BACKGROUND:Sema3A is a power secretory osteoprotective factor.However,studies about Sema3A-modified dental pulp stem cells(Sema3A-DPSCs)are rare. OBJECTIVE:To explore the osteogenic differentiation ability of Sema3A-DPSCs and their regulatory effect on the osteogenic differentiation of the pre-osteoblast cell line MC3T3-E1. METHODS:First,Sema3A-DPSCs were constructed using a lentivirus infection system carrying the Sema3A gene.Control lentivirus-treated DPSCs(Vector-DPSCs)were used as controls.Sema3A-DPSCs or Vector-DPSCs were co-cultured with proosteoblast line MC3T3-E1 at the ratio of 1∶1 and 1∶3 for 24 hours.Finally,the Sema3A-DPSCs,Vector-DPSCs and their co-cultured cells with MC3T3-E1 were cultured for osteogenic induction and differentiation.Osteogenic gene expression was detected by alkaline phosphatase staining,alizarin red staining and real-time quantitative RT-PCR to evaluate osteogenic differentiation ability. RESULTS AND CONCLUSION:(1)Sema3A mRNA and protein expression levels in Sema3A-DPSCs were significantly up-regulated.The level of secreted Sema3A in cell supernatant was up-regulated.(2)Compared with the Vector-DPSCs,mRNA expressions of osteogenic genes alkaline phosphatase,Runt-related transcription factor 2,osteocalcin and Sp7 transcription factors in Sema3A-DPSCs were up-regulated;the activity of alkaline phosphatase was enhanced,and the formation of mineralized nodules increased.(3)There were no obvious differences in proliferation between Sema3A-DPSCs and Vector-DPSCs.(4)Compared with MC3T3-E1/Vector-DPSCs co-culture system,the expression of MC3T3-E1 osteogenic genes was up-regulated,and the total alkaline phosphatase activity was enhanced and more mineralized nodules were formed in the MC3T3-E1/Sema3A-DPSCs co-culture system.(5)The results suggest that overexpression of Sema3A can enhance the osteogenic differentiation of DPSCs.Overexpression of Sema3A in DPSCs can promote osteogenic differentiation of MC3T3-E1 in the DPSCs/MC3T3-E1 co-culture system.

BACKGROUND:The reciprocal force generated by the molar distalization with clear aligners can lead to anchorage loss.The effect of arch shapes and missing second premolars on anchorage has not been reported. OBJECTIVE:To analyze the effect of arch shapes and missing second premolars on anchorage during molar distalization with clear aligners using the finite element method. METHODS:Cone-beam CT data from an adult male were acquired from the database to establish the maxilla-upper dentition-periodontium-rectangular attachment-clear aligner model.The distal movement amount designed on the bilateral second molars was set to 0.25 mm.First,there were two groups in the study:second premolar bilateral presence and absence groups.Then,four subgroups in each group were created:tapered arch,ovoid arch,square Class Ⅱ Division 1 arch,and Class Ⅱ Division 2 arch groups.The Ansys software was used to calculate the displacement of the anchorage tooth and the stress of the periodontal ligament. RESULTS AND CONCLUSION:Mesial tipping and extrusion of first molars and premolars,labial inclination and intrusion of anterior teeth occurred during the upper second molar distalization with clear aligners.When the bilateral second premolars were missing,the mesial displacement of first molars increased significantly while that of first premolars and anterior teeth decreased in all groups.The square Class Ⅱ Division 1 arch group showed the least anterior labial inclination,while the tapered arch group showed the most.There was no significant difference between the ovoid arch group and the tapered arch group.Moreover,the magnitude of tipping in the square Class Ⅱ Division 2 arch group was slightly higher than that in the Class Ⅱ Division 1 arch group.The stress of the periodontal ligament of the anchorage teeth was concentrated on the cervical and apical regions of the teeth.And the lowest stress level was detected in the square arch group.Compared with the other groups,the stress on the labial cervical area of the periodontal ligaments was also significantly relieved in the square arch group.To conclude,the square arch is more favorable in terms of anterior anchorage control and periodontal ligament stress distribution.Anterior labial inclination efficiency can be increased in cases of Class Ⅱ Division 2 by designing the anterior labial inclination in conjunction with molar distalization.If the second premolar is missing during molar distalization,it is not conducive to opening up the space in the area of the missing tooth.

