Objective:To discuss the anti-inflammatory and antioxidant effect of mesalazine(MSZ)in the RAW264.7 cell model,and to elucidate its therapeutic effect on periodontitis in the rats.Methods:The proliferation rates of RAW264.7 cells stimulated by different concentrations(0,62.5,125.0,250.0,500.0,1 000.0,and 2 000.0 mg·L-1)of MSZ were detected by CCK-8 method to determine the optimal concentration of MSZ for cell treatment.Porphyromonas gingivalis lipopolysaccharide(P.g-LPS)and MSZ were used to treat the RAW264.7 cells,and the cells were divided into control group,P.g-LPS group,and MSZ+P.g-LPS group.The levels of reactive oxygen species(ROS)in the cells in various groups were detected by the DCFH-DA fluorescent probe assay;the malondialdehyde(MDA)levels,glutathione(GSH)levels and superoxide dismutase(SOD)activities in the cells in various groups were detected by ELISA method;the expression levels of inflammatory factors interleukin-8(IL-8)and interleukin-1β(IL-1β)mRNA in the cells in various groups were detected by real-time fluorescence quantitative PCR(RT-qPCR)method.The periodontitis rat model was established by the ligation method combined with the injection of P.g bacterial fluid.A total of 18 rats were randomly divided into control group(without treatment),model group(making period ontits model),and drug administration group(making periodontits model and given MSZ),and there were 6 rats in each group.Micro-CT was used to assess the alveolar bone destruction of the rats in various groups;HE staining was used to observe the morphology of periodontal tissue of the rats in various groups.Results:Compared with control group,the proliferation rate of the cells in 500.0 mg·L-1 MSZ group was significantly increased(P＜0.01),so 500.0 mg·L-1 MSZ was subsequently selected to treat the cells.Compared with control group,the levels of ROS and MDA in the cells in P.g-LPS group were significantly increased(P＜0.01),and the level of GSH and activity of SOD were significantly decreased(P＜0.01),and the expression levels of IL-1β and IL-8 mRNA were significantly increased(P＜0.01);compared with P.g-LPS group,the levels of ROS and MDA in the cells in MSZ+P.g-LPS group were significantly decreased(P＜0.01),the level of GSH and activity of SOD were significantly increased(P＜0.01),and the expression levels of IL-1β and IL-8 mRNA were significantly decreased(P＜0.01).The micro-CT assay results showed that compared with control group,the distance from the cemento-enamel junction to alveolar bone crest(CEJ-ABC)of the rats in model group was significantly increased(P＜0.01),and the bone volume fraction(BV/TV)was significantly decreaced(P＜0.05);compared with model group;the CEJ-ABC of the rats in drug administration group was decreased(P＜0.01),and the BV/TV was increased(P＜0.05).The HE staining results showed that the inflammatory cell infiltration in periodontal tissue of the rats in drug administration group was reduced,and epithelial attachment was restored.Conclusion:MSZ effectively inhibits the production of pro-inflammatory factors and peroxides in the P.g-LPS-induced RAW264.7 cells,improves the cellular anti-inflammatory and antioxidant capacity,inhibits the alveolar bone resorption,and alleviates the inflammation of periodontal tissues in the periodontitis rats.

Objective:To discuss the effects of superelastic nickel-titanium archwires(SENT)and heat-activated nickel-titanium archwires(HANT)on the initial alignment efficiency of mandibular anterior teeth and pain levels of the patients with extraction orthodontic treatment and non-extraction orthodontic treatment by using low-friction self-ligating brackets,and to provide the basis for the selection of the most suitable archwire in orthodontic clinical practice.Methods:Eighty patients underwent fixed orthodontic treatment with self-ligating brackets were randomly assigned to SENT or HANT subgroups,and there were 40 patients in extraction orthodontic treatment group and 40 patients in non-extraction orthodontic treatment group.A single operator fully engaged a 0.014-inch straight archwire into the brackets.The patients,operators,and data measurers were all blinded;the initial clinical alignment efficiency of the archwires of the patients in various groups was observed,and the Little's index was calculated;the visual analog scale(VAS)scores and pain perception of the patients in various groups were recorded 4 h after initial bonding of the appliances and every day before breakfast during the first week of orthodontic treatment;multivariate regression analysis was performed for the initial Little's index,gender,and age,and the influence factors of pain in the patients was analyzed.Results:There were no significant differences in age,gender,and initial Little's index among the patients in extraction group and non-extraction group(P＞0.05).Compared with before treatment,the Little's indexes of the patients in both HANT and SENT subgroups in non-extraction orthedontic treatment group were decreased 4 weeks after treatment,but the difference between groups was not significant(P＞0.05).Compared with SENT subgroup in non-extraction orthodontic treatment group,the Little's index of the patients in HANT subgroup was decreased(P＜0.05).In extraction orthodontic treatment group,there were no significant differences in Little's indexes of the patients between the HANT and SENT subgroups before and after treatment(P＞0.05).The pain perception peaked on the first day after initial bonding and gradually decreased to baseline levels.The patients in SENT and HANT subgroups in both extraction and non-extraction orthodontic treatment groups showed the similar patterns of pain change.There were no significant differences in the average VAS scores and maximum pain intensity scores between the patients in SENT and HANT subgroups at different time points(P＞0.05).The type of archwire had no significant effect on the degree of pain,while time significantly affected the degree of pain.The multivariate regression analysis results showed a significant correlation between initial Little's index and maximum VAS scores of the patients in extraction orthodontic treatment group(b=0.359,P=0.033).Gender and age did not affect the degree of pain of the patients in either group.Conclusion:When applying low-friction self-ligating brackets for orthodontic treatment,the initial alignment efficiency with 0.014-inch HANT archwires is superior to 0.014-inch SENT archwires in non-extraction treatment group,while both archwires show the same efficiency in extraction patients.SENT and HANT archwires do not affect the initial degrees of pain of the orthodontic patients.

