Background This retrospective study investigated the effect of breathing pattern, skeletal class (Class I, Class II), and age on the hyoid bone position (HBP) in normodivergent subjects. Methods A total of 126 subjects (61 males, 65 females) aged 7–9 years and 10–12 years were scanned using cone-beam computed tomography (CBCT). All participants were classified according to the anteroposterior skeletal pattern into (Class I, Class II). Each skeletal group was further divided according to the breathing mode into mouth breathers (MB) and nasal breathers (NB). The HBP was measured accordingly. Independent sample t-test and Mann Whitney U test were used to detect significant differences between the groups, and binary logistic regression was used to identify MB predictive indicators. Results The breathing mode and skeletal class affected the vertical HBP in subjects with 7–9 years, while they affected the anteroposterior HBP in subjects with 10–12 years. Regarding the age effect, hyoid bone was located more anteriorly in the older NB subjects, and hyoid bone was more inferiorly in the older age group. A regression equation of the significant variables was formulated, C3-Me (P: 001, OR: 2.27), and H-EB (P: 0.046, OR: 1.16) were positively correlated with occurrence of MB. Conclusion There were significantly different HBPs among subjects with different anteroposterior skeletal classes, breathing modes, and age cohorts. Moreover, C3-Me, and H-EB were significant predictors and correlated with increased likelihood of being MB subject.

Background Mouth breathing (MB) can affect morphological changes in the craniofacial structures, electromyography is widely used for quantitative analysis of muscle function. Objective The aim was to evaluate the electromyographic (EMG) activities of the anterior temporalis (TA), masseter muscle (MM), orbicularis oris superior (OOS) and mentalis muscle (MT) in children with different vertical skeletal patterns and breathing modes during rest and various functional mandibular movements. Methods BioEMG III was used to measure the variations in EMG activities of TA, MM, OOS, and MT in 185 subjects aged 6–12 years during continuous clenching, rest, maximal intercuspation, lips closed lightly and swallowing. Results The results of logistic regression analysis showed that the model with vertical skeletal patterns as the dependent variable was ineffective (p = .106), while the model with breathing modes as the dependent variable was effective (p = .000). When considering both vertical skeletal patterns and breathing modes, the following significant differences were found. (1) In the normal‐angle group, the EMG ratio in OOS with lips closed lightly of MB was significantly higher than NB (p = .005). (2) In the low‐angle group, EMG ratios in TA and MM during the swallowing of MB were significantly lower than NB (p = .020, p = .040, respectively). (3) In the high‐angle group, EMG ratios of MB were significantly higher in MT during continuous clenching, rest, lips closed lightly and swallowing (p = .038, p = .036, p = .005, p = .028, respectively), and OOS with lips closed lightly compared to NB (p = .005). Conclusion Breathing modes and vertical skeletal patterns interacted to alter maxillofacial EMG activities, with breathing modes having a greater effect.

No abstract

Background This study aimed to evaluate and compare the alveolar bone changes and to investigate the prevalence and severity of orthodontically induced inflammatory root resorption (OIIRR) of maxillary incisors in patients who received treatment with clear aligners (CA) versus conventional fixed appliances (FA), using cone-beam computed tomography (CBCT). Methods One hundred sixty maxillary incisors from 40 patients with similar baseline characteristics based on the American Board of Orthodontics discrepancy index scores were divided into the CA and FA groups. The dentoalveolar quantitative changes were analyzed using pre- (T0) and post-treatment (T1) CBCT. The measured parameters included alveolar bone thickness (ABT), alveolar bone height (ABH), root length (OIIRR), and maxillary incisor inclinations. Results Post-treatment, the average palatal and total ABT significantly decreased in central and lateral incisors in the FA group. In contrast, the CA group’s average labial ABT of the lateral incisors decreased considerably. Regarding the ABH, both groups showed significant labial and palatal marginal bone resorption. In both groups, root lengths significantly decreased after treatment (p < 0.005). The inter-group comparison revealed that ABT and root length had significantly decreased in the FA group compared to the CA group, while the ABH showed no significant difference between the two groups. The mean absolute reductions of ABT and OIIRR in the CA group were significantly less (− 0.01 ± 0.89 and 0.31 ± 0.42) than those in the FA group (0.20 ± 0.82 and 0.68 ± 0.97), respectively. Conclusions CA and FA treatments appear to cause a significant ABT reduction and a statistically significant increased OIIRR in the maxillary incisor region, with a greater extent expected with FA treatment. However, the increased OIIRR values in the majority of both groups’ cases were not clinically significant. Both treatment modalities resulted in a significant ABH reduction, with the highest found in the labial side of lateral incisors in the CA group.

Objective This study aimed to investigate whether the subjects with mouth breathing (MB) or nasal breathing (NB) with different sagittal skeletal patterns showed different maxillary arch and pharyngeal airway characteristics. Methods Cone-beam computed tomography scans from 70 children aged 10 to 12 years with sagittal skeletal Classes I and II were used to measure the pharyngeal airway, maxillary width, palatal area, and height. The independent t-test and the Mann–Whitney U test were used for the intragroup analysis of pharyngeal airway and maxillary arch parameters. Results In the Skeletal Class I group, nasopharyngeal airway volume (P < 0.01), oropharyngeal airway volume (OPV), and total pharyngeal airway volume (TPV) (all P < 0.001) were significantly greater in subjects with NB than in those with MB. Furthermore, intermolar width, maxillary width at the molars, intercanine width, maxillary width at the canines, and palatal area were significantly larger in subjects with NB than in those with MB (all P < 0.001). In the Skeletal Class II group, OPV, TPV (both P < 0.05) were significantly greater in subjects with NB than in those with MB. No significant differences in pharyngeal airway parameters in the MB group between subjects with Skeletal Class I and those with Skeletal Class II. Conclusion Regardless of sagittal Skeletal Class I or II, the pharyngeal airway and maxillary arch in children with MB differ from those with NB. However, the pharyngeal airway was not significantly different between Skeletal Class I and II in children with MB.