The casting removable partial denture（RPD） is one of most commonly prosthesis methods in present. Vitallium is one kind of dental alloy with cobalt, chromium and molybdenum etc. It has three ranks respectively: Vitallium, Vitallium 2000 and Vitallium 2000 plus. Although the traditional casting RPD are commonly used, but it has been limited in the physical capabilities of traditional dental alloy. It would not been done to flexible design on denture especially on denture base. The elasticity of casting clasp is not good, the volume is thick. Because of the Vickers hardness and elongation of Vitallium 2000 and Vitallium 2000 plus are better than traditional dental alloys, so the RPD with Vitallium 2000 has good bending control, deformation rebound and fracture resistance. The benefit of Vitallium 2000 or Vitallium 2000 plus is the RPD with splitting can be designed for some free end clinical cases, to solve some clinical problems.

Objective To investigate and evaluate the appropriate virus titer and transfection efficiency of recombinant adenovirus p53 into the oral dysplastic epithelial cells（POE-9n） and provide reference for oral precancerosis research. Methods The transfection sensitivity of adenovirus into oral dysplastic epithelial cells was evaluated by the recombinant adenovirus p53 containing green fluorescent protein（rAd-GFP）. Different titre rAd-p53 was transfected into oral dysplastic epithelial cells to evaluate the effects of rAd-p53 on cell proliferation inhibition by MTT assay. The expression of exogenous p53 gene in POE-9n cells was detected by immunocytochemistry. Results More than 95% POE-9n cells were transfected by rAd-GFP with MOI from 100 to 500 and there was no statistical difference between different MOI values（r=0.124, P>0.05）. It was found that rAd-p53 had significant inhibition effects on POE- 9n cell proliferation with MOI from 100 to 500, and there were no significant differences at 96 h and 120 h after the transfection on cell proliferation inhibition（P>0.05）. P53 protein was well expressed in rAd-p53 transfected POE- 9n cells. Conclusion Exogenous p53 can be successfully transfected into POE-9n cells by rAd-p53 and the virus titer of MOI 100 was high enough to ensure efficient transfection.

Objective To study the change of the cracks and the influence on overall displacement of the cracked first mandibular molar under different loadings. Methods Three-dimensional finite element models of first mandibular molar with cracks of different depth and length and a control model with no crack were created firstly. Then six loading conditions were applied to the models simulating the real mastication. The changes of the cracks and displacement of the teeth under the six loadings conditions were obtained by finite element method. Results The length and depth of the cracks increased, the cracks of the occlusal surface become wider, and the crack was the widest under the fourth loading condition. Moreover, the edge of the cracks was irregular. The adjacent nodes were not in the same plane. The crack of the distal surface was the widest under the sixth loading condition. Compared to the teeth without cracks, the overall displacement of the teeth with cracks increased, but the increment was limited. Conclusion The change of the cracks is closely related to the initial crack forms and loading conditions.

Objective To investigate an efficient method of primary mandibular osteoblasts（MO） culture. Methods The mandible harvested from 24 h SD rats was stripped off all soft tissues including the periosteum, rinsed and cut to trivial bone block under sterile condition. Then the bone block was subcultured in culture flask after digested with modified repeating enzymatic digestion-adherent explants method. The proliferation of the acquired cells were examined with assay of methyl thiazolyl tetrazolium（MTT） and identified with invert microscope, immunohistochemistry stain of osteocalcin, alkaline phosphorase（ALP） stain and stain of calcified nodules. Results MTT assay showed that the cells grew slowly in 1-3 days of post-inoculation, it was cell growth adaptation period. At seventh day, the cells growth reached highest, then the proliferation of the cells was slow gradually. The cells were identified to be osteoblasts by invert microscope, immunohistochemistry stain of osteocalcin, ALP stain and alizarin bordeaux stain of calcified nodule. Conclusion The modified repeating enzymatic digestion-adherent explants method is an ideal method to obtain and culture neonatal rat′s MO having typical characteristics.

