Patients who suffer from oral -maxillofacial bone defect are always faced with teeth lost, facial aesthetics and functional problems. It is a key point to recover fundamental function and correct the aesthetic defect earlier in such kind of patients. With the development of implantology, microsurgery and computer technology, especially the introduction of implant placement in the field of reconstruction, oral-maxillofacial bone defect has dramatically improved the potential for functional reconstruction of complex defects of the maxilla and mandible.

Objective To study the distribution of stress of simulating teeth with wedge shaped defects in the cervical region. Methods The models of anisotropic enamel of the mandibular first premolar and the opposite maxillary first premolar crown were created. A deffect was introduced into the model of mandibular premolar in the buccal cervical region along the enamelo-dentinal junction（DEJ）. The stress distribution in the cervical region of the mandibular premolar was investigated considering lateral condition simulating working micromotions. In this case, the stroke was applied to the maxillary first mandibular in a stepping procedure using nonlinear contact analysis. Results The stresses were concentrated in the defect of the enamel and dentin at the DEJ in the condition of lateral loading. As the defect length increased in size, the peak maximum principal stress（MPS） value and the magnitude of the stress field along the DEJ both increased. Conclusion Undermined cervical DEJ had a significant effect on the stress distribution in the buccal cervical region.

Objective To analyze the stress distribution of bone around the dental implants with lateral immediate loading of different angles by three dimensional finite element. Methods An adult edentulous mandible was adopted for CT scanning. The CT image was imported to universal surgical integration system to establish a mandible three dimensional mesh model. The real shape of standard thread implant was simulated and the finite element model of mandible with dental implants for immediate loading was established. The models were immediately loaded with 150 N through the angle of 0°, 10°, 20°, 30°. The ANSYS 10.0 was used to analyze the Von Mises stress on the bone around dental implants. Results The accurate finite element model of mandible with dental implants for immediate loading was successfully established. The three dimensional finite element analytical results showed: Under axial load, the Von Mises stress of bone contact surface concentrated on the cortical bone of the implant cervix. The strain distribution was even, and centralized at the cortical bone of the implant cervix, cancellous bone of implant bottom and thread contact area. Under different lateral angle load, the Von Mises stress of bone contact surface also concentrated on the cortical bone of the implant cervix, but the maximum value was 4 times of the vertical loading, the strain distributed unevenly, mainly concentrated on the cortical bone of the implant cervix. With the load angle increased, the stress and the strain value also increased. Conclusion When an axial force was immediately loaded, the stress value and the strain concentration value of bone interface around the dental implants are not apparently concentrated, the stress is distributed well. While a lateral force is loaded, the stress values and the strain concentration values of bone interface around the dental implants apparently increase and the strain are distributed unevenly.

Objective To explore the effects and feasibility of the repairing alveolar bone by combination of bone marrow stromal cells（BMSCs） and fibrin glue（FG）. Methods BMSCs were obtained from the sucking mouse and then separated, cultured to the second generation to get ready for use. The available cells were combined with FG and then immediately implanted into the defect that had been established in one lateral maxilla of 30 SD rats. At the same time pure FG without BMSCs was implanted into the other side. The rats were killed at the 3rd and 6th week after operation. The hematoxylin-eosin staining and Micro-CT were used to observe and evaluate the osteogenesis. Results New bone trabecula formed at experiment side of the rats at 3rd week. The repairing seemed better after 6th week of operation than the control side. There were only fibrous tissues in the control side or none. Conclusion This experiment showed a feasible approach of repairing the defects in alveolar bone of the rats.

Objective To evaluate the effect of different silane couplers on bond strength and durability of two machinable glass ceramics to resin cement. Methods Two machinable glass ceramics（A and B） were silanized by three silane couplers（A, B, C）, and were bonded with a resin cement（G-CEM） to form micro-shear test specimens of six groups. The specimens of each group were subdivided into two subgroups, and their micro-shear bond strength was measured before and after 10 000 thermal cycles. Bond strength data were analyzed by two-way ANOVA. Results Before thermal cycles, the bond strength of ceramic A treated by silane coupler A was lower than that of ceramic B （P=0.002）. The bond strength of ceramic A treated by silane coupler C was significantly higher than that treated by silane coupler A and B（P=0.014, P=0.019）. 10 000 thermal cycles obviously decreased the bond strength of all groups except the group of ceramic A treated by silane coupler B, and no significant difference was found between three silane coupler with either of two ceramic. However the bond strength of ceramic B treated by silane coupler B and C was significantly higher than that of ceramic A（P=0.003, P=0.027）. Conclusion As well as the types of silane coupler, the type of ceramic could affect their bond strength and durability to resin cement.