Objective:To discuss the regulatory effect of physiological tensile stress on the differentiation of chondrocytes,and to clarify the associated signaling pathway mechanism.Methods:The ATDC5 chondrocytes were cultured in vitro and subjected to physiological tensile stress by four-point bending cell mechanical loading device.Initially,the cells were divided into control group and tensile stress group(2 000 μstrain/2 h group),and further divided into different stress magnitudes(1 000,2 000,and 3 000 μstrain)for 2 h,and 2 000 μstrain for different duration time(1,2,and 4 h)groups;the cells without tensile stress were used as control group.Real-time fluorescence quantitative PCR(RT-qPCR)method was used to detect the expression levels of type Ⅱ collagen(Col-Ⅱ),type Ⅹ collagen(Col-Ⅹ),aggregated proteoglycom(Aggrecan),sex-determining region Y-box protein 9(SOX9),vascular endothelial growth factor(VEGF),proliferating cell nuclear antigen(PCNA),Nel-like molecule tyep 1(Nell-1),Runt-related transcription factor 2(Runx2),Indian hedgehog(Ihh),patched homolog 1(Ptch-1),GLI family zinc finger protein 1(Gli-1),and hedgehog interacting protein 1(Hhip-1)mRNA in the cells in various groups;Western blotting method was used to detect the expression levels of Nell-1,Runx2,and Ihh proteins in the cells in various groups.The ATDC5 cells were divided into control group,cyclopamine group,tensile stress group,and cyclopamine + tensile stress group.RT-qPCR method was used to detect the expression levels of Nell-1,Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in various groups;Western blotting method was used to detect the expression levels of Nell-1 and Ihh proteins in the cells in various groups.Results:Compared with control group,the expression levels of Col-Ⅱ,Col-Ⅹ,Aggrecan,SOX9,VEGF,and PCNA mRNA in the cells in 2 000 μstrain/2 h group were significantly increased(P<0.01);after treated with 2 000 μstrain tensile stress for different duration time(1,2,and 4 h)or different tensile stresses(1 000,2 000,and 3 000 μstrain)for 2 h,compared with control group,the expression levels of Runx2 mRNA in the cells in other groups were increased with the prolongation of time or the increasing of tensile stress(P<0.01),and the expression levels of Nell-1,Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA were gradually increased(P<0.01),the expression levels reached the peaking at 2 000 μstrain/2 h,and then decreased but remained significantly higher than that in control group(P<0.01).The Western blotting results showed that the expression levels of Nell-1,Runx2,and Ihh proteins in the cells were consistent with the change trend of mRNA expression levels.After pre-treated with cyclopamine,compared with control group,the expression levels of Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in cyclopamine group were significantly decreased(P<0.01),and the expression levels of Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in tensile stress and cyclopamine+tensile stress groups were significantly increased(P<0.01);compared with cyclopamine group,the expression levels of Nell-1,Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in cyclopamine+tensile stress group were significantly increased(P<0.01);compared with tensile stress group,the expression levels of Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in cyclopamine + tensile stress group were significantly decreased(P<0.01).Compared with control group,the expression level of Ihh protein in the cells in cyclopamine group was significantly decreased(P<0.01),but there was no significant difference in expression level of Nell-1 protein in the cells between control group and cyclopamine group(P>0.05),while the expression levels of Nell-1 and Ihh proteins in the cells in tensile stress group and cyclopamine + tensile stress group were significantly increased(P<0.01);compared with cyclopamine group,the expression levels of Nell-1 and Ihh proteins in the cells in tensile stress group and cyclopamine + tensile stress group were significantly increased(P<0.01);compared with tensile stress group,in the expression levels of Nell-1 and Ihh proteins in the cells in cyclopamine + tensile stress group had no significant differences(P>0.05).Conclusion:After stimulated with physiological tensile stress,Nell-1 can activate the Ihh signaling pathway upstream,and regulate the differentiation of the ATDC5 chondrocytes.