Objective:To determine the direction of traction that has the least influence on temporomandibular joint (TMJ) during mandibular distraction osteogenesis(MDO).Methods:(1) The three-dimensional finite element model was established after the mandible data were obtained by cone beam computed tomography (CBCT) scanning, and the validity of the model was verified. (2) Based on the verified three-dimensional finite element model, the distraction osteogenesis of mandible was carried out with six different directions. (3) The effects of different traction directions on disc pressure, osteotomy displacement, temporal bone pressure and condylar pressure were measured.Results:(1)In the thinnest area of the articular disc, the direction of the minimum stress on the upper and lower surfaces of the disc was "along the direction of the mandible, parallel to the surface of the mandible" . (2) Under the same load, the displacement of each osteotomy surface along the traction direction was different, but the difference was not big, and the effect was basically the same. (3) "Along the direction of the mandible, parallel to the surface of the mandible" and "along the direction of the mandible and parallel to the sagittal plane" had less pressure on the temporal bone than other situations, and the two directions of traction were parallel to the mandible. After the force decomposition, the direction of the condyle was the smallest, so the pressure on the condyle was smaller.Conclusions:A satisfactory TMJ model can be obtained by DICOM. The traction force of "along the direction of the mandible body, parallel to the surface of the mandible body" and "along the direction of the mandible body and parallel to the sagittal plane" had the least effect on the TMJ. When designing the traction direction of MDO, we should not only consider the influence of surgery on the shape of jaw and upper respiratory tract, but also weigh in the influence of traction direction on the TMJ, and determine the direction of traction which has the least influence on the TMJ.

Objective:To determine the direction of traction that has the least influence on temporomandibular joint (TMJ) during mandibular distraction osteogenesis(MDO).Methods:(1) The three-dimensional finite element model was established after the mandible data were obtained by cone beam computed tomography (CBCT) scanning, and the validity of the model was verified. (2) Based on the verified three-dimensional finite element model, the distraction osteogenesis of mandible was carried out with six different directions. (3) The effects of different traction directions on disc pressure, osteotomy displacement, temporal bone pressure and condylar pressure were measured.Results:(1)In the thinnest area of the articular disc, the direction of the minimum stress on the upper and lower surfaces of the disc was "along the direction of the mandible, parallel to the surface of the mandible" . (2) Under the same load, the displacement of each osteotomy surface along the traction direction was different, but the difference was not big, and the effect was basically the same. (3) "Along the direction of the mandible, parallel to the surface of the mandible" and "along the direction of the mandible and parallel to the sagittal plane" had less pressure on the temporal bone than other situations, and the two directions of traction were parallel to the mandible. After the force decomposition, the direction of the condyle was the smallest, so the pressure on the condyle was smaller.Conclusions:A satisfactory TMJ model can be obtained by DICOM. The traction force of "along the direction of the mandible body, parallel to the surface of the mandible body" and "along the direction of the mandible body and parallel to the sagittal plane" had the least effect on the TMJ. When designing the traction direction of MDO, we should not only consider the influence of surgery on the shape of jaw and upper respiratory tract, but also weigh in the influence of traction direction on the TMJ, and determine the direction of traction which has the least influence on the TMJ.

Objective:To identify the risk factors for weaning failure after mandibular distraction osteogenesis in the infants with Pierre Robin sequence.Methods:A retrospective cohort study was conducted to collect clinical records of infants with Pierre Robin sequence underwent mandibular distraction osteogenesis at Guangzhou Women and Children′s Medical Center from November 2016 to May 2019.The inclusion criteria consisted of the following: age <1 yr and no serious cardiopulmonary disease or serious airway malformation.The medical charts were reviewed for sex, age, weight, premature delivery, low birth weight, preoperative intubation, preoperative pulmonary infection, ventilator-associated pneumonia, as well as mechanical ventilation time and distraction length at first weaning.The infants were divided into 2 groups according to the outcome of ventilator weaning at first attempt: successful group and failure group.The risk factors of which P values were less than 0.05 would enter the logistic regression analysis to stratify weaning failure-related risk factors. Results:A total of 140 infants were included in this study, of which 9 cases developed failure of weaning at first attempt after operation, with the incidence of 6.4%.The results of logistic regression analysis showed that the distraction length and incidence of ventilator-associated pneumonia were independent risk factors for weaning failure after operation ( P<0.05). Conclusion:The length of distraction and ventilator-associated pneumonia are independent risk factors for weaning failure after mandibular distraction osteogenesis in the infants with Pierre Robin sequence.

