Objective:The purposes of this study were to clone and sequence the major histocompatibility complex typeÑ(MHCÑ) molecular antigen recognizing gene (H-2Kk) of 615 mice, and to provide the functional gene for transgenic therapy.Methods: The 1.4 kb full-length fragment of H-2Kkgene complementary DNA (cDNA) was amplified from the total RNAof 615 mouse liver by using reverse transcription polymerase chain reaction (RT-PCR). The cDNAwas inserted into PGEM3Zf(+) vector direction- ally, and the competentE.coliJM109 was transformed with the ligated product. The recombinant PGEM3Zf(+)-H-2KkcDNA plasmid was obtained using restricted enzyme analysis of the transfectants. The complete sequence of 615 mouse H-2KkcDNAwas determined by using Sangercs method.Results:The sequences of 615 mouse H-2KkcDNAwere 99% similarwith those of H-2Kk cDNAwhich were reported by other researchers, and the sequences encoding antigen recognizing regions (ARS) were identical with each other.Conclusion:The authors cloned the MHCÑmoleculur antigen recognizing gene (H-2Kk) of 615 mice success- fully and got the functional gene of MHCÑ.

Objective:The purpose of this studywas to investigate effects of cryotreaton the corrosion resistance of SDA-II mediummelt- ing-point castable alloy.Methods:12 samples were divided into three groups, including the control group, the cryotreated group and the cryotreated&post-cryogenic treated group. The cryotreating process was firstly dropping the temperature from room tem- perature to-170ewith dropping rate 3e/min, maintaining-170efor 2hrs, and then returning to ambient temperature with an increasing rate of 1e/min. The post-cryogenic process was maintaining the samples in 300efor 1hr. Finally, all sampleswere subjected to the electrochemical potentiodynamic polarization after immersed in the artificial saliva (ISO/TR10271:1993(E), pH 6.8) for 24hrs at ambient temperature. The exposing area of each sample was 10 mm@10 mm. The electrochemical tests were carried out in the artificial saliva under 37e, with the scanning rate of 20 mV/min, starting potential -200 mV below OCP and stopping current 10-3A. The corrosion currents (Icorr), the pitting corrosion potentials (Eb) and the potentiodynamic polarization curves were observed using the 283 electrochemical corrosion measuring system automatically.Results:For SDA-II medium melt- ing-point castable alloy, cryotreat reduced corrosion rate of the alloy, buthad no effecton the pitting corrosion potential. As far as the post-cryogenic treatment, it didnct affect the corrosion resistance.Conclusion:The results suggested that cryotreatwas an ef- fective procedure in enhancing the corrosion resistance of SDA-II mediummelting-point castable alloy, and itmay be applicable in prosthetic dentistry.

Objective:This study aimed atfinding sensitive indicators in diagnosing facial growth pattern by studying the relationship be- tween the indicators which can reflectfacial growth pattern according to the previous studies and posterior-anterior ratio.Methods: The cephalometric radiographs of 61 teenage children were measured, the posterior-anterior ratio and the other 12 indicators in- cluding Y-axis angle, facial axis angle, cranial basal angle, and the four angles (The sagittal horizontal planeswere analyzed using statistic methods.Results:The MP-SN angle was significantly coincided with the posterior-anterior ratio and Pearson coefficient is -0.922, and little correlation was found between the angles of four sagittal horizontal planes and the posterior-anterior ratio. The positive correlation was found between the length of mandibular ramus and posterior-anterior ratio.Conclusion:The sensitive indi- cators for confirming facial growth pattern are the posterior-anterior ratio and the MP-SN angle.

