[Pathogenesis, diagnostic and therapeutic strategies for radiation-related caries].

Radiation-related caries is a common complication following head and neck tumor radiotherapy. It is a rapidly progressing and widespread destructive disease of tooth tissue after radiotherapy, which greatly affects the life quality of patients after radiotherapy. This article elucidates research progress in the pathogenic mechanisms, diagnosis and caries assessment, treatment, as well as prevention strategies for radiation-related caries, aiming to provide references for clinical prevention and treatment of radiation-related caries.

[Epidemiological characteristics of incident cases and risk factors of hepatitis C infection in Beijing City from 2004 to 2021].

Objective: To analyze the epidemiological characteristics and related factors of hepatitis C in Beijing City from 2004 to 2021. Methods: Descriptive epidemiological method and Joinpoint regression were used to analyze the trend and other epidemiological characteristics of hepatitis C in Beijing City from 2004 to 2021 in National Notifiable Disease Reporting System. According to a 1∶1 matched case-control study design, logistic regression was used to investigate the risk factors of hepatitis C infection in 2021. Results: From 2004 to 2021, the reported incidence of hepatitis C in Beijing City ranged from 2.37/100 000 to 10.46/100 000. The reported cases were mainly aged 30-60 years, and most of them were chronic. The reported incidence of hepatitis C showed an initial increase from 2004 to 2006 (APC=45.37%, 95%CI:-1.56%-114.69%), and declined after 2006 (APC=-9.21%, 95%CI:-10.70%-7.70%). Logistic analysis showed that history of surgery (OR=1.84, 95%CI: 1.08-3.14) and previous blood transfusion (OR=34.22, 95%CI: 8.05-145.41) were risk factors for hepatitis C infection. Conclusion: The reported incidence of hepatitis C in Beijing City increases first and decreases later. It currently remains at a low level. The risk factors of infection are surgery and blood transfusion history. Safe blood supply and preventing iatrogenic transmission should be focused on the prevention of hepatitis C transmission.

Investigation of the relationships among respiratory syncytial virus infection, T cell immune response and intestinal flora.

The aim of this work was to evaluate the relationships among respiratory syncytial virus infection, T cell immune response and intestinal flora. Peer-reviewed papers published in English were collected through extensive searches performed in PubMed, Web of Science, Google Scholar, and China National Knowledge Infrastructure databases. The articles were reviewed to extract relevant information on the immune responses of Th1/Th2 and Treg/Th17 to respiratory syncytial virus infection in the body. RSV (Respiratory syncytial virus, RSV) infection leads to imbalance between Th1/Th2 and Treg/Th17 immune cells, resulting in Th2 or Th17 dominant immune responses, which can generate immune disorder and aggravate clinical symptoms. Intestinal micro-organisms play very important roles in maintaining stable immune environment, stimulating immune system maturation and balancing Th1/Th2 and Treg/Th17 immune systems in children. In our review of various papers from around the world, we speculated that the steady state of intestinal bacteria was disturbed after children got infected with RSV, resulting in intestinal flora disorder. Then, the imbalance between Th1/Th2 and Treg/Th17 immune cells was increased. Both intestinal flora disorder and RSV infection could cause cellular immunity imbalance of Th1/Th2 or Treg/Th17, eventually leading to disease deterioration and even a vicious cycle. Normal intestinal flora can maintain immune system stability, regulate the dynamic balance of Th1/Th2 and Treg/Th17 and prevent or mitigate adverse consequences of RSV infection. Because probiotics can improve intestinal barrier function and regulate immune response, they can effectively be used to treat children with recurrent respiratory tract infections. Using conventional antiviral therapy strategy supplemented with probiotics in the treatment of clinical RSV infection may be better for the body.

[Diversity of root canal morphology in mandibular first premolars and its clinical strategies].

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.

[Application of lateral upper arm free flap in the repair of postoperative defects of oral cancer].