BACKGROUND:The thin alveolar bone in the lower anterior region increases the risk of labial bone resorption when intruding the teeth with clear aligners.The effect of sagittal overcorrection design on the labiolingual control of mandibular anterior teeth intrusion has not been fully investigated. OBJECTIVE:To explore the effect of overcorrection on the changes in the displacement and stress of the mandibular anterior teeth,especially the cervical and apical regions. METHODS:Through a male volunteer cone-beam CT data,the three-dimensional reconstruction of the mandible and teeth was conducted in the MIMICS and GEOMAGIC software.Moreover,the models of periodontal ligaments,attachments,and appliances were created in the SOLIDWORKS software.First,the study was divided into canine intrusion group and incisor intrusion group.Then,the overcorrection(0°,1°,2°)was designed on the bilateral mandibular central and lateral incisors.A total of six models were established.The models were assembled and imported into the ANSYS software to analyze and calculate the displacement and stress level. RESULTS AND CONCLUSION:(1)In the canine intrusion group,canines intruded and tipped lingually while incisors extruded and tipped lingually.In the incisor intrusion group,canines extruded and tipped lingually while incisors intruded and tipped lingually.(2)Without overcorrection,the incisors necks moved lingually while apexes moved labially.With overcorrection,the incisors tended to be upright,followed by labial tilt.The least cervical and apical displacements were detected under 1° overcorrection.(3)With overcorrection,the incisal cervical stress concentration area shifted from labial to lingual in the canine intrusion group,whereas the stress concentration area shifted from lingual to labial in the incisor intrusion group.(4)The incisors tended to tilt lingually when intruding the mandibular anterior teeth with clear aligners.The sagittal overcorrection design was conductive to maintain the stable position of incisors.However,the amount of overcorrection should be moderate.Excessive overcorrection might increase the labial inclination tendencies of incisors.

Objective To measure the anatomical parameters of the first maxillary molars in children of different age groups and evaluate the age-related changes in dental crowns.Methods A retrospective analysis was conduc-ted on cone beam computed tomography(CBCT)images of 4-8-year-old children.NNT software was used to ana-lyze multiple important indicators of maxillary first molar.Results A total of 308 first maxillary molars,including 154 pediatric patients,were evaluated in this study.The thickness of the pulp apex H1(left,P=0.01;right,P=0.02)and the thickness of the pulp chamber floor H3(left and right P＜0.01)were positively correlated with age,while the height of the pulp cavity H2(left and right P＜0.01)and the height of the palate tip D1(left P=0.003,right P=0.002)showed a negative correlation with age.There was no significant correlation between the height of the buccal tip and age(P＞0.05).There were significant differences in H1 and H3 between the 4-year-old and 5-year-old age groups between the 8-year-old age group(P＜0.05),as well as significant differences in H2 and D1 between the 4-year-old and 5-year-old between the 6-year-old,7-year-old and 8-year-old age groups(P＜0.05).Conclusion The age-related changes in the crowns of the first maxillary molars are important references for the clinical treatment,and can be accurately measured through CBCT data.

Objective To study the differences in features of event-related potentials(ERPs)and target detection accuracy between five brain regions(frontal,temporal,central,parietal,and occipital)in target detection tasks based on rapid serial visual presentation(RSVP)brain computer interface(BCI)under six target concealment conditions.Methods Twelve participants were selected for the study,whose scalp electroencephalogram(EEG)signals were collected under the six concealment conditions using a NeuroScan SynAmps2 EEG acquisition system.The ERP waveforms,P300 amplitudes and latencies,among other things,were compared across the five brain regions.The hierarchical discriminant component analysis(HDCA)algorithm was used to classify the EEG signals while the differences in classification accuracy were probed across the five brain regions.Results(1)Under the six concealment conditions,target images elicited distinct ERP waveforms in all the five brain regions;(2)For P300 amplitudes,the temporal region exhibited the smallest values;(3)Regarding P300 latencies,the parietal and central regions showed longer durations than other brain regions(except for small camouflage and small occlusion conditions);(4)In terms of classification accuracy,the parietal and central regions outperformed other brain regions(except for the large camouflage condition).Conclusion The selection of parietal and central channels can offer a new perspective for enhancing the performance in concealed target detection based on RSVP-BCI,and is expected to spark new ideas for the design of miniaturized,simple and wearable BCI devices.