Objective:This investigation aimed at explore the total distribution of neuropeptide Y-like immunoreactive (NPY-LI) fibers and their changes post-trauma in rat temporomandibular joints (TMJs).Methods: Six groups of rats were killed individually before trauma, 1, 3, 7, 14 and 28 days after trauma. TMJs were extracted totally, and the avidin-biotin-peroxidase complex method and image analysis were employed to detect NPY-LI fibers in frozen sections of TMJs.Results: NPY-LI fibers were distributed extensively in TMJs, except the central disc band and bone, and they were mainly located around blood vessels, especially arteries. The densities of fibers in the six groups were 160.4±27.5, 95.8±16.4, 88.6±14.5, 114.3±17.0, 135.0±20.7, 158.6 ±19.5(unit:mm+2).Conclusion: NPY-LI nerve fibers are distributed extensively in the periphery of blood vessels of TMJs and densities changed dynamically when TMJs were impacted. NPY may play an important role in pathologic change of TMJ by regulating local blood circulation.

Objective:The purpose of this study was to observe the healing process of palate wound with denuded bone restored with transplanted buccal or palatal mucosa and to elucidate the mechanism of maxillary growth inhibition following palate repair.Methods: 32 Japan white rabbits, 5 weeks old, were selected as the subjects for this study. They were divided into 4 groups at random. The rabbits in group I was the control without receiving any treatment. The rabbits in group II, III, IV was surgically denuded the bone of palate, and afterwards, the rabbits in group II were not received further restoration, but rabbits in group III and IV were restored with transplanted buccal and palatal mucosa respectively. From 2 to 14 weeks after surgery, at regular intervals, palatal wounds were observed by using a light microscope. Histological changes were also compared among different groups.Results: It was found in group II that dense connective tissue was formed 2 weeks after the surgery, and Sharpey′s fibers was formed between the scar and bone tissue 4 weeks after the surgery. However, no Sharpey′s fiber was found in group III and group IV, and in the latter two groups, the histological character of tissue was similar to that of the control.Conclusion: Prevention of the attachment of Sharpey′s fibers to the palatal bone could be effectively accomplished by covering the denuded palatal bone with the transplanted buccal or palatal mucosa.

Objective:The aim of this study was to set up an animal model of osteoarthritis (OA) in the rabbit temporomandibular joint (TMJ).Methods:0.3 ml of 1.6% papain solutionwas injected into the upper compartment of each leftTMJ of six Japanese big ear white rabbits, and the same volume of saline was injected into the upper compartment of leftTMJ as control. The rabbitswere sacrificed 2, 4, 6 weeks respectively afterinjections and the TMJ specimenswere pathologically examined.Results:The degenera- tive changes were demonstrated in the TMJs injected with papain,such as thinner articular cartilage, fibrillation and destroyed car- tilage matrix, and inflammation, proliferation, and degeneration of the synovial tissue. All these changes were much worse with prolonged observation time. Some kinds of reparative changes appeared in the sixth week after papain injection.Conclusion: Pathological similarities between papain induced rabbitTMJ osteoarthritis and human TMJ osteoarthritiswere observed. This animal model has good reproducibility and hence can be used for exploring pathogenesis of this disease and selection of treatments for os- teoarthritis of TMJ.

Objective:The purpose of this study was to study the masticatory muscles affected by distraction osteogenesis of the mandible.Methods:The distraction osteogenesis (DO) was applied to distract the leftmandible of 6 mongrel dogs thatwere divid- ed into three experimental groups. After different distraction phase and consolidation phase, the masseter and the digastric muscle were taken out. The specimenswere stained using hematoxylin/eosin and enzyme histochemistry. Afterwards, the specimenswere observed with a light microscope to study the morphologic changes of the muscles. The contents of enzyme in the different groups were measured by VIDAS.Results:The masseter showed consequently atrophy, but the digastric muscle showed a progress of his- tomorphologic reconstruction, including atrophy and hypertrophy. The changes of the contents of enzyme and histomorphology were identical in the masticatory muscles.Conclusion:The digastric muscle parallel to the vector of mandibular distraction adapts the distraction by the way of atrophy, regeneration and hypertrophy. And the contents of enzyme appear to decrease at the beginning, increase afterwards, and return to the normal level finally. But the masseter perpendicular to the vector of mandibular distraction shows consequent atrophy, and the contents of enzyme consequently decrease, which means the metabolism decrease.