Objective: To explore the clinical application and efficacy of lateral upper arm free flap (LUAFF) for one-stage repairing of soft tissue defect after oral cancer surgery. Methods: This article was a retrospective analysis of clinical data of 46 patients receiving treatment of one-stage repairing of soft tissue defect with LUAFF after oral cancer surgery in Hunan Cancer Hospital, from June 2019 to June 2021. Among these cases, 40 were males, and 6 were females. The patients' ages were from 23 to 64 years old. The clinical data of patients were reviewed and outcomes were evaluated. SPSS 23.0 software was used for statistical analysis. Results: In the LUAFF of 46 patients, flap area ranged from 5.0 cm×3.5 cm to 15.0 cm×7.0 cm; the mean pedicle length was 8.15±1.42 cm; the mean artery diameter was 1.20±0.41 mm (range, 1.5 to 2.5 mm); the mean diameter of the largest veins was 2.15±0.52 mm; and the median number of perforators was 2.6 (range, 1 to 4). All donor sites were closed primarily. Two cases had arterial anastomosis thrombosis, but their flaps were successfully saved with urgent re-anastomosis of the vessels. The overall flap survival rate was 93.5%(43/46), with flap necroses after operation in three cases. No patient received tracheotomy. The average hospital stay time of patients after operation was 9.4 days. The follow-up time was 6-24 months, elbow and wrist movements on the operative side were normal, and the upper limb muscle strength was not affected. Conclusions: LUAFF is a suitable choice for the repairs of small-moderate tissue defects in oral cancer surgery, with consistent perforators in the flap, simple harvest method, concealed donor-site scar, and high survival rate.

[Distributive characteristics of HBV DNA CpG islands in HBsAg positive mothers and its relationship with intrauterine transmission].

Objective: To investigate the type, length, and CG loci of HBV DNA CpG islands in HBsAg positive maternal C genotype and its relationship with intrauterine HBV transmission, so as to provide a new perspective for the study of intrauterine transmission of HBV. Methods: From June 2011 to July 2013, HBsAg-positive mothers and their newborns who delivered in the obstetrics and gynecology department of the Third People's Hospital of Taiyuan were collected. Epidemiological data were collected through face-to-face questionnaires and electronic medical records. Serum HBV markers and serum HBV DNA were detected by electrochemiluminescence and quantitative fluorescence PCR, respectively. Intrauterine transmission of HBV was determined by positive HBsAg and/or HBV DNA in femoral venous blood before injection of HBV vaccine/Hepatitis B immunoglobulin within 24 h of birth. A total of 22 mothers and their newborns with HBV DNA load ≥106 IU/ml in intrauterine transmission were selected as the intrauterine transmission group, and 22 mothers with HBV DNA load ≥106 IU/ml without intrauterine transmission were chosen as the control group by random seed method. The distribution prediction of CpG islands of HBV DNA in 39 mothers with genotype C by HBV DNA sequencing was analyzed. Results: Among 39 mothers with HBV C genotype, 19 were in the intrauterine transmission group, and 20 were in the control group. The HBV DNA of 39 patients with genotype C traditional CpG island Ⅱ and Ⅲ, while the control group had traditional CpG island Ⅰ and novel CpG island Ⅳ and Ⅴ. The length of CpG island Ⅱ and Ⅲ and the number of CG loci of CpG island Ⅱ in the intrauterine transmission group differed from those in the control group (P<0.05). The CpG island Ⅱ length ≥518 bp and the number of CG loci ≥40 in the intrauterine transmission group (11/19) were significantly higher than those in the control group (2/20) (P<0.05). The length of CpG island Ⅱ and the number of CG loci in the X gene promoter region (Xp region) were higher than those in the control group (P<0.05). In the HBV intrauterine transmission group, most of maternal (12/19) HBV DNA CpG island Ⅱ completely covered the Xp region, which was significantly higher than that in the control group (5/20), and the number of HBV DNA Xp region CG loci was higher than that in the control group (P<0.05). Conclusions: The distribution of maternal C genotype HBV DNA CpG islands is related to intrauterine transmission. The length of CpG island Ⅱ and the number of CG sites may increase the risk of intrauterine transmission of HBV.

