Dental plaque is structurally a kind of biofilm which contains a variety of micro-organisms. The interreaction of oral micro-organisms may affect the nature, forms, and toxicity of the dental plaque biofilm, as well as the localization and field planting of bacteria inside the biofilm. The signal transduction existed between the bacterium has an important effect on the formation and virulence of bacterial biofilm. This reviewing paper focuses on the latest research progress of human oral microbial community and dental plaque biofilm.

In recent years, three dimensional imaging registration has been developed rapidly in clinics. Medical image registration plays an important role in the research of orthodontic image processing field. In this study, we introduce the applications of CT registration on several clinical cases. After the registration of the pre- and post-treatment CT data, the position changes of teeth and the modeling of alveolar bone and the adaptive changes of soft tissue can be assessed precisely respectively. The three dimensional registration provides us a new and precise method to study the outcome and mechanism of orthodontics. And more studies of three dimensional registration should be performed to promote three dimensional oral medical assessment researches.

Objective After sinboneHT bone replacement（SBR） was implanted in animals, to evaluate the biocompatibility of SBR and compounded in autogenetic bone in the proportion of one to one in order to prepare for the clinical applications in the future. Methods Bone defects of 10 mm×10 mm×2 mm was made at the mandibular of rabbits, then SBR with different granule diameter and autogenetic bone was compounded in the proportion of being applied in the left defects, while autogenetic bone was implanted in the right defects and nothing was used in the right reformed defects. Animals were sacrificed at 2, 4 and 8 weeks respectively. The biologic capacity was evaluated with anatomy, X-rays studies and histology. Results SBR has better biocompatibility, which can effectively accelerate the reconstruction of bone defects and help the new bone by being compounded with autogenetic bone. It provides the appropriate scaffold or template which would allow cellular infiltration, attachment and multiplication. Conclusion SBR is a kind of bone substitute material with good biocompatibility. SBR compounded with self-bone has a better regeneration function.

Objective To investigate the clinical and pathological characteristics of salivary duct carcinoma（SDC） so as to provide basis for the diagnosis and therapy of SDC. Methods Eight patients suffered with SDC treated in Affiliated Stomatological Hospital of Kunming Medical College from March 2001 to February 2009 were studied retrospectively including the clinical data. Meanwhile, eight tumor specimens were examined for vascular endothelial growth factor（VEGF）, cytokeratin（CK）, gross cystic disease fluid protein（GCDFP）-15, androgen receptor（AR）and oncogene C -erBb -2 protein expression via immunohistochemistry. Results Of the eight patients with SDC, five tumors grew in the parotid gland, the majority of the patients had facial nerve paralysis, three had recurrence. Computerized tomography（CT） showed that no obvious margin and similar crystal. Immunohistochemical staining for the expression of VEGF, CK, GCDFP -15 and C -erbB -2 were carried out in all SDC, while AR in majority. Conclusion SDC is a high-grade malignant carcinoma among all salivary carcinoma, immunohistochemical analysis of SDC has revealed a variety of similarities to ductal carcinoma of the breast. GCDFP-15, AR and C-erBb-2 may play an important role in pathological diagnosis for SDC.

Objective To compare the bonding properties of three kinds of cements by observing the bonding interfaces of cements and root canal dentin. Methods 15 extracted mandibular premolars were divided into 3 groups, and were cemented by Rely X luting, Panavia F and Paracore 5 mL, respectively. Each tooth was sectioned into two parts and the dentin -cement interfaces at the coronal, middle and apical parts of the fiber post were oberved by scanning electron microscope（SEM）. The length of hybrid layer was also recorded. Results Hybrid layer was not clearly found in group one, which could be seen on the dentin-cement interfaces of group two and three. Resin tags and lateral adhesives were also observed in group three. From the apical to the coronal part, microgaps seemed gradually smaller in group one, while the hybrid layer became thicker in both group two and three. Conclusion The totaletch resin cement bounds tightly with dentin, and owns a more superior bonding property than self-etch resin cement and resin modified glass ionomer cement.