Objective To explore an overcorrection quantization method and related influencing factors through analyzing relationships between the achieved and preset intrusion values of mandibular anterior teeth with clear aligners.Methods Twenty pa-tients receiving Invisalign were recruited.The relative intrusion values in the ClinCheck software were recorded as the preset intrusion.The achieved intrusion values were measured through the digital model superimposition.Statistical analysis was conducted to assess the differences and linear relationships between the preset and achieved intrusion values,and investigate the effect of related factors such as intrusion amounts on the intrusion efficiency.Results For the mandibular anterior teeth,the mean intrusion efficiency was 62.2%,with the highest in the central incisors and the lowest in the canines.The intrusion amounts,incisors labial inclinations,and canine at-tachment types affected the intrusion efficiency.The differences between the preset and achieved values were significant,and the linear relationship existed.The formula of the intrusion overcorrection for the mandibular anterior teeth is"Z=(W-0.110)/0.533-W".Z re-presents the overcorrection and W represents the ideal intrusion.Conclusion The preset intrusion values in the treatment protocol could not be fully achieved.Moreover,correction should be designed in cases of mandibular canine intrusion,large amountsof intru-sion,orlingually inclined incisors.Compared to the optimized attachments,the vertical rectangular attachments on the mandibular ca-nines could improve the efficiency.

Objective To evaluate and compare the treatment efficacy between concentrated growth factor(CGF)and blood clots(BC)as scaffolds in regenerative endodontic procedures(REPs).Methods Twenty young permanent teeth from 18 healthy children with pulp necrosis or periapical periodontitis were randomly divided into CGF group and BC group.In the CGF group(n=10),after ap-ical bleeding,CGF was inserted into the root canal as a stent.In the BC group(n=10),by stimulating apical bleeding,blood entered the root canal and produced blood clots as scaffolds.Clinical examination and apical X-ray shooting were conducted for each follow-up visit.Cone beam computed tomographic(CBCT)images were acquired preoperatively and at the 24-month recall.The increase of root length,root wall thickness,and newly-formed calcified tissue were calculated.Results The root length increased by(1.68±0.90)mm in the CGF group and(2.36±1.34)mm in the BC group.Root wall thickness increased by(0.44±0.34)mm in the CGF group and(0.50±0.31)mm in the BC group.There was no statistically significant difference in root lengthening and root wall thickening between two groups(P＞0.05).The amount of newly formed calcified tissue in the CGF group((22.13±19.12)mm3)was significantly less than that in the BC group((42.97±22.69)mm3)(P＜0.05).According to the goals for success outlined by American Association of Endodontists(AAE),90%(9/10)of the CGF cases and100%(10/10)of the BC cases achieved the primary and secondary goals(P＞0.05).40%of the CGF cases(4/10)and 60%of the BC cases(6/10)achieved the tertiary goal(P＞0.05).Conclusion CGF is found to be use-ful as a scaffold for REPs,but the success rate is slightly lower than that of BC group and the difference is not statistically significant.

Objective To explore the effect of melatonin(MT)-modified PEEK implant assisted by polydopamine(PDA)coating on osteointegration in osteoporotic rats.Methods MT was adhered to PEEK implants with PDA coating as carrier.The physicochemical properties of the materials were analyzed by SEM image,water contact angle,FTIR and protein adsorption experiment.OVX-rBMSCs were inoculated on the surface of PEEK sheet and cultured.The cytoskeleton was stained and cell adhesion morphology was observed.Cell proliferation activity was evaluated by CCK-8 assay;key enzyme activities for osteogenic differentiation were analyzed by ALP stai-ning,and expression levels of osteoblast-related genes COL-1,Runx2,OPN,OCN,BMP-2 and ALP were detected by quantitative real-time PCR.In addition,implants were implanted into the femur of osteoporotic rats and bone volume on the implant surface was de-tected and quantified by Micro-CT.Results MT was successfully loaded on PEEK;the cell adhesion was better,and the proliferation activity and osteogenic differentiation ability were significantly higher than those of control group(P＜0.01).In the rat osteoporosis mod-el,there was more new bone formation around the modified PEEK implant(P＜0.01).Conclusion MT-modified PEEK implants have excellent biocompatibility and improve osteointegration in an osteoporotic environment.