[Effect of activation of Toll-like receptor signaling pathway of peripheral blood mononuclear cell in recombinant hepatitis B surface antigen immune response].

Objective: To explore the effect and mechanism of activation of peripheral blood mononuclear cell (PBMC) Toll-like receptor (TLR3) signaling pathway in recombinant HBsAg (rHBsAg) immune response. Methods: White blood cells were collected from peripheral blood of 13 healthy donors in the preparation of blood products. PBMC was isolated and treated with Poly I:C (Poly I:C group) and PBS (control group) respectively. 48 h later, some cells were collected and the expressions of TLR3 signaling pathway proteins were detected by flow cytometry. After activating (Poly I:C group)/inactivating (control group) TLR3 signaling pathway, rHBsAg was given to both groups for 72 h, and the proportions of DC, T, B cells and their subsets in PBMC were detected by flow cytometry. Paired t-test, paired samples wilcoxon signed-rank test and canonical correlation analyses were used for statistical analysis. Results: The percentage of TLR3 protein-positive cells (19.21%) and protein expression (8 983.95), NF-κB protein expression (26 193.13), the percentage of pNF-κB protein-positive cells (13.73%) and its proportion in NF-κB (16.03%), and the percentage of pIRF3 protein-positive cells (12.64%) and its proportion in IRF3 (21.80%) in Poly I:C group were higher than those in control group (11.54%, 8 086.00, 22 340.66, 8.72%, 9.71%, 9.57%, 19.12%) (P<0.05), and the percentage of TRIF protein-positive cells (89.75%) and protein expression (304 219.54) were higher in Poly I:C group than in the control group (89.64%, 288 149.72) (P>0.05). After PBMC stimulation by rHBsAg, the proportions of mDC (2.90%), pDC (1.80%), B cell (5.31%) and plasma cell (67.71%) in Poly I:C group were significantly higher than those in the control group (1.83%, 0.81%, 4.23%, 58.82%) (P<0.05). Results of canonical correlation analysis showed that the expression of TLR3 protein was positively correlated with the proportions of plasma cells, the expression of pIRF3 protein was positively correlated with the proportions of plasma cells and mDC, and the percentage of pNF-κB protein-positive cells and the percentage of pIRF3 protein-positive cells were positively correlated with the proportion of CD4+T cells. Conclusions: Poly I:C can activate TLR3/TRIF/NF-κB and TLR3/TRIF/IRF3 signaling pathway, promote the function of downstream signaling molecules, and then promote the maturation of DC, induce the immune responses of CD4+T cell, and promote the maturation and activation of B cells and the immune response of rHBsAg.

[Analysis on influencing factors of HBV intrauterine transmission based on integration of decision tree model and logistic regression model].

