Objective　To investigate the effect of specific anti_streptococcus mutansIgY againststreptococcus mutanson dental caries development in rats.Methods　35 wistar rats were divided into 5 groups: group A received IgY gargle; group B received IgY lyophilized powder; group C received sterilized water as control; group D and E received egg yolk food with orwith- out specific IgY individually. Theywere all fed with caries_inducing diet 2000#. The number of caries scoreswas counted by the procedure of Keyes′.Results　There was a significant lower mean of caries scores in groups treated with IgY lyophilized powder and gargle. Bytreatingwith egg_yolk food contained specific IgY, the mean of caries scores decreased comparingwith notreatment group.Conclusion　Local passive immunization with specific anti_streptococcus mutans IgY may be an effective way to prevent the development of dental caries.

Objective　To observe the expression patterns of matrix metalloproteinase-3 and its inhibitor, tissue inhibitor metalloproteinases (TIMP)-1, in remodeling phase of mandibular distraction osteogenesis.Methods　Bilateral mandibular osteot- omies were performed in 8 mature rabbits. The mandibles were lengthened 6 mm using a custom-made distractor with a rate of 1 mm/d. All animals were killed in 4 weeks after completion of distraction. The distracted calluses were harvested and processed for histology and immunohistochemistry of MMP-3 and TIMP-1.Results　Elevated expression of both MMP-3 and TIMP-1 was found in the distracted calluses resulting frommandibular lengthening. Positive staining forMMP-3 was seen in the osteoblasts and osteocytes, and TIMP-1 was mainly localized in osteoblasts.Conclusion　MMP-3 and TIMP-1 appear to play important roles in the remodeling of new bone created by mandibular distraction osteogenesis.

Objective　To studythe roles of the Notch2-Delta signaling in the differentiation of dental pulp cells into odon- toblastsin vitro.Methods　A long-term culture system was used as a model for the study of proliferation and differentiation of pulp cells into preodontoblasts. The expression patterns ofNotch2and its ligand Delta in different phases of long-term cultured den- tal pulp cellswere studied by immunohistochemistry andwestern blotting. Furthermore, the effects of rhBMP-2 on the expression of Notch signaling members were studied.Results　Notch2and its ligand Delta expressed in all phases of dental pulp cells and the sites and levels of their expression changed with different phases. rhBMP-2 could significantly up-regulated the expression of Delta in the phase of later cell nodule formation.Conclusion　This study demonstrated that Notch signaling pathway played roles in the differentiation of long-term cultured human dental pulp cells which formed nudules that were slightly mineralized and had ul- trastructural features reminiscient of preodontoblasts, and it may be the mechanism that control pulpal cell’s responsiveness to sig- naling molecules in the healing of wound pulp.

Objective　To establish human periodontal ligament fibroblasts (HPDLFs) that express bone morphogenetic protein 2 and observe their osteogenesisin vivo, so as to provide fundamental data for future study on gene therapy of periodontal defect treatment.Methods　The phagemid expression vector for BMP-2 (pBK-B2) was transfected intoHPDLFs by usingLipofect AMINE. The BMP-2 expressionwas determined by immunohistochemical ABCmethod. The BMP-2 gene transfectedHPDLFswere injected into thigh muscle of nude mice under sterile condition. Specimenswere collected in 21 days after injection and underwent normal procedures forfixation, decalcification, embedding, incising and stainingwithHE.Results　The results demonstrated that BMP-2 protein expressed in HPDLFs after BMP-2 gene transfection. The HPDLFs transfected with BMP-2 gene could induce new bone formation at the injection site.Conclusion　The results indicated that BMP-2 gene was transfected successfully and ex- pressed efficiently in HPDLFs. The HPDLFs transfected with BMP-2 gene are capable of inducing new bone formationin vivo.

Objective　To elucidate the molecular structure of pyruvate oxidase gene promoter.Methods　The 1·30 kb fragment with promoter activity, amplified from upstream ofStreptococcus oralispyruvate oxidase gene (Sopox), was cloned into vector PBK-CMV. The positive transformedE.coliJM109 clone was selected, the recombinant plasmidwas further identifiedwith restriction mapping analysis. The positive recombinant plasmid was studied with sequence analysis.Results　After digesting the recombinant plasmid withHindⅢ, 1% agarose electrophoresis showed 1·30 kb fragment, which was consistent with predicted size. Sequence analysis revealed 1 350 bp.Conclusion　TheSopoxpromoter region is sequenced. Further characterization of the Sopoxpromoter region will elucidate the molecular mechanism of H2O2production ofstreptococcus oralis.