Objective:The purpose of study aimed atinvestigating the technique of culturing oral epithelia in vitro and to setup an exper- imental model for further reconstructing oral mucosa in vitro.Methods:The oral mucosa was taken from young NewZealand rab- bits, and the mucosa was digested with enzyme and suspended in liquid to form cellular suspension. Being seeded, the cellswere cultured motionlessly. The mediumwas changed regularly and the cellswere subcultured.Results:The cultured cellswere all ep- ithelial cells without fibroblasts, and they were proved to be diploid cells. The cellswere subcultured in 1~13 generationswhich survived for50~60 days.Conclusion:The oral epithelium of youngNewZealand rabbit can be cultured in vitro, maintaining the ability to proliferate in a certain period. It is a pilot study to reconstruct oral tissue in vitro.

Objective:The purpose of this studywas to evaluate the advantages and disadvantages of vascularized free fibula flap as a new method for mandibular reconstruction.Methods:25 cases (17 male to 8 female)who have received mandibular reconstructionwith free vascularized fibular flaps in ourhospitalwere studied retrospectively. The average length of the fibula grafts is1010 cm (range from 515 to 16 cm). 3 cases received primary insertion of osteointegrated dental implants into the free fibula flap, and all these 5 implants survived.Results:All flaps except 1 were viable. 62% of the cases took normal diet postoperatively, and the remainder took soft diet as well. All patients spoke clearly. No ankle unstability was reported. And the aesthetic assessments in all patients were good or fair.Conclusion:Vascularized free fibular flap takes its distinct advantages to other autogeneous free bone flaps and is confirmed to be one of the optimal methods for mandible reconstruction by our study.

Objective:This study aimed at investigating effects of exogenous interleukine-10 (IL-10) on IL-6 and intercellular adhesion molecular (ICAM-1) expression in inflamed gingival tissue.Methods:The expression of IL-6 and ICAM-1 was examined using im- munohistochemical techniques. Inflammatory gingival tissue treated with IL-10 was taken as the experimental group and the same patient.s inflammatory gingival tissue without treatment of IL-10 was included into the control group.Results:IL-6 expression was found mainly in monocytes, macrophages, lymphocytes, endotheliocytes and fibroblasts. The expression of ICAM-1 was found mainly in epithelial cells, monocot-macrophages, lymphocytes, endotheliocytes and fibroblasts. The immunohistochemical optical density (IOD) of the expression of IL-6 and ICAM-1 was detected by using Image-Proplus software, and the results showed thatthe expression in the experimental group differed significantly from that in the control group.Conclusion:The exogenous IL-10 may down-regulate IL-6 and ICAM-1 expression in inflammatory gingival tissue.

Objective:The aim of this study was to investigate the features of mast cell subtypes and relationship between mast cells and pathogenesis of oral lichen planus.Methods:Mast cells in the tissue of oral lichen planuswere stainedwithAlcian blue /safranine in order to demonstrate mature and immature mast cells, and the constituent ratio of these two subtypes was calculated. After- wards, LUZEX-F image pattern analysis system was applied to demonstrate the size of these two subtypes and their morphological features.Results:The constituent ratio of mature and immature types of mast cells in the tissue of oral lichen planus was signifi- cantly different from that in the normal tissue (P<0101), and such difference was also demonstrated among different types of this malady, including papule-, net- and erosion-type of oral lichen planus (P<0105). There was significant difference between the sizes of mature and immature mast cells (P<0101) and also the sizes, amount and distribution of the plasma granules within these two mast cells.Conclusion:It could be implied that mast cells might play a role in the pathogenesis of oral lichen planus.