Objective: To investigate the influencing factors of HBV intrauterine transmission and their interaction effects by integrating logistic regression model and Chi-squared automatic interaction detector (CHAID) decision tree model. Methods: A total of 689 pairs of HBsAg-positive mothers and their neonates in the obstetrics department of the Third People's Hospital of Taiyuan from 2007 to 2013 were enrolled, and the basic information of mothers and their neonates were obtained by questionnaire survey and medical record review, such as the general demographic characteristics, gestational week and delivery mode. HBV DNA and HBV serological markers of the mothers and newborns were detected by fluorescence quantitative PCR and electrochemiluminescence immunoassay respectively. The CHAID decision tree model and unconditional logistic regression analysis were used to explore the factors influencing HBV intrauterine transmission in neonates of HBsAg-positive mothers. Results: Among the 689 neonates, the incidence of HBV intrauterine transmission was 11.47% (79/689). After adjusted for confounding factors, the first and second logistic multivariate analysis showed that cesarean delivery was a protective factor for HBV intrauterine transmission (OR=0.25, 95%CI: 0.14-0.43; OR=0.27, 95%CI: 0.15-0.46); both models indicated that maternal HBeAg positivity and HBV DNA load ≥2×105 IU/ml before delivery were risk factors of HBV intrauterine transmission (OR=3.89, 95%CI: 2.32-6.51; OR=3.48, 95%CI: 2.12-5.71), respectively. The CHAID decision tree model screened three significant factors influencing HBV intrauterine transmission, the most significant one was maternal HBeAg status, followed by delivery mode and maternal HBV DNA load. There were interactions between maternal HBeAg status and delivery modes, as well as delivery mode and maternal HBV DNA load before delivery. The rate of HBV intrauterine transmission in newborns of HBeAg-positive mothers by vaginal delivery increased from 19.08% to 29.37%; among HBeAg-positive mothers with HBV DNA ≥2×105 IU/ml, the rate of HBV intrauterine transmission increased to 33.33% in the newborns by vaginal delivery. Conclusions: Maternal HBeAg positivity,maternal HBV DNA ≥2×105 IU/ml and vaginal delivery could be risk factors for HBV intrauterine transmission in newborns. Interaction effects were found between maternal HBeAg positivity and vaginal delivery, as well as vaginal delivery and high maternal HBV DNA load. Logistic regression model and the CHAID decision tree model can be used in conjunction to identify the high-risk populations and develop preventive strategies accurately.

[Effect of lipopolysaccharide-stimulated exosomes from human dental pulp stem cells combined with stromal cell-derived factor-1 on dental pulp regeneration].

Objective: To investigate the effect of exosomes from mild-inflammation- stimulated human dental pulp stem cells (hDPSC) combined with stromal cell-derived factor-1 (SDF-1) on dental pulp regeneration in rats. Methods: Primary hDPSCs were isolated, cultured and then stimulated by using lipopolysaccharide (LPS). The exosomes from the hDPSCs with (L-EXO) or without (N-EXO) LPS were extracted by overspeed differential centrifugation and were identified by transmission electron microscopy and Western blotting. Forty SD rats, aged 6-8 weeks, were equally divided into S group (SDF-1 alone), L+S group (L-EXO combined with SDF-1), N+S group (N-EXO combined with SDF-1) and blank control group (no substance implanted into the root canal) by random number table method. Bilateral mandibular first molars were used as the experimental teeth to establish pulpless root canal models and different contents were implanted into the root canals according to the groups. All rats were over-anesthetized and sacrificed at the 30th day after content implantation. Bilateral mandibular tissues were taken for histological evaluation by means of HE, Masson and immunohistochemical stainings. Results: The HE staining showed new pulp-like tissue in the root canals of all three experimental groups. The amount of new tissues and the number of cells in the tissues were greatest in L+S group and least in S group. Masson staining showed that the mineralized tissue in L+S group was arranged longitudinally along the root canal wall and the collagen fibers were arranged in an orderly fashion, while those in N+S group showed an irregular and disordered distribution. Quantitative analysis of the area of neovascularization in each group showed that the density of vessels in the L+S group [(2.03±0.65)%] was significantly higher than that in the S group [(0.65±0.05)%] and the N+S group [(1.06±0.38)%] respectively (F=5.879, P<0.05). Immunohistochemical staining showed that the expression of CXC chemokine receptor 4 (CXCR4) was significantly lower in S and L+S groups than in N+S group, with a statistically significant difference (F=8.633, P<0.01). Conclusions: Exosomes secreted by hDPSCs combined with SDF-1 might increase the amount of new tissue in the root canal and the density of blood vessels in the tissue. L-EXO showed a stronger effect than N-EXO did. The combination of L-EXO with SDF-1 might result in more regular arrangement of mineralized tissue and collagen fibers in the regenerative tissues.

