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 evaluate the clinical efficacy of invisible orthodontic appliances without brackets for the distal movement of maxillary molars to improve the ability of orthodontists to predict treatment outcomes.Methods Web of Science,Cochrane Library,Embase,PubMed,Wanfang Database,CNKI Database,and VIP Database were searched for studies investigating the efficacy of invisible orthodontic appliances for distal movement of maxillary molars in adult patients and published from database inception to August 1,2023.A total of three researchers screened the studies and evaluated their quality and conducted a meta-analysis of those that met quality standards.Results This study included 13 pre-and postcontrol trials with a total sample size of 281 patients.The meta-analysis revealed no sig-nificant differences in the sagittal or vertical parameters of the jawbone after treatment when compared with those before treatment(P＞0.05).The displacement of the first molar was MD=-2.34,95％CI(-2.83,-1.85);the displacement was MD=-0.95,95％CI(-1.34,-0.56);and the inclination was MD=-2.51,95％CI(-3.56,-1.46).There was a statistically significant difference in the change in sagittal,vertical,and axial tilt of the first molar before and after treatment.After treatment,the average adduction distance of the incisors was MD=-0.82,95％CI(-1.54,-0.09),and the decrease in lip inclination was MD=-1.61,95％CI(-2.86,-0.36);these values were significantly different from those before treat-ment(P＜0.05).Conclusion Invisible orthodontic appliances can effectively move the upper molars in a distal direc-tion and control the vertical position of the molars.When the molars move further away,there is some degree of com-pression and distal tilt movement,which is beneficial for patients with high angles.The sagittal movement of incisors is beneficial for improving the patient's profile.

Tooth ankylosis is a clinical condition where the tooth cementum directly fuses with the surrounding alveolar bone,leading to functional and aesthetic defects.The etiology involves genetic,metabolic,and local stimulation factors.The diagnosis of tooth ankylosis requires a combination of clinical manifestations and imaging examinations to improve the diagnostic accuracy.The treatment of tooth ankylosis presents significant challenges.Orthodontic treatment combined with other disciplines offers a new,comprehensive treatment approach,integrating traditional orthodontic techniques with osteotomy,distraction osteogenesis,orthodontic bone traction,corticotomy,dislocation,and autologous tooth transplantation techniques.The treatment of tooth ankylosis requires the cooperation of multiple disciplines,and the experts from orthodontics,oral surgery,and oral medicine collaborate to develop the optimal treatment plan.This comprehensive treatment method achieves better outcomes compared with traditional treatments.This review discusses the etiology,diagnosis,and orthodontic combined multidisciplinary treatment methods of tooth ankylosis,analyzes the advantages and disadvantages of various treatment options,evaluates the efficacy and risks,and provides new perspectives for the treatment of tooth ankylosis.