Not only can esthetic clasps removable partial dentures reserve some advantages that removable partial denture itself has such as non-preparation or less preparation and cheap price, but also can bring metal-free smile to the patients, which is an new effective and affordable treatment option for partial edentulism. This article introduced the basic concepts, principle, various types of esthetic design and related clinical application.

Objective To study the differences between amelogenesis imperfecta（AI） teeth and normal human（NH） teeth in wear properties. Methods The ultrastructure of the human tooth enamel from adult patient diagnosed with AI was investigated using atomic force microscope（AFM） and compared with the surface of normal human tooth enamel. The composition of tooth enamel of AI teeth and normal human teeth were analyzed by energydispersive X-ray spectroscopy（EDX）. The properties of micro-friction and wear between AI teeth and normal human teeth were compared using nano-scratch technology and scanning electron microscope（SEM）. Results The AI teeth were found porosity and the loosely packed hydroxyapatite was distributed randomly compared with normal human teeth. The amount of C was higher while the amount of Ca, P were lower in AI teeth than normal human teeth. The friction coefficient of both AI teeth and normal human teeth was increasing with the load increased and the friction coefficient of AI teeth was higher than normal human teeth with the same load. Meanwhile, the destruction of AI teeth was more severe than normal human teeth with the same load. Conclusion The AI teeth has significant differences with normal human teeth on micro-structure, composition and micro-friction and wear properties. Thus, we need to have a general consideration of all these results when doing clinical restorations.

Objective To screen the differentially expressed genes of stem-like cells in tongue squamous cell carcinoma using suppression subtractive hybridization（SSH）. Methods The cells with high and low expression of aldehyde dehydrogenase（ALDHbr and ALDHlow） were isolated respectively from human tongue squamous cell carcinoma Tca8113 cell line. SSH was used to identify differentially expressed genes in those two groups. Positive cell clones with high/low-expressed ALDH were screened randomly for the genetic sequences and function analysis by the bioinformatics technology. Results Total 62 differentially expressed genes were identified, most of which got involved in regulation of cell cycle, cellular differentiation and other biology activities as gene ontology（GO） analysis indicated. Signal pathway analysis revealed 12 pathways related to 11 genes changed significantly. Conclusion Several potential novel biomarker candidates of tongue cancer stem cells were identified and they may provide important insights into the functions and characteristics of human tumor stem cell.

Objective The study was aimed to provide insights into cell proliferation ability alteration of human
periodontal ligament fibroblasts（HPDLF） under two different types of stimulation, cyclic tensile and compressive stress, and screen the differentially expressed genes to have a comprehensive understanding of the molecular mechanism of changes in proliferation. Methods Primary HPDLF were subjected to cyclic tensile and compressive stress（0.5 Hz, 4 000 μstrain） for 2 h through a four-point bending strain system. After that, cell proliferation ability was examined by flow cytometry. Then the gene expression profile was investigated by microarray analysis. Results Mechanical stress slowed a down proliferation of cells. S phase cells and proliferation index（PI） decreased. Differentially expressed genes were mainly located at nucleus and focus in transcription factor activity related genes, and most of them were involved in the regulation of transcription factors. Among them, more were in group of compressive stress. Conclusion 1）Under mechanical loading, HPDLF proliferation were slowed and cell cycles were arrested. 2）Cell cycle arrest and the slowdown proliferation, which can be viewed as an adaptation and protection mechanism of cells to have more time to decide how to respond to mechanical stimuli, and the differential gene expression reflect the behavior of cells. The result of the response is gene transcription changes at first, and the most important biological response is the nuclear transcription. 3）HPDLF are more sensitive to cyclic compressive stress.

