Objective：To research the effect of quorum sensing inhibitor furanone C-30 on initial biofilm formation of Streptococcus mutans. Methods：The in vitro synthetic quorum sensing inhibitor furanone C-30 was prepared with BHI medium in which Streptococcus mutans was cultivated into different final concentration of 10μmol/L,100μmol/L. Biofilms were formed after being incubaed at 37℃ for 24 h, followed which the kinetic quantification of biofilm formation was detected by BioFilm Ring Test. Results：The furanone C-30 group with a concentration of 100μmol/L was shown to inhibit the biofilm formation by Streptococcus mutans significantly(P<0.05). The time of magnetic beads immobilized and the value of BFI were both different between the 100μmol/L furanone C-30 group and the control groups. Conclusions：Quorum sensing inhibitor furanone C-30 in the concentration of 100μmol/L can inhibit the biofilm formation of Streptococcus mutans. It may direct a new way for the prevention and therapy of caries.

[Abstract] Objective：To prepare a novel poly（lactic-co-glycolic acid）（PLGA）/collagen composite membrane for guided bone regeneration, characterize the membrane, and evaluate the effect on proliferation of osteoblastic cells. Methods：PLGA and type I collagen were combined together to prepare a two-layered membrane. The functional groups, surface topography and contact angle of the composite membranes were characterized by attenuated total reflectance Fourier transform infrared spectrometer （ATR-FTIR）, field emission scanning electron microscopy （FESEM） and contact angle meter. Osteoblastic cell line MC3T3-E1 was chosen to seed on the membranes. MTT and flow cytometry （FCM） were used to value the cell proliferation. Results：The spectrum of ATR-FTIR showed that collagen layer was successfully grafted onto the PLGA surface. The characteristic microstructure of interlaced fibers of collagen was observed by FESEM. The contact angle of composite membrane was significantly lower than pure PLGA. The results of MTT and FCM demonstrate the cell viability and proliferation index of cells cultured on PLGA/collagen membrane were significantly higher than PLGA. Conclusions： The PLGA/collagen composite membrane prepared in this study combined synthetic and natural polymers into a versatile entirety and adopted the advantages of the both.

[Abstract] Objective：To study the relationship between miR-200a expression and human ameloblastoma. Methods：RNAhybrid and miRanda software were applied to predict the β-catenin targeting miRNAs. 30 cases of human ameloblastoma and 5 cases of normal tooth germ tissues were selected to detect the expression of miR-200a by real-time PCR technology. Results：MiRNA targeting prediction showed that both the 68th to 96th base pairs and the 69th to 94th base pairs in β-catenin mRNA contained a miR-200a binding site. Compared with normal tooth germ tissues, the expression of miR-200a showed an obvious down-regulation in human ameloblastoma tissues, which difference was statistically significant (P < 0.05). Conclusions：There is a relationship between the expression of miR-200a with human ameloblastoma, and miR-200a might be one of the targeting gene of β-catenin.

[Abstract] Objective：To investigate the presence of red bacterial complex (Porphyromonas gingivalis (Pg) , Tannerella forsythus (Tf) and Treponema denticola (Td)) in pulp tissue with retrograde pulpitis. Methods：Pulp tissue was collected from 40 teeth with retrograde pulpitis. Pg, Tf, Td and the total bacteria in the samples were assayed respectively using SYBR Green real-time PCR. Results Pg, Tf and Td were detected in 22.5%, 82.5 and 47.5% of the samples respectively. There is a synergistic action among Pg, Tf and Td (OR=2.83（1.26~6.38）). Conclusions：The red complex was related to the infection in retrograde pulpitis.

[Abstract] Objective：To observe the effects of salvia miltiorrhiza and drynaria on the construction of paradentium in orthodontic teeth movement. Methods：72 female 8-week-old SPF Wister rats were selected.They were randomly divided into three groups：the salvia miltiorrhiza group, the drynaria group and the control group.Then the animal model for orthodontic tooth movement was established.Every day, 6 g/kg water apozem of salvia miltiorrhiza , 6 g/kg water apozem of drynaria and 3 ml normal saline were drenched to the three groups respectively. Strengthened the force every 7 days.The rats were executed in batch on the 7th、14th、21st、28th days after orthodontic treatment. Peeled off the skull, distanced the tooth movement and measured the alveolar bone density.The tissue slices from the periodontium of the maxillary first molar were observed under optical microscope. Data was analyzed with PASW statistics 18. Results：Distances of the teeth movement in the salvia miltiorrhiza group and the drynaria group were greater than the control group(P<0.05), while no significant difference was found between the two experimental groups (P>0.05).The light microscope showed that the number of osteoclasts in all groups increased rapidly in the beginning, but stabilized later. The amount of the osteoclasts in the two experimental groups both increased more dramatically than the control group(P<0.05), whereas no significant difference were observed between themselves (P>0.05). Although the alvelor bone density presented to a downward trend in all groups, the two experimental groups declined slowly(P<0.05), and no difference was discovered between them(P>0.05). Conclusions：Gavage of salvia miltiorrhiza and drynaria decoction can promote the formation of osteoclast in the periodontal membrane of rats and maintain the alveolar bone density, which is conducive to orthodontic tooth movement in rats.