Objective To quantify the interleukin（IL）-1β mRNA and IL-6 mRNA expression induced by lipopolysaccharides（LPS） extracted from Porphyromonas endodontalis（P.endodontalis） in osteoblasts, and to relate P. endodontalis LPS to the bone resorptive pathogenesis in the lesions of chronic apical periodontitis. Methods MG63 cells was pretreated with PD98059 or SB203580 for 1 h and then treated with P.endodontalis LPS for 6 h. The expression of IL-1β mRNA and IL-6 mRNA were detected by reverse transcription polymerase chain reaction（RTPCR） technique. Results The production of IL-1β mRNA induced by P.endodontalis LPS decreased in osteoblasts pretreated with PD98059. Both of the production of IL-1β mRNA and IL-6 mRNA induced by P.endodontalis LPS decreased in osteoblasts pretreated with SB203580. Conclusion The synthesis of IL-1β mRNA stimulated by P.endodontalis LPS in MG63 probably occur via extracellular signal-regulated kinase（ERK） 1/2 and p38 mitogen activated protein kinase（MAPK） signal transduction system. The synthesis of IL-6 mRNA stimulated by P.endodontalis LPS in MG63 probably occur via p38MAPK signal transduction system.

Objective To determine whether polymorphisms in the estrogen receptor（ER） genes are associated with chronic periodontitis in a Chinese population overall the Shanxi territory. Methods 109 patients with chronic periodontitis and 99 healthy controls were recruited in this study. Genomic DNA was extracted from oral mucosa swab sample of each subject by the Chelex-100 method. Determination of the ER-α and -β polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism（PCR-RFLP）, respectively. Results The analysis of the XbaⅠ polymorphisms in ER-α gene revealed significant differences between patients and controls. The detection frequency of XX genotype was significantly higher in the chronic periodontitis patients than in control subjects. The difference between the female chronic periodontitis patients and healthy controls was statistically significant, but no difference was found between the male patients and controls. Nevertheless, no significant association was noted in the frequency of both RsaⅠ and AluⅠ polymorphisms in ER-β gene between chronic periodontitis and controls. Conclusion It is indicated that the ER-α XX genotype may be a susceptible indicator for chronic periodontitis in female Han Chinese subjects.

Objective To analyze the influence of four types（classⅡ long elastic, class Ⅱ short elastic, class Ⅲ long elastic, class Ⅲ short elastic） of inter-arch elastics on the stress distribution and displacement of temporomandibular joint（TMJ）. Methods To reconstruct a three-dimensional element model of left craniofacial bones with TMJ, maxilla, mandible and dentition with MBT straight wire appliance by CT images, Mimics, Ansys software. The influence of four types elastic on the model was analyzed by simulating the clinical conditions. Results The stress distribution and displacement of TMJ under four types of elastics have been acquired. The stress distributed rule of condition 1 and 2 was similar, compression stress centred on the frontal surface of the condyle, while stretching stress centred on the posterior surface. The stress distributed rule of condition 3 and 4 was similar too, the frontal surface of the condyle was most stretching stress, while posterior surface was most compression stress. The displacement of the condyle of condition 1 and 2 was overall forward and downward with a clockwise rotation, the displacement of the condyle of condition 3 and 4 was overall backward and upward with a anticlockwise rotation. Conclusion Class Ⅱ long elastic and short elastic, class Ⅲ long elastic and short elastic, the stress distributed rule was similar, the strength under short elastics was gentle under the same strength value. Overall displacement was downward and forward under class Ⅱ elastics, the condyloid made a clockwise rotation. Overall displacement was upward and backward under class Ⅲ elastics, the condyloid made a counterclockwise rotation.