Objective To investigate the correlation of morphological characteristics and failure modes of two types
of glass-fiber posts luted with self-adhesive resin cement and etch-and-rinse adhesive system. Methods Thirty-six
intact single-rooted premolars were collected and removed the crown. After root canal therapy, teeth were randomly divided into 4 groups. Group A: Self-adhesive with POPO fiber post. Group B: Etch-and-rinse with POPO fiber posts. Group C: Self-adhesive with Para Post. Group D: Etch-and-rinse with Para Post. Each root was sectioned into six 1mmthick serial slices and a push-out test was performed. The dentin-cement-post adhesive interface of each specimen and failure modes after fracture were evaluated by stereomicroscope observation. Results Interface morphology observe indicated that voids present in group B（64.2%） and D（66.7%） were significantly higher than group A（5.8%） and C （13.7%）（P ＜0.001）. Interface gaps appeared at the resin -dentine interface in group D（41.2%） were significantly higher than group A（13.5%） and C（11.8%）（P＜0.008 3）, and the failure modes in each group were significantly different （P＜0.008 3） except for group A and B（P=0.69）. Conclusion Voids present in cement layer were associated with the luting agent involved. Morphological characteristics of the fiber post-resin luting agent-root dentin adhesive interface were discrepant with failure modes in different root region. There were interaction between adhesive systems and fiber posts.

Objective To investigate the morphology of the soft palate in normal individuals with digital radiography, when they pronounced the high vowel of“i”, and to provide the references for therapy of the cleft palate. Methods In this study, the sample comprised 27 normal subjects. With the digital cephalometry, the morphology of the soft palate when pronouncing the high vowel of“i”was observed. And the dimensional difference of the soft palate when pronouncing between different gender was studied. Results When pronouncing the high vowel of“i”, the morphology of the soft palate was like the shape of the knee. And it could be divided into two parts: Horizontal and vertical. The length of the vertical part in male group was （24.92±2.03）mm, the length of the vertical part in the female group was （20.66±2.77）mm. The length of the vertical part was different between male and female group（P<0.001）. Conclusion The morphology of the palate when pronouncing the high vowel of“i”is similar. And the velar length of the vertical part of the male is longer than the female.

Objective To investigate the electromyographic activities of anterior temporalis（TA）, masseter muscle （MM）, digastric anterior（DA）, sternocleidomastoid（SCM） at postural position（MPP） and various mandibular movements in prognathic patients. Methods Thirty-two patients with prognathism were selected from the clinic of oral and maxillofacial surgery of China Medical University. 36 healthy college students with normal occlusion were selected as normal controls. A BioEMG Ⅱ diagnostic system with BioFLEX surface electrode was used to record the electromyographic activities of the above muscles. Results Compared with the control group, the electromyographic activities of TA, SCM and DA in prognathic patients were higher in MPP. The electromyographic activities of TA, MM were significantly lower than the control group in clenching（P<0.01）. In protrusion, the electromyographic activities of TA, MM and SCM in prognathic patients were higher than the control group（P<0.01）. In retrusion, the electromyographic activities of TA, SCM in prognathic patients were higher than the control group（P<0.01）. Conclusion The masticatory muscles electromyographic activity of prognathism is abnormal.