[Hashimoto's encephalopathy presenting with isolated cerebellar ataxia in 13 children].

Objective: To analyze the clinical characteristics, treatment and prognosis of Hashimoto's encephalopathy presenting with isolated cerebellar ataxia in children. Methods: A retrospective analysis was performed on the clinical features, laboratory tests, neuroelectrophysiological examination, imaging, treatment and outcomes of 13 patients with Hashimoto's encephalopathy presenting with isolated cerebellar ataxia, who were admitted to the Department of Pediatric Neurology of Guangzhou Women and Children's Medical Center from January 2016 to May 2021. Results: Among the 13 cases, 6 were males and 7 were females. The onset age was 2.6 (2.0,3.3) years, 9 children had precursor infection or vaccination before the first course of disease. All the 13 children had gait abnormalities or unsteady sitting, 10 had intentional tremor, 6 had dysarthria, 3 had body tremor, 2 had nystagmus, 3 had fatigue, 3 had hypotonia, 2 had vomiting and 1 had irritability. Thyroglobulin antibody (TgAb) was 500.0 (298.9,587.2) kU/L and thyroid peroxidase antibody (TPOAb) was 621.9 (449.6,869.4) kU/L in 13 cases. Autoantibodies were positive in 9 cases, and cerebrospinal fluid leukocytosis was seen in 4 cases. Regarding electroencephalography result, 4 cases had background slowing and 1 case had occasional sharp waves. Among the 3 patients who had relapses, 1 had cerebellar atrophy shown on cranial magnetic resonance imaging (MRI) during the recurrence. All the patients received intravenous immunoglobulin (IVIG) and intensive methylprednisolone therapy during the first onset, followed by the disappearance of the symptoms, 1 patient had repeated episodes which was decreased after immunosuppressive treatment with Rituximab.Followed up for 25.0 (22.5,33.3) months after the last episode, 12 achieved complete remission and 1 had a wide base gait. Conclusions: Trunk ataxia is the common symptom of Hashimoto's encephalopathy presenting with isolated cerebellar ataxia in children.Children with cerebellar ataxia should be tested for TgAb and TPOAb to detect Hashimoto's encephalopathy, avoiding missed diagnosis and treatment delays; IVIG and intensive steroid therapy is effective, and immunosuppressive therapy for patients with multiple relapses could reduce the recurrence.

[Prevention and treatment of initial stage caries during orthodontic treatment].

Malocclusion is the third most common disease in the human oral cavity, closely behind caries and periodontal diseases. Along with the cultural and socio-economic progress, demands for orthodontic treatment is increasing year by year. However, the early stage caries, a most common complication in patients receiving orthodontic treatment using fixed appliances, has become a serious challenge to the prevention of dental caries and the esthetic outcome of orthodontic treatment. It deserves both dental workers and patients to pay attention and to take preventive and therapeutic measures on this issue.

[Plasm trimethylamine-N-oxide level and association with lesion severity in coronary heart disease patients with type 2 diabetes mellitus].

