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·To investigate the regulatory effects and underlying mechanisms of mouse mandibular osteoblasts on B cell differentiation and development.Methods·Single-cell suspensions from mouse mandibular bone were prepared using an optimized enzymatic digestion method and induced to differentiate into osteoblasts in vitro.Osteogenic potential was validated by real-time quantitative PCR(RT-qPCR),alkaline phosphatase(ALP)staining,and alizarin red S(ARS)staining.The spatial localization relationship between osteoblasts and B cells in mandibular tissues was examined via immunofluorescence staining.High-purity hematopoietic progenitor cells were isolated using fluorescence-activated cell sorting.A Transwell co-culture system was established to assess the regulatory effects of different osteoblast concentrations(5×104,2.5×105,and 5×105 cells/well)on B cell differentiation(5×104 cells/well).Flow cytometry and RT-qPCR were employed to evaluate B cell viability and differentiation.Additionally,RT-qPCR was used to analyze the expression of osteoblast-secreted factors associated with B cell development during osteogenic differentiation.Results·Mandibular osteoblasts exhibited robust osteogenic potential,as confirmed by ALP/ARS staining and high expression of osteogenic markers(Runx2,Osx,Ocn,and Alp)via RT-qPCR.Immunofluorescence revealed close spatial proximity between osteoblasts and B cells in mandibular tissues.In the co-culture system,osteoblasts promoted B cell differentiation in a concentration-dependent manner.RT-qPCR and immunofluorescence demonstrated that osteoblasts significantly upregulated key genes involved in B cell development(Ebf1,Rag1,Il7r,and Pax5;all P<0.001).Furthermore,osteoblast-derived factors(Il7,Baff,and Flt3l)were markedly elevated during osteogenic differentiation(all P<0.05).Conclusion·Mandibular osteoblasts enhance B cell differentiation and development in a concentration-dependent manner,likely through secreting growth factors that upregulate critical B cell differentiation genes.

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·To investigate the regulatory effects and underlying mechanisms of mouse mandibular osteoblasts on B cell differentiation and development.Methods·Single-cell suspensions from mouse mandibular bone were prepared using an optimized enzymatic digestion method and induced to differentiate into osteoblasts in vitro.Osteogenic potential was validated by real-time quantitative PCR(RT-qPCR),alkaline phosphatase(ALP)staining,and alizarin red S(ARS)staining.The spatial localization relationship between osteoblasts and B cells in mandibular tissues was examined via immunofluorescence staining.High-purity hematopoietic progenitor cells were isolated using fluorescence-activated cell sorting.A Transwell co-culture system was established to assess the regulatory effects of different osteoblast concentrations(5×104,2.5×105,and 5×105 cells/well)on B cell differentiation(5×104 cells/well).Flow cytometry and RT-qPCR were employed to evaluate B cell viability and differentiation.Additionally,RT-qPCR was used to analyze the expression of osteoblast-secreted factors associated with B cell development during osteogenic differentiation.Results·Mandibular osteoblasts exhibited robust osteogenic potential,as confirmed by ALP/ARS staining and high expression of osteogenic markers(Runx2,Osx,Ocn,and Alp)via RT-qPCR.Immunofluorescence revealed close spatial proximity between osteoblasts and B cells in mandibular tissues.In the co-culture system,osteoblasts promoted B cell differentiation in a concentration-dependent manner.RT-qPCR and immunofluorescence demonstrated that osteoblasts significantly upregulated key genes involved in B cell development(Ebf1,Rag1,Il7r,and Pax5;all P<0.001).Furthermore,osteoblast-derived factors(Il7,Baff,and Flt3l)were markedly elevated during osteogenic differentiation(all P<0.05).Conclusion·Mandibular osteoblasts enhance B cell differentiation and development in a concentration-dependent manner,likely through secreting growth factors that upregulate critical B cell differentiation genes.