Objective To establish a finite element model of canine segmental mandibular reconstruction by partial- cortical-cutting distraction osteogenesis. Methods The geometry model was established by Mimics software via reading the data of DICOM format from CT and was cut with Magics software. The finite element model was established and was analyzed by MARC software. Results A finite element model of canine segmental mandibular reconstruction by partial -cortical -cutting distraction osteogenesis was established. The model was composed of five parts. These five parts were felted via Magics software. The Von Mises stress of the joint region of slice and the slide segment were 34.60 MPa when the slide segment was retained 1.4 mm width during distraction osteogenesis with the force of 12 N. Conclusion The biomechanics analysis can be complated through the finite element model of canine segmental mandibular reconstruction by distraction osteogenesis that retains lingual cortical bone.

Objective To study the morphologic and growing alterations of oral cancer cell line Tca8113 before and after cocultured with tumor stromal fibroblasts（TSF） and normal stromal fibroblasts（NSF） respectively, and evaluate the influence of mesenchymal cells on tumor cells. Methods TSF and NSF were isolated and cultured. To observe the morphologic change of Tca8113 cells after cocultured with TSF and NSF respectively. Results When cocultured with NSF, the Tca8113 cells proliferated as rapidly as monocultured to form colonies, while the NSF proliferated slowly to form pieces and then joined each other to form network. The NSF network segmented and surrounded the colonies of cancer cells so that the cancer cells shrank, turn round, broke away from the bottom and floated into the medium. The cancer cells proliferated actively but they were elbow out entirely in the end. TSF proliferated slowly when cocultured with cancer cells, projected several branched protrusions. The cancer cells proliferated along the two sides of protrusions of TSF, or projected short protrusions to connect the body or protrusions of TSF, and overlaid the protrusions gradually, finally, cover the body. In the end, TSF melt away, and the cancer cells took on the figure of TSF. Conclusion The results do suggest that, oral cancer cell line Tca8113 are restrained when coculture with NSF, but are promoted when with TSF.

Objective To construct a three-dimensional finite element model of reconstructed mandible and analyze the stress distributions of the model. Methods CT scan and CAD/CAM software was used to develop the three-dimensional finite element model of reconstructed mandible and stress analysis was performend with ANASYS 7.0 software. Results The three-dimensional finite element models of normal mandible and reconstructed mandible were constructed. The stress analysis discovered an unbalanced stress distribution in the mandible. Conclusion Reconstructing mandible with fibular flap not only damages its structure, but also induced the badness of its biomechanical environment, in which condyle was the most sensitive region during the stresses in the mandible were changed.

Objective To access the feasibility of employing metabonomics method in clinical studies. This pilot study intends to introduce nuclear magnetic resonance（NMR）-based metabonomics method to elucidate the metabolism of non-syndromic cleft lip and/or palate（NSCLP） patients. Methods High-resolution 1H NMR spectroscopy was performed on blood plasma obtained from NSCLP and non -malformed children. All signal of 1H NMR spectra were recognized within MESTRE -v4.7, and the 1H NMR spectra integration into bins（or buckets） across the spectral regions of bin 0.04 was performed automatically in MESTRE-v4.7. The resulting data matrix was further analyzed, which was performed by SIMCA-P 11.0. The principal component analysis（PCA） was applied to the centered data to explore any clustering behavior of the samples. Results The results demonstrated the metabonomic difference in plasma between NSCLP and non-malformed children at least lies in 3-Hydroxybutyrate γ-CH3, arginine and valine. Arginine excretion appeared to be higher in the non-malformed children population, while NSCLP population excreted higher concentrations of 3-Hydroxybutyrate γ-CH3 and valine. Conclusion The present study clearly demonstrated the great potential of the NMR-based metabonomics approach in elucidating the NSCLP plasma metabolism and the possibility of application in clinic diagnosis and screening.