Objective:To analyze the characteristics of upper airway three-dimensional CT images in children with laryngoscope exposure.Methods:50 cases of Pierre Robin sequence who suffered mandibular distraction osteogenesis were included. Preoperation, Cone beam CT scan was performed to get upper airway anatomy information. Images were imported into medical engineering software Mimics for 3D reconstruction. The related anatomical parameters such as the cross-sectional area of the epiglottis tip, oral volume, palatopharynx volume, and glossopharyngeal volume were measured. The exposure of glottis was observed by direct laryngoscope after anaesthesia. According to Cormack-Lehane classification, 2 groups were divided into groups (group A, 30 cases), non exposure group (group B, 20 cases), and the difference of image data between the two groups was compared.Results:Comparing CT measurement index values of the two groups, it was found that there were no statistically significant differences in D4, D8, D10, D11, angle 3, angle 6 and oral volume between the two groups ( P≥0.05), while there were statistically significant differences in other indicators between the two groups ( P<0.05). The area of the airway at the tip of epiglottis and the volume of palatopharyngeal cavity are of great significance to the differential diagnosis of laryngoscopic exposure in children with Pierre Robin sequence, and the decision tree model was established accordingly. Conclusions:The decision tree model based on the area of the airway at the tip of epiglottis and the volume of the palatopharyngeal cavity can predict the difficulty of laryngoscopic exposure in children with Pierre Robin sequence.

Objective:To analyze the characteristics of upper airway three-dimensional CT images in children with laryngoscope exposure.Methods:50 cases of Pierre Robin sequence who suffered mandibular distraction osteogenesis were included. Preoperation, Cone beam CT scan was performed to get upper airway anatomy information. Images were imported into medical engineering software Mimics for 3D reconstruction. The related anatomical parameters such as the cross-sectional area of the epiglottis tip, oral volume, palatopharynx volume, and glossopharyngeal volume were measured. The exposure of glottis was observed by direct laryngoscope after anaesthesia. According to Cormack-Lehane classification, 2 groups were divided into groups (group A, 30 cases), non exposure group (group B, 20 cases), and the difference of image data between the two groups was compared.Results:Comparing CT measurement index values of the two groups, it was found that there were no statistically significant differences in D4, D8, D10, D11, angle 3, angle 6 and oral volume between the two groups ( P≥0.05), while there were statistically significant differences in other indicators between the two groups ( P<0.05). The area of the airway at the tip of epiglottis and the volume of palatopharyngeal cavity are of great significance to the differential diagnosis of laryngoscopic exposure in children with Pierre Robin sequence, and the decision tree model was established accordingly. Conclusions:The decision tree model based on the area of the airway at the tip of epiglottis and the volume of the palatopharyngeal cavity can predict the difficulty of laryngoscopic exposure in children with Pierre Robin sequence.

Objective To analyze the anatomical characteristics of the upper airway in Pierre Robin sequence pediatric patients with difficult laryngoscopy using the computed tomography-based three-dimensional reconstruction.Methods Fifty pediatric patients of both sexes with Pierre Robin sequence,aged 10-101 days,weighing 2.0-6.3 kg,of American Society of Anesthesiologists physical status Ⅲ,scheduled for elective mandibular distraction osteogenesis under general anesthesia,were enrolled in this study.Cone beam CT scan was performed to obtain upper airway anatomy information during the natural sleep before operation.Images were imported into medical engineering software MIMICS 17.0 to reconstruct the three-dimensional images of the oral and maxillofacial bones and airways.The related anatomical parameters were measured,including the distance between the alveolar ridge of the upper central incisor and root of the epiglottis (D1),distance between the root of the epiglottis and midpoint of glottis (D2),distance between the bilateral lower edge of the mandible and midpoint of glottis (D3),distance between the alveolar ridge of the lower central incisor and the lower edge of the mandible (D4),length of the mandibular ramus (D5),length of the mandible body (D6),and length of the total mandible (D7),angle between lines D1 and D2 (angle 1),the angle between line D2 and the alveolar ridge of the upper central incisor to the midpoint of glottis (angle 2),the angle between lines D3 and D4 (angle 3),the angle of the point of the upper central incisor alveolar ridge to the trailing edge of the hard palate and then to the root of epiglottis (angle 4),the angle of bilateral mandible (angle 5),the angle of the point of gnathion to the two gonions (angle 6),the airway cross-sectional area at the tip of epiglottis,volume of oral cavity,volume of velopharyngeal cavity,and volume of glossopharyngeal cavity.Fiberoptic bronchoscope-guided endotracheal intubation was performed under topical anesthesia with lidocaine.Propofol,sufentanil and cis-atracurium were intravenously injected to induce anesthesia after successful intubation,and then the pediatric patients were sent to the operating room.Anesthesia was maintained by inhalation of sevoflurane.The exposure of glottis was observed with a laryngoscope.Pediatric patients were divided into difficult laryngoscopy group (group A) and non-difficult laryngoscopy group (group B) according to whether they presented with difficult laryngoscopy (Cormack-Lehane classification Ⅲ or Ⅳ).Results Compared with group B,the airway cross-sectional area at the tip of epiglottis and in the volume of velopharyngeal cavity were decreased (P＜0.05),and no significant change was found in D1,D2,D3,D4,D5,D6,D7,angle 1,angle 2,angle 3,angle 4,angle 5,angle 6,volume of oral cavity or volume of glossopharyngeal cavity in group A (P＞0.05).Conclusion The three-dimensional CT images of the upper airway show characteristic changes in Pierre Robin sequence pediatric patients with difficult laryngoscopy,and the main manifestations are the decrease in the airway section area and in the volume of the palatopharyngeal cavity at the tip of the epiglottis.

