Dental trauma could be largely classified into three groups: Hard tissue injuries, pulp injuries and periodontal tissue injuries. Since pulp injuries are reported in tooth fracture, displacement and avulsion, it is commonly thought that pulp injuries were involved in almost every type of dental injuries. The sequelae of pulp tissue after dental injuries include pulp survival, pulp calcification and pulp necrosis. Dental trauma mostly occurs in 7-15 yearold children. The treatment and prognosis of dental trauma in children are more complicated than those in adults because of the developmental nature of the young permanent teeth. The evaluation of pulp damage and treatment after dental injuries in growing young permanent teeth are discussed in this paper.

Objective To elucidate the possible mechanism of oral carcinogenesis and to explore the value of clinical application of the detection of cytokeratin（CK） 19 for oral squamous cell carcinoma（OSCC） patients. Methods The cancerous tissues, para-cancerous tissues and excised lymph nodes were collected from 20 operated patients with OSCC. The patients didn′t receive radiotherapy and chemotherapy before hospitalization. The relative expression of CK19 mRNA in those tissues was detected by fluorescent quantitative polymerase chain reaction（FQ-PCR）. Results The expression of CK19 mRNA in the cancerous tissues was 1.85 and 1.66 times higher than that in normal oral mucosa and in para-cancerous tissues, respectively. The expression of CK19 mRNA in lymph nodes from 9 patients with OSCC was positive and the positive rate was 45%（9/20）. The positive rate of CK19 mRNA in all lymph nodes from 9 patients with OSCC was 81.8%（18/22）, and the positive rate of CK19 mRNA in all lymph nodes from 20 patients with OSCC was 41.9%（18/43）. CK19 mRNA level in the cancerous tissues relative to para-cancerous tissues and normal oral mucosa of the patients whose CK19 mRNA expression was positive was lower than that of the patients whose CK19 mRNA expression was negative in lymph nodes, respectively. Conclusion The possible reason that the expression of CK19 mRNA in the cancerous tissues was higher than that in para -cancerous tissues and normal oral mucosa was that the CK19 synthesis in cancerous tissues increased obviously. The detection of CK19 mRNA in lymph nodes was regarded probably as one of the markers for detecting OSCC micrometastasis in lymph nodes. The detection of CK19 mRNA in lymph nodes by FQ-PCR was more sensitive than hematoxylin-eosin staining in diagnosing OSCC micrometastasis.

Objective To construct a small interfering RNA（siRNA） eukaryotic expression vector specific for methylene tetrahydrofolate reductase（MTHFR） gene and to observe its silencing effect on MTHFR gene. Methods The expression vectors of PsiRNA-MTHFR were constructed by gene recombination and then were nucleofected into the primary cultured MEPM cell. At 48 h and 5 d after nucleofection, the expression of MTHFR in the levels of mRNA and protein was detected by real-time quantitative polymerase chain reaction（Real-Time PCR） and Western blot. Results The eukaryotic expression vector of PsiRNA-MTHFR, which significantly down-regulated mRNA and protein of MTHFR at 48 h and 5 d after nucleofection, were successfully constructed. Conclusion Eukaryotic expression vector of siRNA specific for MTHFR is successfully contructed, which lays the basis for its application in the mechanism research of MTHFR gene regulating embryo palate shelves fusion.

Objective To develop a best chitosan film for using as a drug sustained-release system through the evaluation of the sustained-release property, degradation property, and cytotoxicity to osteoblast. Methods Orthogonal experiments were designed to determine the best combination of chitosan film preparations. Drug release rate was determined with Coomassie brilliant blue G250. In a separate study, chitosan films were placed into the test tubes with buffer solution and 107 U/L lysozyme. The degradation rate was calculated. Osteoblasts derived from fetal rat calvarial were cultured on chitosan films. Cell proliferation was tested by methyl thiazolyl tetrazolium（MTT） assay. The relative growth rate was calculated and the cytotoxicity was graded. Results The best processing condition was 1% acetic acid, chitosan concentration of 2 mg/mL, 6% sodium tripolyphosphate（STPP） concentration, and cross - linking time of one hour. The resulting chitosan film released 33.13％ of bovine serum albumin（BSA） within 8 d, 36.73% of BSA within four weeks and the cytotoxicity grade was 0 or 1. Conclusion This chitosan film possesses good sustained release property, and a good degradation rate.

