Objective To explore the characteristics and correlation of the chin and airway in females with skeletal Class Ⅱ mandibular retraction for reference for clinical diagnosis and therapy.Methods This study was approved by the hospital Medical Ethics Committee.Forty cases of skeletal Class Ⅱ mandibular retraction adult females with aver-age angle were selected as the research group,and sixty cases of skeletal Class Ⅰ patients with average angle were se-lected as the control group.Cone-beam computed tomography(CBCT)images for all subjects were analyzed using three-dimensional modeling software.Measurements included the chin morphology,position,and upper airway morphology.Results Compared with skeletal Class Ⅰ patients,patients with skeletal Class Ⅱ mandibular retraction had smaller an-terior chin thickness,base bone volume,chin total volume,and larger chin angle,chin depression,chin curvature,and alveolar area with statistically significant differences(P＜0.05).Gn-V,Gn-H,Po-NB distance,and facial angle were smaller,and the Y-axis angle was larger in patients with skeletal Class Ⅱ mandibular retraction with statistically signifi-cant differences(P＜0.05).Upper airway total volume,transverse and sagittal diameter of the glossopharynx upper boundary were smaller in patients with skeletal Class Ⅱ mandibular retraction with statistically significant differences(P＜0.05).The correlation analysis between the morphology and position of the chin and the morphology of the upper airway in patients with Class Ⅱ mandibular retraction showed that there was a negative correlation between chin angle and laryngopharynx length in patients with Class Ⅱ mandibular retraction(r=-0.277,P＜0.01).There was a negative correlation between Po-NB distance and palatopharyngeal length(r=-0.222,P＜0.05).Chin height(r=-0.261,P＜0.01)and basal bone area(r=-0.225,P＜0.05)were negatively correlated with the transverse diameter of the palato-pharyngeal upper boundary.The minimum chin thickness(r=0.245,P＜0.05),chin angle(r=0.249,P＜0.05),and al-veolar area(r=0.213,P＜0.05)were positively correlated with the sagittal diameter of the palatopharyngeal upper boundary.Gn-V(r=0.217,P＜0.05)and Po-NB distance(r=0.208,P＜0.05)were positively correlated with the trans-verse diameter of the glossopharynx upper boundary.Anterior chin thickness was negatively correlated with the sagittal diameter of the laryngopharynx upper boundary(r=-0.211,P＜0.05).Chin depression was negatively correlated with the sagittal diameter of the laryngopharynx lower boundary(r=-0.237,P＜0.05).Chin curvature was positively corre-lated with the transverse diameter of the laryngopharynx lower boundary(r=0.231,P＜0.05).Conclusion Patients with skeletal Class Ⅱ mandibular retraction exhibit thinner chins.The sagittal position of the chin is backward,and the vertical position is upward.Patients with skeletal Class Ⅱ mandibular retraction have a narrow glossopharyngeal airway.There is a correlation between the morphology and position of the chin and the morphology of the upper airway in pa-tients with Class Ⅱ mandibular retraction.

In the field of dental aesthetics,digital aesthetic design plays a crucial role in helping dentists to predict treatment outcomes vis-ually,as well as in enhancing the consistency of knowledge and understanding of aesthetic goals between dentists and patients.It serves as the foundation for achieving ideal aesthetic effects.However,there is no clear standard for this digital process currently in China and abroad.Many dentists lack of systematic understanding of how to carry out digital aesthetic design for treatment.To establish standardized processes for dental aesthetic design and to improve the homogeneity of treatment outcomes,Chinese Society of Digital Dental Industry(CSD-DI)convened domestic experts in related field to compile this consensus.This article elaborates on the key aspects of digital aesthetic data collection,integration steps,and the digital aesthetic design process.It also formulates a decision tree for dental aesthetics at macro level and outlines corresponding workflows for various clinical scenarios,serving as a reference for clinicians.