Objective To clone the VEGF165 gene and to construct eucaryotic expression vector, investigate the effect of overexpressed VEGF165 and transforming growth factor β1（TGFβ1） on the mineral-related genes in human cells from apical papilla. Methods Total RNA of ECV304 cell was extracted. The VEGF165 gene was amplified by reverse transcription-polymerase chain reaction（RT-PCR）, and then was subcloned into eucaryotic expression vector pcDNA3.1hisA to construct the recombinant vector pcDNA3.1hisA-VEGF165. After being identified by digestion and DNA sequencing, pcDNA3.1hisA-VEGF165 and pcDNA3.1hisA-TGFβ1 were transfected into human cells from apical papilla. Then the efficiency of gene transfection and the expression of bone sialoprotein（BSP）, dentin  sialophosphoprotein （DSPP）, osteocalcin（OCN）, dentin matrix protein 1（DMP1） were detected by Real-Time polymerase chain reaction（PCR）. Results Cloned VEGF165 gene sequences and inserted into expression vector of the VEGF165 sequences showed 100% homology related to the sequence in GenBank database. VEGF165 and TGFβ1 mRNA were upregulated after transfection. The expression of DSPP mRNA were significantly increased in each experiment group（P＜0.05）. The expression of OCN mRNA were increased significantly in the group transfected with pcDNA3.1hisA-TGFβ1 and transfected with two plasmids（P＜0.05）. The expression of BSP mRNA were not varying（P＞0.05）, while no expression of DMP1 mRNA in each experiment group. Conclusion The recombinant eucaryotic expression vector of pcDNA3.1hisA-VEGF165 was constructed successfully. VEGF165 and TGFβ1 can induce the expression of most mineral-related genes and they may play a key role during the differentiation of human cells from apical papilla.

Objective To introduce a modified model for quantitative testing of glucose microleakage by constant air pressure and evaluate the sealing ability of four root canal sealers including AH Plus, Roeko Seal, Cortisomol and RC Sealer. Methods Fifty-six straight maxillary anterior teeth were randomly divided into four experimental groups with 12 samples in each group, group A: AH Plus, group B: Roeko Seal, group C: Cortisomol, group D: RC Sealer, and positive and negative control group with 4 samples in each. After regular root preparation, samples in experimental groups were obturated by cold gutta-percha lateral compaction technique with sealers according to group description. Control groups were obturated with cold gutta-percha only. Through the model above, the value of glucose microleakage
from crown to root was measured at 1, 3, 5, 7, 10, 15, 20, 25, 30 days with the glucose oxidase-peroxidase method （GOD-POD）. Results At day 1, 3, 5, no significant difference of microleakage was found between group A and B （P>0.05）. The same result was also seen between group C and D. From 7 days, microleakage value in each experimental group gradually increased, and statistical difference was found between groups（P<0.05）. Conclusion This new
model using constant air pressure is easy to establish, sensitive and practical. Among all the sealers evaluated, polydimethylsiloxane based root canal sealer, Roeko Seal has the greatest sealing ability, while epoxy-amine resin based AH Plus is second and Zinc Oxide based Cortisomol and RC Sealer have the least sealing ability.

Objective To study the intercellular communication of alveolar bone during traumatic occlusion at early stage in rats. Methods The occlusal surface of the upper left first molar of rat was raised by placing a stainless steel wire to induce occlusal trauma in the lower left first molar. After 24 hours, the alveolar bone tissues of the lower jaws first molars at the both sides were taken out under anesthesia. The various 27 000 genes were identified with genomewide microarray, and further were investigated with reverse transcription-polymerase chain reaction（RT-PCR） and Pathway analysis. Results Total 586 gene were found to be changed, 106 different signal pathways got involved with Pathway analysis, including cell adhesion molecules（CAMS）, adhesions junction, gap junction, focal adhesion and tight junction, and the cytokines associated with bone metabolism in above 5 signal pathways were all down-regulated. Conclusion At the early phase of the occlusal trauma, intercellular communication in rat’s alveolar bone were inhibited.