Objective To evaluate the effect of different concentrations of ethylenediamine tetraacetic acid（EDTA） paste on the removing root canal smear layers and the degrees of erosion on the surface of the root canal walls at the different portions of canal. Methods Sixty human teeth with single root were instrumented using step-back technique, then were divided into six groups and treated with different concentrations EDTA paste and NaClO solution. Group A: 0.9% saline; group B: 5.25% NaClO+5% EDTA; group C: 5.25% NaClO+10% EDTA; group D: 5.25% NaClO+15% EDTA; group E: 5.25% NaClO+17% EDTA; group F: 5.25% NaClO+20% EDTA. Then the teeth were split, the root canals with different treatments were examined with scanning electron microscope at the coronal, middle and apical thirds for smear layers removal and the degrees of erosion. Results The effect of EDTA paste on removing smear layers at the coronal, middle thirds of the root canal increased with the concentrations. 15% EDTA paste could remove the smear layers at the coronal and middle thirds of the root canal, but the effect on apical third was invalid, and no erosion could be found in the root canal wall. 17% and 20% EDTA paste produced the erosion to the root canal wall. Conclusion The concentrations of the EDTA paste can influence the effect of the removing smear layers, and the concentration beyond 17% would produce the erosion to root canal wall.

Objective To study the post-operative pain-related factors in lower third molar extraction, and to find an effective prevention program. Methods The first phase of the study was a clinical follow-up of 450 cases of lower third molar extraction. Factors associated with post-operative pain were analyzed, and difficulty assessment protocol of the tooth extraction was build. On this basis, a pain-prevention clinical plan was constitute, and implemented in the second phase of 450 cases（selectively systemic or local medication）. Treatment effects were observed. Results There were no significant differences between the two phase groups on the distribution of ages, sex, difficulty of tooth extraction, operation time, and other related factors, means that they were statistically comparable. Tooth extraction difficulty and operation time were most important predictive factors for post-operative pain. Local infective factors（including caries） and women′s menstrual cycle also account for late stage pain. Through targeted pre-operative medication or post-operative alveolar socket treatment, pain was significantly reduced or prevented. Conclusion Reasonable peri-operative drug control basing on the difficulty assessment can provide a comprehensive and individualized control of pain after tooth extraction. Also, excessive or inappropriate using of drugs is largely avoided.

Objective To study the effect of ultrasonic irrigation in deactivating and eliminating the endotoxin in the root canals of chronic periapical periodontitis. Methods 10 maxillary premolars with 2 root canals extracted because of serious chronic periapical periodontitis were opened conventionally and prepared with modified double-flared technique with apical foramen sealed. 30 μL 3% H2O2 solution was introduced into each root canal and 2 minutes ultrasonic vibration was given. Samples were taken before and after ultrasonic vibration. 10 maxillary premolars with 2 root canals of chronic periapical periodontitis of 10 patients in clinic were selected. The root canals of them were instrumented as above, followed by 2 minutes ultrasonic irrigation with asepsis distilled water. Samples were taken before, after root canal preparation and after ultrasonic irrigation. The endotoxin activity of them was tested by kinetic turbidimetric limulus test. Results The mean endotoxin activity of extracted premolars before ultrasonic vibration was 4.069 EU·mL-1 while after ultrasonic vibration it was 16.410 EU·mL-1. There was great statistical difference between them（P<0.01）. The endotoxin activity after ultrasonic vibration was significantly higher than that of before vibration. The clinically mean endotoxin activity before, after root canal preparation and after ultrasonic irrigation were 44.860, 4.099, and 0.116 EU·mL-1 respectively. There was great statistical difference between the endotoxin activity  before and after root canal preparation（P<0.01）. After the preparation, the endotoxin activity droped obviously. There was great statistical difference between the endotoxin activity before and after ultrasonic irrigation（P<0.01）. After ultrasonic irrigation, the endotoxin activity droped obviously. Conclusion Under the condition of simulating clinical work presence, the ultrasonic irrigation can not intensify the effect of the root canal rinse solution in deactivating the endotoxin of infected root canals, but it may intensify the effect of the root canal rinse solution in eliminating the endotoxin of infected root canals.

