[Morphological changes of upper airway in patients with skeletal Class â ¢ malocclusion after bimaxillary surgery and correlation analysis].

PURPOSE: To analyze the morphological changes of the upper airway and related influencing factors in patients with skeletal Class Ⅲ malocclusion after bimaxillary surgery. METHODS: Twenty skeletal Class Ⅲ patients who underwent Le Fort I osteotomy and bilateral sagittal split ramus osteotomy(BSSRO) for maxillary advancement and mandibular setback were selected. The patients received CT scans before(T0) and 3-6 months after surgery, and the images were reconstructed three-dimensionally with Dolphin Imaging 11.9 software. Changes in the volume, cross-sectional area, and landmarks of each soft and hard tissue of the airway were measured. Statistical analysis of the data was performed using SPSS 25.0 software package. RESULTS: The volume of nasopharyngeal airway increased after operation (P＜0.05), and the volume of oropharyngeal airway decreased significantly(P＜0.01). The cross-sectional area of the airway at the plane of the second cervical vertebra was significantly decreased (P＜0.01), and the coronal and sagittal diameters were decreased(P＜0.05). The change of nasopharyngeal airway volume was moderately positively correlated with the sagittal change of the posterior nasal spine (r=0.460, P＜0.05), and the change of oropharynx and laryngopharyngeal airway volume was positively correlated with the vertical change of the midpoint of the soft palate(r=0.496, 0.696, P＜0.05). The airway cross-sectional area in the second and third cervical vertebra planes and the sagittal diameter of the airway in the third cervical vertebra plane were positively correlated with the vertical changes of the midpoint of the soft palate(r=0.474, 0.629, 0.547, P＜0.05). The change of airway cross-sectional area at the third cervical vertebra plane was moderately negatively correlated with the change of mandibular plane angle(r=-0.536, P＜0.05). CONCLUSIONS: The volume and cross-sectional area of oropharyngeal airway in skeletal Class Ⅲ patients after bimaxillary surgery will decrease. However, the total upper airway volume doesn't change significantly. The changes in the upper airway are correlated with the changes in some soft and hard tissue landmarks.

[Cone-beam CT measurement of morphological changes of the root and alveolar bone of the central incisor during orthodontic treatment with extraction].

PURPOSE: To study the effect of orthodontic treatment with extraction on root resorption and alveolar bone morphology of the central incisor in adult patients. METHODS: Eleven adult patients receiving orthodontic treatment were enrolled, and asked to take cone-beam CT(CBCT) scanning before and after treatment. Root resorption of the upper and lower central incisors after treatment, changes in alveolar bone thickness and height of alveolar bone were measured and compared. Statistical analysis was performed using SPSS 23.0 software package. RESULTS: The length of the tooth and root was reduced to a certain degree. The change in root length of the maxillary incisor was larger than that of the mandibular incisor. The alveolar bone width of the lingual and palatal neck of the central incisor showed some reduction, and alveolar bone width of the palatal neck of the upper central incisor and the middle lingual side of the mandibular central incisor changed to a certain extent. The width of the alveolar bone in the middle labial side of the mandibular central incisor increased, but the alveolar bone on the lingual and palatal side increased after orthodontic treatment, which was more obvious than that of the maxillary central incisor. CONCLUSIONS: Orthodontic treatment with tooth extraction is accompanied by a certain degree of root resorption of the central incisor and alveolar bone on the lingual and palatal side. However it is also accompanied by an increase in the amount of alveolar bone on the labial side. More fenestration and dehiscence are observed in the mandible.