BACKGROUND:At present, bone substitute filling is mainly used for bone defect repair. In order to understand the effect on bone defect repair, it is necessary to look into the microstructure changes of bone defects after bone substitute implantation. Synchrotron radiation-based micro-computed-tomography (SR-μCT) can be used to make high-resolution, high-resolution three-dimensional imaging without slicing and dyeing, and has high scientific and clinical value. OBJECTIVE:To explore the feasibility of SR-μCT in micron-level bone osseointegration examination in oral medicine. METHODS:This randomized controlled animal experiment was completed at the Fifth Central Hospital of Tianjin, Tianjin, China. A rabbit model of mandibular defect was made in 24 male New Zealand white rabbits. The model rats were randomly divided into four groups and received autologous bone, Bio-oss bone meal,β-tricalcium phosphate powder and no implantation (negative control group) in the defective area, respectively. Bone samples, including the defect area and the surrounding normal bone tissue, were taken at 2, 4, 8 weeks postoperatively for SR-μCT examination, fol owed by histopathological examination, in order to observe the repairing effects of different types of bone implant materials from different angles. The study protocol has been approved by the Ethics Committee of the Fifth Central Hespital of Tianjin in China. The study procedures were completed in accordance with the Guidance Suggestions for the Care and Use of Experimental Animals of China and the guidelines of the National Institutes of Health, USA. RESULTS AND CONCLUSION:In this study, SR-μCT could be used to observe the bone microstructure and osseointegration with no damage to samples to collect accurate quantitative data, including bone volume, number of bone trabeculae and bone mineral density. Therefore, SR-μCT can fully analyze the biocompatibility of bone implant material in vivo, give insight into the micron-level changes of different types of bone implant materials in the bone defect, thereby providing experimental evidence to improve bone defect healing.

Objective To investigate the incidence of dental fluorosis and pit caries in school-age children from binhai new area of Tianjin, and to discuss the relationship between dental fluorosis and pit caries, providing the guidance for the prevention and treatment of them. Methods Referring to WHO’s“Oral Health Surveys Basic Methods”(Fourth Edition) and protocols of the third national oral epidemiology investigation, 3 778 children aged 7 to 9 year-old with similar levels of education were investigated for their dental fluorosis and fissure caries using the cross sectional survey method. Results The data showed that the incidence of dental fluorosis was less than 10%in the samples, and the community fluorosis index (CFI) was 0.075. The caries prevalence rate and mean decayed missing filled tooth (DMFT) of first permanent molars were 15.57%and 0.46 in male students, and those were 17.41%and 0.58 in female students. There were no significant differences in the caries prevalence rate and DMFT of first molar between male and female children (χ2=2.345, P>0.05). There were statistically significant differences in the caries rate and DMFT between different age groups (χ2=172.576, P<0.05), and both increased with age. Conclusion After years of defluoridation project in Tianjin, the detection rate and index of dental fluorosis in children have showed a downward trend. The caries prevalence rate may be related to the eruption rate of the first permanent molar.

Objective To study the effect of carbonated drinks on primary and permanent teeth replacement in Chil-dren. Method Dog tooth enamel samples were soaked in coca-cola, sprite and pure soda, and the calcium, phosphorus lev-el were analysed. Dental papilla stem cells were separated and cultured in the conditioned medium by adding three drinks. PCR and western blot were used to detect mRNA and protein levels of activator of nuclear factor-k B receptor ligand (RANKL), osteoprotegerin (OPG) and vitamin D receptor (VDR) , then the possible role of each gene and interactions rela-tionship were analyzed. Results Compared with saline, coca-cola and sprite showed their significantly decalcification and dephosphorization role, while plain soda water showed calcium and phosphorus protective effect. These three drinks had no effect on mRNA and protein levels of RANKL gene (P>0.05). Coca-cola and sprite can reduce OPG mRNA and protein lev-els, and at the same time increase transcription and expression of the VDR gene. Plain soda water has no effect on the OPG gene manifestation, but can significantly reduce the transcription and translation level of the VDR gene. Conclusion Car-bonated drinks may affect the dental health of the children's primary and permanent teeth replacement by regulating bone re-lated gene expression and vitamin D receptor family.