Objective The purposes of this study was to investigate the effects of luting agents on the resultant color of IPS e.max all-ceramic veneer restorations, and to evaluate the similarity of try-in pastes and the corresponding luting agents on the final color. Methods Disc-shaped ceramic specimens were fabricated and seated on four shades of resin specimens to mimic the complex of ceramic veneer laying on tooth substrates. Try-in pastes and luting agents（Shades of TR, B0.5, A1, A3, WO） were applied into the inter-layer of ceramic and resin specimens, respectively. The color of the combinations was measured using a spectrophotometer and subsequently converted to CIE L*a*b* values. Color changes after luting agent applied, and between try-in paste and corresponding luting agent were calculated and registered as ΔEresin and ΔEpaste-resin. Results ΔEresin value of A2, A3 backgrounds was more than 1.0. ΔEresin value of A4, A5 backgrounds was less than 1.0. The ΔEpaste-resin value of A3 backgrounds was more than 1.0, whereas, A2 was less than 1.0（except for shade WO）. The ΔEpaste-resin value of shade WO was significantly different from other shades of luting agents. Conclusion The color of ceramic veneer restorations were affected by luting agents with A2, and A3 background colors. The agreement of the try-in paste and the corresponding luting agent was excellent for A2 background（except for WO）

Objective To investigate the effects of root canal preparation treated by endodontists of different levels in different difficulty associated with the root canal anatomy factors. Methods Totally 422 teeth with 901 root canals were randomly selected from the Conservative Dentistry Department, West China Stomatology Hospital, and these teeth were respectively treated by junior specialist postgraduates, senior specialist postgraduates and endodontic specialists. Grading criteria of root canal risk factor and root canal therapy difficulty assessment were found based on 6 items: Tooth type, working length, root curvature, calcification, number of canals, and the previous endodontic treatment. The effects of root canal preparation with different difficulty in different groups were analyzed with R×C Chi-square test. Results Success rates of root canal preparation in junior group and senior group during three difficulty groups were statistically different（P<0.05）, and the root canal therapy difficulty group Ⅰ>group Ⅱ> group Ⅲ. The operator factors in root canal therapy difficulty group Ⅰ and group Ⅱ were not significantly different （P>0.05）. But in root canal therapy difficulty group Ⅲ, the endodontic specialist group have highest success rate in root canal preparation. Conclusion The cases of root canal treatment should be treated by endodontist of corresponding level according to the difficulty. In difficult cases, endodontic specialist can provide better root canal preparation result.

Objective To study the incidence rates, clinical charateristics of oral hairy leukoplakia（OHL） and its relation to the immune status in a sample of human immunodeficiency virus（HIV）-infected adults in Yunan, China. Methods 1 060 adult patients with HIV from January 2008 to June 2010 were evaluated. The age, gender, education grade, diagnosis time of HIV-infected, route of transmission, xerostomia, oral candidiasis, high active antiretroviral therapy and CD4 lymphocytes counts. The occurrence of OHL was recorded by oral examination. The relationship of CD4 lymphocytes counts and the incidence of OHL were analyzed by statistical methods. Results There were 94 OHL patients in 1 060 HIV patients（8.9%）. The average age of the OHL patients was （39.33±10.45） years old. 90% OHL was found on the two lateral aspect of the tongue. The CD4 lymphocytes of 70.2% OHL patients were less than 200 mm-3. Conclusion OHL is a frequent finding in patients with indicates severe immunosuppression and associated with the reduction of CD4 lymphocytes.

Objective To investigate 16 to 22-year-old young adults’perception of malocclusion, dental health and aesthetic firstly. To investigate the perception differences between young adults and orthodontists, and factorson perception difference. Methods A sample of 16 to 22-year-old young adults was selected randomly in Department of Stomatology, Hospital of Nanjing Army Command College. A questionnaire, which consisted of socioeconomic status, index of orthodontic treatment need and dental health component（DHC） questionnaire, was proposed to them. Index of orthodontic treatment need comprised aesthetic component（AC） and DHC. An orthodontist measured orthodontic dental models of participants. Participants chose AC degree and DHC degree by their subjective perception. An orthodontist chose AC degree and DHC degree by their objective measurement. Results 71.08% and 70.59% of 204 participants respectively chose‘no need treatment’of AC degree and DHC degree by their subjective perception. 19.12% and 9.80% of participants were respectively chosen‘no need treatment’of AC degree and DHC degree by orthodontist’s objective measurement. Objective measurement degree of orthodontist was higher than subjective perception degree of participants. Subjective perception of participants was little related to objective measurement of orthodontists. AC degree of male participants’subjective perception was lower than the female. DHC degree of urban participants’subjective perception was higher than the rural. DHC and AC degree of only child participants’subjective perception was higher than non-only child. Conclusion Perception about malocclusion, dental health and aesthetic had significant difference between 16 to 22- year -old young adults and orthodontists. Young adults tended to think that their teeth were more beautiful and he althy. The female young adults than the male tended to think that their teeth were not enough beautiful. Urban young adults were more unsatisfactory about their dental health than the rural. Only child young adults were more unsatisfactory about their dental aesthetic and health than the non-only child.

