The role of APOD in the proliferation and migration of human dental pulp cells / 口腔疾病防治

Objective@#To explore the role of apoliprotein D (APOD) in the proliferation and migration of human dental pulp cells (DPCs) and to provide a basis for the use of APOD to promote pulp regeneration. @*Methods@#APOD expression in human dental pulp cells was inhibited by siRNA. The inhibition effect of APOD was confirmed by qPCR and Western blot. After APOD inhibition, colony formation experiments and CCK8 assays were employed to confirm the proliferation ability of dental pulp cells. Transwell assays were used to verify the cell migration ability after the inhibition of APOD expression.@*Results @# After inhibiting APOD expression, the colony formation rate in the si-apod group was reduced compared with the NC group, and the difference was statistically significant (t=7.624, P=0.002). The CCK8 experiment showed that the OD value in the si-apod group decreased at 3, 5 and 7 d compared with that in the NC group (P < 0.05). Transwell results showed that the number of cell divisions was 57.25 ± 4.03 in the si-apod group and 154.50 ± 8.39 in the NC group, and the difference was statistically significant (t=10.45, P < 0.001).@*Conclusion@# Inhibition of APOD expression in dental pulp cells inhibits their proliferation and migration ability.

CBCT detection of the incidence of middle mesial canal and isthmus in the mandibular first molar / 口腔疾病防治

Objective @# To analyze the morphology and incidence of middle mesial canal (MM) and isthmus in the mandibular first permanent molar by cone-beam computed tomography (CBCT).@*Methods@# Statistical analysis was performed on images from patients who underwent CBCT examination in the Department of Radiology at Stomatological Hospital, Southern Medical University. Samples exhibiting root canal treatment, root resorption and calcification were excluded. Data regarding sex, age, the presence or absence of isthmus and MM, and the number of roots and root canals were recorded.@*Results @#Of the 217 mandibular first molar samples, 8 (3.7%) had an MM, and 2 (0.9%) had an independent apical foramen. The overall incidence rate of isthmus was 57.1%; this rate was 50.7% in the cervical third of the root canal, 17.5% in the middle third, and 13.4% in the apical third. The incidence rate of isthmus was 61.8% on the left side, 52.3% on the right side, 58.7% in males, and 55.8% in females. No significant difference was found between the left and right sides or between females and males (P > 0.05). The incidence rate of isthmus in people under 60 was greater than 50% but was significantly lower in people older than 60.@*Conclusion@#Only a very small proportion of MMs have an independent apical foramen in the mandibular first molar. The incidence of isthmus in the mesial root of the mandibular first permanent molar is high, and isthmus usually occurs in the cervical third of the root canal. During root canal treatment or apical surgery, attention should be given to the physical and chemical preparation of the isthmus.

Role of TRAF6 in inflammatory responses of human osteoblast-like cells with Enterococcusfaecalis / 口腔疾病防治

Objective @#Explore the role and status of tumor necrosis factor receptor-associated factor 6 (TRAF6) in the inflammatory response of human osteoblast-like cells MG63 which was triggered by Enterococcus faecalis (E. faecalis) and its lipoteichoic acid (LTA)@*Methods@# SiRNA technology was applied to silence the TRAF6 gene of MG63 cells, Using E.faecelis and its LTA to stimulate the silence MG63 cells with different hours. After that, using real-time PCR technology to detect toll-like receptor 2 (TLR2) and TRAF6 gene expression and using ELISA assay to detect proinflammatory cytokines interleukin-1β and TNF-alpha expression levels.@*Results@#When MG63 cells was infected by E. faecalis, its LTA, TLR2 and TRAF6 gene level has increased to varying degrees (P< 0.05); interleukin-1β and TNF-alpha expression was significantly higher (P< 0.05). When TRAF6 gene of MG63 cells was silenced by siRNA, pro-inflammatory cytokines interleukin-1β, interleukin-6, interleukin -8 and TNF-alpha expression decreased significantly (P< 0.05).@*Conclusion@#E. faecalis and its toxic components is identified by MG63 cells mainly through TLR2 receptors. The major virulence factor in periapical infections caused by E. faecalis is LTA.

Tissue transglutaminase (TG2) activity regulates osteoblast differentiation and mineralization in the SAOS-2 cell line

Tissue transglutaminase (type II, TG2) has long been postulated to directly promote skeletal matrix calcification and play an important role in ossification. However, limited information is available on the expression, function and modulating mechanism of TG2 during osteoblast differentiation and mineralization. To address these issues, we cultured the well-established human osteosarcoma cell line SAOS-2 with osteo-inductive conditioned medium and set up three time points (culture days 4, 7, and 14) to represent different stages of SAOS-2 differentiation. Osteoblast markers, mineralization, as well as TG2 expression and activity, were then assayed in each stage. Furthermore, we inhibited TG activity with cystamine and then checked SAOS-2 differentiation and mineralization in each stage. The results showed that during the progression of osteoblast differentiation SAOS-2 cells presented significantly high levels of osteocalcin (OC) mRNA, bone morphogenetic protein-2 (BMP-2) and collagen I, significantly high alkaline phosphatase (ALP) activity, and the increased formation of calcified matrix. With the same tendency, TG2 expression and activity were up-regulated. Furthermore, inhibition of TG activity resulted in a significant decrease of OC, collagen I, and BMP-2 mRNA and of ALP activity and mineralization. This study demonstrated that TG2 is involved in osteoblast differentiation and may play a role in the initiation and regulation of the mineralization processes. Moreover, the modulating effects of TG2 on osteoblasts may be related to BMP-2.