Objective:The purpose of this study was to investigate the anti-metastatic effects of nm23-hl gene on high pulmonary-metastatic adenoid cystic carcinoma cell line(ACC-M) .Methods: 20 BALB/C nude mice were randomly divided into two groups, and one group was injected with 5x10 nm23-hl positively-transfected cells via tail vein; The other group was injected with non-transfected cells as the control. One week after injection, 2 mice of each group were killed, 4 weeks after that the remaining mice were killed for gross and histological examination. Results: There was no obvious difference between the two groups 1 week after injection observed by naked eye examination. 4 weeks after the injection, there were lots of gray-white metastatic nodules on the surface of mice lung of the non-transfected group, while only a few metastatic nodules were found in the transfected group. The histological results accorded with the above visual observation. Conclusion: nm23-hl gene could inhibit the pulmonary metastasis of ACC-M. More

Objective: The aim of this study was to investigate the expression of Smadl gene in human dental papillae cells (HDPC) and the transduction process and, to explore the molecular mechanism of odontoblast differentiation during tooth development process at a signaling transduction level. Methods: Immunohistochemical staining of HDPC derived from primary culture stimulated by transforming growth factor B1(TGF-B1) and recombinant human bone morphogenetic protein (rhBMP2) were used in this investigation. Results: The expression of protein of Smadl gene was found in HDPC stimulated by TGF-ji and rhBMP2 , but no significant difference was found between these experimental groups and the control group. Smad2 was found nuclear translocation accumulation form cytoplasm, when HDPC were treated by rhBMP2 .Conclusion: The expression and translocation accumulation of the protein of Smadl gene in HDPC were detected at the first time. The signaling transduction of rhBMP2 in dental papilla cells could be mediated by Smadl translocation and accumulation in nucleus.

Objective:The purpose of this study was to investigate the effects of chemical polishing on pure titanium castings. Methods: Three groups of pure titanium castings (15 mm x 15 mm x 1.4 mm) were prepared, and each group contained 5 castings. Group A was sandblasted for 5 minutes; After sandblasted, Group B and C were polished using conventional machine-grinding and chemical- polishing method for about 60 seconds, respectively. And then the weight loss of Group B and Group C, surface roughness and thickness of oxidized membrane of all castings were measured. The effects were evaluated by naked eye examination. Results: The castings in Group C were polished chemically to mirror surface. The weight loss of the castings polished chemically was more than that polished using the conventional machine-grinding method. The Ra values were significantly different among the three groups. The metalloscopy indicated that the surface was evenly covered with a layer of oxidized membrane of 8 fan after polishing. Conclusion : The chemical polishing of pure titanium castings is efficient method, which can be available in clinic.

Objective: The aims of this study were to prepare the vector of MHCI functional gene ( H-2Kk) of 615 mice, and to get the monoclone cell strains with MHC I molecule function.Methods: The MHC I (H-2Kk) cDNA of 615 mouse was inserted into PLX-SN retrovirus plasmid, and E. coli JM109 was transformed by the ligated product. The recombinant plasmid PLXSN-H-2K was obtained by restriction enzyme analysis. The PAS 17 packet cells were transfected by the recombinant plasmid. The transfected PA317 cells were screened under the G418 selective stress. The G418 resistant monoclone cell strains were picked up and employed to prepare the retrovirus solutions. The NIH3T3 cells were transfected by the retrovirus solutions in different dilutions. The titres of the retrovirus solutions were determined by counting the G418 resistant NIH3T3 cell clones, and the G418 resistant mono-clone PAS 17 cell strain which could produce high litre retrovirus solution was selected.Results: The titres of the retrovirus solutions with successful transfection were 1.6 x 104 to 1.1 x 105 colony forming units (CFU) per ml. The PAS 17 monoclone cell strains grew well with the patches, and produced many products of H-2Kk. Conclusion: The reconstruction and packeting of the recombinant retrovirus plasmid PLXSN-H-2K cDNA could be available in further study on MHC I transgenic therapy for malignant tumor on 615 mice.

