Objective To simulate a finite element model for biomechanical analysis of mandible chin blast injury and analyze the mechanism of maxillofacial blast injury.Methods The three-dimensional element model of human mandible blast injury was established to simulate the dynamic process of injury to the mandible chin.Von Mises stress and effective strain were evaluated in biomechanical study of the simulation results.Results The dynamic damage process of human mandible chin blast injury was simulated successfully.In the condition of 1 000 mg and 3 cm,the Von Mises stress and effective were maximum at condylar neck region (9.1 × 106 Pa,0.62 × 10-3ε),were second at mandibular angle region (6.1 × 106 Pa,0.42 × 10-3ε),and minimum at mental foramen region (6.1 × 106 Pa,0.39 × 10-3ε).Blast distance rather than blast equivalent produced more effect on the mechanical parameters and damage degree.Conclusions Von Mises stress and effective strain can be applied to the evaluation of bone tissue damage.The finite element method is effective in simulating mandible blast injury and can provide a new thought and approach to clinical treatment of oral and maxillofacial blast injury.

Objective To develop a three-dimensional element model of pig mandible impact injury and test the simulation results in an attempt to determine the feasibility and reliability of finite element numerical simulation method used in the maxillofacial impact injury.Methods CT data was used to develop a three-dimensional finite element model of pig mandible impact injury,and the dynamic process of impact injury was simulated.The simulation results were compared with the animal experiment and had energy check to validate the reliability and feasibility of the modeling and simulation methods.Results The three-dimensional finite element model was established successfully,containing 61,512 hexahedrons,5,450 tetrahedrons,4,030 trihedrons,and 67,159 nodes.The simulation process was realistic,and the simulation results showed no statistical difference with the animal experiment with regard to strain,acceleration,and other biomechanical properties (P ＞ 0.05).The simulated damage shape had a high similarity with animal specimens,and the result of energy check also complied with energy conservation law.Conclusion Finite element method is effective to simulate the dynamic process of mandible impact which ensures a correct and reliable model and simulation,and thus can be used to analyze the mechanism of maxillofacial impact injury.

Objective The simulation of the human mandible injury was carried out by using the finite element simulation technology ,and the biomechanical analysis of simulation results was developed to explore the mechanism of injuries .Methods The Chinese Visible Human digital data were used to establish the three-dimensional element model of mandible injuries ,and the dynam-ic processes of human mandible injuries in different conditions were simulated ,and the biomechanical analysis were carried out by u-sing the Von Mises stress and effective strain .Results The three-dimensional element model of mandible injuries was established , the dynamic damage and fracture of human mandible were simulated successfully ,the mandibular angle and condylar were the predi-lection parts of high-stress ,high-strain and fractures .Conclusion The Von Mises stress and effective strain can be used to predict and judge the bone tissue injuries ,the finite element method can simulate the impact injuries of mandible effectively ,and the simula-ted results can provide guidance and reference for basic research and clinical treatment of oral and maxillofacial injuries .

Objective Finite element numerical simulation technique was applied to simulate the dynamic projectile injury process of human chin in different injury conditions and the mechanism of injury was discussed by using biomechanical analysis . Methods The 3D finite element model of human mandible projective injury was established to simulate the dynamic projectile inju‐ry process of human chin in different injury conditions (high ,medium and low speeds) ,and the simulation results were used to com‐parative analysis of biomechanics .Results The dynamic damage process of human chin projectile injury was simulated successfully in different injury conditions ,and the more serious injury of mandible was caused by faster speed .Conclusion The finite element method can simulate the projectile injury of mandible effectively ,and can provide a new thought and method for basic research and clinical treatment of oral and maxillofacial war injury .

Objective To investigate the safety and effectiveness of ultrasound-guided paravertebral anaes-thesia combined with propofol in the thoracoscopic sympathectomy. Methods Total 63 male and 59 female patients with hyperhidrosis were recruited. The patients were equally divided into two groups:group A and C. Patients in group A received ultrasound-guided paravertebral anaesthesia combined with propofol. Patients in group C received general intravenous anesthesia with endotracheal intubation. The heart rate (HR),mean arterial pres-sure(MAP)and the oxygen saturation(SpO2)at the time of entering the operating room(T0),completing anesthe-sia(T1),incising the skin(T2),cutting the T4 sympathetic trunk(T3),completing the operation were record-ed. The awake time after operation ,VAS score after operation and postoperative throat discomfort were also record-ed. Results The two groups successfully completed the surgery. There were no significant differences of the HR , MAP and SpO2 at T0-T4 between the two groups. There were significant differences of the awake time after opera-tion,postoperative feeding time and hospitalization expenses. The VAS score after operation of group A were better than group C(P<0.05)at T2 h,T4 h,T8 h,and T12 h. There was no significant difference of VAS score at T24 h between the two groups. Conclusion Ultrasound-guided paravertebral anaesthesia combined with propofol can pro-vide a safe and effective approach for patients receiving the thoracoscopic sympathectomy.