Objective: To establish a quantitative three-dimensional method based on intraoral scan to evaluate the changes of soft tissue, and to evaluate the changes of supracrestal gingival thickness (SGT) in skeletal class Ⅲ patients induced by periodontal regenerative and corticotomy surgery (PRCS). Methods: Twenty-two systematically and periodontally healthy skeletal class Ⅲ patients (4 males and 18 females, aged between 19 and 35 years), who were in need of combined orthodontic-orthognathic treatment and referred to the Department of Periodontology from the Department of Orthodontics and the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from January, 2018 to March, 2019, were collected in the study. The teeth involved were 112 anterior teeth (46 maxillary anterior teeth and 66 mandibular anterior teeth). PRCS in anterior tooth area was conducted before orthodontic decompensation. Probing depth (PD), bleeding index (BI) and keratinized gingiva width (KGW) were recorded before surgery and 6 months post-surgery. The intraoral digital impressions of maxillary and mandibular anterior teeth were obtained by 3-shape intraoral scanner before surgery and 6 months after surgery. The Standard Tessellation Language (STL) files were processed using Geomagic qualify 12.2 software to establish the soft tissue morphological measurement model, and to quantitatively analyze the changes of gingival thickness situated 1 to 2 mm apical to the free gingival margin on the median sagittal measurement plane. Results: Probing depth and bleeding index had no significant difference before and 6 months after operation (P>0.05). KGW in 6-month post-operation group [(5.18±2.32) mm] was significantly higher than that in pre-operation group [(4.22±1.43) mm] (P<0.05). Supracrestal gingival thickness situated 1 to 2 mm apical to the free gingival margin also significantly increased 6 months after surgery (P<0.05). The changes of gingival thickness situated 1 to 2 mm apical to the free gingival margin in the upper anterior area were (0.68±0.56) and (1.00±0.69) mm, respectively. The changes in the lower anterior area were (0.38±0.42) and (0.58±0.45) mm, respectively. The gingival changes of the upper anterior teeth were also significantly higher than those of the lower anterior teeth (P<0.01). Conclusions The described quantitative measurement based on intraoral scan could be an effective method for quantitative evaluation of the changes of soft tissue. PRCS could safely increase the supracrestal gingival thickness as well as KGW in skeletal class Ⅲ patients who were in need of combined orthodontic-orthognathic treatment.

Acute respiratory failure due to acute hypoxemia is the major manifestation in severe coronavirus disease 2019 (COVID-19). Rational and effective respiratory support is crucial in the management of COVID-19 patients. High-flow nasal cannula (HFNC) has been utilized widely due to its superiority over other non-invasive respiratory support techniques. To avoid HFNC failure and intubation delay, the key issues are proper patients, timely application and improving compliance. It should be noted that elder patients are vulnerable for failed HFNC. We applied HFNC for oxygen therapy in severe and critical ill COVID-19 patients and summarized the following experiences. Firstly, to select the proper size of nasal catheter, to locate it at suitable place, and to confirm the nose and the upper respiratory airway unobstructed. Secondly, an initial ow of 60 L/min and 37℃ should be given immediately for patients with obvious respiratory distress or weak cough ability; otherwise, low-level support should be given first and the level gradually increased. Thirdly, to avoid hypoxia or hypoxemia, the treatment goal of HFNC should be maintained the oxygen saturation (SpO) above 95% for patients without chronic pulmonary disease. Finally, patients should wear a surgical mask during HFNC treatment to reduce the risk of virus transmission through droplets or aerosols.
Aged ; Betacoronavirus ; isolation & purification ; Cannula ; Coronavirus Infections ; therapy ; Humans ; Oxygen ; administration & dosage ; Pandemics ; Pneumonia, Viral ; therapy

Acute respiratory failure due to acute hypoxemia is the major manifestation in severe coronavirus disease 2019 (COVID-19) induced by severe acute respiratory syndrome coronavirus 2 infection. Rational and effective respiratory support is crucial in the management of COVID-19 patients. High-flow nasal cannula (HFNC) has been utilized widely due to its superiority over other non-invasive respiratory support techniques. To avoid HFNC failure and intubation delay, the key issues are proper patients, timely application and improving compliance. It should be noted that elder patients are vulnerable for failed HFNC. We applied HFNC for oxygen therapy in severe and critical COVID-19 patients and summarized the following experiences. Firstly, to select the proper size of nasal catheter, to locate it at suitable place, and to confirm the nose and the upper respiratory airway unobstructed. Secondly, an initial flow of 60 L/min and 37℃ should be given immediately for patients with obvious respiratory distress or weak cough ability; otherwise, low-level support should be given first and the level gradually increased. Thirdly, to avoid hypoxia or hypoxemia, the treatment goal of HFNC should be maintained the oxygen saturation (SpO) above 95% for patients without chronic pulmonary disease. Finally, patients should wear a surgical mask during HFNC treatment to reduce the risk of virus transmission through droplets or aerosols.
Aged ; Betacoronavirus ; Cannula ; Coronavirus Infections ; complications ; therapy ; Humans ; Hypoxia ; etiology ; prevention & control ; therapy ; Masks ; Oxygen ; administration & dosage ; Oxygen Inhalation Therapy ; instrumentation ; standards ; Pandemics ; Pneumonia, Viral ; complications ; therapy