Objective To determine the root canal initial taper of mandibular second premolars of 13-23 year-old people by using Micro-CT. Methods 23 extracted, single root, human root canal of mandibular second premolars of 13-23 year-old people were selected. The teeth were embedded in resin. The resins were scanned using Micro-CT at a resolution of 10 μm. The photographs at each level of 1 mm perpendicular to the long axis of the tooth were chosen. Bucco-lingual（BL） and mesio-distal（MD） diameters of each canal were measured at cervical, middle and apical third of the canals. Finally the taper were calculated and analyzed. Results The average taper of cervical, middle, and apical third of adolescents′ root canals were 0.06, 0.08, 0.07（mesio-distal direction） and 0.32, 0.21, 0.25 （bucco -lingual direction）. The difference was not observed among three level on mesio-distal direction about the canal taper by t-test（P>0.05）, but there was difference among three level on bucco-lingual direction about the canal taper by t-test（P<0.05）. Conclusion The change of bucco-lingual taper of mandibular second premolar of 13-23 year-old people is obvious, and the smallest taper is in middle third of the canal. The mesio-distal taper of the canals is smaller than the bucco-lingual taper and the change of mesio-distal taper isn′t obvious.

Objective To assess the early variation of clinical periodontal indexes and Porphyromonas gingivalis
（P.gingivalis） in subgingival plaques of orthodontic adults. Methods 11 orthodontic adults were selected. Clinical periodontal indexes of observed teeth were examined at three different time points: Before orthodontic treatment, the first month after treatment and the third month after treatment, and subgingival plaques were collected simultaneously at each time point. Clinical periodontal indexes included four ones: Plaque index（PLI）, sulcus bleeding index（SBI）, probing depth（PD）, and attachment loss. We used real -time quantitative polymerase chain reaction to detect and quantitate the number of total bacteria and P.gingivalis in each sample to obtain positive rate of P.gingivalis and the percentage of P.gingivalis in total bacteria. Results PLI and SBI of the first and third month were more than that of the baseline（P<0.05）. PD rose at the first month after treatment（P<0.05）, and then dropped at the third month. PD of all the 11 participants was lower than 2 mm. No attachment loss was found. The positive rate of P.gingivalis was stable（45.5%） and the proportion of P.gingivalis had no significant difference（P>0.05） at each time point. Conclusion Fixed orthodontic appliances caused plaque accumulation, accordingly slight gingiva inflammation and the increasement of P.gingivalis occurred in the early stage, but none periodontitis was found.

Objective The disinfection efficiency of a compound disinfectant spray with trichloro hydroxyl diphenyl ether on dental impression and plaster model, which have been contaminated by pathogens, were evaluated in this study. Methods As experimental group, germ-free alginate impressions and plaster models were sprayed with the compound disinfectant of different density trichloro hydroxyl diphenyl ether or indophors for 5, 10 and 15 min, after which were smeared with five tested pathogens, including Staphylococcus aureus, Escherichia coli, Saccha - romyces albicans, Streptococcus mutans and black spore variants of Bacillus subtilis. The colonies were counted after sampling, inoculate and culture, which were used to deduce the killing logarithm value as the standard of the disinfecting efficiency. Results The compound disinfectant spray with 3 000 mg·L-1 trichloro hydroxyl diphenyl ether was effective to all tested pathogens for 10 min whatever on the impressions or the plaster models. The disinfectant spray with same concentration was more effective on the alginate impression than on the plaster model in the same time（P＝0.000）. Conclusion The compound disinfectant spray with trichloro hydroxyl diphenyl ether is an effective antiseptics for alginate impressions and plaster models.

Objective To study the influence of cervical settling method on marginal accuracy of wax patters. Methods 24 wax patterns were made on the standard cast specimens and round capsules of which twelve patters were made with the method of cervical settling（experiment group）, twelve patters were made with the method of wax dripping（control group）. Marginal accuracy of patterns were measured before sublation, sublation half an hour and twenty-four hours. Results The results revealed that marginal accuracy had significant difference between the cervical settling methods and wax dripping methods（P<0.05）. There was significant difference between the cervical settling methods measured after half an hour and twenty-four hours（P<0.01）. There was also significant difference between the wax dripping methods measured after half an hour and twenty-four hours（P<0.01）. Conclusion Wax patterns with the method of cervical settling can improve marginal accuracy of patterns. The marginal accuracy of wax patters are influenced by the existing time.