Objective To observe osteoblast apoptosis in diabetic periodontitis. Methods Sixty-two SD rats were randomly divided into three groups： Diabetic periodontitis group（DP）, periodontitis group（P） and normal control group（N）. Diabetes was induced by intraperitoneal injection of streptozotocin（STZ）. Periodontitis was initiated by ligating floss around maxillary second molars and inoculation of Porphyromonas gingivalis（P.gingivalis）. Three or six weeks later, the animals were sacrificed and the specimens were prepared for histological analysis. The percentage of apoptotic osteoblasts was examined. Statistical significance was determined by one-way ANOVA. Results The sequence of percentage of apoptotic osteoblasts among each group was group DP ＞group P ＞group N. Intergroup comparisons demonstrated that diabetic periodontitis and periodontitis might increase apoptosis of osteoblasts. The percentage of apoptotic osteoblasts in group DP was approximately two times higher than that in group P. Conclusion The present study clearly demonstrates that diabetes can increase the apoptosis of osteoblasts in periodontitis.

Objective To evaluate the expression of CD4+, CD8+T cells and cell apoptosis in oral lichen planus （OLP） and investigate the role and the relationship of immunological reaction and cell apoptosis in the pathogenesis of OLP. Methods Immunohistochemical technique was used to study the expression of CD4+, CD8+T cells in 27 OLP cases. TUNEL was used for detecting the cell apoptotic index（AI） in 17 OLP cases. Results The expression of CD4+, CD8+T cells were obviously elevated in lamina propria of OLP group compared with control group（P＜0.05）. There was a strong significance when compared the ration of CD4/CD8 in both group. AI was remarkably increased in epithelia cells and significantly decreased in lymphocytes in lamina propria in OLP cases compared with its expression in the control group respectively. Conclusion The increased amount of CD4+, CD8+T cells in lamina propria of OLP and the change ration of CD4/CD8 suggest that immune response is involved in the pathogenesis of OLP. The abnormal cell apoptosis plays an important role in the pathogenesis of OLP.

Objective To investigate the effect of vascular bundle implantation in autogenous bone graft on angiogenesis. Methods Thirty-six New Zealand white rabbits were evaluated in this study. A portion of bilateral  radial bones of a rabbit were removed as free bone grafts, whose periostea were peeled off. In test group, the external maxillary artery bundle was passed through the marrow cavity of the bone. In control group, there was no vascular bundle implantation. Each bone was placed in masseter muscle separately. The rabbits were sacrificed and the specimens were procured at 3 days, 1, 2, 3, 4 and 6 weeks after surgery for histological observation, Chinese ink perfusion and CD34 immunohistochemistry. Microvessel density（MVD） was assessed in order to evaluate angiogenesis of autogenous bone grafts. Results The bone grafts were found revascularization in 3 days after surgery in the test group, whereas at 2 weeks in the control group. In 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks after surgery, the MVD of test group was significantly higher than that of control group. In 4 weeks after surgery, angiogenesis of test group reached to peak. Conclusion Vascular bundle implantation improved angiogenesis in non-vascularized autogenous bone graft in this study.

Objective To study the influence of transfection with human transforming growth factor-β1（hTGF-β1） gene on the osteogenic potential and differentiation of the cultured human gingival fibroblast（GF）. Methods Enzyme kinetics method was used to measure the effects of the transfection on the alkaline phosphatase（ALP） activity. Immunohistochemistry stain and image analysis were applied to evaluate the alteration of the content of osteopontin （OPN）, bone sialoprotein（BSP）, osteonectin（ON）, osteocalcin（OC） in the GF with transfection. Mineralization nodules formation in vitro was also used. Results The ALP activity of the GF after transfection was higher than the GF without transfection significantly（P<0.05）, and was close to that of the PDLCs（P>0.05）. The content of OC in GF was not improved after transfection, was similar with that of PDLCs（P>0.05）. Under immunohistochemistry stain, the contents of OPN, ON, BSP expressed in GF with transfection were higher than those of GF without transfection（P< 0.05）, but similar to those of PDLCs（P>0.05）. In the mineralized cultured medium, the nodules were observed in the GF with transfection and PDLCs after 21 days and 24 days alternatively. After von Kossa stain, purple mineralization nodules were observed. Conclusion The GF transfected with pcDNA3-hTGF-β1 could express some osteogenic characters, though these characters are restricted.