Objective To investigate the prevalence and potential risk factors of dentine hypersensitivity of adults in rural of Sichuan province. Methods All representative samples, including 630 adults living in rural of Sichuan Province, were selected by multi-stage, stratified and random sampling. The dentine hypersensitivity of all 630 cases was surveyed with questionnaire and oral clinical examination. SPSS 18.0 software was used for statistical analysis. Results 27.9% of all subjects were suffered from dentine hypersensitivity, sour was the most common stimulus of dentine hypersensitivity. The first premolar was the most common tooth with dentine hypersensitive, which occupied 27.4% of the total affected teeth. Female, acid regurgitation symptom, low frequency of toothbrush replacement（over 3 months）, high tooth-brushing force and frequency of fresh fruits consumption（over 2 times per week） probably were high risk factors of dentine hypersensitivity. Conclusion The prevalence of dentine hypersensitivity occurrs in rural of Sichuan province is high, thus for future the publicity and education on dentine hypersensitivity preventive should be strengthened.

Objective The objective of this study is to investigate with cone-beam computed tomography（CBCT）the tooth length of permanent upper canines near the cleft area in patients with complete unilateral cleft lip palate （UCLP） and to compare the findings with its contralateral tooth, including full length, crown length, root length and top root ratio. Meanwhile, the teeth near the cleft area having anomalies are also recorded. Methods A sample of 20 patients with complete UCLP who accepted the CBCT scan were selected. The raw data were constructed along the longitudinal axis of the upper canines, and the full lengths, crown lengths, root lengths of upper canines of all patients were measured using 3-D measurement software associated to CBCT． The full lengths, crown lengths, root lengths and top root ratios of the upper canines accepted paired-t test. The anterior teeth near the cleft area having anomalies and positions of the clefts were also recorded. Results The full lengths, root lengths and top root ratios of the upper canines had statistical difference between the cleft side and non-cleft side（P<0.01）, except the crown lengths （P>0.05）. 20 lateral incisors near the cleft area had anomalies（100%）. Conclusion The lengths of upper canines on
the cleft side are shorter than those of the non-cleft side, and the root lengths are affected more. The teeth near the cleft side prove to be abnormal, especially the lateral incisors.

Objective To investigate the clinicopatholigic features of reactive hyperplasia of lymph nodes in maxillofacial regions. Methods Thirty-two patients with lymph node reactive hyperplasia（LRH） were analyzed clinicopathologically including pathomorphologic manifestation and immunohistochemical expression. Results Histopathology of 32 patients showed significant hyperplasia in folliculus lymphaticus, marginal zone lymph, paracortical area lymph, and seldom mixed hyperplasia. Immunohistochemical study showed that the hyperplastic lymphocytes were mainly composed of CD20 positive B cells positive in 23 cases（72%）, CD3 positive T cell in 7 cases（22%）, CD20 positive T cell and CD3 positive B cell partially as well as histiocytes in 2 cases（6%）. Atypical hyperplasia was found in 10 cases. Conclusion Hyperplastic lymphocytes in LRH of maxillofacial regions are mainly composed of B cells. Malignant transformation may occur in these patients with atypical hyperplasia. Regularity follow up is necessary for these patients.

