Objective：To evaluate the effect of histone deacetylase 8 (HDAC8) on osteoblast differentiation of rat bone marrow mesenchymal stem cells (BMSCs). Methods：Rat BMSCs were isolated and cultured by the method of whole bone marrow adherent and transfected with HDAC8 overexpression lentiviral vector. Real-time PCR, Western blot were applied to estimate the change of osteogenic capacity after 7 days of osteogenic induction and Alizarin red stain was used to estimate the mineralization capacity after 14 days of osteogenic induction. Trichostatin A (TSA), one kind of histone deacetylase inhibitor, acted on BMSCs with HDAC8 overexpression and the change of osteogenic capacity of cells after 7 days of osteogenic induction was estimated by real-time PCR and Western blot. Results：For BMSCs with HDAC8 overexpression, the expression of osteogenesis-related genes at mRNA and protein levels were all lower than those in control group after 7 days of ostogenic induction and the capacity to form calcified nodules was lower than that of the control group after 14 days of ostogenic induction. The osteogenesis-related genes expression of BMSCs with HDAC8 overexpression which was treated with TSA were all higher than those in untreated group after 7 days of ostogenic induction (P<0.05). Conclusions：HDAC8 could suppress osteogenic differentiation of rat BMSCs.

Objective：The aims of this study were to investigate bacterial flora associated with the apical segment of teeth with persistent periapical periodontitis. Methods： Apical root samples from root-end surgery were collected from 13 teeth with persistent periapical periodontitis. The DNA of the bacteria in 13 samples was processed for ampli?cation via polymerase chain reaction and separated with denaturing gradient gel electrophoresis. Selected bands were excised from the gel and sequenced for identi?cation. Results： All samples presented with several bands (strong and weak), which indicates a polymicrobial community. In our research, 26 excised bands were selected to identify the primary community members. The isolated strains consisted of facultative anaerobic bacteria, obligate anaerobic bacteria and aerobic bacteria. The prevalence rates of Actinomyces sp. oral and Propionibacterium were highest (84.6% and 61.5%, respectively). Conclusions：Bacterial floras associated with the apical segment of teeth with persistent periapical periodontitis are polymicrobial community. Actinomyces sp. oral and Propionibacterium are likely to be important contributors to persistent periapical infection.

Objective： To investigate the radiosensitivity of cancer stem cells in squamous cell cacinoma of tongue. Methods：CD133+/CD44+ and CD133-/CD44- subpopulation cells were sorted by magnetic cell sorting (MACS). Single isolated CD133+/CD44+ and CD133-/CD44- cell was cultured in RPMI-1640 mediun，which contained 10 ng/mL basic fibroblast growth factor (bFGF)，and 20 ng/mL epidermal growth factor (EGF). Immunofluorescence was applied to detect the expression of CD133 and CD44 in these two subpopulation cells. CCK-8 assay was performed to analyze the radiosensitivity of the two subpopulations. Results：Cell immunofluorescence showed that CD133 and CD44 could be detected in CD133+/CD44+ cells while they could not be detected in CD133-/CD44- cells. Radiation therapy had a more obvious inhibitory effect on CD133-/CD44- cells than on CD133+/CD44+ cells. Conclusions： The cancer stem cells in squamous cell carcinoma of tongue(CD133+/CD44+ cells) that sorted by MACS showed strong capability of tumor's resistance to radiation therapy than that of CD133-/CD44- cells.

Objective：To study the surface characteristics and biocompatibility of four kinds of biological membranes in order to compare their applications of cell adhesion and proliferation，as well as interaction between materials and membrane types. Methods：By casting or electrospinning, we fabricated poly(ε-caprolactone)(PCL) membranes and poly(lactic-co-glycolic acid)(PLGA) membranes. Field emission scanning electron microscope (FESEM) was used to detect the surface microstructure of the membranes. After Cell line MC3T3-E1 was seeding to all membranes, we tested cell proliferation of 1,3,7days by Cell counting Kit-8 (CCK-8) assay, while estimating cell adhesion by confocal laser scanning microscope (CLSM) and real-time quantitative polymerase chain reaction (RT-qPCR). Results：FESEM pictures showed pores on cast membranes, while interwoven fibers were observed on electrospun membrane surfaces. CCK-8 tests showed MC3T3-E1cells prefer two PLGA groups than PCL groups（P<0.05）, no matter how the membranes were fabricated（P＞0.05）. Despite PCL electrospun membranes, cells were observed spreading well on other membranes by CLSM. RT-qPCR tests showed there are interactions between materials and membrane types, and PCL cast membrane group showed highest integrin gene expression（P<0.05）. Conclusions：PLGA membranes contributed to MC3T3-E1 cell proliferation, while PCL cast membranes were suitable for cellular adhesion. Other than singly using one kind of material or fabrication method, combination use of PLGA, PCL by casting or electrospinning will become the trend to fabricate biological membranes.