Objective To compare the effect of three kinds of extraction model on high angle bimaxillary protrusion patients. Methods A total of 30 patients with Class Ⅰ malocclusion and bimaxillary protrusion, aged 14-25 years old, were selected and divided into three groups. Four first premolars were extracted in the first group. The two maxillary first premolars and two mandibular first molars were extracted in the second group. The two maxillary first premolars and two mandibular first molars were extracted in the third group, and two additional micro-implants used as orthodontic anchorage in maxilla. Three groups were all treated with MBT appliance. Cephalometric analysis were carried out before and after treatment, and the results were analyzed with statistics. Results 1）About the hard tissues, compared with the first group, there were statistically significant differences of N-Me, SGo/NMe, ANS-Me, FH/ MP, SN/MP, and ODI in the second and the third group after treatment（P<0.01）. 2）About the soft tissues, the teeth and the alveolar bone, compared with the first group, there were statistically significant differences of Pg-Pos, Li- SnPos, Si-LiPos, LL-E, L1-NB, L1/NB, U1/L1, L7-MP in the second and the third group after treatment（P<0.01）. 3）All patients received consummate orthodontic treatment and obtained fine occlusion. Facial profiles were improved significantly after orthodontic treatment. Conclusion 1）After orthodontic treatment with mandibular first molars extraction, FH/MP, SN/MP, N-Me, ANS-Me, L1-NB and L1/NB decreased respectively, and soft tissue profiles were improved significantly. 2）Additional micro-implant used as orthodontic anchorage in maxilla significantly contributed to the maxillary incisor retraction and subsequent soft tissue change. 3）The first molars extraction and additional micro- implant used as orthodontic anchorage are efficient in improving the facial profiles for high angle bimaxillary protrusion patients.

Objective To investigate the morphology of maxillary permanent central incisors of people in Sichuan so as to provide some guidance for emulational restoration of fixed prosthesis. Methods Fifty -eight extracted maxillary permanent central incisors were selected from people in Sichuan. All of the teeth involved in this study were selected according to certain criterions. The length and width of the anatomical crowns, the length and the width of the developmental grooves and the angles formed by the two sides of the developmental grooves were measured. Results The average length and width of anatomical crowns in Sichuan people were （11.9±1.3）mm and （8.7± 0.8）mm respectively. And the average length and width of the developmental grooves were （5.7±0.9）mm and （2.1± 0.5）mm respectively. There were no statistical differences between the length of the mesial and distal developmental grooves and so were the width. The ratio of the length of crowns to that of the developmental grooves was 2.1, while for the width, it was 4.2. The angles of the mesial and distal developmental grooves formed by its two sides were 23°±4.7° and 23°±5.7° respectively. Conclusion The average length and width of maxillary permanent incisors were close to Wang′s report, which means the length and width of the maxillary permanent incisors of people in Sichuan were quite close to those of Chinese people. The ratio of the length of anatomical dental crowns to that of the developmental grooves was steady, and so was the ratio of the width of them. The angles of the developmental grooves were quite steady too. These may help us in making fixed prosthesis.

