Objective　To compare the antibacterial effect between sodium fluoride andGalla Chinesisin biofilm model. To evaluate the feasibility of application ofGalla Chinesisin the clinical practice of caries prevention.Methods　Streptococcus mu- tans,Streptococcus sanguis,Streptococcus salivariusandActinomyces naeslundiihad been chosen as the experimental bacteria. In the experiment, biofilmmodelwas constructed, and two agentswere added in the media. After a period of continuous culture, the number of bacteria adhering on the HA disc was examed, the planktonic pH in the flow cell was recorded continuously, and the morphology of the biofilmformed on theHAdisc was observed by SEM.Results　①Galla Chinesiscould inhibitthe growth of the four oral bacteria in the biofilm just as sodium fluoride.②Galla Chinesisand sodium fluoride could prevent the descent of the planktonic pH in the flow cell,butGalla Chinesiswas less efficient than sodium fluoride.③The biofilms formed after application ofGalla Chinesisand fluoride, but the bacterial cells had less matrixthan those applicatedwith sucrose.Conclusion　Galla Chi- nesisis one kind of effective cariostatic natural agents.

Objective　To improve the design of the devices used for automatic elasticity distraction osteogenesis, and to pre- liminarily testify their feasibility for clinical application.Methods　The internal automatic distraction devices were constructed by three parts, including sinusoid shape memory alloy distractor, reconstructive plate and mini-plate. The animal model of trifocal bone transport reconstruction of canine mandibular mentis was duplicated, in which a 6 cm mandibular mentis segment was re- moved and the transport disc was created by osteotomy in both ends of the mandibular defect. The plateswere used for internal fix- ation and shape reconstruction of the mandible. They also served as transport distraction guidance for the elasticity distractor.Re- sults　The new devices could complete bone transport as expected. Regenerated bone segments were formed in two months and both sides of the mandibular body were lengthened. Because of the narrow angle and obstruction from the thick soft tissues in the mentis area, the ultimate symphysis mentalis was not reconstructed.Conclusion　The design of the internal elasticity distraction devices showed potential feasibility for clinical practice. But further studies are still needed for better control of the strength and balance of distraction forces.

Objective　To study the expression of Runx2/Cbfa1 in the developing dentin and differentiating odontoblasts.Meth- ods　A postnatal mice teeth developing model was built histologically. Immunohistochemical technique was adopted to determine the expression of Runx2/Cbfa1 in the developing pulpo-dentinal complex in mice.Results　Runx2/Cbfa1 was merely present in predentin in the exact and before the 11th day′s postnatal stages. Meanwhile, it was positively located in odontoblasts and dental pulp cells in root region, but negatively in coral part after the 11th day′s stages.Conclusion　Runx2/Cbfa1 may play an impor- tant role in the deposing of tooth dentin and in the differentiating of odontoblasts and pulp cells.

Objective　To detectPorphyromonas gingivalis(P.gingivalis) in buccal epithelial cells and subgingival plaque from periodontally healthy subjects and patients with chronic periodontitis.Methods　40 subjects were included in the healthy group and 39 subjectswere included in the diseased group in this study. Cells and subgingival plaque sampleswere collected. The extracted DNAwas amplifiedwith universal primers andP.gingivalisspecies-specific primer.Results　P.gingivaliswas detect- ed in 37.5% of subgingival plaque samples and 32.5% of buccal mucosa samples in the healthy subjects, but 69.23% of subgin- gival plaque samples and 46.15% of buccal mucosa samples in the periodontitis group. Highly statistically significant differences were observed between healthy and periodontitis groups in the detections ofP.gingivalisof subgingival plaque samples.Conclu- sion　P.gingivalismay be one of oral flora because it can be detected in the healthy population and not lead to destruction of supporting structures of the teeth.

Objective　To evaluate the masticatory efficiency of implant supported dentures in partially edentulous patients and the patients′satisfaction onmasticatory function.Methods　The masticatory efficiency of implant supported dentures of 22 patients were tested. The questionnaire of the patients′satisfaction about masticatory function had also been collected. The correlativity of the masticatory efficiency of implant supported dentures and the scores evaluated by patients onmasticatory functionwere analyzed. Results　There were no differences in masticatory efficiency between implant supported denture and non-implant supported den- ture (natural teeth and porcelain-fused-to-metal fixed bridges). The patients gave high scores to the satisfaction about masticatory function in the questionnaire. But the test results of masticatory efficiency were not related with the scores evaluated by patients. Conclusion　The implant supported denture could meet the requirement of normal masticatory function. The patients were sati- sfactory with the masticatory function of implant supported dentures, but the patients′subjective evaluation about masticatory func- tion was probably influenced by varied factors.