Objective:This study was designed to find out the changes in microflora on the stress-bearing areas after insertion of remov- able partial dentures, and in turn to explore the difference between such changes caused by metal bases and acrylic resin bases re- spectively.Methods:Sixteen patients who were ready to accept removable partial dentures were selected and divided into two groups. Eight patients used metal baseswhile the other eight patients used acrylic resin bases. Then at the following three points: before dentureswere inserted, one month afterwearing and three months afterwearing, the total cultivable flora were counted and the proportions of bacteria detected on the stress-bearing areaswere calculated.Results:No matterwhat type of baseswas select- ed, the wearing of removable partial denture enhanced the accumulation of microflora on stress-bearing areas. The percentages of Candida albicansandLactobacillidetected on stress-bearing areas also increased significantly (P<0.05). When such changes were compared, the authorsfound thatthe incrementofCandida albicanscaused by acrylic resin baseswas higherthan that caused by metal bases (P<0.05).Conclusion:The wearing of removable partial dentures forms new retention areas between the bases and the stress-bearing areas, as a result enhances the deposit of microbe and facilitate the growth ofCandida albicansandLacto- bacilli. Compared with increment ofCandida albicanscaused by metal bases, the increment relating to acrylic resin bases ismore evident.

Objective:The skeletal ClassÓmalocclusion often occurs in ethnic Asia population, and it is difficult to obtain an ideal re- sults if only treatedwith protraction headgear (PH). However, the combined rapid palatal expansion (RPE), Edgewise Technique and PHcan reach it, so the authors investigated the methods and characteristics of combined RPE, Edgewise Technique and PHin the treatment of skeletal ClassÓmalocclusion.Methods:Fifteen patients, aged 8.5~12 years, including six males and 9 fe- males, with skeletal ClassÓmalocclusion and maxillary retrusionwere selected for this study. Radiographs of left hand and wrist showed that all patients were at the pre-pubertal stage. The duration of treatmentwas nine months on average.Results:The SNA and A-ptm increased with a mean of cephalometric analysis, which showed significant difference (P<0.05).Conclusion:Obvi- ous skeletal and profile changes can be achievedwith combined RPE, Edgewise Technique and PHin the treatmentof early skele- tal ClassÓmalocclusion.

Objective:The purpose of this study was to evaluate the effects of squamous cell carcinoma on oral bacteria.Methods:This study investigated the microbial contents of the plaque on the surfaces of oral squamous cell carcinomas. Samples were obtained from the central surface of lesions, contiguous healthy mucosa and saliva of 42 patients with oral squamous carcinoma before and after operation.Results:The median of bacterial colony forming units per milliliter (CFUs/ml) of saliva before operation was 8.10@108CFUs/ml. The median of CFUs per square centimeterof the tumor surface was5.21@105CFUs/cm2whichwas signif- icantly higher than that of the healthy (the control) mucosa (1.77@104CFUs/cm2,P=0.0001). The CFUs per square cen- timeterof mucosa surface at the operative zone was 4.34@105CFUs/cm2which was also significantly higher than that of the healthy (control) mucosa(7.24@104CFUs/cm2,P=0.0001).Conclusion:Oral carcinoma can break the balance of oral mi- croflora, which may be one of the reasons leading to the high susceptivity of these compromised patients to systemic infection.

Objective:The purpose of this study was to evaluate the effects of the exogenous phosphatase and tensin homology deleted on chromosome 10 (PTEN) gene on in vitro growth of the highly metastatic mucoepidermoid carcinoma cell line M3SP2.Methods: The growth of the exogenous PTEN transfected mucoepidermoid carcinoma cells M3SP2-PTEN gene was studied by analyzing cell growth curves, mitosis index and clone formation efficiency and compared with its parental cell line M3SP2and the vector pBabe- puro-transfected cell line M3SP2-pBp.Results:The doubling time (h) ofM3SP2, M3SP2-pBp andM3SP2-PTENwere 24.50, 24. 76 and 31.74; the mitosis index(j) were 53.0?6.20, 49.0?5.24 and 16.2?3.2; the clone formation efficiency (%) were 37.37, 35.01 and 10.40, respectively. The M3SP2-PTEN cells also revealed 57.05%~71.46% inhibition of growth from day 3 to7 and 65%~72% inhibition of clone formation compared with the parental cells.Conclusion:These data provide evidence that the exogenous wild-type PTEN have remarkably inhibitory effects on in vitro proliferation of the highly metastatic mucoepidermoid carcinoma cell line M3SP2.