Objective To offer some reference for micro-implant′s development and population by analyzing clinical application of two kinds of micro-implant systems. Methods 38 patients treated with MIA（micro-implant anchorage） and 28 patients treated with SDIA（self-driven titanium implant for orthodontic anchorage） were included. Analyzing the rate of lost implants, the gum′s reactivity and the efficiency of moving teeth summarized the excellences and shortcomings of two systems. Results 1）Six of MIA implants fell off after being inserted. Seven of SDIA implants lost when they had been implanted for a month. But they were stable after being inserted again. 2）The gum around 12 SDIA implants got inflammation symptom, but the gum around MIA implants was normal. 3）Both MIA implants and SDIA implants could move teeth effectively and persistently when they were stable. Conclusion When we apply micro-implant in clinic, we should prevent it from closing roots of teeth and choose the small tip micro-implant. The embedded position should be in area of attachment gum. At the same time, the areas around the tip of micro-implant should be keeping clean.

Objective To investigate the interface bond and thermal compatibility between Mark Ⅱ machining ceramic and Vita VM9 veneering porcelain. Methods A bar shaped specimen（30 mm×15 mm×1 mm in size） of Mark Ⅱ block was prepared, with 0.5 mm-deep notch（vertical to the long axis of specimen） at the middle of the bottom surface. The upper surface was veneered with 0.3 mm VM9 dentin base porcelain. Then the specimen was fractured from the notching site and the fracture surface was examined under scanning electron microscope（SEM） and electron microprobe analyzer（EMPA） with electron beam of 1 μm in diameter. Another ten specimens（30 mm×15 mm×1.5 mm in size） were fabricated and the temperature of thermal shock resistance were tested. Results SEM observation showed tight bond between these two materials and EMPA results showed penetration of Al element from Mark Ⅱ block into veneering porcelain and Ca element from veneering porcelain into Mark Ⅱ block occurred after sintering baking. The average temperature of thermal shock resistance for specimens in this study was（194.0±10.3）℃. Cracks were mainly distributed in veneering porcelain. Conclusion Chemical bond exists between the Mark Ⅱ machining ceramic and Vita VM9 veneering porcelain, and there is good thermal compatibility between them.

Objective To compare the adaptation of porcelain fused-to-metal（PFM） restorations made from Ni-Cr alloy, precious alloy and galvanized forming copings after cementation and to provide a theory guidance for their application. Methods Three kinds of crowns （Ni-Cr alloy, precious alloy and galvanized forming） were manufactured and cleaned by ultrasonic vibrate with alcoholic solution for 5 minutes, and cemented on their dies as their order. All the crowns were cemented by polycarboxylate zinc-cement and maintained 10 minutes. After coated in the center of methyl acrylic resins, all the samples were cut vertically along buccolingual direction. The cement thickness of PFM was measured by scanning electron microscope and the data were analyzed by multivariate ANOVA. Results No significant difference was found between the cement thickness of precious alloy crown and galvanized forming crown（P> 0.05）, while both of these two kinds of crown had significant differences in cement thickness with Ni-Cr crown（P< 0.05）. Conclusion The adaptation of precious alloy crown and galvanized forming crown are superior to Ni-Cr crown.

Objective The purpose of this study is to study the sealing ability and the furcal appearance of repairing subpulpal wall perforation with resinous inlay. Methods Fifty newly extracted human molars were randomly divided into three experiment groups（group A, group B, group C, 15 teeth each） and one control group（5 teeth）. In experiment groups, perforations were made perpendicularly to the center of the pulp chamber floor. Perforations of group A and B were repaired with resinous inlay and sealed by AH Plus sealer and luting glass-ionomer, respectively. Perforations of group C were directly repaired using light-cure composite resin. Perforations were not made in five teeth of control group. The furcal appearances were evaluated under stereomicroscope after repairing. Microleakage was measured by glucose oxidase detection． Results The fineness rate of furcal appearances with resinous inlay repairing were 83.3%, while the fineness rate of furcal appearances with light-cure composite resin directly repairing were 46.7%. There were statistics difference between resinous inlay repairing and light-cure composite resin directly repairing（P<0.05）. There were statistics difference among the daily microleakage of three experiment groups, group A