Objective　To study the changes of root canal curvatures and apical transportation index when the curved root ca- nals were prepared by hand-use ProTaper, stainless steel K-files or nickel-titanium K-files.Methods　Forty-five extracted mo- lars, with the degree of root canal curvature from twenty to forty, were divided into fifteen sections in curvature sequence. After that, three canals of each section were randomly distributed to three different instrumentation groups. One group of themwas pre- pared by hand-use ProTaperwith crown-down technique. The othertwo groupswere instrumented by stainless steel or nickel titani- um K-files with modified step-back technique to working length. The standard digital radiographs were taken to record the profiles of root canals and the positions of the tips of the instruments. The change of curvature degree between pre- and post-instrumenta- tion and the apical transportation indexes (ATI) among three groups were analyzed respectively using SAS statistical software.Re- sults　The change of curvature degree between pre- and post-instrumentation for stainless steel K-files groupwas largest, and the ATI of stainless steel K-files group was significantly greater than that for nickel titanium K-files group (P<0.05). The canals prepared by hand-use ProTaper was smallest in the change of curvature and ATI among the three groups(P<0.01).Conclusion 　When preparing curved molar canals, hand-use ProTaperwith crown down technique can obtain better shaping effect and higher efficiency.

Objective　This study was to find out the most suitable concentration of added NaF to enough bonding strength of brackets.Methods　Sixty-four teeth were randomly divided into A, B, C and the control group. NaF of four different concentra- tions (1·23%, 2%, 3% and 0%) was added into 35% phosphoric acid. The fourgroup teethwere etchedwith four kinds of flu- oride etching fluid respectively andwere bondedwith brackets. Four specimens in each groupwere selected byturns after1, 4, 12 and 24 weeks of bonding. The shear bond strength of the teethwere tested, and the adhesive residual index (ARI) of bonding in- terface were recorded.Results　The shear bond strength at fourtesttime in each groupwas no significant (P>0·05). Therewas statistical difference of the shear bond strength between fourgroups(P<0·05), and group Cwas lowerthan the othergroups. The ARI was no statistical difference between four groups.Conclusion　The effects of etching and bonding had no significant changes when the concentration of added NaFwas nomore than 2%. The shear bond strength decreasedwhile the concentration ofNaFwas higher than 3%.

Objective　To investigate the distribution and drainage of lymphatic vessels of tongue, and to provide anatomical evidence for treatment of tongue cancer.Methods　Indirect lymphatic injection was employed, combined with clearing method with winter green oil and corrosive cast technique, to study the distribution of lymphatic vessels of tongue. Anatomical methods were used to detect the sentinel lymph nodes in different region of tongue.Results　The lymphatic vessels of dorsal mucosa com- posed of lymphocapillary vessels and anstomosing side brancheswere present by superficial and deep capillary networks. The distri- bution of lymphatic networks extend fromtip to base and from one board to another, andwas not influenced bythe sulcus terminalis and median lingual sulcus. Lymphatic vessels in the muscular portion communicated with lymphocapillary network of dorsal and ventral mucosa, which made the lymphatic vessels of tongue to be an integrity network structure. These characters of distribution influenced the lymphatic drainage of tongue. The results showed principal sentinel lymph nodes (SLNs) for anterior part of tongue were submental lymph nodes, submandibular lymph nodes and juguloomohyoid lymph nodes, for lateral part and middle part of tongue were submandibular lymph nodes, jugulodigastric lymph nodes and thyroid lymph nodes, and for root part of tongue were jugulodigastric lymph nodes. SLNs for every injection regionwere all presented at bilatral neck, but the frequency of stained SLNs at homolateral neck was more than that at contralateral neck.Conclusion　The lymphatic vessels of tongue arranged like a net- work, which made the lymphatic drainage at variousways and made the distribution of sentinel lymph nodes to be bilateral and dis- persive.