Objective To compare the penetration abilities of resin infiltration into natural initial caries lesions with those of adhesive in vitro. Methods Thirty-six extracted human molars and premolars showing proximal white spot lesions were selected. Teeth roots were removed, and the crowns were cut across the caries lesions perpendicular to the surface. Corresponding lesion halves were etched for 2 min with 15% hydrochloric acid gel and were subsequently treated with either adhesive or resin infiltration. Specimens were observed with confocal laser scanning microscopy（CLSM） in dual fluorescence mode. In confocal microscopic images, penetration depth（PD） and lesion depth （LD） were defined as the distance from the surface to the deepest point of red and green fluorescence, respectively. The penetration percentages（PP） were calculated. Results At the same level of caries, mean maximum lesion LD were comparable for both lesion halves（P＞0.05）. But mean maximum PD and PP of the resin infiltration were significantly higher than those of the adhesive（P＜0.01）. Conclusion Penetration of enamel caries lesions is observed in the adhesive and the resin infiltration. But the resin infiltration is capable of penetrating almost completely into enamel parts of natural caries lesions.

Objective To study the repair effect of low intensity pulsed ultrasound（LIPUS） irradiating combined with guided bone regeneration（GBR） on the defect of Beagle dog canines periodontal bone. Methods Four canine teeth of every beagle dog（8 beagle dogs） were randomly distributed: Group 1（LIPUS disposal + GBR+ autogenous bone graft group）, group 2（LIPUS disposal + autogenous bone graft group）, group 3（GBR + autogenous bone graft group）, blank control group. The model of periodontal bone defect was established in the 1/3 part of the root buccal area. According to the group division, autogenous bone were grafted, group 1 and group 2 were disposed by LIPUS 20 min·d-1. The intensity of ultrasound were 30 mW·cm-2. Group 1 and group 3 were injected with Bio-Gide collagen membrane. The beagle dogs were executed at 6 and 8 weeks of the disposal of LIPUS and then Micro-CT test and analysis were conducted to periodontal bone defect area of each group. Results By clinical observation, there were different degrees of shrinkages of the area of periodontal bone defect in each group. The Micro-CT test analysis indicated that there was a statistical difference among the number, the thickness as well as the size of bone trabecula of each group
（P <0.05）. However, there was no statistical difference （P ＞0.05） in terms of bone issue measurement index between 6 to 8 weeks of each group. Group 1 had the most new bone. Conclusion LIPUS has the potential to promote the repair of periodontal bone defect. Therefore the combination of LIPUS and GBR may be more conducive to the repair and regeneration of periodontal bone defect.

Objective To analyze the mechanism of fluorine by systemic analysis of fluorination-demineralizationremineralization experiments. Methods The enamel specimens were randomly assigned to untreated group（group A）, non-fluoride group（group B）, low-fluoride group（group C） and high-fluoride group（group D）. The in vitro model of fluoride enamel was established in group C and D. Based on that, the establishment of demineralization model and remineralization experiment by pH-cycling in group B, C and D were followed. All enamel specimens were observed by stereomicroscope and scanning electron microscope and compared in surface microhardness value. Results There was distinct difference in micro-morphologic appearance on fluoride enamel surface. Artificial caries of fluoride enamel showed a relatively complete surface, the surface microhardness after demineralization and remineralization in fluoride group was higher than non-fluoride group（P<0.05）. Conclusion The fluorinated enamel can enhance cariostatic potential and remineralization capacity of dental enamel.

Objective To assess referral cases for root canal therapy to provide clinical evidence with establishment of referral system. Methods A questionnaire was designed to collect 312 cases（355 teeth） referred to Department of Conservative Dentistry and Endodontics, West China School of Stomatology, Sichuan University for root canal therapy from April to June in 2011. The questionnaire consisted of questions such as age, gender, occupation, general disease and medical histories of patients, sources. Difficulty of treatment before therapy and reasons for referral were evaluated. Results In 355 referral teeth, the most were mandibular first molars（17%）, the greatest percentage of reasons were calcified root canals（30%）, the second was root canal retreatment（24%）. 72% of teeth belong to the complicated difficulty（Class Ⅲ）, while 7% were listed as the uncomplicated difficulty（Class Ⅰ）. No significantly difference from different sources was found（P=0.9）. Conclusion Establishment of referral system needs cooperation with every dentist. Difficulty of cases for root canal therapy before treatment should be first evaluated to treat or to refer. Referral cases for root canal therapy should be treated by endodontist of corresponding level according to the difficulty.

