Resident standardization training of dentists is a very important program for the dental students , during which they are trained to be capable of analyzing cases logically and carrying out the treatment suitably. The students who study in this period always have a certain level of basic knowledge and with the full passion for clinical practice, so it's important for them to develop the correct clinical thinking method and form a life-long learning habit. However, the traditional teaching models can't catch up with today's more and more divergent and complicated demands of teaching and learning. The new ori-ented teaching models of PBL and CBL may offer us new ways to carry out the resident standardization training more efficiently, simulate the student's passion of learning and gain wider experience in short time, for their student-centered and clinical cases-guided characteristics.

Objective:To establish peri-implantitis model in beagle dog. Methods:Mandibular first, second and third premolar and first morlar of 5 beagle dogs were extracted. 3 months after tooth extraction,6 branemark pure titanium implants were bilaterally inserted into the posterior mandible in each dog. After healing-abutment connection, cotton ligatures were placed around the healing-abutments and then plaque was accumulated. Clinical and radiographic recording were repeated 1,3 and 5 months respectively after baseline data had been obtained. Surgical recording and pathological changes of peri-implant bone morphology were studied. Results:1,3 and 5 months after the formation of ligature-induced peri-implant inflammation, plaque index,pocket depth and gingival index were singnificantly increased(P

Objective To establish a multiplex loop-mediated isothermal amplification(mLAMP)method for simultaneous detection of Salmonella,Vibrio parahaemolyticus (VPH)and Listeria monocytogenes (LM).Methods Three sets of mLAMP primers were designed to specifically target bcfD of Salmonella and tlh of VPH and iap of LM.The respective single LAMP assay of the three kinds of bacteria was developed,and the ratio of primer concentration was optimized to develop a multiplex LAMP system.The specificity and sensitivity of multiplex LAMP were observed.Results Turbidity monitoring results in real time suggests that the mLAMP was highly specific and amplification could be obtained within 45 min under isothermal conditions.The sensitivity of this mLAMP was found to be 300 fg/μl genomic DNAs for Salmonella and 4.2 pg/μl for VPH and 4.5 pg/μl for LM,which was consistent with conventional PCR.Conclusion The mLAMP described can potentially facilitate simultaneous detection of three kinds of bacteria in a large number of food samples, which could be used as a primary screening method and as a supplement to classical detection methods.

Objective To establish a polymerase spiral reaction (PSR) method for rapid detection of influenza A/H1N1 virus.Methods Six sets of primers were designed for influenza A/H1N1 virus HA gene, and the results were determined with real time kinetic turbidimetric assay and colorimetry method.Results and Conclusion The best primers were selected from six sets of primers, and the best temperature was determined as 65 degrees Celsius.Further experiments showed that the best primer had good specificity for detection of influenza A/H1N1 virus,without cross reactions with 14 other respiratory tract pathogenic nucleic acids.The sensitivity was up to 100 copies,and consistent with that of PCR.So a PSR method is established for rapid detection of the influenza A/H1N1 virus, which is simple, quick, highly specific and sensitive,and especially applicable to field and grass-roots units.

Objective·To explore the role of advanced platelet-rich fibrin(A-PRF)in osteochondral regeneration.Methods·Bone-marrow mesenchymal stem cells(BMSCs)and knee joint chondrocytes were obtained from New Zealand rabbits.A-PRF was obtained by low-speed centrifugation of the heart blood of rabbits.The histological structure of A-PRF was observed by an optical microscope.The release of growth factors in A-PRF was detected by ELISA,including platelet-derived growth factor,transforming growth factor-β,insulin-like growth factor,vascular endothelial growth factor,epidermal growth factor and fibroblast growth factor.A-PRF's cytotoxicity and capability for promoting the proliferation of rabbit BMSCs were detected by live/dead double staining and MTT methods.The effect of A-PRF on the gene expression of type Ⅱ collagen,aggrecan,alkaline phosphatase(ALP)and osteocalcin(OCN)in rabbit BMSCs was detected by real-time fluorescence quantitative polymerase chain reaction(qRT-PCR).Transwell chambers were used to determine the effect of A-PRF on the migration ability of rabbit BMSCs and the chondrocytes.Rabbit knee osteochondral defect models were established,and 18 rabbits were randomly divided into 3 groups.The A-PRF group(n=6)was implanted with A-PRF in the defect,the A-PRF+BMSCs group(n=6)was implanted with rabbit BMSCs on A-PRF,and the control group(n=6)did not undergo implantation.The rabbits were sacrificed 12 weeks after surgery and the knee joint specimens were stained with hematoxylin-eosin(H-E),toluidine blue and safranin O/fast green.Based on the surface morphology and histology of the knee joints,the International Cartilage Repair Society(ICRS)scoring system was used for macroscopic and histological scoring.Results·A-PRF had a loose network structure and can slowly release growth factors.No cytotoxicity to rabbit BMSCs was observed after adding A-PRF,and the the capability for promoting the proliferation of rabbit BMSCs was significantly increased at 24,48 and 72 h after adding A-PRF(all P<0.05).Chondrogenesis-related gene Ⅱ collagen and aggrecan,as well as osteogenesis-related genes ALP and OCN were significantly up-regulated(all P<0.05).After adding A-PRF,the migration abilities of rabbit BMSCs and chondrocytes were significantly enhanced(both P<0.05),and the migration ability of rabbit BMSCs was significantly higher than that of chondrocytes(P=0.025).The joint surface morphology in the rabbit knee joint defect models was observed.It can be seen that the defects in the A-PRF group and the A-PRF+BMSCs group were basically restored,while the the defects in the control group were only covered by soft tissue.In the ICRS macroscopic score,there was no statistical difference between the A-PRF group and the A-PRF+BMSCs group,but the scores of the two groups were all significantly higher than those of the control group(all P<0.05).According to the histological results,both the A-PRF group and the A-PRF+BMSCs group formed osteochondral repair,but the cartilage in the A-PRF group was more mature,while the control group formed fibrous repair.In the ICRS histological score,there was no statistical difference between the A-PRF group and the A-PRF+BMSCs group,but the scores of both the groups were significantly higher than those of the control group(both P<0.05).Conclusion·Autologous A-PRF has good biocompatibility and the capability for promoting the proliferation of BMSCs.It can promote the repair of cartilage and subchondral bone both in vitro and in vivo.