Objective This study investigated the effect of silicon coating（SiO2） by solution-gelatin（Sol-Gel） technology on bonding strength of titanium and ceramics. Methods Sixteen pure titanium specimens with the size of 25 mm×3 mm×0.5 mm were divided into two groups（n=8）, test group was silicon coated by Sol-Gel technology, the other one was control group. The middle area of the samples were veneered with Vita Titankeramik system, the phase composition of two specimens were characterized by X-ray diffraction（XRD）. The bonding strength of titanium/porcelain was evaluated using three-point bending test. The interface of titanium and porcelain and fractured titanium surface were investigated by scanning electron microscope（SEM） with energy depressive spectrum（EDS）. Results Contents of surface silicon increased after modification with silicon coated by Sol-Gel technology. The mean bonding strength of test group and control group were（37.768±0.777）MPa and（29.483±1.007）MPa. There was a statistically significant difference（P =0.000） between them. The bonded ceramic boundary of test group was wider than control group. Conclusion Silicon coating by Sol -Gel technology was significant in improving bonding strength of titanium/Vita Titankeramik system.

Objective To study the deactivation of the endotoxin in artificial glass root canals with ultrasonic vibration. Methods 80 artificial glass root canals were randomly divided into 8 groups: Ultrasonic vibration of 5 minutes, 7 minutes, 10 minutes, ultrasonic vibration of 5 minutes together with 3% H2O2 solution, only 3% H2O2 solution, ultrasonic vibration of 5 minutes together with 5.25% NaClO solution, only 5.25% NaClO solution and the control. Standard endotoxin solution was introduced into each root canal. Different time′ s ultrasonic vibration was applied to different groups. After ultrasonic vibration, the endotoxin activity of each group was tested by kinetic turbidimetric limulus test. Result There were no significant differences among the groups of different time ultrasonic vibration and the control（P>0.05）. There was great statistical difference between each group with root canal rinse solution and the control（P <0.001）. The endotoxin activity of the test was significantly lower than the control. There was no significant difference between the groups of only rinse solution and rinse solution together with ultrasonic vibration. Conclusion Under the condition of this study, the only ultrasonic vibration can not deactivate the endotoxin of infected root canals and can not intensify the effect of root canal rinse solution.

Objective To evaluate the ability of Biopure MTAD in removing smear layer in vitro. Methods Forty extracted single-rooted human teeth were randomly divided into five groups：Distilled water in group A, 5.25% NaClO and 17% EDTA in group B, 1.3% NaClO in group C, 1.3% NaClO and Biopure MTAD in group D, 1.3% NaClO and 3% EDTA in group E. The canals were prepared and irrigated with one of the five different irrigating agent respectively. The amount of smear layer and erosion on the surface of the root canal walls were examined with scanning electron microscope. Results The whole surfaces of root canals in group A and C were covered by smear layer. The surfaces of root canals in the coronal and middle thirds of samples in group B, D, E were free of smear layer（P＞0.05） and the apical third of canals in the group D were significantly cleaner（P＜0.05） than that in group B and E. The coronal and middle sections were significantly eroded in group B compared with group D and E（P＜0.05）. The degree of erosion in the apical section was not statistically different among group B, D and E （P＞0.05）. Conclusion Biopure MTAD and 1.3% NaClO are effective irrigating agents for removal of the smear layer on the surface of root canal. There is no significant change in the structure of the surface of root canal.

Objective To determine the current radiographic practices of root canal treatment（RCT） undertaken by endodontists, general dentist practitioners（GDPs） and interns, and to analyze the relationship between the usage of periapical films and the quality of RCT. Methods The patients who had received RCT treatment in West China College of Stomatology were investigated at random and were divided into three groups: Endodontists treating group, GDPs treating group and interns treating group according treating physician. The usage status of periapical film were investigated by the well designed questionnaires. The obturation quality of postoperative films were evaluated. Chisquare analysis was used to compare usage rates of periapical films of three groups. Mann-Whitney test was used to determine the relationship between the usage of periapical films and the quality of RCT. Results 571 teeth of 412 patients were investigated. In endodontists treating group, GDPs treating group and interns treating group, the usage rates of preoperative films were 95.3%, 89.5% and 92.1% respectively. The usage rates of working length films were 5.2%, 1.1% and 5.8% respectively. The usage of master point films was 94.8%, 72.1% and 97.4% respectively. The usage of postoperative films was 97.9%, 76.3% and 95.3% respectively. There were statistically significant differences among the working length films, master point films and postoperative films of three groups（P<0.05）. The periapical films of adequate quality RCT and inadequate quality RCT were 3.14±0.639 and 2.84±0.736 respectively. There was statistically significant difference between periapical films of adequate quality RCT and inadequate quality RCT（P< 0.05）. Conclusion Radiographic practices of endodontists and interns are more standardized than GDPs. Quality RCT is related to radiographic practices. Standard radiographic practices would be benefit to RCT.