Objective　To compare the suppressive effects of tramadol and low-dose ketamine on postoperative hyperalgesia af- ter remifentanil-based anaesthesia.Methods　Atotal number of sixty ASAⅠ~Ⅱadult patients who undergone the operation of cranio-cervical regionwere assigned to three groups randomly,controlled group(Group C), tramadol group(GroupT) and low-dose ketamine group(Group K). Before the end of surgery, Group T was given tramadol 0·3 mg/kg, Group K was given ketamine 0·5 mg/kg and Group C wasn′t given any medicine. When the visual analogue scale (VAS) score of the group C was over five, tramadol 0.3 mg/kg was given to the patients. The four-level verbal rating scale after trachea extubation, VAS score, the time of requiring analgesia again by patients and adverse drug reactions such as nausea, vomit, diplopia and hallucination were recorded for 24 hours after surgery.Results　After operation, the VAS score of Group Cwas much higher than that of Group K in the first 4 hours and Group Twas higher than Group K during 2, 3 and 4 hours (P<0·05). The time of requiring analgesia by patients in Group C and Group Twas earlier than Group K. The adverse drug reaction showed no significant difference in three groups. Conclusion　Low-dose ketamine had significant suppressive effect on patients with postoperative hyperalgesia and acute opioid tolerance after remifentanil-based anaesthesia.

Objective　To study the characteristics of dental arches in the patients with facial asymmetry.Methods　20 facial asymmetrical patientswere chosen as the study subjects. Theywere 8 boys and 12 girls, aged from12-yearto 16-year old. 20 nor- mal occlusion persons without signs of facial asymmetry were chosen as control. Dental casts were measured by 3-dimension mea- suring machine. Dental arch asymmetry, coordination between upper and lower dental arch, and dental inclinationwere measured. SAS 6·03 was used in statistical analysis.Results　The distance from cuspid and the first bicuspid to the median palatal raphe in the side of crossbite was largerthan that of contralateral side in maxilla. The distance from cuspid, bicuspids and the firstmolarto the midline in the side of crossbite was smaller than that of contralateral side in mandible(P<0·05). The dental arch width of cuspid and first premolar in maxilla was smaller than that of mandible(P<0·05). Significant buccal inclination of the maxillary posterior teeth coupledwith lingual inclination of the mandibular posteriorteethwas found on the crossbite side. In contrast, signif- icant lingual inclination of the maxillary posterior teeth coupled with buccal inclination of the mandibular posterior teeth was found on the contralateral side(P<0·05).Conclusion　Thewidth of upper anterior dental archwas smaller, and the inclination of up- per and lower posterior teeth between crossbite side and counterside was different in facial asymmetry patients.

Objective　To establish a method for isolating and culturing mouse dental follicle cells and to study the phenotype characteristics of dental follicle cells.Methods　Mandibular first molars from 9 day old Balb/c mice were digested with 1% tryp- sin, subsequently, and the dental follicle was enucleated from the tooth germ and cultured. The shape and ultrastructural appear- ance of dental follicle cellswere observed under phase-contrastmicroscope and scanning electron microscope(SEM). Immunocyto- chemistrywas used to detect the expression of alkaline phosphatase (ALP), bone sialoprotein(BSP) and osteopontin(OPN).Re- sults　Three types of cells were isolated: some were cuboidal/polygonal; some were elongated, spindle-shaped, fibroblast-like cells; and a minor, third cell type was very thin and elongated. The cytoplasm of the first two cell types was filled with abundant granules. The cells were pleomorphism under SEM and had many filipodia and microvilli. According to whether there were fila- ments overlying the surface, the cells could be divided into two subtypes. Some but not all follicle cells expressed ALP, BSP and OPN.Conclusion　The cultured dental follicle cells consisted of several cell phenotypes and had the potential of differentiating in- to cementoblasts, periodontal ligament fibroblasts and osteoblasts.

Objective　To evaluated the cytotoxicity of a newnano-hydroxyapatite (n-HA)root canal sealer.Methods　In this study, the cytotoxicity was evaluated by the method of MTT assayin vitro, and culture medium F12 as control, three concentra- tions of the soaking material cultured with mouse osteoblast separately, to test the cell relative growth rate(RGR) of every group. Results　The toxicity graduation of the n-HA root canal sealer tends to 0 with the culture time increasing. The cell survival rate of n-HA root canal sealer showed high relatively. The OD value of cell was similar for the negative control and the extracts(P> 0·05).Conclusion　The result indicated that n-HA root canal sealer was compatible with the testcells.