Objective To study the link of Helicobacter pylori salive test cassette（HPS） and 13C-urea breath test （13C-UBT） on detecting Helicobacter pylori infection of stomach, and the sensitivity as well as specificity should be determined. Methods A screening trial of 13C-UBT and HPS tests was carried out 130 patients included 106 positive and 24 negative results of 13C-UBT. As gold standards of 13C-UBT, a comparison study with HPS was evaluated using Bayes formula. Results The sensitivity, specificity, accuracy, positive and negative predictive value of HPS was 68.87%, 58.33%, 66.92%, 87.95%, 29.79% respectively. The coincidence was 66.92%. Conclusion There is a correlation between results of 13C-UBT and HPS. Combination of 13C-UBT and HPS may compensate the blind zone of 13C-UBT
in detecting oral Helicobacter pylori infection. 13C-UBT could not be used as a gold standard to judge the validation of HPS in detecting Helicobacter pylori oral infection. The methods can be used at the same time in clinic.

Objective To evaluate the report quality of randomized controlled trials（RCT） of oral and maxillofacial surgery in China during 2000—2009. Methods A comprehensive electronic search was carried out through Chinese Biomedical Literature Database（CBM）, VIP Database for Chinese Technical Periodicals（VIP） and China National Knowledge Infrastructure（CNKI）, and 19 kinds of journals of stomatology in China were also hand-searched. We identified RCT published between 2000 and 2009, and classified into oral and maxillofacial surgery and labeled “random”and assessed the quality of these reports using the consolidated standards of reporting trials（CONSORT） statement. Results 53 RCT articles were included. Reporting quality of the 53 articles was not high and the CONSORT score was 8.2±2.5. Conclusion The reporting quality of RCT of oral and maxillofacial surgery in China is poor. The  CONSORT statement should be used to standardize the reporting of RCT.

Objective To observe the microscopic characteristic of the bonding interface between resin cement and dentin before and after using Nd: YAG laser, and evaluate the effects of the Nd: YAG laser on the shear bond strength of 3 resin cements to dentin. Methods 30 human premolars were cut into nearly equal halves, prepared to expose the dentin and randomly divided into two groups: Laser group and control group. The teeth in the laser group were processed with pulse Nd: YAG laser（0.8 W, 10 Hz） for 25 s, and then the teeth were bonded using 3 resin cements（RelyX ARC, Panavia F and RelyX Unicem） to dentin. All teeth in the control group were directly filled with 3 cements. The shear bond strength of specimens was measured. Each fractured specimen was examined under dental microscope. And 6 new human premolars were prepared into standard bonding specimens. After 3 teeth processed with pulse Nd: YAG laser, all teeth were bonded using 3 resin cements. To observe the microscopic characteristics of the bonding interface between resin cements and dentin. Results Nd: YAG laser on dentin surface could increase bond strength of Panavia F and RelyX Unicem（P＜0.05）. And the laser could decrease bond strength of RelyX ARC （P＜0.05）. Most of the fractured adhesive dentin surfaces were adhesive failure modes. Scanning electron microscope （SEM） observation demonstrated that Nd: YAG laser irradiation on dentin surface could decrease the hybrid layer and resin tags between the resin cements（RelyX ARC and Panavia F） and dentin. The interface between RelyX Unicem and dentin showed no obvious change, and resin tags were not observed. Conclusion Nd: YAG laser on dentin surface can increase bond strength of Panavia F and RelyX Unicem. Therefore, they can be used together in clinic.