Objective To evaluate the clinical effect of indirect cast post core by two different impression methods between silicone rubber impression and agar/alginate combination impression. Methods 389 massive destruction teeth after root canal therapy were randomly divided into two groups（group A and group B）. The teeth of group A was treated by silicone rubber impression material for making indirect post core impression. The teeth of group B was treated by agar/alginate combination impression for making indirect post core impression. The effect of two different impression methods was evaluated. Results The success rate of making indirect post core impression by silicone rubber impression method was higher than that of making impression by agar/alginate combination impression method. Significant difference was found in making indirect post core impression between premolars and molars by two different impression methods（P <0.05）, while there was no significant difference in making indirect post core impression of anterior teeth by two different impression methods（P>0.05）. Conclusion The clinical effect of making indirect post core impression by silicone rubber impression method is better than that of making impression by agar/ alginate combination impression method.

Objective To investigate the oral health status of freshmen of university students and to guide their oral hygiene behaviors. Methods 6 575 freshmen of Peking University students were investigated in this study according to the criterion issued by World Health Organization（WHO） on the basic methods of oral health investigation and China oral health epidemiology survey protocol. The inspection item included caries, gingivitis, malocclusions and impacted teeth. Results In 6 575 freshmen of university students, the prevalence rate of caries, gingivitis, malocclusions and impacted teeth were 35.47％, 60.87％, 19.70％ and 24.62％, respectively. There were statistical significance between the prevalence rate of caries, gingivitis, malocclusions and impacted teeth of male and female（掊2= 131.94, P＜0.001；掊2=216.85, P＜0.001；掊2=14.54, P＜0.01；掊2=23.56, P＜0.001）. There were statistical significance between the prevalence rate of caries, gingivitis and impacted teeth of postgraduate and undergraduate（掊2=4.62，P＜ 0.05；掊2=129.56，P＜0.001；掊2=178.05, P＜0.001）, while there was no statistical significance between the prevalence rate of malocclusions of postgraduate and undergraduate（掊2=0.61, P＞0.05）. Conclusion The oral health status of freshmen of university students are not ideal． It is necessary to strengthen the propaganda education of prevention and protect to freshmen of university students.

Objective This study was undertaken to evaluate the influence of labial surface contours and collum angles of the maxillary anterior teeth on torque. Methods 206 extracted maxillary teeth were selected, including 77 central incisors, 68 lateral incisors and 61 canines. All specimens were scanned by cone beam dental computed tomography（CT）. Three-dimensional reconstructed images were made by using the CT software. The median sagittal planes of all teeth were selected and then analyzed by the Auto CAD software. For each tooth, the angles between tangent lines to the labial surface at four different heights along the surface and the longitudinal axis of the crown were measured. The collum angle was also measured. Results Between 3.5 mm and 5.0 mm level of bracket heights, for the variation of 0.5 mm, the torque differed by 1.5° for the maxillary central incisors and 2° for the maxillary lateral incisors and canines. The mean collum angle values for the maxillary central incisors, lateral incisors and canines were 0.88°, 3.87° and -3.30°. Conclusion The biological variation in tooth morphology would influence the torque after orthodontic treatment in different ways.

Objective To analyze changes of myoelectrical activity of anterior funicle of temporal muscle（TA） and masseter muscle（MM） after raising vertical distance of occlusion by flat bite plate during treatment of deep overbite in order to approach an optimal raised vertical distance. Methods A total of 70 persons were selected and divided into two groups: Experiment group（36 patients） with deep overbite and control group（34 persons） with individual normal occlusion. The experiment group was subdivided into three groups that were respectively raised D, D+2 mm and D+4 mm（D means free way space, mm）. Electromyologram（EMG） was utilized to measure the average  peak potential of TA and MM on quiescent condition before treatment and two weeks after wearing flat bite plate. Results 1）Before treatment, the average peak potential of experiment group was obviously higher than that of the control group（P<0.05）. 2）After two weeks the potential of TA and MM of all persons in experiment group was obviously lower than before（P<0.05）, the degree between the group D+2 mm and the group D+4 mm was not manifestly different, but both of the two groups were more obvious than the group D. Conclusion The raised vertical distance of occlusion by flat bite plate, which exceeded free way space, was favourable to the functional recovery of masticatory muscles.