Objective: To investigate the association between trimethylamine-N-oxide (TMAO) and the degree of coronary atherosclerosis in coronary heart diseases (CHD) patients with type 2 diabetes mellitus. Methods: Consecutive patients, who underwent coronary angiography due to suspected CHD in Beijing Hospital from November 2016 to January 2018, were screened in this cross-sectional study. According to blood glucose level, previous medical history and coronary angiography results, they were divided into CHD without type2 diabetes mellitus(CHD-nDM) group and CHD with type2 diabetes mellitus(CHD-DM) group. Plasma TMAO levels in each group were measured by LC-MS/MS. Spearman correlation analysis was used to evaluate the correlation between TMAO and the number of diseased vessels and Gensini scores. Multivariate logistic regression was used to analyze the correlation between TMAO and high Gensini scores. Results: A total of 590 patients were enrolled in the study, including 238 patients in CHD-DM group and 352 patients in CHD-nDM group. Patients were older, body mass index, blood pressure level, prevalence of history of hypertension and statins use were higher in CHD-DM group than in CHD-nDM group (all P<0.05). The proportion of patients with multivessel disease (2 or more vessels) was also higher in CHD-DM group than in CHD-nDM group (P<0.001). Gensini score was higher in CHD-DM group than in CHD-nDM group (P<0.05). Fasting blood glucose, glycosylated hemoglobin and urea were significantly higher, while low-density lipoprotein cholesterol and hemoglobin were significantly lower in CHD-DM group than in CHD-nDM group (all P<0.05). The levels of TMAO was significantly higher in CHD-DM group than in CHD-nDM group (P<0.001). Spearman correlation analysis showed that TMAO was positively correlated with the number of diseased vessels, Gensini score, age and blood glucose level (r=0.178, 0.189, 0.260, 0.111, respectively, all P<0.01). Multivariate logistic regression analysis showed that, TMAO level was still positively correlated with high Gensini score in CHD-DM group (OR=2.25, 95%CI 1.16-4.38, P=0.017), but not in CHD-nDM group (OR=1.29, 95%CI 0.72-2.31, P=0.386) after adjusting for age, sex, body mass index, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol, triglyceride, history of hypertension, hyperlipidemia, smoking and statin use. Conclusions: In CHD patients with tupe 2 diabetes mellitus, the plasma TMAO level is significantly increased and is independent and positively correlated with the degree of coronary artery disease.

Potential of Bradyrhizobia inoculation to promote peanut growth and beneficial Rhizobacteria abundance.

AIMS: To investigate the effects of three symbiotic Bradyrhizobium strains on peanut growth and on rhizobacterial communities in flowering and harvest stages in an organic farm, also to evaluate the role of plant development in influencing peanut rhizobacterial microbiota and correlations among the inoculants, rhizobacterial communities and plant growth. METHODS AND RESULTS: Peanut seeds were inoculated with three individual Bradyrhizobium strains, plant growth performance was measured in two developmental stages and rhizobacterial communities were analysed by Illumina sequencing of rpoB gene amplicons from peanut rhizosphere. The three bradyrhizobial inoculants significantly increased the nodule numbers and aboveground fresh weight of peanut plants regardless of the different growth stages, and the pod yields were increased to some extent and significantly positively correlated with Bradyrhizobium abundances in rhizosphere. Principal coordinate analysis indicated that the rhizobacterial communities were strongly influenced by the inoculation and peanut developmental stages. The bradyrhizobia inoculation increased relative abundances of potentially beneficial bacteria in peanut rhizosphere, and also altered rhizobacterial co-occurrence association networks and important network hub taxa. Similarly, plant development also significantly influenced the structure, composition and co-occurrence association networks of rhizobacterial communities. CONCLUSIONS: Bradyrhizobial inoculants increased peanut growth and yields, they and plant development affected the assembly of peanut rhizobacterial communities. SIGNIFICANCE AND IMPACT OF THE STUDY: Rhizobial inoculants improved the host plant performance that might also be associated with the dynamic changes in rhizobacterial community except enhancing the biological nitrogen fixation and helps to profoundly understand the mechanism how rhizobia inoculants improve plant growth and yields.

[HBx promotes ubiquitination and degradation of ZO1 and increases the migration and invasion of liver cancer cells].