Objective　To investigate the antigenicity of the peptide vaccineHDS fromStreptococcus mutansglucosyltrans- ferase and its ability to induce protective immune responses in an experimental ratmodel of dental caries.Methods　Artificial an- tigenHDS-KLH, peptide HDS, glycosyltransferase were injected to immunize rats. Measurement of the specific anti-HDS,GTF IgG or IgA concentration in saliva and serumwere undertaken by ELISAamongthe experimental groups. Gnotobiotic ratmodelwas developed when challengedS.mutansand a caries promoting diet. The jaws of the ratswere selected and dyed. The Keyes caries score for each jawwere counted.Results　The level of serum and salivary specific anti-HDS IgG and IgA in the group immunized by HDS-KLHwas significantly higher than that in control group (P<0·05). The Keyes caries score of GTF,HDS andHDS-KLH immunized group were significantly lowerthan that of control group, especially lower in smooth tooth surface.Conclusion　Artifi- cial antigen HDS-KLH could induce immune response. As a peptide vaccine, HDS-KLH could reduce the caries incidence in ex- perimental rat model.

Objective　The purpose of this studywas to evaluate the morphological changes of Er,Cr:YSGG laser irradiat- ed dental hard tissues by scanning electron microscopy (SEM).Methods　12 freshly extracted premolarswere treatedwith fissure bur, Er,Cr:YSGG laser at 4 watt, Er,Cr:YSGG laser at 6 watt, respectively, and then bisected transversally and longitudinally. The tooth slice were prepared with conventional methods and observed by SEM.Results　Compared with fissure bur, laser treat- ment resulted in a rather scaly and rough surface. The sectionswere free of smear layer, with open dentinal tubules. No carboniza- tion and thermal damages were observed. The laser at 6 watt appeared rougher than at 4 watt, occasionally caused micro-cracks. Conclusion　The utilizing of Er,Cr:YSGG laser can contribute to enhance the bond strength between restorative materials and dental hard tissues. It suggests that higher energy could be applied in cutting enamel, whereas the lower energy in dentin.

Objective　The purpose of this studywas to offer pathological reasons for partial parotidectomy adopted in pa- rotid pleomorphic adenoma treatment.Methods　Continuous slices from 25 cases of primary parotid pleomorphic adenoma were carefully examined and the extra-envelope infiltration, the budding and the primary multi-centerwere measured and recorded.Re- sults　The range of extra-envelope infiltration and buddingwas limited in 0·09~0·285 mm out of tumor capsules, whichwas far less than the safe boundary(1 cm)of the partial parotidectomy. Two cases with multi-centers were found, but all the centers were aggregated together and encapsulated in a united envelope.Conclusion　Partial parotid parotidectomy is a safe method and can remove the tumor completely in parotid plemorphic adenoma treatment.

Objective　To prepare the controlled-release delivery gutta-percha points containing metronidazole compound (CDGMC) and to determine its release ratein vitro.Methods　The drug points were made by using compound drugs and gutta- percha as a carrier, and CDGMCwere prepared followed by enveloping a release membrane outward. The best formulawas select- ed according to the release parameters of the drugs extracted in the release experimentsin vitro. The CDGMCwere placed into the extracted teeth after root canals were routinely prepared. The non-drug CDGMC was used as the control. The absorbency of the drugs in normal saline (37℃,pH7.4) was determined timely. The percentage of release and cumulated release of the drugswere calculated according to the concentrations of drugs in medium.Results　Thein vitroexperiments showed that this system con- tained 1 880μg ofmetronidazole and 267μg of ciprofloxacin. The experiments in healthy single root canal showed thatthe drug re- lease amounts around the perioapical areawere metronidazole 88·54μg/ml and ciprofloxacin 9·05μg/ml in 10 days.Conclusion　 CDGMC can continuously release effective drug concentrations more than 10 days and could be considered as an ideal method for clinical application.

