Objective:To investigate the effects of differential torque of maxillary posterior teeth with clear aligner on anterior teeth 3D mechanics.Methods:4 maxillary models were designed for differential torque of posterior teeth on the basis of 3D me-chanical test model with first premolar extraction.The stereolithography models were made with the same size as the standard model by 3D printing.According to the torque of the 6 keys to normal occlusion of Andrews,the standard torque of Andrews was used in group A1.The posterior teeth with lingual-crown torque of 5° were used in groups A2,and those with buccal-crown torque of 5° and 10° were respecitvely used in group A3 and A4.4 sets of corresponding clear aligners were fabricated with a 0.75 mm thick thermoplastic material.Each group had 12 pairs of the same clear aligners.The anterior teeth underwent 0.25 mm activation for en-mass retraction.The six-axis force/torque transducer measurement system was used to measure the force applied by the clear align-ers on the anterior teeth in the 3D directions.Results:In buccolingual direction:in group A1,the 4 incisors received lingual force,in groups A2-A4,the anterior teeth received labial force,and the force on the central incisors was greater than that on later-al incisors.In mesiodistal direction:in group A1-A4,4 incisors received mesial force,and the force on lateral incisors was greater than that on central incisors;in group A1-A4,the canines received distal force;the force on canine in group A4 was greater than that in A2 or A3 groups(P＜0.05).The force in the vertical direction on the anterior teeth among the 4 groups(P＞0.05).Conclu-sion:When en-mass retraction of the anterior teeth with clear aligner,attention should be taken to the torque of the incisors and the tip of the canines.When the posterior teeth with standard torque,the activation of labial-crown overcorrection of the anterior teeth should be increased.When the posterior teeth with lingual-crown torque or buccal-crown torque,the activation of labial-crown over-correction of the anterior teeth should be appropriately reduced.Increasing the mesial overcorrection design of canines may avoid the extrusion of anterior teeth and the deepening of o-verbite due to the distal inclination of canines.

Objective:To investigate the effects of differential torque of maxillary posterior teeth with clear aligner on anterior teeth 3D mechanics.Methods:4 maxillary models were designed for differential torque of posterior teeth on the basis of 3D me-chanical test model with first premolar extraction.The stereolithography models were made with the same size as the standard model by 3D printing.According to the torque of the 6 keys to normal occlusion of Andrews,the standard torque of Andrews was used in group A1.The posterior teeth with lingual-crown torque of 5° were used in groups A2,and those with buccal-crown torque of 5° and 10° were respecitvely used in group A3 and A4.4 sets of corresponding clear aligners were fabricated with a 0.75 mm thick thermoplastic material.Each group had 12 pairs of the same clear aligners.The anterior teeth underwent 0.25 mm activation for en-mass retraction.The six-axis force/torque transducer measurement system was used to measure the force applied by the clear align-ers on the anterior teeth in the 3D directions.Results:In buccolingual direction:in group A1,the 4 incisors received lingual force,in groups A2-A4,the anterior teeth received labial force,and the force on the central incisors was greater than that on later-al incisors.In mesiodistal direction:in group A1-A4,4 incisors received mesial force,and the force on lateral incisors was greater than that on central incisors;in group A1-A4,the canines received distal force;the force on canine in group A4 was greater than that in A2 or A3 groups(P＜0.05).The force in the vertical direction on the anterior teeth among the 4 groups(P＞0.05).Conclu-sion:When en-mass retraction of the anterior teeth with clear aligner,attention should be taken to the torque of the incisors and the tip of the canines.When the posterior teeth with standard torque,the activation of labial-crown overcorrection of the anterior teeth should be increased.When the posterior teeth with lingual-crown torque or buccal-crown torque,the activation of labial-crown over-correction of the anterior teeth should be appropriately reduced.Increasing the mesial overcorrection design of canines may avoid the extrusion of anterior teeth and the deepening of o-verbite due to the distal inclination of canines.

Objective:To investigate the intervention of melatonin(MT)in the expression of circadian genes in patients with pulmonary fibrosis and to analyze the mechanism by which it alleviates the progres-sion of pulmonary fibrosis.Methods:By utilizing the Gene Expression Omnibus(GEO)database,we identified differentially expressed circadian genes between patients with pulmonary fibrosis and controls.We analyzed the correlation between circadian genes and pulmonary function as well as genes related to pulmonary fibrosis.A bleomycin-induced mouse model of pulmonary fibrosis(BLM group)was construc-ted to observe the expression differences of PER2 and CRY2 by sequencing and immunohistochemical staining in the BLM group and after MT intervention(BLM+MT group).Hematoxylin and eosin(HE)staining and Masson staining were used to observe the effects of MT on fibrosis.We used Western blot to detect the expression of P-smad2/3 in lung epithelial cells induced by transforming growth factor β(TGF-β).Reverse transcription quantitative real-time PCR technology was employed to investigate the rhythmic expression changes of circadian genes in the control group,TGF-β group,and TGF-β+MT group.Fi-nally,luzindole,a MT receptor antagonist,was used to intervene in TGF-β+MT group,and Western blot was used to explore the receptor dependence of MT in alleviating TGF-β-induced epithelial-mesen-chymal transition.Results:(1)Analysis of the GEO dataset(GSE)revealed a negative correlation be-tween circadian genes PER2 and CRY2 and the expression of TGF-β,and a positive correlation with pul-monary function indicators in patients.(2)Transcriptome sequencing analysis of lung tissue in BLM group found that the expression of PER2 and CRY2 was significantly reduced compared with the normal group.Histopathological staining results showed that the lung tissue structure of the normal group was in-tact and clear,with thin alveolar septa;in the BLM group,there was a large increase in collagen fibers and disordered alveolar structure;compared with the BLM group,the BLM+MT group had reduced col-lagen fiber proliferation and inflammatory cell infiltration;the expression of PER2 and CRY2 in the BLM group was lower than in the normal group,and the expression in the BLM+MT group was increased com-pared with the BLM group.(3)In vitro lung epithelial cell experiments with TGF-β intervention showed that compared with the control group,the expression of P-smad2/3 increased in the TGF-β group,and MT intervention inhibited the inducing effect of TGF-β on P-smad2/3,while intervention with the MT re-ceptor antagonist reversed this phenomenon.The results indicated that MT could inhibit the activation of the TGF-β pathway,and this process was dependent on MT receptors.(4)The 48-hour rhythm experi-ment in lung epithelial cells showed that the mRNA rhythm of PER2 and CRY2 in the TGF-β+MT group was close to 24 hours and showed a trend towards restoring the rhythm of the control group,while the ad-dition of the MT receptor blocker tended to make the rhythm duration and amplitude of both groups ap-proach that of the TGF-β group.Conclusion:MT,by binding to its receptors,can restore the periodic expression of the circadian genes PER2 and CRY2,thereby inhibiting the activation of the TGF-β classi-cal pathway and suppressing the pathological process of epithelial-mesenchymal transition in pulmonary fi-brosis.This finding provides new molecular targets and potential therapeutic strategies for the treatment of pulmonary fibrosis.