Objective To determine the incidence of human herpes virus（HHV） 1-4 type including herpes simplex virus type-1（HSV-1）, herpes simplex virus type-2（HSV-2）, varicella-zoster virus（VZV）, Epstein-Barr virus（EBV）in the saliva of human immunodeficiency virus（HIV）-infected patients. Methods The incidence of salivary HSV-1, HSV-2, VZV and EBV from 245 HIV-seropositive individuals and control group was used to investigate by polymerase chain reaction（PCR） or nested PCR. The data was analyzed by SPSS 18.0 statistical software. Results In the 245 HIV-seropositive individuals, the detection rates of HSV-1, HSV-2, VZV, EBV were 29.0%, 3.3%, 4.1%, 82.0%. In the control group, the detection rates of HSV-1, HSV-2, VZV, EBV were 13.3%, 0, 0, 36.7%. Four HHVs were significantly
more prevalent in the salivas of HIV-seropositive persons than those in the control group（P<0.01）. The detection rates of HSV-1, HSV-2, VZV and EBV DNA were no difference between the HIV-positive group with highly active antiretroviral therapy（HAART） and HIV-positive group without HAART（P>0.05）. Conclusion There is a high prevalence of HHV infection in HIV-infected people in Yunnan. The most common virus are EBV, followed by HSV-1, but VZV and HSV-2 are rarely detected. HHV co-infection is also observed.

Objective To systemically investigate receptor activator of nuclear factor -κB ligand（RANKL） and macrophage colony-stimulating factor（M-CSF） induced differentiation of osteoclasts. Methods Mouse protein-protein interaction（PPI） database NIA and published microarray dataset GES16749 were used to construct and analyze PPI network of RANKL and M-CSF induced mouse monocyte RAW264.7. Results In the PPI network, transforming growth factor beta receptor 1（TGFBR1）, Rous sarcoma oncogene（SRC）, myelocytomatosis oncogene（MYC） and integrin beta 3（ITGB3） were able to interact with more proteins and they were the key nodes in the signaling transduction. Conclusion TGFBR1, SRC, MYC and ITGB3 might be the key points of RANKL and M-CSF induced  differentiation of osteoclasts.

Objective To compare the effect of three techniques in root canal preparation on coronal microleakage of endodontically treated teeth. Methods Forty-eight human single-rooted teeth were divided into 4 groups randomly and subjected to different techniques on removal of smear layer. Group A, the control group, irrigation with
hydrogen peroxide（H2O2 ） and normal saline（NS）; group B, smear cleared with 5.25% sodium hypochlorite（NaClO） and ethylenediamine tetraacetis（EDTA） gel; group C, irrigation with Odontoson-M ultrasonics; group D, smear layer removed with Nd: YAG laser irradiation . Two specimens of every group were split longitudinally into equal segments and canal walls at coronal portion were examined under scanning electron microscope（SEM）. Then ten teeth of every group were filled with warm vertical condensation by Obtura Ⅱ thermoplasticized gutta-perch injection technique and sealed with zinc oxide eugenol（ZOE）. The teeth were immersed in 20 g·L-1 methylene blue for 7 days, then were demineralized, dehydrated and cleared. Linear dye penetration was determined under a steremicroscope. The data were statistically analyzed. Results In group A, there were smear layer and debris remained and dentinal tubules were covered. In
group B and group C, the smear layer of root canals were removed and dentinal tubules were open. In group D, the root canal dentinal tubules were sealed or semi-sealed and the smear layer were melted and ablated. The mean length of coronal microleakage for group A, B, C, D were （2.15±0.38）, （1.75±0.28）, （2.04±0.40）, （1.73±0.36）mm. The analysis showed that the linear in group A was longer than that in group B and group D clearly（P<0.05）. Conclusion
The coronal microleakage following root canal treatment could be reduced by removing smear layer with different techniques in root canal preparation.