Objective: To study the effect of hepatitis B virus X protein (HBx) expression level on migration and invasion of zonula occludens protein-1 (ZO-1) in HepG2 liver cancer cells. Methods: Liver cancer cells were transfected with HBV full gene plasmid (pcDNA3.1-HBV1. 1 or pcDNA3.1-HBV1.3), empty plasmid (pcDNA3.1) and HBV-encoded protein plasmids (pHBc, pHBs, pHBp and pHBx), respectively. Western blot and RT-PCR were used to detect ZO1 protein and mRNA levels. Immunoprecipitation was used to detect transfected pHBx. Western blot was used to detect ZO1 ubiquitination levels. Transwell chambers were used to assess cell migration and invasion. Cell proliferation and lactate dehydrogenase assay was used to detect siRNA transfecting targeting ZO1. Flow cytometry was used to detect cell apoptosis and cycle. The data was compared between two and multiple groups by using an independent sample t-test and one-way analysis of variance. Results: Compared with the empty plasmid, ZO1 protein level in HepG2 cells after transiently transfected with pHBV1.1 and pHBV1.3 was decreased by 42.99% ± 6.8% and 55.0% 5 ± 4.56%, respectively, and their mRNA levels did not change significantly. ZO1 protein level in Huh7 cells was decreased by 17.46% ± 4.94% and 47.53% ± 3.38%, respectively. ZO1 protein level after transfection with pHBx was decreased by 47.02% ± 3.4%, while the ZO1 protein level after transfection with pHBc, pHBs and pHBp did not change significantly. ZO1 mRNA level was unaffected with pHBx transfection. ZO1 ubiquitin level and cell migration and invasion ability in HepG2 cells was significantly increased with transfected pHBx. HepG2 cells proliferation, apoptosis and cycle after transfection with ZO1-targeted siRNA did not change significantly, but the migration and invasion ability were significantly increased. Conclusion: HBx can increase the migration and invasion of liver cancer cells by promoting the ubiquitination and degradation of ZO1 protein level.

[Curing method affecting the formation of oxygen inhibition layer on the surface of resin cement].

OBJECTIVE: To explore the conversion of resin monomer, the change of inorganic component and the influencing factors on the oxygen inhibition layer formed on the cured surface of resin cement. METHODS: Three kinds of resin cement were divided into three groups: (1) light-cured group: RelyX Veneer, NX3 (light-cured), Variolink N; (2) dual-cured group: RelyX U200 Automix, NX3 (dual-cured), Multilink Speed; (3) chemically-cured group, and the above 3 types of dual-cured resin cement cured without illumination could be used as chemically-cured resin cement. Each sample was provided with and without oxygen exposure of two matching surfaces, cured respectively, and the variables of light intensity and illumination time were set in the light-cured group and the dual-cured group. Scanning electron microscopy was used to observe the samples' surface morphology. Energy dispersive spectrometer was used to analyze the samples' composition of surface elements. Confocal Raman spectroscopy was used to measure the monomer conversion of resin cement and to obtain the thickness of the oxygen inhibition layer. RESULTS: (1) On the surface of cured resin cement, the weight percentage of oxygen element in the aerobic side was higher than that in the anaerobic side (P < 0.05), and the weight percentage of inorganic element was lower than that in the anaerobic side (P < 0.05). (2) The surface monomer conversion of the cured resin cement on the aerobic surface was significantly lower than that on the anaerobic surface (P < 0.05), and the surface monomer conversion on the aerobic surface and the anaerobic surface was the lowest in the chemically-cured group (P < 0.05), the dual-cured group was the highest (P < 0.05), and the light-cured group was between them. With the increase of light intensity or illumination time, the surface monomer conversion increased (P < 0.05). (3) The thickness of the oxygen inhibition layer was the thickest in the chemically-cured group [(40.27±2.81) µm](P < 0.05), the thinnest in the dual-cured group [(21.87±5.42) µm](P < 0.05) and light-cured group [(23.73±3.84) µm] was between them. With the increase of light intensity or illumination time, the thickness of the oxygen inhibition layer of resin cement decreased (P < 0.05). CONCLUSION: When resin cement is exposed to oxygen, it will form an oxygen inhibition layer, its surface's inorganic filler is less, the surface monomer conversion is lower. The surface monomer conversion and the thickness of oxygen inhibition layer are affected by curing mode and illumination factors.