Objective To investigate the anatomic feature of the canal isthmus of mandibular permanent incisors by Micro-CT. Methods Thirty-three mandibular permanent incisors with two canals were selected through the radiograph in proximal view. These teeth were then scanned using Micro-CT and reconstructed. The scanning layer thickness was 20 μm. We observed the apical 6 mm of the 33 roots, and 300 sections were gained each tooth, giving a total of 9 900 sections. The numbers of canals at each level in the apical 6 mm were recorded. The num - bers of sections showing isthmuses at each level of the root canals were recorded too. Data were analyzed using the Chi-square statistic to test the null hypothesis that location of the sections in each of the apical 6 mm and presence of the isthmus were independent. The minimum root canal wall thickness was measured in each of the apical 6 mm of the roots. Results Isthmuses were found to be present at all levels with prevalence from 10.0% to 85.5%. The Chi-square test indicated a significant difference in the distribution of isthmuses with section（P=0.001）. The incidence of isthmuses was higher at the apical 3-6 mm level, and the highest incidence（85.5%） was at 5 mm level. There were many more sections containing complete isthmuses（49.7%） than those containing partial isthmuses（4.5%）. The thickness of the minimum root canal was less than 0.5 mm. Conclusion The mandibular incisors have a high incidence of isthmus and are narrow in proximal direction. Debridement of the isthmus is a major challenge during surgical and nonsurgical root canal treatment.

Objective To evaluate the outcome of alveolar cleft bone grafting using dental 3D-CT, and identify the position of the bone bridge. Methods Eighteen unilateral complete alveolar cleft patients were chosen in this study and using dental 3D-CT to evaluate the position of the bone bridge after three month bone graft. The alveolar cleft was divided at several section, the bone bridge position were checked, and the position of graft bone bridge were calculated. Results In mesial and distal direction, there was no difference between mesial and distal bone bridge（P>0.05）. In labial and palatal direction, labial bone bridge was more than palatal bone bridge（P<0.001）. In vertial direction, bone bridge which at one third of apical root and middle root of the central incisor root, was more than bone bridge which at alveolar crest and nasal base. Conclusion After secondary alveolar bone graft, bone bridge in alveolar cleft position is most located at labial and apical third and middle third of the central incisor root.

Objective To explore the multi-differentiated capability of human periodontal ligament cell population （hPDLP）, and provide a theoretical basis for the periodontal regeneration by tissue engineering technique. Methods hPDLP was cultured from periodontium of human tooth by the outgrowth method. STRO-1 and CD146 expression were investigated by flow cytometry. hPDLP was induced to odontogenic/osteogenic-like and adipogenic-like cell. The multilineage differentiation capacities of hPDLP were evaluated by alizarin red stain, oil red O stain, anti-CD146 and STRO -1 immunocytochemistry, and reverse -transcriptase polymerase chain reaction analysis. Results hPDLP was isolated from human periodontium and most of the cells retained their fibroblastic spindle shape. hPDLP can be induced into osteoblast -like cells and adipocyte -like cells, and calcium deposition and lipid droplets were detected perspectively. And the eighth generation of hPDLP had weaker potential into adipocyte-like cells than the first passage, however, there was no difference to the aspect of calcification ability between the two passages. Conclusion hPDLP cultured in vitro can differentiate into adipocytes and osteoblasts, and the first to third passage cells may have the predominance of differentiation potential.