Objective:The purpose of this study was to determine the thermal, mechanical properties and density of the composite infiltrated with GI-Ⅱtinted infiltration glass.Methods: The bar-shaped aluminum oxide and glass/alumina composite specimens with the size of 20 mm×5 mm×5 mm were prepared, with two free-end surfaces perpendicular to the long axis of the specimens and parallel to each other. The thermal expansion curves were obtained on a TMA2940 thermal analyzer with heating rate of 5℃/min and temperature range of 25℃ to 1000℃. The bar-shaped specimens with the size of 25 mm×5 mm×2 mm were fabricated and employed to test the density using Archimede’s method. The flexural strength, elastic modulus were measured by means of 3-point bending test with the same specimens. The fractured specimens were indented with Vicker’s diamond pyramid under load of 49 N for 15 seconds to determine the hardness and indentation fracture toughness.Results: The thermal expansion coefficient of the glass/alumina composite was 7.620×10+{-6}℃+{-1}(25～500℃), which was higher than that of Vitadur alpha veneering porcelain. The 3-poit flexural strength, elastic modulus, Vicker’s hardness, indentation fracture toughness and density were 389.6 MPa, 92 GPa, 9.409 GPa, 3.2425 MNm+{-3/2} and 3.662 g/cm+3 respectively.Conclusion: The thermal expansion of the GI-Ⅱ glass/alumina composite is compatible with that of Vitadur alpha veneering porcelain, and the material could meet the strength demands for clinical use.

Objective:The purposes of this study were to determine the spectral transmittance of GI-Òglass/alumina composites and to explore the effects of different specimen thickness and firing arts of glass infiltration on the transmittance. Datawere comparedwith those of Vita In-Ceram Alumina materials.Methods:Plate-shaped specimens 1215 mm in diameter, with 3 thickness (015, 110, 115 mm), 6 colorgroups forGI-Òand 4 colorgroups forVita In-CeramAlumina were fabricated. Specimens of colorAL2 for In- Ceram and IG2 forGI-Òwere selected in the study of relationship between different infiltration arts and transmittance. Five infil- tration time duration and three temperatureswere studied. A spectrophotometerwith standard A light source paralleled lightbeam 5 mm in diameter and spectra range 380~780 nmwas employed to measure the spectral transmittance.Results:The range of spec- tral transmittance were 217%~415% for GI-Òand 214%~512% for Vita In-Ceram Alumina. Transmittance decreased with specimen thickness, buttheywere not linearly related. Transmittance ofGI-Òtended to increase and thatofVita In-CeramAlumi- na decreased as the infiltration temperature elevated. The transmittance increased with infiltration time less than 4 hours and re- ducedwith prolonged time over 6 hours for both materials.Conclusion:GI-Òglass/alumina composite has comparatively lower translucency. Influences of factors as color, thickness and infiltration arts on translucency of restorations should be considered in the clinical selection of the all-ceramic materials.

