The aim of this study is to evaluate the longitudinal transverse growth of the maxillo-mandibular complex in untreated children using the Cone Beam Computed Tomography (CBCT). Two sets of scans on 12 males (mean 8.75 years at T1 and 11.52 years at T2) and 18 females (mean 9.09 years at T1 and 10.80 years at T2) were analyzed using Dolphin 3D imaging. The transverse widths of various maxillary and mandibular skeletal landmarks and the dentoalveolar and dental landmarks at the level of first molars were measured. Overall, there were greater increases in the transverse dimension in the posterior than anterior portions of the maxilla and mandible. The increase in intergonial width of the mandible seems to be primarily due to the lengthening of the mandibular body. The dentoalveolar process at the first molar level increases at an equal rate corono-apically and is independent to the changes in molar inclination. When comparing maxillary dentoalveolar changes with that of the mandible, greater increases were noticed in the maxilla, which might be explained by the presence of sutural growth in the maxilla. Moreover, the first molars maintain their coordination with each other despite the differential increase in the maxillary and mandibular dentoalveolar processes.

Objectives: To evaluate nasal soft and hard tissue changes immediately post–rapid maxillary expansion (RME) and to assess the stability of these changes using cone beam computed tomography (CBCT). Materials and Methods: A total of 35 treatment group (TG) patients (18 girls, 17 boys; 9.39 ± 1.4) had a pre-RME CBCT and a post-RME CBCT approximately 66 days after expansion, and 25 patients had a follow-up CBCT 2.84 years later. A total of 28 control group (CG; no RME) patients (16 girls, 12 boys; 8.81 ± 1.6) had an initial CBCT and a CBCT an average of 2.25 years later. Soft and hard tissue nasal landmarks were measured in transverse, sagittal, and coronal planes of space on CBCT scans. Differences within the same group were evaluated by paired t -tests or Wilcoxon signed-rank tests. Long-term comparisons between TG and CG were evaluated by independent-sample t -tests or Wilcoxon rank-sum tests. Results: Immediately post-RME, there were statistically significant mean increases of 1.6 mm of alar base width, 1.77 mm of pyriform height, and 3.57 mm of pyriform width ( P < .05). CG showed the significant increases over 2.25 years ( P < .001). Compared with CG, the long-term evaluation of TG demonstrated only pyriform height and pyriform width showed a statistically significant difference ( P < .01). Conclusions: Although RME produced some significant increase on the nasal soft tissue immediately after expansion, it regressed to the mean of normal growth and development over time. However, long-term evaluation of TG compared with CG showed only pyriform height and pyriform width to be affected by RME.

Lip bumper (LB) therapy is used as a treatment approach for mild to moderate crowding without extraction of teeth. Previous studies demonstrated that LB increases arch length through molar uprighting and lateral expansion. However, the effects of LB on mandibular incisors are inconclusive. The controversial results from different studies may be due to limitations including absence of a control group and/or use of 2D radiography. To address this issue, the current retrospective longitudinal CBCT study compared a rapid maxillary expansion (RME) group with no lower treatment [16 patients (9 females, 7 males); median age 8.86 years at T1 and 11.82 years at T2] and an RME + LB group [18 patients (13 females, 5 males); median age 9.46 years at T1 and 12.10 years at T2]. The CBCTs taken before and after phase 1 treatment were 3D superimposed based on the mandibular structure and were measured to determine the angular and linear changes of the mandibular incisors over the course of LB treatment. For comparisons between different timepoints within a group, a Wilcoxon matched-pairs signed rank test was used. For intergroup comparisons, a Mann–Whitney U test was used. Both groups showed eruption and protrusion of the mandibular incisors during the observation period, while there was no significant change in proclination of the lower incisors. When comparing the discrepancy of change between groups, there was no statistically significant difference detected. In summary, by utilizing a longitudinal 3D database, the current study demonstrated that the effect of LB on the position of the mandibular incisors is limited.

Objectives: To investigate the effects of buccal osteotomy angulation on surgically assisted rapid palatal expansion (SARPE) patterns. Materials and Methods: A finite element analysis (FEA) model of the maxilla with Haas expander was constructed from a cone beam computed tomography (CBCT) image using Mimics, Geomagic, and solidWorks software. One-mm-thick buccal osteotomies were created with different combinations of 0°, 10°, 20°, and 30° from the horizontal plane to simulate differences in bilateral osteotomy angulation. Springs were placed at the buccal osteotomy gaps to mimic the strain of the bone callus. After applying 150 Newton of expansion force at the level of the expander jackscrew in each FEA scenario, the expansion pattern of the hemimaxillae was evaluated in Ansys software. Results: Scenarios with 20° (0–20°; 10–30°) and 30° (0–30°) differences resulted in significant transverse asymmetric expansion. Among the groups with 10° difference, 0–10° resulted in relatively parallel expansion, while 10–20° and 20–30° experienced V-shaped expansion with more anterior widening. Conclusions: A larger difference between the angulations of the left and right buccal osteotomies resulted in increased asymmetry in both the transverse and vertical dimensions after expansion.