Objective To synthesize a novel nano-antibacterial inorganic filler and provide a new way to give dental composite resin antibacterial property. Methods Quaternary ammonium iodide N,N,N -trimethyl -3 -（trimethoxysilyl） propan-1-aminium iodide were organically synthesized firstly and then the N,N,N-trimethyl-3-（trimethoxysilyl） propan-1-aminium iodide was grafted to the nano-silica particle to synthesize the antibacterial inorganic fillers nano-silica particle grafted with quaternary ammonium salt. All the products were analyzed and identified by infrared spectrum analysis. Then Streptococcus mutans were chosen as experimental object to analysis the antibacterial property of nanoantibacterial inorganic filler. Results Quaternary ammonium salt was grafted to the surface of nano-silica particles successfully by infrared spectrum analysis. Compared with the control group, the nano-silica particle grafted with quaternary ammonium salt had a strong bactericidal effect on Streptococcus mutans（P<0.01）. Conclusion The nano-silica particle grafted with quaternary ammonium salt has a strong antibacterial property and could be used to improve dental composite resin antibacterial property.

Objective To study the effect of bleaching on the mechanical properties of human dentin. Methods The finite element method（FEM） based the cohesive zone model had been employed to study the fracture resistance of human dentin. There types of dentin were considered, i.e. original dentin, dentin after direct-bleaching and indirectbleaching. Results The bleaching treatments had large impact on the crack growth resistance of human dentin. The initiation toughness（1.48 MPa·姨m）, growth toughness（3.90 MPa·姨m·mm-）1 and plateau toughness（3.25 MPa·姨m） of human dentin were reduced to 1.29 MPa·姨m , 3.45 MPa·姨m·mm-1 and 2.71 MPa·姨m respectively after indirectbleaching. The worst case was the direct -bleaching which causes significant reductions in the growth toughness
（0.14 MPa·姨m·mm-1）and plateau toughness（1.63 MPa·姨m）respectively, while the initiation toughness remained the same as that after indirect-bleaching. Conclusion The cohesive zone modeling is an effective tool in characterizing the fracture behavior of human dentin. Bleaching treatments reduce the crack growth resistance of human dentin and increase the risk of fracture of teeth.

Objective To study the influence of three different metal alloy surfaces treated with primer methacryloxy propyl trimethoxyl silane（γ-MPS） coupling agent on the bond strength of Filtek Z350 resin. Methods Total 36 specimens of nickel-chromium（Ni-Cr） alloy, pure titanium（Ti） and aurum-palladium（Au-Pd） alloy, each of 12 pieces produced by lost wax casting method, were divided into 6 groups. After treated with γ-MPS on the bonding surface, experimental group samples were adhered to Filtek Z350 resin, then compared with the surface without γ-MPS treatment. The tensile and shear strength of each group tested and the fracture sections were observed with scanning electron microscope（SEM）. Results Comparing the Ni-Cr alloy and pure Ti experimental group with them in control
group, the shearing strength of the experimental group was higher, and the differences were significant（P<0.001）. The shearing strength of the experimental group and control group of Au-Pd alloy were not significant（P>0.05）. Comparing the experimental groups, the shearing strength of pure Ti was higher than Ni-Cr alloy, both were higher than Au-Pd alloy（P<0.01）. These entire specimens were adhesive fracture. Comparing with the control group, Ni-Cr alloy and pure
Ti experimental group showed more resin juts in the fracture surface, while the Au-Pd alloy in experimental group showed less resin juts. Conclusion γ-MPS can enhance the adhesion between metal and resin, but it is also related to the metal composition. γ-MPS can significantly increase the bond strength of resin and Ti or Ni-Cr alloy, but not the case of Au-Pd alloy and resin.