Objective：To establish a tongue epithelial carcinoma model in Sprague-Dawley rats and to study the expression of Notch1 in different phases of carcinogenesis. Methods：A total of 40 Sprague-Dawley rats were divided into four groups: A, B, C and D. Rats in experimental groups B, C and D were fed with 0.004% 4-nitroquinoline-1-oxide (4-NQO) dissolved in drinking water for 8, 16 and 24 weeks, respectively; while rats in control group A were fed with normal distilled water. Rats in experimental groupB, C and D were sacrificed at 8, 16, 24 weeks, respectively, along with 3 rats from normal group A, simultaneously. The tongue samples were dissected and detached for HE staining and Notch1 immunohistochemistry studies. Results：Different pathological changes including mild dysplasia, moderate-to-severe dysplasia, in-situ carcinoma and invasive carcinoma were observed with the advance of administration time. Positive expression rate of Notch1 in normal mucosa, dysplasia, carcinoma were 20%(2/10), 64.7%(11/17) and 84.6%(11/13), respectively(P<0.01). In normal tongue mucosa, the positive staining of Notch1 was mainly distributed in stratum basale, while it extended from stratum basale to stratum corneum as the progression of carcinogenesis. Conclusions：Notch1 promotes the carcinogenesis of tongue mocosa and its expression on membrane may play a role in tongue carcinoma.

Objective: To compare the changes of chemical components and contact angles on the surface of PMMA after O2-plasma and Ar-plasma treatment. Methods: 24 test specimens were prepared from an acrylic resin denture material. The specimens were placed in a glass tubular reactor. Imposition of 60W of power created the condition under which plasma treatment was carried out for 2 min. X-ray photoelectron spectroscopy(XPS) studies and contact angle measurements were performed. Results: After O2-plasma and Ar-plasma treatment, the O/C atomic ratios increased from 0.289 to 0.682 and 0.593. Contact angles were reduced from 66.32 °to 41.35 °and 46.16° respectively. Conclusions: Within the limitations of this study, both O2-plasma and Ar-plasma treatment have effect on increasing the amount of oxygen atoms and improving wettability of PMMA. But, the effect of O2-plasma was better than that of Ar-plasma.

Objective： To evaluate the root canal working length measurement on dental digital radiographs, in order to provide reference date for the clinical application. Methods： According to experimental criteria, 99 extracted anterior teeth were collected in this study. After opening the pulp chamber, the gutta percha point was fixed in the root canals, with its tip reached the anatomical apical foramens first and then retreated a little. By imitated X-ray parallel techniques, the distance from the top of gutta percha to the apex was measured in the digital images with the software, and compared with the actual length of gutta percha on the extracted teeth through the SPSS 17.0 software. And these data represented the distance from anatomical apical foramens to apex. Results：Imitated X-ray parallel techniques resulted in almost no magnification. There was no significant difference between the distances from anatomical apical foramen to apex on both X-ray images and the extracted teeth (P>0.05). The anatomical apical foramens were both over 50% around apex. The difference between the anatomical apical foramen to apex was longer in the side ones than the vertical ones (P<0.01). Conclusions：Direct digital radiography system is reliable in the measurement of root canal working length, but the distance from foramina to the anatomic root apex should be taken into consideration.

The Maxillofacial Structures of patients with cleft lip and palate are different from ordinary people ,that is because of the severity of deformities and the influence of surgery.To measure and analyse the maxillofacial tissue of the patients before and after operation, will evaluate the operation for the treatment of the patients more intuition, also can provide a more reliable anatomical basis and theoretical support for sequential treatment of Cleft lip and palate. Common measurement methods are photo measuring, X-ray measurement method and 3D measurement.The photo measuring method is simple and useful, with low cost but not accurate enough; X-ray measurement method has reliable and acceptable results for most scholars, but not convenient; 3D measurement method, which is accurate, efficient and simple, can analyze the facial appearance objectively and quantitatively, and be applied widely.