 [ Abstract] Objective To study the fitness of color dimension between Vitapan 3D-Master shade guides and nature teeth. Methods 2 159 nature teeth from Nanjing population and Vitapan 3D -Master shade guides were analyzed by dental chromameter ShadeEye NCC on CIE L*a*b* color system. Results 1）The color dimension of natural teeth displayed a broader range than those from Vitapan 3D-Master shade guides. Comparing with incisor group, canine -premolar group had better fitness with Vitapan 3D-Master shade guides. 2）In color space, incisor values a* shifted toward green（-a*）, while the shade guide values a* located toward red（+a*）. The shade guide lacked tabs of values L* 71—78 and a* -1.5—-0.2 for natural incisor. 3）According to the perceptibility threshold △E*ab<1.4, the match rates with Vitapan 3D-Master shade guides was 33% in incisor group and 50% in caninepremolar group. Conclusion Vitapan 3D-Master shade guides had inferior match with nature teeth from Nanjing population, especially in incisor.

Objective To investigate the distribution of rag genotypes of Porphyromonas gingivalis（P.gingivalis） in chronic periodontitis patients. Methods Subgingival plaque samples were collected from 50 chronic periodontitis patients. The occurrence of P.gingivalis was determined by polymerase chain reaction（PCR） using 16S rDNA-specific primers. Distribution of rag genotypes was assessed in P.gingivalis positive samples by PCR. Results The occurrence of P.gingivalis was 70.7%, and the distribution of four rag genotypes among P.gingivalis positive samples was as follows: rag-1 60.4%; rag-2 23.6%; rag-3 44.3%; rag-4 15.1%, respectively. Conclusion P.gingivalis with various rag genotypes was present in subgingival plaque samples from chronic periodontitis patients, and P.gingivalis with rag-1 and rag-3 were more predominant in chronic periodontitis patients, which may be associated with the development of periodontitis.

Objective To investigate the reinfection rate of Helicobacter pylori（H.pylori） in gastric mucosa by two measures of oral plaque control on patients, and to demonstrate the necessity and better method of plaque control on those patients. Methods 148 patients suffered gastritis or gastroduodenal ulcer were assigned into test group 1（54 patients）, test group 2（55 patients） and control group（39 patients）. 13C -urea breath test proved that there were no H.pylori in their gastric mucosa. Daily plaque control was used in test group 1, oral professorial interventions were added into test group 2, neither daily plaque control nor oral professorial interventions was conducted in control group. All patients were conducted 13C-urea breath test again after half a year to determine the reinfection rate of H.pylori in gastric mucosa. Results 5 patients were eliminated because of stopping mouthwash in the test group 1, 8 patients failed to control dental plaque in the test group 2. The infection rates of H.pylori in gastric mucosa of test group 1, test group 2 and control group were 67.3％, 19.1％, 82.1％, respectively. The infection rate of H.pylori of test group 2 was lower significantly than that in control group and test group 1（掊2＝ 33, P<0.05；掊2＝31.06, P<0.05）. There were no significant difference between test group 1 and control group（掊2＝2.43, 0.1

Objective To investigate the color stability and translucency of four composite resin cements after ultraviolet（UV） aging. Methods 20 composite resin cement disks for four groups（Group A, dual cured, Biscem; Group B, light cured, Choice; Group C, self cured, PermaCem; Group D, self cured, RelyX Aplicap） were prepared according to their manufacture recommendation. Changes in color and translucency of test samples were determined before and after UV aging for 8, 16 and 24 hour using the CIE L* a* b* system by a colorimeter. The results were analyzed by LSD multi -compare tests. Results The color changes of composite resin cement disks suffering UV aging were significantly different when irradiated different time. For the same irradiated time, Group C had the highest delta E, and Group B and D had the smaller ones. Translucency was found no difference among different irradiated time for group A, B and D. Translucency of group C decreased after UV aging. Conclusion Translucency  0f composite resin cement kept stable after UV aging, and color coordinate changed after UV aging.

