OBJECTIVE To develop and validate interpretable machine learning models for predicting the risk of medication-related osteonecrosis of the jaw （MRONJ） and surgical outcomes， thereby providing quantitative support for MRONJ risk assessment and treatment decision-making.METHODS Two study cohorts were established. Cohort A adopted a nested case-control study design to develop a predictive model for the risk of MRONJ onset. Cohort B comprised patients with MRONJ from Cohort A who underwent surgical treatment and met the follow-up eligibility criteria， and employed a prospective follow-up cohort study design to develop a predictive model for the efficacy of MRONJ surgery. After missing-data processing， variable standardization， and encoding， predictive features were selected using the least absolute shrinkage and selection operator （LASSO） regression， and collinearity was assessed using the variance inflation factor （VIF）. Random Forest （RF）， eXtreme Gradient Boosting （XGB）， Multi-layer Perceptron （MLP）， Support Vector Machine （SVM）， and Gaussian Naive Bayes （NB） models were subsequently developed using the selected features. Hyperparameter optimization and internal performance evaluation were performed using two-level nested cross-validation repeated 20 times. In Cohort B， the synthetic minority over-sampling technique （SMOTE） was applied within the inner training folds to address class imbalance. Model performance was comprehensively evaluated using the receiver operating characteristic （ROC） curve， the precision-recall （PR） curve， calibration curve， and decision curve analysis （DCA）. Shapley additive explanations （SHAP） were used to quantify the relative contributions of individual clinical features to model predictions.RESULTS Seven clinical features， including alkaline phosphatase and tooth extraction， were retained for Cohort A； whereas eight clinical features， including age and duration of medication use， were retained for Cohort B. In Cohort A， the area under the ROC curve， the area under the PR curve， Brier score， sensitivity， and specificity of the RF model were 0.94， 0.92， 0.09， 0.92， and 0.85， respectively； the corresponding values in Cohort B were 0.93， 0.93， 0.12， 0.83， and 0.93， respectively. The results of calibration curves and DCA indicated that the RF models achieved favorable calibration and clinical net benefit， with VIF values for all variables below 5. SHAP visualization results showed that alkaline phosphatase， tooth extraction， and cumulative drug dose made substantial contributions to MRONJ risk prediction in Cohort A， whereas age， duration of medication use， and MRONJ stage contributed substantially to surgical outcome prediction in Cohort B.CONCLUSIONS The RF-based models for predicting MRONJ risk and surgical outcomes demonstrated good discrimination， accuracy of probabilistic predictions， and potential clinical utility during internal validation. These models may provide decision support for comprehensive MRONJ risk management and individualized clinical decision-making. However， external validation in independent， multicenter， and geographically diverse cohorts is still required.

Periodontitis is a chronic periodontal disease with a high incidence, and chronic obstructive pulmonary disease (COPD) is considered to be a chronic airway inflammatory disease. In recent years, many studies have observed that there is a potential relationship between periodontitis and COPD. The periodontal condition of patients with COPD is relatively poor, and the composition of their oral microbiome is different from that of healthy people. The inflammation “spillage”and hypoxia may induce the occurrence and development of periodontal disease. At the same time, the risk of COPD in periodontitis patients may be related to the inhalation of periodontal pathogens and inflammatory factors. Regular periodontal sequence therapy can reduce the risk of acute exacerbation of the disease to a certain extent. Since periodontitis and COPD are both chronic progressive diseases characterized by chronic inflammation and accompanied by proteolytic destruction of connective tissue, they may share a common pathophysiological process and may be intrinsically linked. This article reviews the latest research progress on the relationship between chronic periodontitis and COPD, and possible interaction mechanism, in order to provide insight for further study on the interaction between the two conditions.

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.

BACKGROUND: The neurotoxicity and cardiotoxicity of bupivacaine have been reported frequently. However, the studies on bupivacaine-induced muscle toxicity are few.
OBJECTIVE: To establish and evaluate local intramuscular injection of bupivacaine on the changes in histomorphology and ultrastructure of rat multifidus muscle at various time points.
METHODS: A total of 54 male Sprague-Dawley rats weighing 280-320 g were randomly divided into black group (n=18), model group (n=18) and model control group (n=18). Each group was then equal y subdivided into three subgroups according to time points (4, 7 and 14 days) (n=6). Both sides of multifidus muscle of the rats (L4 and L5) were injected with 0.5% bupivacaine. The morphological and ultrastructural changes of multifidus muscle were observed and analyzed with light microscope and transmission electron microscope at 4, 7 and 14 days after model establishment.
RESULTS AND CONCLUSION: (1) A single intramuscular injection of 0.5% bupivacaine induced muscular damage. (2) Hematoxylin-eosin staining results showed fiber necrosis, inflammatory cel infiltration, and a smal amount of macrophages in local skeletal muscle. (3) Under the transmission electron microscope, the structure of myofibrils was destroyed or disintegrated; kinds of bands and lines were indistinct, disrupted or disappeared; the structure of mitochondria was abnormal, the mitochondrial cristae were reduced or disappeared. In the 7- and 14-day groups, multifidus muscle proliferated and repaired. (4) Ultrastructural change scores in skeletal muscle were significantly higher in the model group than in the blank and model control groups (P < 0.05). Above scores were significantly greater in the 4-day group than in the 7- and 14-day groups (P < 0.05), and higher in the 7-day group than in the 14-day group (P < 0.05). (5) Results suggest that a single intramuscular injection of 0.5% bupivacaine can result in pathological changes of skeletal muscle from morphology and ultrastructure. This method can establish a suitable model of skeletal muscle injury.

Objective To observe over-time changes in rat blood flow in the skins of related meridian points during physiological status, the pathological state of ischemic myocardial injury and low or high frequency electroacupuncture intervention and explore the post effect of different frequency electroacupuncture on related meridian points after treating ischemic myocardial injury. Method Fifty male Wister rats were randomized into five groups: blank control, sham operation, model, low frequency electroacupuncture (meridian point A) and high frequency electroacupuncture (meridian point B), 10 rats each. Blood flow in the skins of bilateral points Neiguan (PC6), Ximen (PC4) and Tianquan (PC2), and non-meridian and non-acupoint control points was measured by laser speckle contrast imaging in every group immediately and at 30 and 60 min after the end of three treatments. Statistical analysis was made. Result Blood flow in the skins of bilateral points Neiguan, Ximen and Tianquan was significantly lower in the blank control group than in the model group (P<0.01,P<0.05). Blood flow in the skin of every acupoint increased in varing degrees after low or high frequency electroacupuncture treatment. Blood flow in bilateral points Neiguan, Ximen and Tianquan regions in meridian point group A was closer to that in the blank control group immediately after treatment. Blood flow in three left-side and three right-side acupoint regions in meridian point group B was closer to that in the blank control group at 30 and 60 min, respectively, after treatment. Conclusion The immediate effect of low frequency electroacupuncture on blood flow in acupoint regions is better than high frequency electroacupuncture during intervention in ischemic myocardial injury. The post effect of high frequency electroacupuncture on blood flow in acupoint regions is better than low frequency electroacupuncture during intervention in ischemic myocardial injury.