Objective:The purpose of this study was to study the adaptive alterations in the bilaminar zone (BZ) of temporomandibular joint following disc displacement. Methods: Thirty Japanese white rabbits were used in this study. The right joints of 24 rabbits were subjected to surgical disc displacement (DD) . The sections were studied using hematoxylin and eosin, Alcin bluin and Res-orcin-fuchsin staining, and in situ detection of apoptosis.Results: Apoptotic chondrocytes in bilaminar zone were most obviously at 1 or 2 weeks after operation. Following alterations could be also found in bilaminar zones using microscopy: derangement, fragment, hylination of collagen fibers and diminution in the number of cell. Elastic fibers reduced in number and ran irregularly. Conclusion: The bilaminar zone will be remodeled following disc displacement and become a disc-like tissue. So, the bilaminar zone may function as a disc after disc displacement.

Objective;The purpose of this study was to investigate the effects of chondroitin sulfate-A (CS-A) on culture of osteoblasts in vitro.Methods: Various concentrations of CS-A were added to the cultures of human osteoblasts, and the cell proliferation quantity, calcium content and alkaline phosphatase activity of cell layers were evaluated. Results: The CS-A in low concentrations (1 mg/ml and 0.5 mg/ml) promoted the proliferation of osteoblast, while in high concentration(10 mg/ml )inhibited the proliferation of osteoblast slightly. The CS-A prevented calcium accumulation in the cell layers, although CS-A had no inhibition on alkaline phosphatase activity. Condusion: The CS-A can affect proliferation and mineralization of osteoblast, but has no effect on differentiation of osteoblasts.

Objective:The purpose of this study was to investigate effects of chemotherapy on tongue squamous cell carcinoma by detecting the apoptosis, proliferation and expression of Bcl-2.Methods: A total of 60 samples were studied, including tongue squamous cell carcinomas with chemotherapy (10 cases), tongue squamous cell carcinomas (30 cases), tongue squamous cell papillomas (20 cases) . The samples were investigated using immunohistochemical stain and in situ detection technique. Results: The apoptosis index (AI) was significantly lower in the group of squamous cell carcinomas compared with the squamous cell papillomas, but the proliferation index (PI) in the former group was significantly higher than the latter( P < 0.05). Compared with the group of squamous cell carcinomas, the apoptosis index increased, but proliferation index decreased in the group of chemotherapy ( P < 0.05). Bcl-2 positive cell index (BI) in the group of squamous carcinomas significantly decreased after chemotherapy (P < 0.05). hi the group of squamous cell carcinomas with chemotherapy, AI was negatively correlated with PI (r= -0.739) and, BI was negatively related with AI (r= -0.787) . Conclusion: The mechanism of chemotherapy is associated with inhibition of proliferation and induction of apoptosis, which may be determined by decreasing the expression of Bcl-2. It indicates that the pre-opera-tive chemotherapy is important for clinical prognosis of patients with tongue squamous carcinomas.

Objective: The aim of this study was to investigate effects of immediate loading on peri-implant bone reconstruction. Methods : 26 endosseous implants in 8 patients were classified into two groups, including the groups of immediate loading and delayed loading. Digital Panoramic X-ray examination was employed to examine the quality and quantity of peri-implant bone. Results: In the group of immediate loading, the bone density was increased in both the marginal alveolar area and the peri-implant area. And the decrease was more evident in the immediate loading group than that in the delayed loading group. Conclusion: The choice of appropriate prosthesis treatment is very important for bone rehabilitation, especially to patients with implants under immediate loading.

Objective: The purpose of this study was to evaluate the antimicrobial efficacy of tinidazole. Methods: A total of 51 patients with periodontitis and pericoronitis were selected for this study. Among these patients, 25 of them were treated by local application of metronidazole stilus, and 26 of them were treated with tinidazole stilus. During the same period, patients were sampled, cultured and the bacteria were grown in an anaerobic chamber for 5 ~ 7 days. The MIC50 and MIC90 of tinidazole and metronidazole were determined by using two-fold agar dilution technique against 200 wide-type isolates isolated from patients with periodontitis and pericoronitis.Results: Tindazole had stronger antibacterial activities against Porphyromonas gingivalis, Prevotella, intermedia., Fusobacteruan spp. and Peptostreptococcus spp. The MIC50 and MIC90 were 0.25, 0.25, 0.25, 8and0.5, 0.5, 1, 8 mg/L respectively. The elimination rate was 94.4- 100% . The antimicrobial activity of Tinidazole was significantly stronger than metronidazole ( P < 0.05) . Conclusion: Tinidazole stilus can be applied locally in the treatment of periodontitis and pericoronitis.