Objective To evaluate the effectiveness of treatment with maxillary protraction with or without rapid palatal expansion（RPE） for skeletal Class Ⅲ malocclusion in mixed dentition. Methods A total of 31 children with Class Ⅲ malocclusion in mixed dentition were selected, and 15（group A） received maxillary protraction treatment with RPE, the other 16（group B） received maxillary protraction without RPE. Cephalometric films were taken before and after treatment, and traditional and Pancherz analysis were used. Results The average duration of treatment was 10.14 months in group A and 9.77 months in group B respectively（P >0.05）. According to Pancherz analysis, maxillary basal bone moved forwards by 2.99 mm in group A and 3.33 mm in group B respectively（P>0.05）, mandibular basal bone moved backwards by 0.07 mm in group A, while forwards by 0.80 mm in group B（P>0.05）, the overjet increased by 4.51 mm in group A and 6.37 mm in group B respectively（P<0.05）, and the molar relationship improved by 4.97 mm in group A and 4.73 mm in group B respectively（P>0.05）. The effects were clinically satisfactory in the both groups. Lower molar moved forwards by 1.18 mm in basal bone in group A, while backwards by 1.20 mm in group B（P <0.05）. Traditional cephalometric analysis showed no statistic differences between the two groups except that upper incisior showed greater procline in group B than in group A（P<0.05）. Conclusion The study shows that maxillary protraction treatment, with or without RPE, is clinically satisfactory to correct early skeletal Class Ⅲ malocclusion.

Objective To investigate the effect of self-developing investment（FUS-invest） on the reactive layer of titanium castings. Methods Three 10 mm×10 mm×1 mm pure titanium castings were founded using FUS-invest. Metallographical structure of reactive layer was observed. X-ray diffraction（XRD） and scanning electron microscope with energy-dispersive spectrum（EDS） were used to analyze the status of composition of the casting surface. Micro-Vickers hardness was measured. Results The metallograph indicated that the reactive layer was composed of coare flakeshaped α phase of grains. The value of micro-Vickers hardness with the range 243 to 314 MPa had not significantly difference under the depth of 105 μm beneath the surface. The XRD pattern clearly showed the peaks of ZrO2, SiO2, Mg2TiO4 and TiO2. EDS analysis demonstrated that the main elements were Al, Si, Zr and Cl. Conclusion FUS-invest is suited for pure titanium casting because of the thin reactive layer and less change to metallographical structure.

Objective To study the dental caries status of the 65-74 years old people in northeast of China, analyze the distribution of caries in the group of people, and provide scientific basis for establishing the oral health care policies. Methods The representative samples were selected by multi-stage, stratified and random sampling from the three province of northeast of China. Dental caries of 2 364 people aged 65-74 were recorded according to WHO criteria. SPSS 12.0 software was used to analyze the data. Results 1）Among 2 364 elderly people in northeast of China, the prevalence of dental caries was 67.5% and DFT was 2.68, the composition of filling was 10.82%. 2）The prevalence of coronal caries was 66.4% and DFT was 2.55. The composition of filling was 11.37%. 3）The prevalence of root surface caries was 48.4% and DFT was 1.64. The composition of filling was only 1.8%. Conclusion The prevalence of dental caries among elderly people in northeast of China is still very high, and the filling rate is low. The community based oral health promotion should be strengthened and preventive-oriented oral health care systems are needed in northeast of China.

Objective Saccharomyces albicans is the main opportunistic pathogen which is also the common member of oral microflora, and the biofilms they formed have spontaneous drug tolerance compared with planktonic ones. Saccharomyces biofilm population can produce subpopulation of cells which can tolerant high concentration of antifungal drugs. They are called persisters. Many researches indicated that drug efflux gene such as CDR or MDR gene plays the very important roles in yeast drug resistance. The objective of this study is to illuminate the mechanism of Saccharomyces albicans biofilm drug tolerance related with drug efflux gene, especially to the persisters formation. Methods Test the minimal inhibitory concentration（MIC） and SMIC80 （ sessile minimal inhibitory concentration 80%） of 24 h biofim of totally 7 defective strains of drug efflux pump gene with Amphotercin B. And treat the 24 h biofilm by fluconazole, micronazole, clotrimazole combined with CDR1 inhibitor Enniatin B respectively and antifungal drugs alone as control, then scrapped the biofilm, cultured on the YPD agar. By CFU counting, the numbers of biofilm persisters were determined. Results All the defective strains have the similar MIC and SMIC80 for 24 h biofilm with wide type strains. CDR1 inhibitor Enniatin B can help antifungal drugs especially micronazole and clotrimazole to eliminate the biofilm persisters. Conclusion Saccharomyces albicans drug efflux gene may minor associated with 24 h biofilm drug tolerance. Drug efflux gene CDR1 may play an role in persisiters related biofilm drug tolerance.