Objective To evaluate the marginal microleakage of porcelain-fused-to-metal crown using four different  cements. Methods Sixteen porcelain-fused-to-metal crowns were built and randomly divided into 4 group, luted onto standard prepared human forward molars using four different cements（glass ionomer cement, resin-modified glass ionomer cement, PanaviaF, Super-Bond C&B adhesive luting system）. After temperature cycling test, all the crowns were then submerged in 2% fuchsin for 24 h. The marginal microleakage at tooth cement interfaces was observed using light stereomicroscopy and evaluated in classification index. The marginal microleakage grade of 4 groups were analyzed by SPSS 13.0. Results The PanaviaF demonstrated the least marginal microleakage, Super-Bond C&B adhesive luting system, resin-modified glass ionomer cement showed an intermediate level of marginal microleakage, glass ionomer cement was associated with severe marginal microleakage（total, 掊2=157.60, P<0.01; among the different groups, P<0.05）. Conclusion Adhesive resin luting system which is the first selection in clinical is better than glass ionomer cement and is good at porcelain-fused-to-metal crown.

Objective To compare the clinical effect between reattachment of permanent anterior teeth with crown fracture using dual-cured resin combined with dentin pin and conventional method. Methods 49 permanent anterior teeth of 38 patients which had intact incisal edge segments were divided into two groups. In experimental group reattachment was conducted by dual-cured resin combined with dentin pin, while in control group only dual-cured resin was adopted. Cases were assessed clinically by one year’s followed up. Results The success rate was 95% in experimental group and 64% in control group after one-year’s follow-up（P<0.05）. Conclusion The clinical effect of reattachment with dual-cured resin combined dentin pin to treat anterior crown fracture is superior to conventional method.

Objective To investigate the orthodontic retention and adjustment of the occlusion after orthognathic surgery. Methods 18 patients were divided into three groups. Group Ⅰ : Cases with skeletal Class Ⅰ bimaxillary protrusion treated by subapical osteotomy; Group Ⅱ : Cases with skeletal Class Ⅱ mandibular retrusion treated by sagittal split mandibular advancement surgery; Group Ⅲ: Cases with skeletal Class Ⅲ treated by Le Fort Ⅰ osteotomy on maxilla and sagittal split osteotomy on mandible. There were 6 patients in each group. Three kinds of orthodontic elastic tractions were used based on different categories of malocclusion and different types of operation. Results 18 patients attained functional occlusion after the orthodontic occlusion adjustment. There was no relapse and malocclusion by surgery. Conclusion Intermaxillary elastics based on different categories of occlusion and different kinds of surgery can improve the occlusion after orthognathic surgery and attatin the functional occlusion.

Objective To study if quantum dots fluorescent probes can be applied to detect P53 protein and Bcl- 2 protein in tissue of human tongue squamous cell carcinoma. Methods By indirect immunofluorescence assay the same particle size quantum dots fluorescent probes were applied to detect P53 protein and Bcl-2 protein respectively. Different particle size quantum dots fluorescent probes were applied to detect P53 protein and Bcl-2 protein simultaneously in paraffin-embedded tissue section of human tongue squamous cell carcinoma under fluorescent microscope. Results P53 protein and Bcl-2 protein can be combined with quantum dots fluorescent probes and specific fluorescene can be observed with ultraviolet light excited. P53 protein was mainly distributed in the nucleus, and Bcl-2 protein major in the cytoplasm. P53 protein and Bcl-2 protein can be combined with different particle size quantum dots fluorescent probes respectively in the same paraffin-embedded tissue section of human tongue squamous cell carcinoma and two kinds of fluorescene can be observed. Conclusion Quantum dots fluorescent probes can be applied to detect two kinds of specific protein in paraffin-embedded tissue section of human tongue squamous cell carcinoma.