In recent years, clear aligner technology has been maturing and is rapidly gaining popularity in the orthodontic market for its aesthetic and removable properties. However, despite the background of its large-scale clinical application, mechanical properties of clear aligners need to be studied in depth. This paper reviews the factors influencing mechanical properties of clear aligners and the current status of research to provide evidence-based guidance for clinical application.

Objective:To investigate the expression of miR-211-5p in peripheral blood of patients with myelosuppression after neoadjuvant chemotherapy for breast cancer and its effect on Notch signaling pathway by targeting cyclooxygenase 2 (COX2) gene Regulation mechanism.Methods:From Jan. 2018 to Jan. 2021, 185 breast cancer patients who received neoadjuvant chemotherapy in Linyi People’s Hospital for the first time were included as the research objects. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the mRNA expression levels of miR-211-5p, COX2 gene and Notch signaling pathway related genes (Notch1, Jagged1 and Hes1) . The miR-211-5p mimic, inhibitor, mimic NC, and inhibitor NC were transfected into SD rat bone marrow mesenchymal stem cells, and the mRNA expression of miR-10a-3p and COX2 genes was detected by qRT-PCR for 48 hours. Western blot method was used to detect the protein expression levels of Notch signaling pathway related genes.Results:The relative expression of miR-211-5p in patients with severe myelosuppression was 2.41±0.32, which was significantly higher than that in patients with mild myelosuppression (1.53±0.18) ( t=6.385, P<0.001) ; The relative expression of COX2 gene mRNA in patients with severe myelosuppression was 3.64±0.74, which was significantly lower than that in patients with mild myelosuppression (5.37±1.02) ( t=7.469, P<0.001) . In patients with severe myelosuppression, there was a significant negative correlation between miR-211-5p and COX2 gene mRNA levels ( r=-0.694, P=0.006) . The results of the dual luciferase report experiment confirmed that COX2 was the target gene of miR-211-5p. The relative expression of Notch1, Jagged1, and Hes1 mRNA in peripheral blood of patients with severe myelosuppression were 2.35±0.41, 2.76±0.46 and 3.04±0.52, respectively, which were significantly lower than those in patients with mild myelosuppression (4.12±0.63, 4.53±0.58 and 5.12±0.67) ( t=5.367, 6.114 and 6.135, respectively, P<0.001) . After transfecting SD rat bone marrow mesenchymal stem cells with miR-211-5p mimics and inhibitors, the relative expression of miR-211-5p in the mimic group was 3.46±0.49, significantly higher than that in the mimic NC group (2.24±0.32) The relative expression of miR-211-5p in the inhibitor group was (1.28±0.19) and (2.33±0.37) inhibitor NC group ( P<0.001) , while the relative expression of miR-211-5p in the inhibitor group was significantly lower than that in the other three groups ( P<0.001) . The mRNA expression of COX2 gene in mimic group was 2.73±0.36, which was significantly lower than that in mimic NC group (4.05±0.59) , inhibitor group (6.15±0.86) and inhibitor NC group (4.18±0.65) ( P<0.001) , while mRNA expression of COX2 gene in the inhibitor group was significantly higher than that in the other three groups ( P<0.001) . The expression of Notch1, Jagged1, and Hes1 in the inhibitor group was significantly increased, while the expression of Notch1, Jagged1, and Hes1 in the mimic group was significantly decreased. Conclusion:The expression level of miR-211-5p in peripheral blood of severe myelosuppressed patients with breast cancer after neoadjuvant chemotherapy is significantly increased, and the Notch signaling pathway can be inhibited by targeted down-regulation of COX2 gene expression.