ObjectiveTo evaluate the effects of rapid maxillary expansion (RME) on mid-facial depth in early mixed dentition and to investigate the relationship between change in mid-facial depth and maxillary sinus and nasal cavity.MethodsA total of 35 patients with mixed dentition treated with a Haas expander were included in this retrospective study. All patients underwent a cone-beam computed tomography scan before and after rapid maxillary expansion. The Wilcoxon signed-rank test was performed to evaluate the changes in maxillary width, facial depth, maxillary sinus, and nasal cavity volume before and after expansion. Multiple linear regression analysis was applied to evaluate the correlations among them.ResultsThe hard and soft tissue facial depth in the middle third increased significantly (P < 0.001). The gain on the outer sagittal plane (1.04–1.52 mm) was slightly bigger than that on the inner sagittal plane (0.91–1.30 mm). Maxillary width and nasal cavity width increased 3.42 ± 0.93 mm (P < 0.001) and 2.25 ± 0.77 mm (P < 0.001), respectively, after treatment. A gain was also achieved in both nasal cavity volume (2,236.15 mm3, P < 0.001) and maxillary sinus volume (1,227.33 mm3, P < 0.001). Multiple linear regression analysis showed that with the increase in maxillary sinus volume, the facial depth increased as well (B = 0.455–0.683, P < 0.05). Also, statistically significant correlations were found between nasal width and nasal cavity volume (B = 0.384, P < 0.05).ConclusionThe depth of the middle third face increased significantly. The facial depth increase was related to the enlargement of maxillary sinus volume, while the nasal cavity volume gain was related to the nasal width increase. This indicated that RME might enhance the fullness of the mid-face and facilitate the patency of nose breathing.

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Background: Speech sound disorders are produced irrespective of the type of orthodontic appliance. The present systematic review aimed to compare the speech impediments created during orthodontic treatment with the labial appliances (LA), lingual appliances (LI), and orthodontic aligners (OA). Methods: The studies were searched from PubMed, Scopus, Web of Science, Embase, and Cochrane Library from 2000 to 25 Feb 2022. A manual search was also performed. The study’s quality was assessed by the Cochrane Risk of Bias Tool and the Newcastle-Ottawa Quality Assessment Form. Two reviewers performed study selection and data extraction. Results: From a total of 1298 articles, 21 studies were selected, including 3 randomized clinical trials (RCTs), 15 prospective studies, 2 retrospective studies, and 1 cross-sectional study. Two RCTs were assessed as having a "low" risk of bias, and one was considered unclear. Twelve nonrandomized studies were classified as "high" and six as "moderate" quality. Six studies compared LA and LI, three studies compared LA and OA, one study compared LI and OA, and eleven studies only evaluated single orthodontic appliances. Conclusion: Based on the evidence available, LA seemed to impact minimally on speech, and the duration was the shortest; LI caused more speech impediments and had greater difficulty adapting; OA produced mild to moderate speech impediments, and the adaptation time was between the two.