Objective: To explore the effect of different miniscrew placement heights on the distribution of biological forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization, to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments. Methods: Mimics, GeomagicStudio 2017, SolidWorks 2016, and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the following six working conditions: working condition 1 was the control group without miniscrews; working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm, 7 mm, 4 mm, and 1 mm from the top of the alveolar crest, respectively; working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane. Results: On the sagittal axis, miniscrew anchorage caused distal displacement of all teeth. Compared to the control group, in the miniscrew group, the displacement of the anterior molars exceeded that of the second molars. On the vertical axis, the result in the control group was similar to backward bending; the results in the miniscrew groups resembled the effect of a lever, lowering the lateral incisors and canines and raising the central incisors and first premolars. On the coronal axis, the second premolars and the first molars showed lingual displacement in the control group, and only the premolars and first molars showed lingual displacementin the miniscrew groups. The canines were the teeth that were most strongly affected by the change in miniscrew placement height. Conclusion The higher the miniscrew position is, the stronger the protective effect on the anterior anchorage. According to the miniscrew placement height, the mandibular arch should be properly narrowed, the central incisors and first premolars should be lowered, and the lateral incisors and canines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective To explore the effect of different miniscrew placement heights on the distribution of biologi-cal forces produced by clear aligner combined with intramaxillary traction for mandibular molar distalization,to identify the miniscrew location that is conducive to the protection of lower anterior tooth anchorage and to provide a reference that can be used when designing clinical treatments.Methods Mimics,GeomagicStudio 2017,SolidWorks 2016,and Ansys workbench were used to establish finite element analysis models and perform mechanical analysis under the fol-lowing six working conditions:working condition 1 was the control group without miniscrews;working conditions 2 to 5 had miniscrew in the buccal bone cortex between the first and second molars of the lower jaw 10 mm,7 mm,4 mm,and 1 mm from the top of the alveolar crest,respectively;working condition 6 had the miniscrew in the center of the buccal tongue at the anterior edge of the ascending branch of the lower jaw 5 mm above the occlusal plane.Results On the sagittal axis,miniscrew anchorage caused distal displacement of all teeth.Compared to the control group,in the miniscrew group,the displacement of the anterior molars exceeded that of the second molars.On the vertical axis,the result in the control group was similar to backward bending;the results in the miniscrew groups resembled the effect of a lever,lowering the lateral incisors and canines and raising the central incisors and first premolars.On the coronal ax-is,the second premolars and the first molars showed lingual displacement in the control group,and only the premolars and first molars showed lingual displacementin the miniscrew groups.The canines were the teeth that were most strong-ly affected by the change in miniscrew placement height.Conclusion The higher the miniscrew position is,the stron-ger the protective effect on the anterior anchorage.According to the miniscrew placement height,the mandibular arch should be properly narrowed,the central incisors and first premolars should be lowered,and the lateral incisors and ca-nines should be raised when designing clinical treatments.

Objective:To explore the current status of surgery for portal hypertension to grasp current status and future development of surgery in China.Methods:This study is jointly sponsored by China Hepatobiliary & Pancreatic Specialist Alliance & Portal Hypertension Alliance in China (CHESS).Comprehensive surveying is conducted for basic domestic situations of surgery for portal hypertension, including case load, surgical approaches, management of postoperative complications, primary effects, existing confusion and obstacles, liver transplantation(LT), laparoscopic procedures and transjugular intrahepatic portosystemic shunt(TIPS), etc.Results:A total of 8 512 cases of portal hypertension surgery are performed at 378 hospitals nationwide in 2021.Splenectomy plus devascularization predominated(53.0%)and laparoscopy accounted for 76.1%.Primary goal is preventing rebleeding(67.0%) and 72.8% of hospitals used preventive anticoagulants after conventional surgery.And 80.7% of teams believe that the formation of postoperative portal vein thrombosis is a surgical dilemma and 65.3% of hospitals practiced both laparoscopy and TIPS.The major reasons for patients with portal hypertension not receiving LT are due to a lack of qualifications for LT(69.3%)and economic factors(69.0%).Conclusions:Surgery is an integral part of management of portal hypertension in China.However, it is imperative to further standardize the grasp of surgical indications, the handling of surgical operation and the management of postoperative complications.Moreover, prospective, multi-center randomized controlled clinical studies should be performed.