Objective:The aim of this study was to evaluate the effects of different free flap transfers for head and neck reconstruction in a new microsurgery unit. Methods: 150 consecutive free flap transfers performed in 144 patients from May 1999 to October 2000 were reviewed. Data concerning the operation included date of surgery, defect description and site, stage and histology of tumor, flap type, recipient vessel and type of anastomosis used and complications. Results: The free radial forearm flaps were the commonest flaps used, and followed by free fibula flaps, rectus abdominis flaps, scapular flaps, illiac crest flaps, and latissimus dorsi flaps. The success rate of all flaps was 98% . The overall complication rate was 34% . The vessel thrombosis rate was 6% , and the flap salvage rate was 66.7% . Conclusion: Free tissue transfer in head and neck region is safe and reliable and, is superior to the conventional pedicled flap technique.

Objective: The purpose of this study was to summarize some experience in surgical treatment of cleft palate of infants. Methods: In this study, a total of 531 cases of infants with different subtypes of cleft palate, aged 2 to 12 months, treated with an operation were retrospected. The time of operation, blood loss during operation, and complications were analyzed. Results: The time of operation and blood loss during operation was related with the width of clefts (each F < 0.05) . When compared with the conventional procedures, which required the age of infants must over 1 year, infants with cleft palate was operated before one year had the advantage of less blood loss during operation and lower incidence of fistula. But there was no significant difference in bleeding after operation, time of operation and death rates due to surgery. However, the latter had higher incidence of obstruction airway. Conclusion: Palatoplasty in infants is safe and beneficial, if the electric surgical technique is good, and indications of operation can be properly considered.

Objective:The purpose of this study was to investigate morphological changes of dentine after exposure to Nd: YAC laser. Methods: The second maxilla and mandible molar was selected, and slices with 1.5 mm thickness were prepared from each tooth by suing a high-speed bur. Two horizontal sections of shces were obtained, one at the occlusion enamel-dentinal junction and the other from the position of 1.5 mm lower than the enamel-dentinal junction. A square of 3 mm x 4 mm area on each of the four dentinal slices was irradiated under the laser with four different parameters (1 W, 10 Hz, 100 mj and with different time of 5 s, 10 s, 15s, 20s). After the specimens became dry and covered with gold, the morphological changes of each slice were observed with a scanning electronic microscope (SEM). Results: Laser with the above four parameters blocked dentinal tubule orifices. With the time of irradiation increased, the melting level and sealing depth of dentinal slices increased, but crack and pit were found in the region of irradiation. Conclusion: The density of 41.6 J/cm (10 Hz, 100 mj) can blocked dentinal tubule orifice, and will not cause large crack and pit structure.

Objective:The aim of this study was to detect fungi in infected root canals and possible correlation between penetration of fungi and clinical symptoms and signs. Methods: One hundred and nine cases of canals with necrotic pulp were selected for this study. After smearing, fixing and staining, the root canals were treated with periodic-acid-schiffs (PAS) method. Finally, the samples were observed under a microscope and the clinical data and results of PAS staining were analyzed. Results: The positive rate of PAS staining was 28.44% . Remarkable differences were demonstrated in positive rates between exposed and unexposed canals. There was no obvious correlation between the results of PAS staining and clinical symptoms and signs. Conclusion: Fungi could exist in the root canals which were infected through caries, cuneiform defect and etc.

The purpose of this study was to study the relationship between genetic diversity within glucosyltransferases of Streptococcus mutans and dental caries.Methods: The isolates were collected from patients of the caries-active group harbored the Streptococcus mutans strains producing higher water-insoluble glucans and patients of the caries-free group harbored the strains with lower water-insoluble ones. The gtfBC (961一5574 bp) of the DNA from isolates was amplified by polymerase chain reaction (PCR) .Genetic diversity of gtfBC~assessed using restriction fragment-length polymorphism (RFLP) with restriction endonucle- ases: Hinf工，Mbo I and Taq I .Results: The differences in the gtf PCR-RFLP patterns among strains~revealed when di- gested with几 rd l.The number of subjects harbored the longest band 1.9 kb pattern in the caries-active group was significantly ~than the caries-free group(P<0.05).Conclusion: The genetic diversity within glucosyltransferases of isolated strains might be related to differences in the production of water-insoluble glucans.