Objective To investigate the differently expressed Homeobox genes between adenoid cystic carcinoma of salivary gland and normal gland tissue, and find out the effect of Homeobox genes on oncogenesis and differentiation of adenoid cystic carcinoma of salivary gland. Methods Six strictly paired specimens including adenoid cystic carcinoma and its surrounding normal gland tissue and two pairs of specimens including cell strain of adenoid cystic carcinoma and its surrounding normal gland tissue were established. Customized Oligo microarray which contains probes of 232 human Homeobox genes was used to analyze and conclude two groups of different genes data. RTPCR technique was used to examine the mRNA expressing level of highly suspected relevant genes of adenoid cystic carcinoma in different specimens. Obvious differently expressed Homeobox genes were found through statistical analyses. Results In tissue specimens Homeobox genes were found 67 up-regulated and 54 down-regulated, and in cell specimens Homeobox genes were found 12 up -regulated and 15 down -regulated. One up -regulated gene and 7 down-regulated genes were found both in tissue and cell specimens, among which EVX1 and PITX1 were the most frequent. RT-PCR showed that there was statistical expressing difference between TGIF, EVX1 and normal gland tissue in ACC-M. Conclusion As the key gene to cellular proliferation and differentiation, Homeobox genes are closely relevant to the oncogenesis of adenoid cystic carcinoma of salivary gland.

Objective To study the feasibility of dendritic cells（DCs） vaccine on the therapy of tongue carcinoma and find the better way of antigen load. Methods The antigen peptides of Tca8113 cells were obtained by acid eluted technique and repetitive freeze thaw method. Separating T cell and inducing dendritic cells were obtained from human peripheral blood monocyte. Divided into three groups: Weak acid elution method antigen group, anti-freezethaw method antigen group, and the control group（without tumor antigen）. T cells and DCs were mixed to culture by different effector-target ratio. Using MTT assay measured the quantities of absorbance and calculated stimulation index. Dendrtic cells pulsed with antigen were mixed with T cells by different effector-target ratio. MTT assay was used to measure the quantities of absorbance and calculate killing rate. Results DCs vaccine was constructed successfully. DCs vaccine can induce T lymphocytes to kill Tca8113 cells and display the dose-effect relationship. There was significant difference among the three groups. The acid eluted and repetitive freeze thaw groups were better than the control group. The acid eluted group was better than repetitive freeze thaw group. Conclusion DCs vaccine can induce T lymphocytes to kill Tca8113 cells. The antigen peptides obtained by acid eluted technique is better than repetitive freeze thaw method in immunotherapy of tongue cancer.

Objective To determine the antibacterial activity of six kinds of natural herbs in Yunnan on normal oral predominant bacteria in vitro. Methods Agar dilution method, the antimicrobial susceptibility testing of anaerobes which was recommended by National Committee for Clinical Laboratory Standard（NCCLs）, was used to determine the antimicrobial susceptibility of herbs to 21 kinds of oral model strains and clinical isolates. The results were expressed by minimum inhibitory concentration（MIC）. Results All six kinds of herbs were effective to the oral predominant bacteria. For the ten kinds of cariogenic bacteria, the MIC of caesalpinia sappan lignum was between 5-10 mg·mL-1, and the MIC of other herbs was above 20 mg·mL-1. For the eleven kinds of predominant bacteria which normally involved in pulp periapical disease and periodontitis, the MIC of caesalpinia sappan lignum was below 0.062 5 mg·mL-1, and the MIC of the terminalia chebula retz was between 10-20 mg·mL-1, and the others were above 20 mg·mL-1. Conclusion The six kinds of herbs in Yunnan could be used in treatment or prevention of oral bacterial diseases.

