally moved (Figure 13D,H,L; Figure 14D,H,L,P). CBCT superimposition showed that the roots of the maxillary molars on both sides had disto-palatally moved (Figure 13H,L). When the movement of the roots in the right first molar was measured using Figure 13L as an example, the mesio-buccal root had moved 1.49 mm distally and 0.47 mm palatally, the disto-buccal root had moved 2.28 mm distally and 0.92 mm palatally, and the palatal root had moved 0.48 mm distally and 0.49 mm palatally. In the right second molar, the mesio-buccal root had moved 3.08 mm distally and 0.53 mm palatally, the disto-buccal root had moved 3.19 mm distally and 1.55 mm palatally, and the palatal root had moved 1.96 mm distally and 1.63 mm palatally (Table 2). After a 3-month interval, the pre- and post-treatment CBCT images were superimposed again, and all measurements were repeated to check the intraexaminer reliability. All operations were performed by a single examiner. A paired t-test performed using SPSS software (version 20; IBM, Armonk, NY, USA) showed no significant differences between the two measurements. [PERSON]'s formula was used to calculate the method error [22]. Thus, pre- and post-treatment CBCT image evaluations provide detailed treatment results that are not visible in the 2D radiographic images and are useful information for future treatment. Figure 13: Three-dimensional cone-beam computed tomography (CBCT) images of the relationships between the maxillary molars and maxillary sinus. (**A–D**) CBCT coronal section at the crown level of the maxillary first molars (_arrow_), CBCT axial sections at post-treatment (_gray_) and pretreatment (_green_), and their superimposition; (**E–H**) CBCT coronal section at the root level of the maxillary first molars (_arrow_), CBCT axial sections at post-treatment (_gray_) and pretreatment (_green_), and their superimposition; (**I–L**) CBCT coronal section at the root apex level of the maxillary first molars (_arrow_), CBCT axial sections at post-treatment (_gray_) and pretreatment (_green_), and their superimposition. The distances were recorded on cone-beam computed tomography images as positive values if the crowns or roots moved palatally and negative values if the crown or root moved buccally. Abbreviations: 6C, the crown of the right first molar; 7C, the crown of the right second molar; 6 MB, the meso-buccal root of the right first molar; 6 DB, the disto-buccal root of the right first molar; 6P, the palatal root of the right first molar; 7 MB, the meso-buccal root of the right second molar; 7 DB, the disto-buccal root of the right second molar; 7P, the palatal root of the right second molar; UM, unmeasurable. Figure 14: Three-dimensional cone-beam computed tomography (CBCT) images of the relationships between the maxillary molars and maxillary sinus.