Objective To investigate the effects of titanium miniplates used for anchorage between the maxilla and the mandible for maxilly hypoplasia in cleft patients.Methods Miniplates were inserted into the infrazygomatic crests and between the canine and lateral incisor in the mandible on both the right and left sides in 6 subjects (mean age,11.3 years).Maxillomandibular elastics were attached between the upper and lower miniplates on each side.Cephalometric radiographs of each patient were evaluated at the beginning of treatment and at the end of active protraction treatment.Results A-point movement was increased mean 3.67 mm,SNA angle and ANB angle were increased by 2.75° and 3.1° respectively.Wit's appraisal was increased by 4.52 mm,and upper lip to E-plane was decreased mean 2.8 mm in a mean of 15 months and the significant difference was found (P＜0.05).Miniplates stability was excellent in all patients throughout treatment.Conclusions Remarkable advancement in the middle face and consequent fullness in the soft-tissue profile can be achieved by using titanium miniplates protraction for maxilly hypoplasia in cleft patients in the late mixed-dentition and initial stage of permanent dentition period.

Objective To retrospectively analyze echocardiography findings and left hearst function in patients with patent ductus arteriosus (PDA) after transcatheter closure. Methods 28 patients admitted between January 2012 and December 2012 in our hospital for PDA transcatheter closure were included. Assessment of cardiac structure, hemodynamics and cardiac function parameters during preoperation and in postoperation 3 days, 1 month and 6 months were studied. Results Statistical significant difference was found at 3 days, 1 month and 6 months postoperation when compared with pre-operation in terms of left atrial diameter, left ventricular end-diastolic diameter, left ventricular end systolic diameter and other doppler measurements ( all P < 0. 05 ) . Six-minute walk test ( 6MWT) tolerance improved when compared to preoperation level (P < 0. 05). Better improvement in LVEF and LVES was observed in patients age ≤14 years old when compared to patients > 14 years old after operation ( P < 0. 05 ) . Conclusions Transcatheter closure of PDA can improve cardiac function and correct early hemodynamic abnormalities patients in younger age group show more benefit from the procedure.

OBJECTIVETo assess the value of chromosome microarray analysis (CMA) for identifying the etiology of patients with congenital cleft lip and palate.

METHODSTwenty-two patients with no identifiable chromosomal aberrations by conventional cytogenetic technique were selected. DNA was extracted and hybridized with Affymetrix CytoScan(TM) HD arrays following the manufacturer's protocol. The data were analyzed with a CHAS v2.0 software.

RESULTSCMA analysis has identified submicroscopic copy number variants (CNVs) in all of the cases, which have ranged from 100 kb to 1.8 Mb. Potential pathogenic CNVs were identified in 5 patients (22.7%), which involved microdeletions and microduplications on 8p23.1, 10q22.2-q22.3, 6q26, 20p12.1 and 18q12.3. MYST4, MACROD2 and SOX7 genes are likely the causative genes.

CONCLUSIONCMA is an effective method for identification of etiology in patients with cleft lip and palate. CMA should be provided for patients with cleft lip and palate but a normal karyotype. Especially for those with additional structural abnormalities, there is a high risk for submicroscopic chromosomal aberrations.

Child ; Child, Preschool ; Chromosome Aberrations ; Chromosome Disorders ; diagnosis ; genetics ; Cleft Lip ; diagnosis ; genetics ; Cleft Palate ; diagnosis ; genetics ; DNA Copy Number Variations ; Female ; Humans ; Infant ; Male ; Microarray Analysis

Objective The purpose of this study was to evaluate the outcome of autogenous bone grafts in unilateral cleft lip and palate patients following early orthodontic tooth movement,and to determine the volume of new bone formation in the bone grafted region with spiral computed tomography.Methods Computed tomography scans of 12 patients were taken immediately preoperatively and at 6 months postoperatively.The patients underwent bone grafting between 9 and 13 years of age were divided into two groups based on whether postoperative orthodontic tooth movement were initiated or not.Three-dimensional models were created in each period,and the defect of alveolar cleft and volume of the newly formed bone were calculated in each patient.The roots of the moved teeth and their positions to the alveolar bone were also observed.Results The preoperative cleft width and cleft volume were not significantly different between both groups.The volume of the newly formed bone in group A was (0.98±0.23) mm3,significantly higher than that in group B,which was (0.73± 0.15) mm3.The rate of newly formed bone in group A was (72.5 ± 11.9)％,significantly higher than that in group B,which was (53.2±9.7)％.The cleft adjacent teeth could move smoothly into the bone grated area,with no root resorption observed in the computed tomography scans.Conclusions Early orthodontic tooth movement can reduce bone resorption in autogenous bone grafted unilateral cleft lip and palate patients through the observation of spiral computed tomography.It plays an active role in the bone remolding process after bone grafting.