Objective To evaluate the accuracy of Cercon CAD/CAM system and the influence of different spacer thickness and spacer coverage area on the internal and marginal fit of the copings. Methods A stainless steel master model of first molar was replicated. After scanning, designs of copings were made with different spacer thickness and spacer coverage area. There were six groups: S10C70, S10C90, S30C70, S30C90, S60C70, S60C90. Measurements of the adaptation were performed with silicone impression material and an image analysis system. Results Univariate ANOVA showed that variation in the internal fit of copings was related to measuring location, spacer thickness and spacer coverage area. There was significant difference between different spacer coverage area groups, and significant difference between spacer thickness 10 μm and 30 μm groups, 10 μm and 60 μm groups, no significant difference between spacer thickness 30 μm and 60 μm groups. Mean marginal fit was （27.7 ±7.6）μm. There was statistically significant difference between both mesial, distal marginal gaps and both buccal, lingual marginal gaps. No difference between mesial and distal marginal gaps, and between buccal and lingual marginal gaps. Conclusion The accuracy by Cercon CAD/CAM system for the marginal and internal fit of zirconium dioxide copings is well within the range of clinical acceptability. Spacer thickness and spacer coverage area have statistically significant influence on the internal fit.

Objective The purpose was to analyze the effects of three sterilization methods（dry heat sterilization, steam sterilization, and chemical sterilization） on the corrosion of dental fissure bur. Methods 200 dental fissure burs were distributed to 10 groups. Bending strength, elastic modulus, and torsional strength were measured by bending and torsional instrument and calculated with special designed software. Among the three sterilization methods, the steam sterilization group showed the most evident. Results The corrosion was most severe in steam sterilization group, followed by chemical sterilization, dry heat sterilization. With the sterilization time increased, bending strength, elastic modulus, and torsional strength decreased respectively. Of the three sterilization methods, the mechanical properties were decreased most evidently by steam sterilization, followed by chemical sterilization and dry heat sterilization. Conclusion It is proved that the bending strength, elastic modulus and torsional strength have a tight relationship with the corrosion of dental fissure burs. The corrosion was most severe in steam sterilization group, followed by chemical sterilization, dry heat sterilization. In regards of the corrosive effect, the dry heat sterilization might be the best way to sterilize the dental fissure burs.

Objective To choose the best retraction agent for the clinic by evaluating cytotoxic effects of six chemical retraction agents on human gingival fibroblasts（HGF） in vitro. Methods HGF were treated with six chemical retraction agents which included 20% Al2（SO4） 3, 5% Al2（SO4） 3, 15.5% Fe2（SO4） 3, 13.3% Fe2（SO4） 3, 0.1% HCl - epinephrine and 0.01% HCl-epinephrine. The damage of direct contact and proliferation inhibit were observed by methyl thiazolyl tetrazolium（MTT） colorimetric assay, the ultra structure was observed under transmission electron microscope（TEM）. Results All of chemical retraction agents caused cell damage and proliferation inhibit. The ability of cytotoxic effect increased in an order of 0.01% HCl-epinephrine<0.1% HCl-epinephrine<5% Al2 （ SO4）3< 20% Al2 （ SO4） 3