Objective　To retrospectively investigate the effectiveness of sphenzygomatic suture as a guide in the reduction of zygomatic complex fracture.Methods　55 cases of zygomatic complex fracture classified according to Zingg classification were treated, sphenozygomatic suture in group 1 (n=36) was reduced first, then the otherfracture linewas reduced, in group 2 (n= 19), malar bone was reduced according to superficial fracture line. Patients were followed up for 4 weeks to 3 months, aesthetic result and X-ray symmetrywere observed.Results　All patients in group 1 were restored with satisfactory facial contour, 35 cases got precise reduction, 5 cases in group 2 were asymmetry.Conclusion　During open reduction of complex zygomatic fracture, sphenozygomatic suture should be reduced at first as a guide, so as to get precise zygomatic complex reconstruction and normal aesthetic outcome.

Objective　To evaluate thein vivoretentive forces of mandibular complete overdenture with Magfit attach- ments, as well as the relation between the location of magnetic attachments and the retentive forces of the denture.Methods　5 patients were selected and treated with mandibular complete overdentures retained by Magfit EX600 and MD800 attachments. A strainometerwas used to measure the retentive forces in anterior, central and posterior parts of the overdenture before and after magnets were set. The vertical and anterior-upper 60°retentive forces of the overdenture were measured one month later.Results　 The retentive forces of the overdentures after setting magnets were significantly greater than that before magnets were set (P< 0·05).There was no significant difference in retentive forces between the different parts (P>0·05). The retentive force in verti- cal direction was greater than that in anterior-upper 60°direction (P<0·025).Conclusion　Magnetic attachments can signifi- cantly improve the retention of mandibular complete overdenture. The location of magnetic attachments greatly influences the re- tentive force of the overdenture.

Objective　The purpose of this study is to evaluate the effect of therapeutic complete denture in rectifying malmaxillomandibular relation of complete.Methods　11 patients were treated with therapeutic complete denture, of which the maxillary premolars and molars were artificial ceramic teeth and mandibular premolar and molar region was just like a splint. The changes before and after the treatment were recorded by mandibular kinesiograph(MKG). The effectwas evaluated by seft-control comparison.Results　After rectifying, the concentration of the closing locus end position evidently increased, the symmetry of mandible motion significantly improved, CRO-ICO three-dimensional slide range decreased and moreover, the teeth had even and stable contact during sliding.Conclusion　The temporary therapeutic complete denture had a fair effect in rectifying malmaxil- lomandibular relation of edentulous patients.

Objective　Clinical data of burning mouth syndrome were investigated in detail and the relation to pain was analyzed in orderto find a clue to clinical treatment.Methods　78 patientswith burningmouth syndrome were examined carefully and 7 factors that related to the degree of pain were analyzed with multivariate stepwise regression.Results　The study demon- strated that the psychological disorder, autonomic nerves system abnormity, oral dryness and high_extravasated blood level were positively related to the degree of pain.Conclusion　The study suggested that psychotherapy, improvement of autonomic nerves system, treatment for oral dryness and Chinese traditional therapy of invigoration of blood circulation were of great importance in curing burning mouth syndrome.

Objective　To evaluate the application and the effect of edentulous ridge expansion(ERE) technique inmaxil- lary endossenous implant placement.Methods　49 patientswith maxillary alveolar ridge atrophy received edentulous ridge expan- sion using condenser. In order to be similar to natural root, dental implantswere selected and placed to tooth missed sites accord- ing to the requirements of aesthetics, function and dimension.Results　49 patients with atrophied alveolar ridge received 86 im- plants. The labio-lingual width augmented from 3·3 to 5·4 mm and the alveolar ridge height from 2 to 7 mm 6 months after opera- tion. The implants osseointergrated tightly with alveolar bone and second-step prosthesis was performed 6 months after implant placement.Conclusion　The edentulous ridge expansion technique can meet the requirements of aesthetics and function and is applicable to endossenous implant placement in maxilla. The method is simple and valuable to clinical application.