This study aimed at investigating the transcription and expression of recombined plasmid pcDNA3-gtfB which en- coding multiple glucosyltransferase-B antigenic gene, and the feasibility of the pcDNA3-gtfB used as gene vaccine.Methods:The pcDNA3-gtfB was transfected intomammalian cell COS-1 with liposome. The total RNAof COS-1 cell transfected by pcDNA3-gtfB was extracted and purified. Using the total RNAas template, the transcription of pcDNA3-gtfBwas assayed by reverse transcription polymerase chain reaction (RT-PCR). The expression product of pcDNA3-gtfB was identified with 5% SDS-PAGE, and then as- sayed usingWestern-blotting. The expression productof pcDNA3-gtfBwas also assayed by using LSAB method, and cell transfect- ed by pcDNA3 as the negative control.Results:Identified by agarose gel electrophoresis, the target gene fragment had the same molecular size (316 kb) as itwas predicted, and it indicated that pcDNA-3gtfB was correctly transcribed into mammalian cells. Proved by SDS-PAGE, the molecularweightof the expression product(116~212 kD) was also the same as itwas supposed to be. Itwas also indicated by Western-blotting and LSAB assay that the expression product induced immunizing response.Conclusion: As gene vaccine, itis importance that the recombined plasmid could be correctly transcribed and expressed inmammalian cells. It was suggested by RT-PCR, LSAB and Western-blotting that recombined plasmid pcDNA3-gtfB could be correctly transcribed and expressed in mammalian cells, and the expression product could induce immunizing response, which support its use as gene vac- cine candidates in the development of anticaries vaccines.

Objective:Glucosyltransferase-B (GTF-B) ofStreptococcus mutanshas been implicated as a principal virulent factor in the development of dental caries. The objective was to use recombined plasmid pcDNA-gtfB expressing multiple antigen of glucosyl- transferase-B as gene vaccine to immunize rats through different route, and to investigate the immunization effects of immunization routes.Methods:Atotal of 18 Wistar ratswere divided into 3 groups, including the quadriceps injection group, the intranasal irri- gation group and the submandibular gland-targeted injection group. The serum IgG and salivary IgAwere assayed by using ELISA afterpcDNA3-gtfB immunization. The serum IgG and salivary IgA in different groups were compared using statistical one-way ANOVA.Results:Compared these 3 groups, the serum IgG in the quadriceps injection groupwasmuch higher than those of other two groups (P<0.01), while the salivary IgA of the submandibular gland-targeted injectionwas much higher than those of other two groups (P<0.01).Conclusion:It is indicated pcDNA3-gtfB is good candidate for anticarious gene vaccine, and sub- mandibular gland-targeted injection is an effective immunization route for stimulating salivary IgA.

Objective:The purpose of this study was to establish two-dimensional magnetic field finite element analysis model of cup- yoke-type magnetic attachment for optimizing the design of magnetic attachments.Methods:Because the magnetic field of cup- yoke-type magnetic attachment is stable axial-symmetrical, the authors only analyzed two-dimensional magnetic field of 1/2 sec- tion. The Maxwell stress betweenmagnet and keeperwas integral analyzed using the finite elementmethod, and the attractive force between magnetic attachments was obtained.Results:Compared the value of calculated attractive force with that of examined, the authors found that the procedure veritably reflected influencing trend of variable factors on attractive force, and the value of former one was 10% less than the laterone.Conclusion:This procedure can be used inmagnetic field calculation of cup-yoke-type mag- netic attachments.

Objective:The purpose of the study was to investigate the prevalence of oral malodor in a group of health cohorts in Cheng- du, China by using different diagnostic methods.Methods:Volatile sulfur compounds (VSCs) level was evaluated by using HalimeterÒ.The organoleptic score and tongue coating index were also evaluated. A questionnaire interview was conducted at the same time.Results:There were 21.61% subjects whose oral VSCs level were more than 300 ppb. No significant difference was found between male and female for the VSCs values. The subjects with malodor (score\6) evaluated by organoleptic score were 28.91%,and the difference between the male and female was significant (P<0.05). Further, a significant correlation could be detected between the VSCs level, organoleptic score and tongue coating index (P<0.05).Conclusion:The study indi- cates that nearly one of fourth people sufferfrom oral malodor. Malodor has significant correlationwith tongue coating, so cleaning of tongue dorsum is very important to reduce oral malodor.