Objective To investigate the significance of cytokine interleukin-12p40（IL-12p40） and interferon-γ （IFN-γ） in tissues formation and development of human oral lichen planus（OLP）. Methods The tissues of 11 cases of normal oral epithelium and 43 cases of OLP were investigated for the expression of IL-12p40 and IFN-γ proteins by using Envision two-step immunohistochemistry. The correlations between the expressions of these two cytokines, and their clinical and pathological significance in OLP were analyzed. Results 1）IL-12p40 and IFN-γ proteins were up-regulated in OLP comparing with that in normal oral mucosa and there was statistical significance between their difference（P<0.05）. 2）The percentage of positive IL-12p40 staining in OLP of IFN-γ positive group was higher than IFN-γ negative group and there was statistical significance between their difference（掊2＝5.828，P＝0.016）. A positive correlation was found between IL-12p40 and IFN-γ proteins in OLP（Spearman r=0.357, P＝0.019）. 3）The percentage of positive IL-12p40 staining in OLP with short course（<6 months） was higher than that in OLP with long course （≥6 months; 掊2= 7.935 , P =0.005）, and a significant association was found between IFN-γ over expression and the degeneration of base cells in OLP lesions（掊2=9.070, P=0.011）. Conclusion These results indicate that at the primary phase of OLP, IL-12 may drive the pathological destruction in OLP lesions by elevating IFN-γ protein locally. IFN-γ may play an important role for the pathological destruction in OLP lesions.

Objective To investigate ligand -gated cation channels P2X3 receptors changes in rat pulp during experimental tooth movement（ETM）, and preliminarily find their possible effect during ETM. Methods 54 male SD rats（200-250 g） were selected and randomly divided into blank group（5 rats）, control group（14 rats） and experimental group（35 rats）. The left maxillary first molar was selected as observation object, the pulp tissue biopsies was taken at different time points to carry out immunohistochemical study. Results Predominant up regulation of P2X3 receptors immunoactivity was found in pulp from 1/6 d to 7 d after experimental tooth movement. It started to significantly increase at 1/6 d, peaked at 3 d, and then decreased continuously until 7 d as compared with the beginning. Conclusion P2X3 receptors have a rhythm change in rat pulp as a result of ETM, speculated that P2X3 receptors is closely related to the tooth movement injury, but the mechanism of action need further researches.

Objective To investigate the immunosuppressive effect of total glucosides of peony（TGP） on sialoadnitis in non-obese diabetic mice（NOD mice） and explore its possible mechanism. Methods 27 female five-weekold NOD mice were randomly divided into three groups: TGP, hydroxychloroquine（HCQ） and normal saline（NS） group. One week later, they were administered intragastrically in TGP, HCQ and NS respectively. Three mice from each group were sacrificed at the age of 10, 15 and 20 weeks. The saliva flow, serum and submandibular glands were collected at these time points. Histological changes of submandibular glands were examined by HE staining. The expression of autoantibodies（SSA, SSB and anti -α -fodrin） and associated cytokines in serum were detected by enzyme -linked immunosorbent assay（ELISA）. Results Compared with the NS group, salivary flow was significantly increased, the extent of the histological changes were ameliorated, the autoantibodies in serum were significantly decreased and the imbalance of Th1/Th2 cytokines was remedied in the mice treated with TGP and HCQ. There were no significant differences between the two groups treated with TGP and HCQ（P>0.05）. Conclusion TGP can effectively ameliorate sialoadenitis on NOD mice. The mechanism was thought to be associated with the protection of submandibular gland from intense inflammation and the correction of Th1/Th2 cytokines imbalance.

Objective The objective of this study is to investigate the influence of zirconia content which is 0- 30.0% weight percentage of matrix on translucency of zirconia-toughened alumina glass-infiltrated ceramics. Methods Seven groups were divided according to different weight percentage of zirconia（0, 2.5%, 5.0%, 7.5%, 10.0%, 20.0% and 30.0%）. After sintering, infiltrating and polishing, spectral transmittance was determined with spectrophotometer under D65 standard source. Contrast ratio was also tested by whiteness colorimeter. Results With mass fraction of zirconia increasing from 0 to 30.0%, spectral transmittance reduced from 0.406% to 0.058%, while contrast ratio value increased from 0.849±0.005 to 1.015±0.006. When zirconia content was 10.0%, contrast ratio was 0.990±0.008. When it was more than 10.0%, transmission rate of the downward trend and contrast ratio of the rising trend became flat. Conclusion Zirconia content has a direct impact on translucency of zirconia-toughened alumina glass-infiltrated ceramic, which is essentially opaque when zirconia content is 10.0%. When mass fraction of zirconia is more than 10.0%, the influence of zirconia content is reduced.