Objective　To examine serum IL-2 and IL-6 levels in BMS patientswith orwithout depression and make clear the relationship between serum IL-2, IL-6 and mood disorder.Methods　Serum IL-2 and IL-6 were examined in 48 BMS patients by means of ELISA. The Hamilton Depression Rating Scale (HDRS) was used to evaluate the depressive symptomatology.Results 　There was no significant difference in serum IL-2 and IL-6 among BMS patients with orwithout depression. Mood disorderwas not correlated to serum IL-2 and IL-6, but positively correlated to pain levels.Conclusion　Depression status may not influence serum IL-2 and IL-6 levels significantly, but it has a relationshipwith BMS. TheHDRS can be used to determine depression status in BMS patients in order to help clinical treatment.

Objective　To provide experimental data of different oral mucosa suitable to repair denudated palate.Methods 　Thirty Japanese white rabbits (5 weeks old) were divided into three groups:Ⅰgroup(left hard palate was denudatedwith right side intact),Ⅱgroup andⅢgroup (both sides of the hard palate were denudated with right side repaired by palatal mucosa or buccal mucosa correspondingly).Then the effect of different transplanted mucosa on preventingmaxillary deformitywas investigated and compared.Results　Maxillary development in the three groupswas same and no significant differences among themwere dis- covered.Conclusion　Buccal mucosa is effective in serving as reparative tissue for preventing maxillary deformity.

Objective　In order to introduce the laser welding technology into root-cap making, this study compared the surface characters and internal structures of laser-melted and cast post-keeper to provide experimental data for clinical application of the technique.Methods　Using untreated keeper as the control group, the surface characters and metallographic structures of the keepers were examined by stereomicroscope, metallographic microscope and SEM, and element analysis were conducted with EPMA.Results　The laser-melted post-keeper basically keptthe original smooth and the internal structure of the keeper, the heat reaction zone was extremely small and elements diffused mutually around the fusion zone obviously. While in the cast post-keeper, the surface was rough and had an oxide-layer. The internal structure changed and a fusion band formed between the base alloy and the keeper, but element diffusion was limited to the fusion zone.Conclusion　Compared with casting, laser welding technique demonstrated less influence on the surface and internal structure of the keepers.

Objective　In order to compare the influence of casting and laser welding on magnetic retentive force, the magnetic retentive forces of laser-melted and cast post-keepers of the magnetic attachments were measuredin vitro.Methods　5 cast and 6 laser-melted post-keeper specimens (Magfit MD800) were formed, respectively. Using untreated keeper as control group, the vertical magnetic retentive forces were measured by a universal testing machine.Results　The average vertical mag- netic retentive force of the laser-melted post-keeper group and the cast post-keeper groupin vitrowere(4·223 3±0·217 0)N, (3·792 9±0·296 4)N, respectively. Compared with the cast post-keeper group, the average vertical magnetic retentive force of the laser-melted post-keeper group was much higherin vitro(P<0·05).Conclusion　Laserwelding had less influence on the magnetic retentive force of the magnetic attachments than casting.

Objective　Dental caries is a transmissible infectious disease in whichS.mutansplays the major role. The purpose of this study was to detect theS.mutanstransmitted strains and non-transmitted strains by AP-PCR fingerprint for laying the foundation of study on the relation between bacterial properties ofS.mutansand its transmission.Methods　Plaque samples were obtained from buccal surfaces of 20 3~4 years old children and their mothers. Caries experience was scored by dmft (DM- FT). Diet regime, breast feeding and care of the childrenwere recorded. 200 Isolates ofS.mutanswere detected byS.mutansB medium and confirmed biochemically. DNA from each isolate was purified and AP-PCR fingerprinting was conducted. Amplicons were separated by electrophoresis in 1·5% agarose gels.Results　45 different patterns among the 200 isolateswere found. There were 10 mothers (50%) and 15(75%) children owning one genotype while 10 mothers and 5 children owning more than one (2 mothers owning 5 types). The data showed that the mothers harbored a more heterogeneous population ofS.mutansthan their children. Comparisons in genotypes between children and theirmothers discovered that 16(80%)children harbored the same geno- types as their mothers, indicating hightransmission in the group of people. Detection of theS.mutanstransmitted strains and non- transmitted strains in mothers demonstrated that 10 (50%) mothers harbored not only transmitted strains but also non-transmitted strains, suggesting that different strains had different ability of transmission.Conclusion　AP-PCR was capable of detecting the S.mutanstransmitted strains and non-transmitted strains. SomeS.mutansgenotypes had higher ability of transmission than oth- ers.