Objective　To detective the relationship between cyclooxygenase-2 (COX-2) and angiogenesis in oral squamous cell carcinoma (OSCC) and its clinical significance through observing the expression of COX-2 and determining microvessel density (MVD) in OSCC.Methods　PV-9000 immunohistochemistry was used to determine the expression of COX-2 and CD34, which was used to determine MVD, in 76 OSCC tissues and 12 normal oral mucosa tissues.Results　Overexpression of COX-2 was de- tected in OSCC, and was more intense compared with normal epithelium (P<0·001). The high expression of COX-2 in OSCC was related to neck lymphnode metastasis, tumor size, TNMstage and histological grade (P<0·05). The MVD value in COX-2- positive group was much higher than that in COX-2-negative group (P< 0·01) and that in normal oral mucosa tissues (P<0·01).Conclusion　The high expression of COX-2 in OSCC was significantly associated withMVD, neck lymphnode me- tastasis, tumor size, TNM stage and histological grade. COX-2 might be one of the important factors in the angiogenesis of OSCC.

Objective　To investigate the spatial and temporal expression changes of fibronectin and integrinβ1 mRNA during fracture healing.Methods　Using in situ RT-PCR technique, the spatial and temporal expression pattern of both fibronectin and integrinβ1 mRNAwas detected on paraffined slices in different rabbit mandibular fracture healing phases.Results　①The mRNA of integrinβ1 and fibronectin was widely expressed in fractured bone cells. The positive stain existed in cytoplasm and nucleolus. ②After 7 days of fracture, increaseded integrinβ1 mRNA expression was observed, and it reached maximal levels approximately 14~30 days post-fracture and returned to normal levels after 60~90 days.③Fibronectin mRNA was detected on 3 days post- fracture, it reached maximal levels at 7~14 days,faint expressionwas detected at 30 days, undetectable 60 days afterwards.Con- clusion　During fracture healing, the mRNA expression of integrinβ1 and fibronectin increased locally, FN and Itgβ1 cooperate with each other,it is suggested that they have an important influence on fracture healing.

Objective　To evaluate the beagles′pulp response following direct pulp capping with Clearfil SE BOND (SB). Methods　130 sound teeth were used. 120 had their pulps mechanically exposed and were divided in two groups. In group A, teethwere capped with SB. In group B, teethwere capped with calcium hydroxide (CH). The left 10 teethwere used as control. After 7, 30 and 90 days, the teethwere extracted and processed for light microscopical examination.Results　In 7 day observa- tion period, inflammatory reaction in SB group was slighter than that of CHgroup, but the difference was statistical insignificant. In the 30 day and 90 day observation period, inflammatory reaction was slight in both groups, but specimens with dentin bridge formation was significantly less in SB group than in CH group (P<0.05).Conclusion　SB showed acceptable biocompatibility with pulp, but its ability to induce hard tissue barrier on pulp exposure is weaker than CH.

Objective　To investigate the target deliver of Cisplatin to oral carcinoma tissues by intravenous injection of Cispla- tin loaded polylactic acid- polyethylene glycol nanoparticles(CDDP-PLA-PEG-NP).Methods　CDDP-PLA-PEG-NP was pre- pared by the emulsion-solvent evaporation method. The buccal cancer model was established in 64 golden hamsters, which were divided randomly into two groups for 32 animals in each group, CDDP-PLA-PEG-NP(6·6 mg/kg ) and CDDP(1 mg/kg)were re- spectively injected into mice tail vein. At 0·083、0·5、1、2、4、6、12、24 h after drug administration. 4 animals in each group were sacrificed and CDDP concentration in the plasma and tumorwere determined by high performance liquid chromatography. Targeting ability was evaluated by targeting index(TI), selectivity index(SI) and relative extraction efficiency(re).Results　The average diameter of CDDP-PLA-PEG-NPwas (143·2±1·8)nm. The diameter distributionwas from 103·5 nmto 175·8 nm. Drug loading and embedding ratio were (15·2±0·9)%,(89.0±0·8)% respectively. Values of TI and SI are more than 1 at 8 time points. The area under CDDP concentration-time curve of oral carcinoma tissues in CDDP-PLA-PEG-NP group was 10.36 times as many as that in CDDP group.Conclusion　CDDP-PLA-PEG-NP can specifically deliver CDDP to oral carcinoma tissues by vein injec- tion. Stealth anticancer nano-particle system can be regarded as a valuable drug deliver system to treat oral carcinoma.