Objective: The purpose of this study was to investigate the relationship between genetic diversity within A-region of surface protein of Streptococcus~(serotype c) and their binding abilities. Methods: The clinical isolates of S. mumps (serotype c) included two groups with different binding abilities (cpm > 2000, cpm<1000)，which were derived from former work in our ex- perimental lab. The bacterial DNA~extracted, and the spaP-a (473一1571饰)~amplified using polymerase chain reaction (PCR)。Genetic diversity of spaP-a~assessed场using restriction fragment-length polymorphism (RFLP) with restriction endo- nuclease Hae.Results: Four different patterns of the spaP-a PCR-RFLP among strains were revealed when digested with Hae皿. The proportions of four genotypes of strains with different binding abilities were different(P<0.05).Conclusion: The genetic di- versity exists within the spaP-a(盯3一1571 bp) of the clinical isolates of S.~( serotype C ).The diversity of strains with higher binding ability was~apparent than those with lower one.

Objective:'The aim of this study was to establish a combined culture model of A/J mouse embryonic palatal shelves mesenchymal and epithelial cells (palatal cells)，and study their biological behavior in vitro. Methods: The A/J mouse embryonic palata cells were harvested from 13-day-old A/J mouse fetus by dissection and sequential digestion with 0.25 % trypsin. The isolated cells were cultured in DMEM/F-12 medium and observed by phase-contrast而croscope, flow cytometer, cytoskeleton staining and PGE2-RIA. Results: The embryonic palatal mesenchymal and epithelial cells grew well and, their morphology and cytoskeleton did not change in vitro. The cells were full of abundant protein and DNA, and had strong ability to metabolize and proliferate Conclusion: The mesenchymal and epithelial cells of A/J mouse embryonic palatal shelves in this combined culture system can keep their basic biological behavior.

Objective: Both ODF (osteoclast differentiation factor, a newly identified member of the tumor necrosis factor super-family) and M-CSF (macrophage colony-stimulating factor) are indispensable for OC (osteoclast) formation. The purpose of this study was to test the possibility that the combination of ODF and M-CSF was sufficient for OC development in primary murine marrow cell culture. Methods: Bone marrow cells were isolated from 5- to 6- week-old mice and incubated in M-CSF (10 ng/ml). After 24 hours, non-adherent cells were harvested and resuspended in a-MEM /BCS. The suspension was added to the wells of 24-well plates with different concentration of ODF and/or M-CSF. TRAP (tartrate-resistant acid phosphatase) staining was used to identify OC. The bone resorption pits on slices of bovine cortical bone were examined with inverted phase contrast microscope, and the changes of Ca2+ concentration in the medium during whole culture period were measured by atomic absorption spectrophotometer. Results: When bone marrow cells were cultured for up to 11 days either in the presence of M-CSF (10 ng/ml) or ODF (50 ng/ml) , no cells expressing TRAP and bone obvious resorption was found. But in the presence of ODF and M-CSF, many TRAP-positive mono- and multi-nucleated cells were formed after 7 days. The number of TRAP-positive miJti-nucleated cells and the change of Ca2+ in the culture medium increased dose-dependently with ODF concentration. Conclusion: The combination of ODF and M-CSF can induce OC formation and bone resorption in murine marrow cell culture, and it can be employed to investigate the direct effects of factors on OC differentiation and activation.

Objective: The purposes of this study were to analyze the expression of 70 kD heat shock protein in the condyle of young rats after unilateral mastication, and investigate the mechanism of temporoinandibular joint disease caused by unilateral mastication. Methods: A total of 12 Wistar rats aged 4 weeks were divided randomly into the control and experimental groups, and the right upper and lower posterior teeth of rats in the experimental group was ground to the gingival level without occlusal contact. HE staining and immunohistochemical methods were performed to evaluate the expression of HSP70 eight weeks after the experiment. Results: The HSP70 was expressed in different areas of the temporomandibular joints, and the staining intensity and location of the positive signals in the mastication side of the temporomandibular joint were stronger than that of the non - mastication side. Conclusion : Elevated HSP70 expression can be found in the condylar cartilage of young rats after unilateral mastication. Further study is necessary to clarify the mechanism of unilateral mastication leading to temporomandibular joint disorder.