Chinese Journal of Dental Research, 02/2018

Over the past few decades, scientific research into neural crest-derived stem cells has progressed rapidly. The migration and differentiation of neural crest-derived stem cells has been an interesting area of research. Stem cells within teeth originating from the embryonic neural crest have attracted increasing attention in clinical and scientific research because they are easy to obtain and have superb stemness. The stem cells within the teeth include dental pulp stem cells (DPSCs), dental follicle stem cells (DFSCs), stem cells from apical papilla (SCAPs), stem cells from human exfoliated deciduous teeth (SHEDs), and periodontal ligament stem cells (PDLSCs). To date, there have been several interesting studies focusing on dental pulp regeneration, neural regeneration and the revascularization for therapeutic applications. Keywords: dental stem cells, dentine/pulp engineering, neural crest cells, neural regeneration, revascularization

Objective: To explore graphene's effects on the gene expression profile of mesenchymal stem cells, and to reveal the mechanisms of graphene-guided osteogenic differentiation. Methods: Human adipose-derived mesenchymal stem cells (hASCs) were cultured on single-layer graphene-coated titanium disks or titanium disks in proliferation medium (control) or osteoinduction medium for 7 days before RNA extraction. After library construction and RNA sequencing, identification of differentially expressed genes was performed through Limma package of R platform, with a cut-off value of log fold change (logFC) > = |1|. Pathway and Gene ontology (GO) analyses were conducted on DAVID Bioinformatics Resources 6.8 (NIAID/NIH). Network analyses were performed by the Ingenuity Pathways Analysis (IPA). Results: Signalling pathway analysis revealed the top five pathways - cytokine-cytokine receptor interaction, neuroactive-ligand receptor interaction, calcium signalling pathway, PI3K-Akt signalling pathway and cell adhesion molecules. GO analyses demonstrated significant changes on cell adhesion, calcium signalling, and epigenetic regulation. IPA network analyses demonstrated that inflammation-related pathways were influenced by graphene, while the downstream factors of histone H3 and H4 were also altered especially under the existence of osteoinduction medium. Conclusion: Graphene promotes osteogenic differentiation of hASCs mainly by influencing cell adhesion, cytokine-cytokine receptor interactions, inflammatory responses, and potentially influences histone H3 and H4 through epigenetic regulation. Keywords: bone tissue engineering, epigenetics, graphene, inflammation, RNA sequencing

Objective: To identify and verify the histone modifier during osteoclastogenesis. Methods: Murine macrophage-like cell line, RAW 264.7 cells, or murine bone marrow macrophages (BMMs) were treated with a receptor activator of nuclear factor B ligand (RANKL) alone or RANKL with macrophage colony-stimulating factor (M-CSF), respectively, to induce differentiation of osteoclast. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to screen different arrays of histone demethylases. Chromatin immunoprecipitation (ChIP) assay was used to examine occupancy of jumonji domain containing 7 (Jmjd7) in the promoter regions of different osteoclast-related genes. Jmjd7 was knocked down using siRNA. Dentine slice assay was used to evaluate bone-resorptive functions. Results: Among the screened histone demethylases, Jmjd7 was significantly downregulated during differentiation of osteoclast. The occupancy of Jmjd7 at the promoter regions of osteoclast-related genes was also decreased. Knockdown of Jmjd7 in RAW 264.7 cells and BMMs enhanced differentiation of osteoclast and increased the expression of osteoclast-related genes, such as c-fos, Dc-stamp, CtsK, Acp5, and Nfatc1. Bone resorptive functions of the cells were also increased. Conclusion: Our study shows that Jmjd7, a histone demethylase, functions as a negative regulator of osteoclastogenesis, and may be a therapeutic target of bone-related diseases. Keywords: Jmjd7, differentiation of osteoclast, RANKL, histone demethylases