Objective To discuss the influence of nano-silica content which was hydrolyzed by tetraethyl orthosioate（TEOS） on the aluminum borate whisker（AlBw） and silica filler composite resins on flexural properties. Methods The nanometer-size silicon dioxide（SiO2） particles were prepared by sol-gel method based on tetraethyl orthosioate. Different proportion of AlBw and SiO2 were fused and attached onto the surface of AlBw through high temperature, then polymerized with resin matrix after surface siliconization and their flexural strength and flexural modulus were determined. The effects of heat treatment to the surface morphology of AlBw and the shapes of the mixture at various proportions were characterized by TEM. Results The flexural properties of dental composite resins with AlBw-SiO2 compound as inorganic fillers were significantly improved. The flexural property of a new type of dental composite resins was（130.29±8.38）MPa, when the mass ratio of AlBw and nano-SiO2 particle was 3∶1. Conclusion Nano-silica content which was hydrolyzed by tetraethyl orthosioate improved flexural properties of the aluminum borate whisker and silica filler composite resins.

Objective To clone the glyceraldehydes 3-phosphate dehydrogenase（GAPDH） gene of Porphyromonas gingivalis（P.gingivalis） and to induce its fusion expression in E.coli. Methods GAPDH was obtained by PCR and was inserted into cloning vector pMD-18-T to construct clone recon. Double enzymes digest the recon pMD18-TGAPDH and the prokaryotic expression vector pET-32a and then connect to get the expressing recon pET -32a - GAPDH. The recombinant expression plasmid which had been confirmed by enzymes digestion was transformed to E. coli competent cells BL21 and induced the expression of GAPDH with isopropyl β-D-1-thiogalactopyranoside（IPTG） of different density. Results DNA sequencing showed that the fragment was 99.802% the same to the sequence published in NCBI. Under the best density, IPTG could be highly expressed. Conclusion The GAPDH had been successfully cloned and expressed in E. coli which gets ready for the following experiment to study the immunity of GAPDH and the homologues antibody preparation.

Objective To investigate the variation of the corrosion resistance of anodized oxidation film on titanium by electrochemical methods. Methods TiO2 nanotube layer was formed on Ti surface by anodization. The morphology was observed with scanning electron microscope（SEM） and the crystal phase was analyzed using X-ray diffraction（XRD） before and after annealing． Polarization curves were examined by electrochemical methods. Results Titanium oxide nanotubes with 80 nm diameter and 400 nm length was seen on Ti after anodization. The annealing nanotubes was anatase crystalline phase by X-ray diffraction analysis. The self-corrosion potential and break-down potential of smooth Ti were significantly lower than TiO2 nanotubes by anodization（P<0.05）. The self-corrosion current and passived current were significantly higher than TiO2 nanotubes by anodization（P<0.05）. Annealing improved the corrosion resistance of anodized oxidation film on titanium. Conclusion The resuIts of electrochemical examinations indicate that the TiO2 nanotubes by anodization increases the corrosion resistance of titanium.

Objective To observe the effect of dexamethasone on the proliferation and apoptosis of embryonic palatal mesenchymal（EPM） cells, and chose a proper concentration of dexamethasone which can effect the ordinary growth of embryonic palatal mesenchymal cells. Methods The primary EPM cells were isolated and cultured in vitro, then we did biological assay. EPM cells were treated with different concentration dexamethasone（1×10-9, 1×10-8, 1×10-7 and 1×10-6 mol·L-1） respectively. The proliferation of EPM cells was evaluated using MTT method. Apoptosis was examined quantitatively with fluorescein stain. Results In the condition of blood serum’s concentration at 10%, optical density step down following the raise of dexamethasone’s concentration. The effect of dexamethasone got to a summit at 3 days. Inhibition rate of dexamethasone at 1×10－6 mol·L-1 was the highest. Conclusion Dexamethasone at 1×10－6 mol·L-1 can not only inhibit the growth of the EPM cells, but also will not lead to a large number of cells death. Therefore, this concentration can be used as a reference standard in future research. The most significant drug action time of dexamethason appears at the third day after administration, then the effect became weaken following the drug metabolism.