Objective The alveolar bone density quantitative measuring system was established on the basis of grey level measuring on standardized-exposed direct digital periapical radiograph by referring to an aluminum step wedge with the aid of computer technique. We tested it′s accuracy and sensibility by measuring a series of specimens and made it possible to estimate the area density of hydroxyl-phosphorite（HP） in the alveolar bone with the system. Methods The average grey level intensity of 19 specimens containing different amount of HP within certain area was measured with the system. The equivalent aluminum thickness（EAT） and corrected grey level intensity（CGL） of each specimen were calculated according to known grey level intensity of the aluminum step wedge and it′ s corresponding thickness. The liner regression equations between EAT, CGL and HP density（mg/mm2） were established. We put the values of EAT and CGL into the equations and calculated the corresponding values of estimated HP density. The bias ratios of estimation were then calculated. We measured two randomly chosen specimens 10 times respectively to calculate the system′s measurement error range, then the sensibility of the system for measuring HP density was calculated according to the regression equations. Results EAT and CGL were significantly correlated with HP density. When EAT was larger than 0.67 mm or CGL larger than 41, the system′s bias ratio of estimated HP density was lower than 5%. When we estimated the HP density with the use of EAT, the system could effectively check out a HP density change larger than 0.17 mg/mm2, with the use of CGL, a HP density change larger than 0.18 mg/mm2 could be effectively checked out. Conclusion The accuracy and sensibility of the quantitative alveolar bone density measuring system are acceptable, it can be widely used to compare alveolar bone density longitudinally and cross-sectionally.

Objective To evaluate the feasibility of identifying oral pathogenic bacteria by comparing the metabolic profiling of putative periodontal pathogens and try to find a convenient and rapid way to discriminate oral microorganisms. Methods Suspensions of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum with same density were prepared and cultured respectively at liquid BHI medium. Then the growth quantity was measured periodically through turbidimetry and the growth curves of the inoculated bacteria were completed. The culture solutions of stable growth phase were sampled and characterized by 1H-nuclear magnetic resonance（1H-NMR）. The data of 1HNMR spectroscope results were analyzed by principal components analysis（PCA）. Results The PCA showed the obvious clustering phenomena and the points of three groups differentially centralized to three clusters. Therefore, the NMRbased metabonomics profiles could discriminate the three different kinds of bacteria. Conclusion The metabonomics is a potential classable method to identify the oral pathogenic bacteria.

Objective To study the effects of Simvastatin on the osteoblast activity of human periodontal ligament（PDL） cells. Methods The third passage human PDL were cultured in conditional mineralization medium with different concentrations of Simvastatin. The cells were divided into A group（0 mol/L）, B group（1×10-9 mol/L）, C group （1×10-8 mol/L）, D group（1×10-7 mol/L） and E group（1×10-6 mol/L）. Alkaline phosphatase（ALP） activity, osteopontin （OPN） and capability of mineralization were measured. Results Differentiation osteoblast and mineralization of human PDL were improved in all treatment groups with different concentrations of Simvastatin（1×10-9, 1×10-8, 1×10-7, 1×10-6 mol/L）. Compared with control group, statistically significant differences were found in 1×10-8 mol/L, 1×10-7 mol/L and 1×10-6 mol/L groups（P<0.05）. The maximum effect was observed at the concentration of 1×10-7 mol/L. Conclusion Optimal concentration of Simvastatin can improve the osteoblastic activity of human PDL.

