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 establish the method of simultaneous determination of four main components of Danggui Liuhuang Decoction,including phellodendrine,palmatine,calycosin,and ferulic acid and provide reference for the quality control of Danggui Liuhuang Decoction.Methods Based on the HPLC-MS/MS analysis method,the positive ion data acquisition mode were adopted for the mass spectrometry detection and the four main components were quantified with multiple reaction monitoring mode(MRM)by ESI source.The chromatographic column was Agilent Extend-C18(5 μm,4.6 mm×250 mm),and gradient elution was performed with methanol and 0.5%formic acid in water.Results The linear range of phellodendrine was from 2-200 nmol/ml,and the linear range of palmatine,calycosin and ferulic acid was from 20-2 000 nmol/ml.The contents of the four components in the seven batches of Danggui Liuhuang Decoction were relatively stable,among which ferulic acid was mainly found in Phellodendrine and Coptidis;Phellodendrine was only detected in cortex phellodendri;the content of calycosin in Scutellaria baicalensis and Astragalus was higher;palmatine was detected in both Phellodendron and Astragalus.Conclusion The method had high sensitivity,good specificity and sample stability,which could meet the requirements of quantitative analysis of Traditional Chinese Medicine compounds,and could provide reference for further pharmacokinetics study on the content changes of traditional Chinese medicine compounds in biological samples.

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.