BACKGROUND: Sampling the autogenous bone always needs to develop the second operational area or harvest surrounding the implant, which will increase the risk of trauma and infection. Therefore autogenous bone powder may be taken into consideration to reclaim and use for the treatment of local bone defect.OBJECTIVE: To construct experimental models of repairing bone defect by autogenous bone powder and implant material, and observe the biocompatibility between materials and host.DESIGN: Single sample observation.SETTING: College of Stomatology, Dalian Medical University.MATERIALS: The experiment was performed at the Animal Experimental Center of Dalian Medical University from August 2005 to April 2006. Five healthy hybrid dogs were used in this study. Titanium nail and Bio-Oss bone implant materials were designed and produced by Xi'an Zhonghang Titanium Biological Materials Co., Ltd.METHODS: The first, second and third premolars of dogs were uprooted and received implantation 3 months later. Four implant sockets were prepared at left and right sides respectively of each dog, totally 40 sockets. One titanium nail was implanted into each socket, totally 40 nails. Autogenous bone powder collected when drilling hole, Bio-Oss implant materials and their mixture at 1:1 were implanted in artificial bone defect at bucca side, respectively, while non-implanted bone was served as blank control.MAIN OUTCOME MEASURES: ①At week 9, recovery of bone mass was recorded. Height of alveolar bone, density of bone trabecula and osseointegration were observed by X-ray film.②Histological change was determined by methylene blue-basic fuchsin method.RESULTS: No titanium nail fell off, so five dogs were all involved in the result analysis.①General condition and bone defect: At week 9 of implantation, wound was well healed, and the titanium nail was stable with total reserved rate of 100%. Compared with blank control, the bone defect mass was less in bones implanted with autogenous bone powder (P＜0.01), and the least in bones implanted with mixed powder, which had optimal recovery.②Recovery of bone mass: X-ray film demonstrated that, 40 titanium nails were closely connected with bone, and the healing was well.③Biocompatibility between materials and host: All titanium nails were closely surrounded by erythroic compact bone, no blue soft tissues were seen between implant materials and bone, and direct bone interface appeared under low power lens.CONCLUSION: It is effective to repair bone defect by autogenous bone powder and implant material in dog models,good hiocompatibility is observed between materials and host.

Guided bone regeneration technique (GBR) is regarded as one of the most important methods to increase the bone amount of alveolar ridge, which is often recommended to be applied in the dental implantation surgery. Barrier membrane is utilized in GBR technique to cover the bone defect and create a secluded space, which prevents the connective tissue from growing into the space and facilitates the growth priority of bone tissue. In recent years, along with the emerging of different kinds of barrier membranes and bone grafting materials, the scope of clinical application of this technology is continuously expanded. This article reviews the classification and property of the membranes and the application situation of guided bone regeneration technology in the field of dental implantation.

In order to adapt to the development of society,an innovative talent cultivation system has been explored to train stomatological specialists with active innovation spirit and strong ability to practise.

This paper introduces the ways to conduct the fixed denture teaching in prosthodontics with the multivariate teaching and learning mode,including information technology and PBL teaching,simulation model system,knowledge integration and the increasing of clinical practice.

BACKGROUND:Autologous bone marrow aspirate concentrate is often applied in patients from Department of Orthopedics and those with severe limb ischemia, but rarely applied in Department of Oral and Maxil ofacial Surgery, especial y in Department of Oral Implantology. The effect of autologous bone marrow aspirate concentrate on promoting peri-implant bone regeneration deserves further studies.
OBJECTIVE:To evaluate the effect of bone marrow aspirate concentrate in the repair of peri-implant bone defect.
METHODS:Bone marrow 5 mL was extracted from posterior superior iliac spine of experimental dogs and bone marrow cel s were counted before and after concentration. Bone defect (4 mm × 4 mm × 4 mm) was prepared in the middle of bilateral mandibular premolar, which was randomly implanted with gelatin sponge plus bone marrow aspirate concentrate, autologous bone and gelatin sponge. At 4 and 12 weeks after surgery, bone defect specimens were histological y observed. The new bone formation rate and new bone mineral density were calculated.
RESULTS AND CONCLUSION:After centrifugation, the concentrations of nucleated cel s in bone marrow aspirate concentrate were increased by (2.78±0.22) times. More colony-forming units were found after cel culture. Histological analysis showed that, significantly higher new bone formation rate and new bone mineral density occurred in gelatin sponge plus bone marrow aspirate concentrate group, compared with autologous bone group and gelatin sponge group at 4 weeks (P<0.05). The new bone formation rate in gelatin sponge plus bone marrow aspirate concentrate group was significantly lower than that of autologous bone group, and higher than that of gelatin sponge group at 12 weeks (P<0.05). However, the difference of new bone mineral density in the three groups was not significant (P>0.05). Autologous bone marrow aspirate concentrate can significantly improve new bone mineral density and quantity in the pre-implant bone defect.