Objective To investigate the adaptive changes of ultrastructure of the dentritic cells（DC） before and after maturation. Methods The murine bone marrow mononuclear cells were induced into immatured dendritic cells with granulocyte-macrophage colony-stimulating factor（GM-CSF） and interleukin-4（IL-4）. The cell morphology was observed under an inverted phase contrast microscope, and the surface markers were detected by flow cytometry. Then the DC was induced to be matured with lipopolysaccharide（LPS） for 48 hours, the ultrastructures of DC was observed before and after maturation under transmission electron microscope and then a comparative analysis was doned. Results The surface processes of matured dentritic cells stimulated by LPS decreased significantly, whereas the organelles and the diameter of nucleolus increased. Conclusion The distribution of surface processes may be associated with the antigen-presenting capacity of DC, and it is also a potential ruler of cell function and status.

Objective To investigate the optimal dosage and timing for 5-bromodeoxyuridine（BrdU） labeling of endothelial progenitor cells（EPCs） from rat circulating blood. Methods The animal model for rat tooth movement was established. EPCs were obtained by density gradient centrifugation. The expressions of specific antigens on cell surface were analysed by immunocytochemistry and fluorescenceochemistry. EPCs were incubated with BrdU at different concentrations（5, 10, 15 μmol/L） for different incubating time（12, 24, 48, 72, 96 h） to identify the optimal BrdU concentration and incubating time for cell labeling. Immunohistochemistry was performed to calculate the labeling index（LI）. Results The culture cell positively expressed CD34, CD133 and could be shown to endocytose DiIac- LDL, FITC-UEA-1. Incubation of the EPCs with BrdU at 10 μmol/L and for an optimal length of 72 h appeared to achieve the highest LI（66.8±2.9）%, which was significantly higher than group of 5 μmol/L（P＜0.05）, while there was no significant difference between the group of 15 μmol/L and 10 μmol/L（P＞0.05）. Conclusion EPCs can be isolated from tooth movement rat circulating blood and cultured. Incubation of the EPCs with BrdU at 10 μmol/L and for an optimal length of 72 h appeared to achieve the optimal LI. This provides a foundation for us to investigate the mechanism of chemiotaxis and differentiation for EPCs.

Objective To establish transplanted models of VX2 tongue carcinoma in rabbits by three methods and compare these models. Methods After establishment of VX2 tumor-bearing rabbits, 72 New-Zealand white rabbits were randomly divided into 3 groups. Intact tumour tissue, modified tumour cell suspension, tumour cell suspension were respectively injected into the middle-third lateral border of the tongues of rabbits in 3 groups to induce transplanted VX2 tongue carcinoma. The histological features, the tumour -take rates and the metastasis rates of the 3 models were observed. Results The tumour-take rate of 3 models were 83.3%, 91.7% and 33.3% respectively; the lymph node metastasis rates were 71.4%, 100.0% and 37.5% respectively; the lung metastasis rates were 35.7%, 81.3% and 0 respectively. The histological features of the transplanted VX2 tongue carcinoma of 3 models were all consistent with those of moderately differentiated carcinoma. Conclusion The biological properties of the transplanted VX2 tongue carcinoma of 3 models is much alike to tongue carcinoma in humans. The model established with modified tumor cell suspension is considered to be more suitable for tongue cancer study.

Objective To explore altered molecular phenotype of lymphatic endothelial cells（LEC） induced by oral cancer cells. It is relevant to develop therapeutic strategies for blocking oral cancer spread through lymphatic vessels. Methods LEC were co-cultured with oral cancer cells in a model. Differential gene expression profiles between tumor-derived lymphatic endothelial cell（TLEC） and LEC were analyzed by Human Genome U133 Plus 2.0 GeneChip arrays. Differential expression genes of functional similarity were classified. Results Differential gene expression profiles revealed that 677 unique genes had at least a twofold change in expression level between the two groups, 384 were overexpressed，and 293 were underexpressed in TLEC. These genes were related to cell adhesion, apoptosis, cell motility, development, and angiogenesis. In addition, some genes were involved in signal transduction, immune response, cell metabolism, and so on. Conclusion LEC and TLEC are distinct at the molecular level. A novel therapeutic strategy of lymphatic metastasis is encouraging and anticipated based upon manipulation of LEC responses to oral cancer cells.