Objective The purpose of this study is to find some appropriate treatments on the dentin of root canal wall to obtain better bonding strength of fiber posts. Methods 36 new extracted non-caries single root canal anterior teeth were collected and post spaces were prepared. The teeth were divided into six groups randomly and processed by different post-space treatments: Sodium chloride irrigation（groupⅠ, control group）; irrigation with 2% chlorhexidine solution followed by 17% EDTA solution（groupⅡ）; irrigation with 3% hydrogen peroxide followed by 17% EDTA solution（group Ⅲ）; irrigation with 5.25% sodium hypochlorite（NaClO） followed by 17% EDTA solution（group Ⅳ）; etching with 35% phosphoric acid-gel for 30 s（group Ⅴ）; 17% EDTA-gel for 1 min（group Ⅵ）. After each post-space treatment, sodium chloride irrigation was applied in Ⅱ~Ⅵ group. Fiber posts were then luted in the treated roots using 3M ESPE RelyXTM Unicem and the thin-slice push-out test was performed. The dentin surfaces and bonding interface were examined under scanning electron microscope. Fracture mode of fiber posts were observed by stereo microscope. Results Group Ⅱ~Ⅵ were effective in getting rid of smear layer. Resin rags of dentin bonding interface were observed in group Ⅱ and group Ⅴ. The majority fracture mode of specimens in each group were mixed mode which contained dentin destruction. Compared with control group, the bonding strength of group Ⅱ , Ⅴ increased obviously（P<0.05）. Conclusion Irrigation with 2% chlorhexidine solution followed by 17% EDTA solution and 35% phosphoric acid-gel etching improved the bonding strength of fiber posts. The depth of post space has no influence of bond strength.

Objective To explore transient expression of the eukaryotic expression plasmid carrying human platelet- derived growth factor-B（hPDGF-B） in gingival fibroblasts of Beagle dog. Methods Plasmid carrying hPDGF-B （EX-A0380-M03） was amplified and identified, and then transfected into gingival fibroblasts of Beagle dog. Reverse transcription polymerase chain reaction（RT-PCR）, immunocytochemistry, enzyme-linked immunosorbent assay（ELISA） and Western bolt were choose to detect the expression of hPDGF-B. Results Target gene carried by EX-A0380- M03 was hPDGF-B. Green fluorescene protein（GFP） expressed by transfected gingival fibroblasts was observed under inverted phase contrast fluorescence microscope（IPCFM）（after 24 hours） and the transfection efficiency was 18%-38% （after 48 hours）. Serials other methods（RT-PCR, immunocytochemistry, and ELISA） mentioned above also convinced that cells expressed hPDGF-B, and the protein that was a kind of fusion protein composed of PDGF-BB and GFP was idenified by Western blot. Conclusion Eukaryotic expression plasmid carrying hPDGF-B was transfected into gingival fibroblasts successfully, and a kind of fusion protein was expressed.

Objective To discuss the trend of displacement on the side of nondistraction when distraction osteogenesis
with unilateral incomplete osteotomy of canine mandible. Methods The method of finite element analysis was used to simulate distraction osteogenesis with unilateral incomplete osteotomy and the displacement of six marked point such as the temporomandibular joint and the angle of mandible and coracoid process and teeth were observed on nondistractional side when the transport disc was distracted with a distance and without a distance. Results When the transport disc was distracted without a distance, the Von Mises stress was 0 in the six marked point of nondisractional side and their displacement in 3 dimensions（X, Y, Z axis） was 0. When the transport disc was distracted with 1 mm width, all marked point had some displacement. Conclusion When distracted and observed from the side of distraction, the mandible at the side of nondistraction has the trend of contrarotation round the center of the transverse ridge midpoint of condyle process on the plane of sagittal, whereas it has the trend of parallel movement approximately in the direction of opposite side on the plane of coronary.

Alcohol withdrawal syndrome（AWS） is a rare complication associated with oral cancer operation. This article reported a case of AWS after resection of squamous cell cancer of the right floor of mouth combined with radical neck dissection and trapezius myocutaneous flap reconstruction. The discussion included diagnosis, treatment and prevention of AWS.