Objective To study the functional roles of 1,25(OH)2D3 in osteogenic differentiation of the dental papilla stem cells. Methods The dental papilla stem cells were isolated and cultured in medium supplemented with different con-centrations of 1,25(OH)2D3 (1, 10 and 100 nmol/L). MTT assay was used to detect the cell growth, and flow cytometry was used to detect the cell cycle. Western blot assay was used to detect protein expression levels of receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG) and vitamin D receptor (VDR). After siRNA silencing VDR expression, protein levels of RANKL and OPG were detected. Results MTT and flow cytometry results showed that there were no sig-nificant differences in the cell proliferation between different concentrations of 1,25(OH)2D3 (1, 10 and 100 nmol/L) and con-trol groups (P>0.05). Western blot results showed that there were protein expressions of VDR, RANKL and OPG in control group. The protein expressions of VDR, RANKL and OPG were increased after adding 1,25(OH)2D3, in which the upward trend was the most significant in VDR. After VDR expression was silenced by siRNA, the protein expression levels of VDR, RANKL and OPG were decreased. Conclusion 1,25(OH) 2D3 affects the osteoblast differentiation process of the dental pa-pilla stem cells by adjusting the VDR expression.

Objective:To summarize the hotspots and developmental status of non-suicidal self-injury research by clustering and co-occurrence to the literature on non-suicidal self-injury on the basis of Cite Space, and in order to provide references for future research and intervention.Methods:Non-suicidal self-injury literature included in the Web of science core collection from January 1975 to August 2020 was searched, and the included literature was visualized and analyzed using Cite Space 5.5.R2 knowledge mapping software.Results:A total of 974 articles were retrieved, and the number of articles published showed an increasing trend year by year, mostly in developed countries. The country with the highest cumulative number of articles was the United States, with a total of 412 articles, and the first organization was Katholieke Univ Leuven, with a total of 42 articles. Key words co-occurrence and clustering showed that the current research focus was on adolescents, suicidal behavior, dialectical behavior therapy, and borderline personality disorder. The most cited literature was by Muehlenkamp.Conclusions:Non-suicidal self-injury research has developed rapidly in recent years. At present, non-suicidal self-injury population, related intervention measures, screening and evaluation tools, Meta-analysis and risk factor analysis are its research frontiers and hot spots.

Type 2 Diabetes Mellitus(T2DM)is a chronic metabolic disease characterized by disorders of insulin and glucose.As a disease closely related to our daily diet,the molecular mechanism of its pathogenesis is still unclear.Sweet taste receptors are a kind of G protein-coupled receptors with 7 times transmembrane.Although the research on the pathogenesis of T2DM has been gradually deepened,there are few studies on the mechanism of sweet taste damage in the state of disease.Therefore,in-depth study of the pathological mechanism of T2DM sweet taste receptor damage is of great significance to further understand the molecular characteristics of sweet taste receptors and explore new targets of traditional Chinese medicine in the treatment of T2DM.In this paper,the biological characteristics of sweet taste receptors,signal transduction mechanism of sweet taste receptors,sweet taste receptors and T2DM,sweet taste receptors and"spleen is sweet"are reviewed in order to provide the latest opinions for the targeted prevention and treatment of this kind of diseases by traditional Chinese medicine and the elucidation of related pathological mechanism.

ObjectiveBidirectional and two-sample Mendelian randomization（MR） method was used to investigate the bidirectional causal relationship between constipation and pneumonia and to understand the potential relationship between the two diseases from a new perspective， providing new targets for future treatment strategies. MethodConstipation and pneumonia datasets were selected from the genome-wide association study（GWAS） website for the European population in 2021. The data related to constipation included 411 623 samples， and the single nucleotide polymorphism（SNP） data were 24 176 599. The pneumonia data contained 480 299 samples with a number of SNPs of 24 174 646. In this study， inverse variance weighting（IVW） was adopted as the main analysis method of MR， supplemented by weighted median method， simple model， weighted model and MR-Egger regression analysis results， and sensitivity analysis was performed to evaluate the robustness of the results. ResultSeventeen SNPs highly correlated with constipation and 12 SNPs highly correlated with pneumonia were finally included. IVW analysis results of forward MR analysis showed that constipation increased the risk of pneumonia｛odds ratio（OR）=1.143， 95% confidence interval（CI）［1.045， 1.249］， P=0.003｝， MR-Egger regression， simple model， weighted model and weighted median analysis all supported the result（P<0.05）. IVW analysis by reverse MR analysis showed that pneumonia did not increase the risk of constipation｛OR=1.138， 95%CI［0.974， 1.329］， P=0.103｝， MR-Egger regression， simple model， weighted model and weighted median analysis also supported this result. ConclusionThe bidirectional and dual-sample MR analysis method is used to confirm the causal relationship between constipation and pneumonia from the perspective of genetic variation， while there is no obvious causal relationship on the contrary. This study will be helpful for the clinical diagnosis and treatment of constipation and pneumonia， and provide a reference for the study of the pathogenesis between the two.