Objective This study investigates the force distributions and movement patterns of the maxillary dentition during molar intrusion with clear aligners,aiming to provide a theoretical basis for optimizing clinical orthodontic treatment strategies.Methods A three-dimensional(3D)finite element model of the periodontal ligament-teeth-clear aligners complex was established to simulate different intrusion modes,including bilateral first molar intrusion,bilateral second molar intrusion,and simultaneous intrusion of bilateral first and second molars.The von Mises stress distribution characteristics and displacement patterns of each tooth under different intrusion conditions were systematically analyzed.Results Compared with simultaneous molar intrusion,the individual intrusion design resulted in greater intrusive movement(4.260-10.500 μm)accompanied by distal-lingual crown inclination(distal displacement:-7.690--5.100 μm;buccal displacement:-20.500--6.750 μm).Anchorage teeth displayed a displacement trend opposite to that of the intruded molars.The anterior teeth demonstrated minimal displacement and low stress levels.During maxillary molar intrusion with clear aligners,the maximum equivalent stress in the periodontal ligaments occurred at the anchorage teeth mesial to the intruded molars,primarily concentrated in the apical region and the mesial aspect of the buccal cervical area.Conclusions A sequential intrusion strategy enhances vertical control efficiency compared to simultaneous intrusion.Unanticipated mesiodistal and buccolingual displacements in the posterior region necessitate the implementation of counteracting mechanisms in aligner design.In clinical practice,priority should be given to monitoring the risks of root resorption and bone remodeling effects in stress-concentrated zones(apical and buccal cervical regions)of anchorage teeth.

Objective This study investigates the force distributions and movement patterns of the maxillary dentition during molar intrusion with clear aligners,aiming to provide a theoretical basis for optimizing clinical orthodontic treatment strategies.Methods A three-dimensional(3D)finite element model of the periodontal ligament-teeth-clear aligners complex was established to simulate different intrusion modes,including bilateral first molar intrusion,bilateral second molar intrusion,and simultaneous intrusion of bilateral first and second molars.The von Mises stress distribution characteristics and displacement patterns of each tooth under different intrusion conditions were systematically analyzed.Results Compared with simultaneous molar intrusion,the individual intrusion design resulted in greater intrusive movement(4.260-10.500 μm)accompanied by distal-lingual crown inclination(distal displacement:-7.690--5.100 μm;buccal displacement:-20.500--6.750 μm).Anchorage teeth displayed a displacement trend opposite to that of the intruded molars.The anterior teeth demonstrated minimal displacement and low stress levels.During maxillary molar intrusion with clear aligners,the maximum equivalent stress in the periodontal ligaments occurred at the anchorage teeth mesial to the intruded molars,primarily concentrated in the apical region and the mesial aspect of the buccal cervical area.Conclusions A sequential intrusion strategy enhances vertical control efficiency compared to simultaneous intrusion.Unanticipated mesiodistal and buccolingual displacements in the posterior region necessitate the implementation of counteracting mechanisms in aligner design.In clinical practice,priority should be given to monitoring the risks of root resorption and bone remodeling effects in stress-concentrated zones(apical and buccal cervical regions)of anchorage teeth.

As the national key discipline and the initiator of oral and maxillofacial deformity group, the Department of Oral and Maxillofacial Surgery persisted in teaching, designed a novel teaching form combining theoretical knowledge and online software practice according to the characteristics of our discipline and carried out "cloud training" via the National Oral Telemedicine Education Platform. Ten lecturers, 325 theoretical students and 50 practical students were investigated by questionnaire in the present study with questions focusing on the geographical distribution and composition of personnel, etc. The results showed that the online course covered a wide range of students and achieved high acceptance and satisfaction rate. The first online software operation course was conducted in an orderly manner, with timely interaction between teachers and students. The students were able to master the design process skillfully. This "cloud training" has achieved good results, but there are still a series of problems that have yet to be resolved, such as network stalls and protection of intellectual property rights. Under the new form, the exploration and analysis of the new mode of online telemedicine specialist education will provide some practical reference for the National Clinical Research Center for Oral Diseases to carry out online telemedicine teaching in the future.