[Abstract] Objective：To determine the ultimate tensile strength (UTS) of molar coronal dentin and the dentin–enamel junction (DEJ) area, and analyze its fracture surface. Methods： A resin composite block was built up on the human third molar occlusal surface. Slice the teeth buccolingually to obtain slices about 1mm thick. Each slice was then trimmed to a dumbbell-shaped specimen with a fine diamond bur, and to reduce a cross sectional area of about 1mm×1mm. DEJ, superficial dentin, middle dentin and deep dentin specimens were obtained from the midcoronal for tensile testing vertically and horizontally. The fracture surfaces were observed by scanning electron microscope. Results：The UTS of dentin at different levels was anisotropic and decrease from superficial dentin to deep dentin (P <0.05). The UTS of DEJ and middle dentin showed no significant difference (P >0.05). SEM micrographs: Fractures did not occur in one single plane along the peritubular dentin and intertubular dentin. The direction of fracture crack was changed in the dentin and enamel. Most DEJ specimens fractured in the nearby enamel. Conclusions：The dentin of molar crown showed higher ability to resistant fracture in the horizontal direction. The dentin–enamel junction provided a crack-arrest barrier for flaws formed in the brittle enamel.

Objective: To evaluate the effect and the regularity of time-related change of class Ⅲ intermaxillary orthopedic force loading on the maxilla of puberty rhesus. Methods: The animal model was established with 6 puberty female rhesus, which were randomly divided into experimental group(wore class Ⅲ twin-block magnet appliance, each 2 rhesus for 3 and 6 month respectively) and control group(did not wear any appliance, each 1 rhesus for 3 and 6 month respectively ). The lateral radiograph was taken monthly and computer-aided system was used for lateral cephalometry. Results:(1)Compare to the control group, the occlusion of experimental group were changed obviously;(2)Cephalometric measurement showed that normal forward and downward development was observed in control group and maxilla moved forward and slight clockwise rotation was observed in experimental group;(3)The spatial change of maxillary was occurred in the first two month, but the maximum value of length was achieved at the third month;(4)There was a limit exist in the reaction of the maxilla to orthopedic force, additional loading can not promote more spatial change or length increase. Conclusions: Class Ⅲ orthopedic force can obviously change the spatial position and length of maxilla and the former occurs earlier.

Objective: To explore the relationship between Osterix (Osx) and the remodeling of periodontal tissue via observing the expression of Osx in rats periodontal ligaments during the orthodontic tooth movement．Methods: 54 male SD rats were randomly divided into 9 groups, according to tooth movement time points of 0,3,6,12,24 h and 3,5,7,14 d. The orthodontic appliance was placed between the upper left first molar and the upper incisors of each rat, while the upper right first molar as the control group. Osx expression in the tissue of each rat was determined by the immunohistochemical SABC method. Results: In the control group, Osx expressed at a low level in the rat periodontal ligament.While in the experimental group, Osx expression reached the maximum after 5 d, furthermore, the Osx immunoreactivity was higher at the tension side than that at the compression side．Conclusions: Osx played an important role in alveolar bone remodeling during the orthodontic tooth movement．

Objective：To investigate the protection of sodium fluoride on the enamel of deciduous tooth from erosion by carbonated beverages. Methods：Seventy-two enamel blocks were made from human deciduous teeth as samples for the study, and were randomly divided equally into three groups, and each group was divided further into two subgroups according to their immersion duration in carbonated beverages (30min or 50min). Samples in experimental group A and B were respectively treated with 0.6% and 1.23% sodium fluoride, while these in control group were without abovementioned managements. Samples of two subgroups were immersed in carbonated beverages (Coca-Cola) for 30 min and 50 min, respectively. After that, the samples were washed with distilled water. And then, the samples were re-immersed in Coca-Cola with same format after the samples in experimental groups were re-treated with the sodium fluoride. Such immersion-wash circling was kept on for 12 h. To assess the resistance, reinforced by sodium fluoride, of enamel of deciduous teeth to acid erosion caused by Coca-Cola, the structural changes on enamel surface were observed with scanning electron microscope. The hardness of enamel was measured by the surface micro-hardness (SMH). Results：Compared to the control, enamel treated with sodium fluorides was more resistant to acid erosion (P<0.05), with the protective effects being commensurate with concentration of fluoride in the foams (P<0.05). As the immersion time in Coca-Cola prolonged, the protection of the foam weakened accordingly. Conclusions：Sodium fluoride could enhance enamel′s resistance to acid erosion caused by carbonated beverages.