Objective:To investigate the influence of 3 methods of fiber posts on fracture resistance of maxillary anterior teeth with flared root canals.Methods:32 human maxillary central incisors were assigned randomly to 4 groups(n =8).The crowns of the teeth were removed at a level 2 mm incisal to the cementoenamel junction(CEJ).After root canal therapy,flared canals were simula-ted in 3 groups.The flared canals were reinforced with resin cement(group A),resin composite(group B)and accessory posts (group C)respectively.In group D flared canals were not created.The same size fiber posts were cemented with resin cement in all groups.After posts cementation and composite resin core formation,all teeth were restored with metal crowns.Then the roots of the teeth were embedded in acrylic resin blocks up to 2 mm below the CEJ.The samples were loaded in a testing machine until failure occurred.Results:The maximum load value(N)for fracture of group A,B,C and D was 295.94 ±69.11,450.51 ±54.68, 479.37 ±77.81 and 618.51 ±87.42 respectively(F =118.127,P =0.000);group B vs C,P >0.05,between each 2 of the other groups,P <0.05.No significant differences were found among the groups in the number of repairable fracture patterns(P >0.05). Conclusion:Reinforcement of flared canal with resin composite and accessory posts can increase the fracture restance of the tooth root and the most of fracture patterns are beneficial for the second repair.

BACKGROUND: As a blood concentrate rich in growth factors and fibrin, platelet-rich fibrin (PRF) is able to significantly promote bone regeneration. PRF mixed with bone substitutes is commonly used to repair bone defects in oral maxillofacial region. But it remains controversial whether PRF as a sole material in sinus floor elevation can produce enough new bone tissues.OBJECTIVE: To evaluate the osteogenic potential of PRF as a sole grafting material in sinus floor elevation by means of an animal model.METHODS: Twelve healthy adult mongrel dogs aged 12-18 months were selected and randomized into three groups (groups A, B and C), with four dogs in each group. Upper first molars on both side of each dog were extracted 12 weeks prior to sinus floor elevation and simultaneous implants placement. Different materials were used to fill in the space between the sinus membrane and implant. Groups A, B and C were filled with PRF, autologus bone particles and autologus blood clot respectively. After 12 weeks, specimens were harvested to analyze the new bone formation by gross observation, X-ray examination and histological evaluation.RESULTS AND CONCLUSION: New bone formation was found to embrace all the implants close to the bony sinus floor, and the tips of all implants were free from bone coverage. The new bone height of groups A, B and C were (3.135±0.288),(3.218±0.345), and (1.898±0.157) mm, respectively. The new bone density of groups A, B and C were (65.06±5.88),(75.34±8.18), and (56.92±4.95) g/cm3, respectively. There were significant differences between the new bone height in groups A and C as well as in groups B and C (P < 0.05). Also, significant differences were found between the new bone density in groups A and B, B and C, A and C (P < 0.05). Within the confine of this experiment, it is feasible to use PRF as a sole grafting material in the sinus floor elevation to generate new bone, but the new bone volume is limited.

Objective To understand the primary structure and potential antigenic epitopes of antigen Pf332(Ag332) of P.falciparum iso late FCC1/HN.Methods　Based on the published Pf332 gene sequence , nine pairs of primers were designed for the PCR amplification of the Pf332 gen e fragments from genomic DNA of P.falciparum isolate FCC1/HN. The amplified gene fragments were subcloned into pMD-18T vectors and sequenced. The sequences were aligned using DNAstar software to obtain the full-length sequence of the gene Pf332. The primary structure and sequence homology of Ag332 were analyzed by SAPS, Tmpred, SingalP and Blastn programs. Three fragments, R0, R1 and R2, cor responding to nt#9595-10083, nt#10339-10767 and nt#10855-11247 of Pf332 gene were subcloned into the eukaryotic expression vector pcDNA3-S separately. The Balb/c mice were immunized with pcDNA3-S-R0, pcDNA3-S-R1 and pcDNA3- S-R2 separately, and the expressions of the recombinant proteins were detected by immunohistochemistry assay. The protective immune responses elicited by DNA I mmunization were analyzed by ELISA and parasite growth inhibition tests in vitro .Results　Nine Pf332 gene fragments were specifically amplif ied, subcloned into pMD-18T vectors and sequenced. Pf332 gene of the P.falci parum isolate FCC1/HN was 16,377 bp in length, encoding a protein of 5,458 ami no acids, about 615.28kDa. The Ag332 contains 17 regions of highly degenerated Glu-rich repeats, with 30.18% Glu in total amino acids of Ag332. Ag332 of P.falciparum isolate FCC1/HN and 3D7 exhibited 94.55 % homology in amino acid residues. The results of immunohischemistry assay showed that R0, R1 and R2 were expressed in mice muscle tissue. The amount of IgG antibody of the groups immu nized with pcDNA3-S-R0, pcDNA3-S-R1 and pcDNA3-S-R2 were higher than those of blank and pcDNA3 groups (P＜0.05). The result of parasite growth inhibition test showed that the immunized sera at 1∶5 dilution of groups of pcDNA3-S-R0, pcDNA3-S-R1 and pcDNA3-S-R2 had an incomplete inhibitor y effect on P.falciparum growth. Conclusion　The antigen Pf332 is an large protein containing highly degenerated Glu-rich repeats. Pf332 gene fragments, R1 and R2 encoding potent antigenic epitope repeats.

Undicalcified autologous dentin particles(UADP)combined platelet rich fibrin(PRF)were used in a case after extraction of the left mandibular second molar for tooth extraction site preservation.CBCT images at 3,9 and 24 months after operation showed that the bone mass maintenance effect was obvious.Histological sections showed a large number of new bone formation around dentin particles.