Objective To examine the flora samples from the tongue dorsum of the atrophic glossitis group and to discuss the relationship so as to provide a thinking pattern for therapy and a clue for deeper research. Methods To collect personal information on 60 cases of atrophic glossitis and 40 cases of volunteers as control. The main items include general status, oral examination, salivary flow rate, pH value and bacteria test. All data were analyzed statistically. Results 1）Among the 60 cases, 75.00% were female patients. Glosso-pain, dry mouth and taste loss were the most common symptoms. 2）In regard to the pathogenic factors, the systematic diseases were often visible, i.e. gastritis, coronary disease and anemia. 3）Oral hygiene of the patients was worse than that of the control group, the saliva flow rate and pH value were lower than that of the control. 4）The statistic analysis showed that the quantity of some bacteria of tongue dorsum and their detectable rate were different between the glossitis group and the control one, between the patients with atrophic glossitis who also suffered from different systematic diseases and the control group, and between the complete type and the partial type. These bacteria included Streptococcus sanguis, Stomatococcus,
Staphylococcus aureus, Saccharomyces, etc. Conclusion Atrophic glossitis is the consequence co-affected by host, circumstances of oral cavity and bacteria. The tangible relationship between atrophic glossitis and micro-ecological changes on glossal dorsum has not been confirmed yet, however, flora change on dorsum may have relations with occurrence, and development of the disease.

Objective To investigate the effect of novel porous calcium phosphate cement（CPC） scaffoldings on attachment, proliferation and differentiation of bone marrow mesenchymal stem cells（BMSCs）. Methods BMSCs of Beagle dogs were implanted and cultured with CPC scaffoldings in vitro, tricalcium phosphate（TCP） and poly（lactideco- glycolide）（PLGA） scaffoldings as controls. The attachment, proliferation and differentiation of BMSCs were detected through morphological characters, growth curve and the semi-quantitative detection of alkaline phosphatase（ALP） and osteocalcin（OC） activity. Results Cell morphology and growth curve illustrated that BMSCs attached to and grown better on the surface of novel porous CPC scaffoldings than that of PLGA group（P<0.05）. Semi-quantitative analysis of ALP showed that ALP expression level in BMSCs on the CPC and TCP group were significantly higher than that
of the PLGA group（P＜0.05）, the CPC group was slightly higher than the TCP group, but no significant difference was found between the two groups（P＞0.05）. The staining and semi-quantitative analysis results of OC demonstrated that calcium deposition of the PLGA group was significantly less than the CPC and TCP group on both observation point（P＜0.05）, but no significant difference between the CPC and TCP group（P＞0.05）. Conclusion The novel porous CPC material used in this study has good biocompatibility similar to TCP but much better than PLGA which is favorable of BMSCs adhesion, proliferation and osteogenic differentiation. The novel porous CPC material is a suitable scaffolding for BMSCs to fabricate tissue-engineered bone in vitro.

Objective To observe the effect of green tea extractive epigallocatechin-3-gallate（EGCG） on degradation of collagen in dental erosion. Methods Sixty-four volunteers with dental erosion were randomly divided into two groups. The custom fitted trays were made from the heat curable braces and were injected with carboxymethyl cellulose sodium（CMC） hydrogel in one group（control group） or CMC hydrogel with EGCG added in another（experimental group）. These trays were used during sleep and removed from oral cavity in the next morning. The content of carboxy-terminal telopeptide of type Ⅰ collagen（ICTP） were determined by radioimmunoassay kit at 1 d before the experiment, and 1, 2, 3, 4 weeks after the experiment. Results Both the types and time showed significant effects on ICTP. The incubation in EGCG resulted in relatively rapid and significant（P<0.05） decrease in the expression level of ICTP compared with the control group. Conclusion EGCG can inhibit collagen degradation and improve the antierosive effect of dentine.

MTA is rarely applied in the repair of root fractured section. A case of maxillary second premolar which fractured ten years ago had been connected with MTA in this article and the cone beam CT was used to evaluate the treatment effect.

A case of Langerhans cell histiocytosis of the mandible was reported. A 34-year-old woman presented with pain for one year on the gingival of the low left jaw, and together with pyorrhea in the past 2 months. The histopathology and immunohistochemical examination confirmed the diagnosis of Langerhans cell histiocytosis.