Objective To investigate the pathogenicity of matrix metalloproteinase 8, 9（MMP-8, MMP-9） regulations of polymorphonuclear leukocytes（PMNs） by challenge of Porphyromonas gingivalis（P.gingivalis） with different fimA genotypes. Methods The studies mainly adopt the isopycnic sedimentation separation to separate the PMNs from human peripheral blood. P.gingivalis ATCC 33277（typeⅠ），WCSP 115（typeⅡ），WCSP 1.5（typeⅢ），W83（typeⅣ）， WCSP 559（typeⅣ） were assessed for their inductions of MMP-8, MMP-9 expression in PMNs. MMP-8, MMP-9 protein levels in culture supernatant were determined by ELISA at different time intervals（5 min, 30 min, 1 h, 2 h） following continuous co-culture of bacteria with PMNs. Results MMP-8 and MMP-9 protein levels produced by PMNs co-culture with the ⅠfimA—ⅣfimA P.gingivalis were significantly stronger than unsimulated group. The velocity and quantity of MMP-8 produced by PMNs co-culture with the ⅡfimA P.gingivalis and ⅣfimA P.gingivalis were more than ⅢfimA, ⅣfimA P.gingivalis. The MMP-9 protein levels produced by PMNs co-culture with the ⅠfimA, ⅡfimA, ⅣfimA P.gingivalis was significantly stronger than ⅢfimA and ⅣfimA P.gingivalis. Conclusion Ⅱ fimA and ⅣfimA P.gingivalis have stronger pathogenicity relatively, which indicate that fimA genotype is associated with pathogenesis of P.gingivalis.

Objective To investigate the effects of incorporating three different zinc oxide（ZnO） on the antibacterial activity of composite resin. Methods The minimal inhibitory concentration（MIC） and minimal bactericidal concentration（MBC） of nano -ZnO, tetrapod -like zinc oxide whiskers（T -ZnOw）, micro -ZnO against Streptococcus mutans were examined by the broth dilution test. Then the three different ZnO were added to the powder of one kind of bicomponent self -cured composite resin at 5% respectively, and the antibacterial activities of the resin specimens were evaluated using the membrane covering method before and after 3-month accelerating aging. Results The MIC values of the three different ZnO against Streptococcus mutans were 78.13, 312.50 and 1 250.00 μg/mL respectively and the MBC values were 156.25, 625.00, 1 250.00 μg/mL respectively. The antibacterial ratios of the resin specimens incorporating with 5% of the three different ZnO were （93.58±5.95）％, （89.42±4.11）％ and （78.97± 3.90）％ respectively, while after 3-month accelerating aging those were （89.01±7.91）％, （84.63±4.72）％ and （72.27± 3.89）％. Conclusion The three different ZnO could improve the antibacterial activity of the composite resin. The nano-ZnO exhibit the strongest antibacterial activity, while the micro-ZnO weakest. The T-ZnOw presents comparatively strong antibacterial activity although with smaller specific surface area.

Objective To evaluate the osteoblastic differentiation and compare the difference in the gene expression of rat bone marrow mesenchymal stem cells（MSCs） affected by a single period of mechanical strain． Methods Bone marrow MSCs were harvested from the femurs and tibiae of SD rats and cultured in vitro. A four-point bending apparatus were used to perform a single 40-minute period of 2 000 με mechanical strain on these MSCs  The proliferation of the MSCs was tested by MTT on scheduled date, and the osteoblastic differentiation of the MSCs was measured by testing the expression of osteocalcin and alkaline phosphate（ALP） activity of these cells. In addition, we have investigated the possible mechanisms underlying the action of the single 40 -minute period of 2 000 με mechanical strain on these MSCs, after profile blotted and handled by bioinformation, the gene expressions of these two periods of MSCs were examined. Results The MSCs have grown well in vitro. Our experiment showed that mechanical environment did not weaken the proliferation of the MSCs. However, the ALP activity and the expression of osteocalcin were significantly up-regulated by the 2 000 με mechanical strain. Using the 27 K Rat Genome Array, 416 different expressions were found. The rate of different genes was 2.8%, of which the expressions of 247 genes increased（61 genes remarkably increased） and 169 genes decreased（74 genes remarkably decreased） in these two periods of MSCs. Conclusion Mechanical strain induced the osteoblastic differentiation of the MSCs, which may be attributed to the different gene levels.