Objective The objective of this study is to investigate the influence of mechanical properties and sintering performance by adding 5% weight percentage aids to nano-compound zirconia toughened alumina（ZTA） ceramics. Methods Micrometer Al2O3 and nanometer ZrO2（quality ratio 4 ∶ 1） were used to get 55% volume percentage slurry. Magnesium oxide and titanium oxide were taken as aids which were 5% weight percentage of the Al2O3 and ZrO2 powder. Five groups（number 0, 1, 2, 3, 4 group） were divided according to different proportion of aids. After gel-casting, the porcelain pieces were sintered at 1 150, 1 200, 1 300, 1 400, 1 450, 1 500, 1 600 ℃ for 2 hours. Static three-point flexure strength, line shrinkage, relative density were measured and scanning electron microscopy（SEM） was used to observe section. Results Number 1（MgO 1%, TiO2 4%） group had the highest bending strength. It was （401.78±19.50）MPa after sintering at 1 600 ℃ for 2 hours and was higher than 0 group （380.64±44.50）MPa. Bending strength became lower than 0 group when MgO was more than 2% or more than that weight percentage of ZTA powder. When MgO content was higher than 2% or more than that weight percentage, there was no difference in relative density raising rate between each sintering assistants groups. When the sintering temperature was higher than 1 200 ℃, all groups showed obvious line-shrinkage and the groups which contained sintering assistants were all was higher than 0 group. Conclusion Adding MgO and TiO2 aids from 1% to 4% weight percentage of ZTA will promote fritting and increase ZTA nano -compound ceramics mechanical properties. Adding 2% MgO aids or more than that weight percent will has no obvious help to increase the relative density raising rate of ZTA nano -compound ceramics and will degrade the mechanical properties of ZTA nano-compound ceramics.

Objective To study the effect of basic fibroblast growth factor（bFGF） on the gene expression of epidermal growth factor receptor（EGFR） by periodontal ligament cells（PDLC） in culture and discuss the effect of bFGF in cell differentiation and periodontal regeneration. Methods Human PDLC were cultured in vitro and cell clone was obtained by the method of limiting dilution. PDLC were stimulated by bFGF, and then gene expression of EGFR was assessed by reverse transcription-polymerase chain reaction（RT-PCR）. Results The mRNA expression of EGFR was promoted by bFGF and the effect was dose-dependent. Conclusion The promotion effect of the mRNA expression of EGFR in PDLC may be one of important factors which participate in the healing process of periodontitis and provide partly theoretical basis of cell differentiation and periodontal regeneration.

Objective To investigate the effect of parathyroid hormone related protein（PTHrP） on proliferation of human osteoblasts（MG-63） under the circumstance of tension force in vitro. Methods An apparatus was designed and fabricated by which force was loaded onto the cultured cells in vitro. Reverse transcription-polymerase chain reaction（RT-PCR） was used for measuring the expression of PTHrP mRNA and c-fos mRNA. The effect of tension force and different PTHrP dose（0, 0.01, 0.1, 1 nmol/L） on the proliferation of human osteoblasts were examined using flow cytometry. Results Various forces of the mechanical stretching exerted different influences on the intensities of the mRNA′ expression. The strain of 12% induced the most remarkable mRNA′ expression. The mitogenesis happened in the group with tension force（12%） combined with PTHrP was more active than that in the group with PTHrP or tension force only. Tension force combined with PTHrP induced significantly more c-fos mRNA than that of tension force only. Conclusion The mechanical stretching can inevitably influence the expression of PTHrP mRNA. The most active mitogenesis happened in the group with tension force combined with PTHrP. The effect may be related with the signaling pathways of c-fos.

Retained deciduous teeth are defined as the succedaneous permanent teeth have erupted while the primary teeth were retained, or the permanent teeth unerupted while the primary teeth remained in the permanent dentition. One case of multiple retained deciduous teeth was reported.

Hypohidrotic ectodermal dysplasia（HED） is a hereditary disorder characterized by abnormal development of tissues derived from ectoderm. A case of hypohidrotic ectodermal dysplasia was reported, and the molecular biological progress in this area were reviewed.