Objective: To investigate whether nerve growth factor (NGF) alters glutamate expression in sensory fibres and glutamate concentration in the masseter muscle of female rats. Methods: Ten female rats were injected with NGF (25 µg/ml, 10 μl) and vehicle into the right and left masseter muscles, respectively. Immunohistochemistry and microdialysis were performed after 3 days to evaluate glutamate expression and concentration in the muscle. Results: The frequency of expression of glutamate in the nerve fibres innervating the masseter muscle was significantly greater 3 days after NGF (56 ± 5%) than after vehicle (39 ± 5%) injection. The majority of fibres co-expressed the neuropeptide substance P (SP); a marker for sensory afferent fibres. There was no effect of NGF on the expression of the excitatory amino acid transporter type 2 (EAAT2). In the microdialysis experiment, mean interstitial glutamate concentration on the vehicle side (21.6 ± 9.8 µM) was not significantly different from that on the NGF side (16.2 ± 9.2 µM). Conclusion: These results suggest that, in part, NGF increases the mechanical sensitivity of the masseter muscle by increasing glutamate expression in the sensory nerve endings in the muscle. This effect was local to the site of the NGF injection, as it was only detectable through immunohistochemistry, but not by microdialysis. Keywords: glutamate, nerve growth factor, sensory fibre, temporomandibular disorders

Objective: To evaluate the temporal trend of inpatients with smoking-associated oral cancer in Shanghai and its surrounding areas and to forecast the public health burden in the next decade. Methods: Data of inpatients with oral cancer were retrieved from Shanghai Ninth People's Hospital during a 15-year period. The annual numbers of inpatients were compared by Chi-test. The hospitalization expenditures were compared by Student's t test. The trend analysis and inpatient forecasting were performed by exponential smoothing, regression models, and the forecasting function in Excel software. The financial burden of smoking-associated oral cancer was calculated by polynomial equation. Results: The annual number of inpatients with oral cancer increased during the study period. Most male patients were reported to have a smoking habit. Among the three estimation methods, polynomial regression model was most fitted to the existing data. By a conservative estimation, the public health burden of smoking-associated oral cancer patients will be 120 million RMB by the year 2026, not including the cost by prevalent patients and the patients' family members. Conclusion: Smoking-associated oral cancer will cost a lot of public resource in the next decade. Efforts should be made to lower the amount of tobacco consumption. Keywords: forecast, health burden, oral cancer, smoking, trend

Objective: To explore associations between mean discrepancy values for the first and second molars (MDVFSs) and generalised aggressive periodontitis (GAgP) using hospital-based periodontal examination records from a large Chinese population. Methods: Data from consecutive patients diagnosed as having chronic periodontitis (CP, n = 51,849) and GAgP (n = 2,706) were included. Patient ages, gender, smoking status, mean full-mouth probing depth (PD), and mean full-mouth attachment loss (AL), as well as MDVFSs for PD and AL, were extracted. Multivariate linear regression was used to test associations between MDVFSs and GAgP. Results: After multivariate risk adjustment for potential confounding factors (age, smoking status, and mean PD and AL), the MDVFSs for PD (OR = 2.20, 95%CI: 2.04 to 2.38, P 0.001) and AL (OR = 1.51, 95CI%: 1.44 to 1.59, P 0.001) were significantly associated with GAgP. The probability of GAgP was associated with MDVFS for PD falling between 0 mm and 2.5 mm (OR = 4.55, 95%CI: 4.01 to 5.17) and MDVFS for AL falling between 0 mm and 3.5 mm (OR = 2.01, 95%CI: 1.86 to 2.16, P 0.001). Conclusion: This study revealed associations between MDVFSs and GAgP, demonstrating that MDVFSs can serve as promising auxiliary references for the differential diagnosis between CP and GAgP. Keywords: aggressive periodontitis, chronic periodontitis, diagnosis

Objective: To evaluate resistin levels in the saliva of patients with chronic periodontitis, and healthy subjects. Methods: Thirty-four subjects aged between 25 and 50 years were included and divided into healthy group (n = 19) and chronic periodontitis group (n = 15). The saliva levels of resistin were assessed by enzyme-linked immunosorbent assay. Comparisons of resistin levels between the two groups were made with the Mann-Whitney Test. Results: The chronic periodontitis group showed significantly higher resistin levels than the control group (P = 0.001). Conclusion: The level of resistin in saliva might help to determine the inflammatory status of periodontal diseases. Keywords: periodontitis, resistin, saliva

Benign osteoblastoma is a rare bone tumour characterised histologically by the production of woven bone spicules, which are bordered by prominent osteoblasts. It mainly affects young adults. We report a rare case of benign osteoblastoma of the maxilla in a 7-year-old boy who presented with a painful swelling on the left hard palate. An incisional biopsy was interpreted as osteoblastic neoplasm most suggestive of osteoblastoma. After excision of the tumour there has been no recurrence for 2 years. Keywords: bone tumour, child, maxilla, osteoblastoma