Objective　The purpose of this study is to examine the levels of salivary SIgA and serum IgG induced by pcDNA3-pac and pcDNA3-gtfB immunization, so as to testify the antigenity of the two gene vaccines.Methods　36 28-day-old Wistar rats were divided into 6 groups, among which 3 experimental groups were vaccinated with pcDNA3-pac, pcDNA3-gtfB or pcDNA3-pac combined with pcDNA3-gtfB, respectively, one positive control was vaccinated with inactive whole cell ofS.mutans JBP and other two negative controls were injected with the vector pcDNA3 or PBS buffer, respectively. All vaccines and materials were delivered with 100μg by submandibular gland injection for 3 times. Then the restricted bacterial model of ratwas construct- ed. Following that all ratswere fedwith cariogenic dietKeyes 2000#for 3 months, saliva and serum sampleswere collected to as- say SIgA or IgG levels by ELASA.Results　The salivary S-IgA levels both in pcDNA3-pac combined with pcDNA3-gtfB group and inactiveS.mutanscell group were higher than others (P<0·01). In groups of pcDNA3 and PBS buffer, they were lowest (P<0·01). The serum IgG levels in the three experimental groups and positive control were higher than that in negative control (P<0·05). It was important that salivary SIgA in groups of gene vaccine and inactiveS.mutansvaccination reached its peak at the 11th week after the first inoculation and kept until the end of the study.Conclusion　Both pcDNA3-pac and pcDNA3-gtfB can express immunogenic protein and induce immune responses of mucosal and humoral immune system in gnobobiotic rats. It is also indicated that the joint gene vaccines immunization is an optimal choice for anticaries strategy.

Objective　The purpose of this study was to evaluate the maximum binding(Bmax) and affinity(Kd value) changes of acetylcholine receptor (n-AchR) in rat lateral pterygoid muscles after functional mandibule advancement.Methods　 40 five-weeks-old male Sprague-Dawley ratswere equally divided into experimental and control group. The mimic functional appli- ances were used in experiment group and the ratswere killed after 1, 3, 7, 14 days. Radio-ligand binding assay (RBA) was ap- plied to determine the maximum binding(Bmax) and Kd value of n-AchR of lateral pterygoid muscle.Results　The Bmax of n- AchR in experimental group was higher than that in control group and the Kd value always kept in high level.Conclusion　The functional orthopedics can increase the Bmax of n-AchR in rapid growing rat lateral pterygoid muscles.

Objective　To establish an experimental model which was the masticatory myocyte culture and force stimula- tionin vitroand study the proliferation changes of cultured masticatory myocytes caused by mechanical compression in young rat. Methods　Flow cytometry (FCM) was used to examine the changes of cellular DNA content and cell cycles of cultured masticatory myocytes.Results　The DNA content in experimental groupswas higherthan that in control. Afterthe compressive forcewas ap- plied for 2 hours, the proliferation index (PI) in experimental group became higher than that in control. Under a continuous pres- sure for 4 hours, the PI in 2 000μstrain group reached the maximum (48·9%) butthe PI in 4 000μstrain group reached the min- imum (39·0%).Conclusion　The proliferation of masticatory myocytes from young rat increased under certain force and certain period of time, but decreased if the force applied was overloaded.

Objective　To compare the influence of different investment materials, methods and crown height on the cast shrinkage of full crowns made of dental base metal alloy.Methods　All of the 288 wax patternswere made and divided into three groups according to their crown height. In every group, wax patternswere invested in metal rings and paper ringswith three types investmentmaterial and castwith base metal alloys. Then the inside diameters of castingswere measured and analyzed by statistical package SPSS.Results　Differences between groups invested with the three types of material were significant(P<0·01).There were significant difference between the groups investingwithmetal rings and paper rings(P<0·01).Conclusion　The component of investment material and invested ring can affect the cast shrinkage of dental base metal alloy apparently.