Objective To establish a three-dimensional finite element model of mandibular distraction osteogenesis （DO） in order to study the influence of distraction orientations to mandibular DO. Methods By using the two finite element models, Von Mises stress and the displacement under different loads were measured. Results The maximum stress in the distract equipment paralleled to the mandibular corpus was two times of that when the distract equipment paralleled to the sagittal axis. Von Mises stress concentration mainly occurred in the loading position and the condylar ante inferior. This phenomenon may lead to partial bone resorption, consequently lead to screw loose and affect the stability of distraction device. When the displacement increased in the model, the maximum stress and displacement showed linear relation. Conclusion The counterforce produced by the device makes lateral displacement in tail. The reaction force could be reduced to a minimum degree when the traction device parallel to the sagittal axis. This study provides theoretical basis for the position of distract equipment and distraction orientations in clinical application.

Objective The adhesion and growth of human periodontal ligament cells（PDLC） on collagen（Col）, hyaluronic acid （HA） and HA/Col scaffolds were studied to evaluate the feasibility of HA/Col as a scaffold matetial in periodontal tissue engineering. Methods Human PDLC cultured in vitro was collected and seeded on Col, HA, HA/Col scaffolds crosslinked by carbodiimide. The influences of scaffolds on cell adhesion and growth were observed by MTT assay. The growth of human PDLC on scaffolds was observed through inverted phase contrast microscope and scanning electron microscope（SEM）. Results The result of MTT assay demonstrated that except the seventh day there was obviously differentiation between each group Col, HA, HA/Col scaffolds at the first, second and fourth day, and HA/Col group was higher than control group all the time. Human PDLC successfully grew on scaffolds. Conclusion HA/Col scaffold was more suitable for human PDLC adhesion compared with Col scaffold and HA scaffold. This indicates that HA/Col scaffold might be a potential ideal candidate for periodontal tissue engineering.

Objective To evaluate the influence of periodontal ligament（PDL） injury on initial stability for immediately loaded mini-implant anchorage. Methods The sample consisted of 153 adult patients with maxillary protrusion deformity. Guiding by the positioning device designed by Choi, 306 mini-implants were inserted by selftapping in the upper right and left buccal areas between the first molars and second premolars. The mini-implants were divided into two groups according to CT scanning. The mini-implant was absolutely separated from PDL（group I）, the mini -implant appeared to touch or overlay on PDL, but not contact to the adjacent roots（group Ⅱ）. If orthodontic force could be applied to the mini-implants for four months, the mini-implant was recorded as successful anchorage. After immediate loading for four months, the analyses were completed by SPSS 9.0 software. Results Of the 306 inserted mini-implants, 162 were absolutely separated from PDL, 136 appeared to touch or overlay on PDL, but not contact to the adjacent roots, and 8 were excluded from this study because of injury to the adjacent root. The success rates of group Ⅰ and Ⅱ were 87.0% and 65.4% respectively. There were significant differences in the success rates between the two groups（P<0.001）. The differences between the two groups in distribution of the upper right and left area had statistical significance（P<0.05）. Conclusion PDL injury is one of the main reasons leading to early loosening of the mini-implant.

Thirty-six implants were placed into 2 patients with fully edentulous jaws. Provisional prosthesis were placed into 34 of 36 implants which implant stability quotient（ISQ） was larger than 60 at the time of fixture placement. After 3 months, osseointegration of implants completed and permanence reparations were made. None implant lost among 18 months to 26 months since the immediate restoration was loaded. The average accumulate bone loss was 0.41 mm.

A facial asymmetry patient caused by temporomandibular joint ankylosis was operated by putting a distraction osteogenesis（DO）-appliance. One week after surgery, the right mandible was distracted. Twenty days after distraction, the height of right mandibular ramus and body increased obviously. Four months after retain of DO-appliance, the right maxilla down-grew automatically and the occluding relation recovered to normal. The DO-appliance was taken out. MEDPOR prosthesis was imbedded in new bone and genioplasty was operated. The facial asymmetry and abnormal occluding relation of the patient were improved obviously.

Squamous cell papilloma is a kind of benign tumor from mucosa stratified squamous epithelium, which usually occurs in cheek, palate, lip and tongue. In this paper, a case of squamous cell papilloma occurred in interdental papilla was reported, and its pathogenesis, clinic features and treatment were discussed.