Objective To explore the capability of human periodontal ligament stem cells（PDLSCs） differentiating into adipose cells in vitro and to determine their changes in cell morphology, structure and function during differentiation. Methods PDLSCs isolated by magnetic-activated cell selection were treated continuously with adipogenic medium for 21 d. Then the cell morphology, ultrastructure, adipose specific markers of low density lipoprotein（LPL） and peroxisome proliferator activated receptor -γ（PPAR-γ） were analyzed by inverted contrast microscope, trans - mission electron microscope（TEM）, flow cytometry, immunofluorescence, RT -PCR and Western blot, respectively. These adipose-like cells were also identified by oil red O staining to determine the formation of lipid droplet, and the non-induced cells were used as control. Results After continuous induction, the treated cells differentiated into adipose-like cells with round shape, and large amount of lipid drop in cytoplasm. 96.54% of the PDLSCs were found to differentiate into adipose cells as showed by flow cytometry, the specific markers of LPL mRNA and PPAR-γ mRNA, and oil red O staining, respectively. Further, PPAR-γ protein was detected in the induced cells in a timedependent manner. Conclusion Human PDLSCs have the potential of differentiating into adipose cells under appropriate condition, and the differentiated cells exhibited characteristics of adipose cells both from cell morphology and from their functions.

Objective To investigate immunohistochemical presentation of fibromodulin in vitro during wound healing of three types of periodontal cells and discuss the role of fibromodulin. Methods Cultured periodontal cells were wounded and followed by observation up to 7 days. The immunohistochemical expression of fibromodulin in periodontal cells was observed. Results Immunohistochemical localization of fibromodulin during cellular wound healing showed that newly migrating periodontal cells toward the wound area were expressed strongly for fibromodulin at day 1 after wounding; thereafter, fibromodulin expression was noted stronger in newly migrating periodontal cells localized in the central part of the wound area than those around the wound area. Conclusion These data suggest that fibromodulin may be involved in the early events of wound healing for periodontal cells.

Objective To investigate the influence of multiple sintering on wear behavior of Cercon veneering ceramic. Methods Samples were fabricated according to the manufacture′s requirement for different sintering times （1, 3, 5, 7 times）. The wear test was operated with a modified MM-200 friction and wear machine in vitro. The wear scars were characterized by scanning electron microscope（SEM） and atomic force microscopy（AFM）. Results With the sintering times increasing, the wear scar width became larger. The correlation was significant at the 0.01 level. Significant difference was observed in wear scar width among different samples（P<0.05）. SEM and AFM results showed that veneering ceramic wear facets demonstrated grooves characteristic of abrasive wear. Conclusion Multiple sintering can decrease the wear ability of Cercon veneer, and the wear pattern has the tendency to severe wear.

Objective To examine the expression of Osterix（Osx）mRNA and protein after application of mechanical force on human periodontal ligament cells（HPDLCs）, and to investigate the role of Osx in orthodontic alveolar bone remodeling. Methods HPDLCs were isolated and cultured in vitro with explant method. Approximately 2.5×105 cells were seeded onto six-well cell culture plates and then were exposed to centrifugal force for 1, 2, 4, 6, 8 or 12 h at 631 r·min-1. The expression of Osx mRNA and protein was measured by reverse transcription-polymerase chain raction （RT-PCR） and Western blot respectively. Immunofluorescence assay was used to detect the expression and subcellular localization of Osx protein by green fluorescence. Results At the initial time point, Osx mRNA had a weak expression and protein was not detected. Under the mechanical stimulation, both mRNA and protein levels of Osx were upregulated in a time-dependent manner. Furthermore, Osx protein was translocated gradually from the cytosol into the cell nuclei. Conclusion The expression and activation of Osx were enhanced by mechanical stress in HPDLCs, which indicates that Osx may play an important role in HPDLCs osteogenic differentiation and periodontal tissue remodeling induced by mechanical stress.

A family with Angle′s Class Ⅱ malocclusion was identified in West China Stomatological Hospital of Sichuan University. The proband was a 22 -year -old woman with Angle′ s Class Ⅱ Division 2 malocclusion with congenitally missing teeth. A total of 15 members of the 3 generations in the family were investigated. There were 7 members（3 males, 4 females） with Angle′s Class Ⅱ malocclusion in the family. The results provide the primary basis for further study to localize the virulence gene.

A 18-year-old female patient after cleft lip and palate surgery with an uncommon complication—precardium area pain were reported. The psychological treatment and nursing along with routine clinical treatment to the patient were applied. The patient had recovered from the precardium area pain after one week treatment.