Objective:To establish an experimental model of residual ridge resorption after mandibular incisor extraction and to study the occurrence mechanisms.Methods:Thirty male Wistar rats were used, the edge of the right mandibular incisor was cut every three days(a total of three times) and the incisor was extracted at three days after the final cut. The animals were sacrificed 0,1,2,4,8,12 weeks respectively after the extraction and the mandibles were dissected out. The length of the alveolar bone and the ratio of extracted side length to unextracted side length were measured on soft X-ray photographs and the mandibles were processed for histomorphometry.Eighteen male Wistar rats were used to observe the morphologic alteration of periodontal tissues by hematoxylin and eosin when the incisor crown was cut at different time intervals.Results:As compared with the unextracted side, the length of alveolar ridge of the extracted side was significantly decreased at 4,8,12 weeks;the ratio of extracted side length to unextracted side length significantly decreased at 4 week after tooth extraction(P

Objective To study the effect of vascular endothelial growth factor(VEGF) on the viability of skin flap treated with radiotherapy at different time after operation and clarify its enhancing effect on angiogenesis.Methods Fifty Wistar rat were randomly divided into 3,5,7,9 d groups and control group.A 3 cm?4 cm full thickness dorsal flap with the pedicle remaining attached at the posterior end in rats and were treated with 60Co radiotherapy at the 2nd,4th,and 6th day postoperatively.The total quantity was 12 Gy.In the experiment groups every rat was given VEGF 120 ng on the 3rd,5th,7th and 9th day.The rats in control group were given the same quality normal saline and radiotherapy.Pathological observation,fluorescence staining and sesuccinic dehyrogenase(SDH) assay were used to measure the blood vessel density,blood vessel diameter,microcirculation and cell vitality of skin flap.Results In 5 d and 7 d VEGF group,the number of average blood vessels and cells of the skin falp was increased compared with control group(P

Objective:To evaluate the ectopia osteogenesis ability of rhBMP-2/nHA/Co compound membrane.Methods:Two membranes were fabricated:(1) nHA/Co group(2) rhBMP-2/nHA/Co group.Both of them was evaluated after implantation under thigh muscle of nude mice for 10,20,30 days.Results:More bone-like structures in rhBMP-2/nHA/Co group were found,than that in nHA/Co group.Conclusion:Collagen and nano-HA are suitable sustained release systems for rhBMP-2 in animal experiment and the rhBMP-2/nHA/Co compound membrane can effectively induce ectopia osteogenesis.

Objective To investigate the effects of recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF)on the gingival wound healing, and to lay a foundation for its application in the field of oral cavity.Methods 16 healthy rabbits were randomly divided into experiment and control groups(n=8).2 mm upper and lower incisors’labial gingivae were removed by scalpel. After operation, rhGM-CSF gel was applied to the surface of the wound gum in experiment group,while saline instead of drugs to the control group.2 rabbits were executed at 3,7,11,and 15 d after operation.HE staining was performed to observe the epithelium and epithelial connective tissue structure, distribution, and the changes of various cells of the rats;the number of positive epithelial cells and fibroblasts were observed by PCNA dyeing.Results On the 3rd day,the inflammatory cell infiltration was found in two groups, but a greater number of the cells were observed in experiment group;neovascularization was seen in both groups on the 7th day,and the fibroblasts and collagen fibers were observed too,but the extent of neovascularization in experiment group was more significant. On the 11th day, the fibroblasts proliferation was seen in two groups,but the extent in experiment group was more widely;on the 15th day,the trauma of gingivae of the rabbits in two groups returned to normal,there was no significant difference between two groups.Over time,the number of epithelial cells in proliferation was gradually increased,reached the peak on the 15th day.The number of fibroblasts began to increase from the 3rd day and reached the peak on the 11th day,and significantly reduced to the lowest value on the 15th day.The number of proliferative epithelial cells in experiment group was significantly higher (P<0.01)on the 3rd day and the 11th day than those in control group (P<0.01);the number of proliferative fibroblasts was significantly higher (P<0.05)on the 11th day and the 15th day than those in control group (P<0.05 ), but there were no significantly statistical differences between two groups at other time pionts(P>0.05).Conclusion RhGM-CSF can promote the infiltration of inflammatory cells, angiogenesis,proliferation of epithelial cells and fibroblasts in gingivae. RhGM-CSF is beneficial with wound healing on gum tissue.

Objective:To observe the repair effect of nano hydroxyapatite/magnesium(nHA-Mg)porous composite material modified by poly lactic acid/glycolic acid copolymer(PLGA) on the jaw bone defect of rabbits,and to elucidate the mechanisms preliminary.Methods:The mandibular defect models of 10 mm×5 mm×1 mm in the 18 rabbits were established.Nine rabbits were selected and implanted with nHA-Mg composite materials modified by PLGA in the left as experimental group and the right as blank control group;the other nine were implanted with nHA-Mg in the left as positive control group and the right as blank control group.The rabbits were sacrificed at 4, 8, 12 weeks (respectively 3 of experimental group and positive control group every time)and the mandibular defect areas were intercepted and observed by imaging and histological examination;the sizes of the newborn trabecula area and residual materials in experimental group and positive control group were compared.Results:Compared with positive control group and blank control group, the percentage of newborn trabecula area of the rabbits in experimental group was increased (P<0.05),and there was no statistic difference between positive control group and blank control group (P>0.05).The imaging results showed that the new bone formation can be observed in experimental group and better than positive control group and blank control group.The paraffin section results indicated that there were visible vascular tissue and newborn trabecula,the osteoblasts gathered around the bone trabecula;a lot of pits were located in the bone trabecula, and the pits contained osteocytes in experimental group.As the prolongation of time,thickened newborn trabecula, dense arrangement and trend of converting to lamellar bone were observed in experimental group.The hard tissue section results showed that the remaining amount of materials in experimental group was more than that in positive control group.Conclusion:nHA-Mg porous composite materials modified by PLGA can effectively reduce the rate of degradation in the body, promote osteogenesis and guide the bone regeneration.

OBJECTIVETo evaluate the effect of parathyroid hormone (1-34) [PTH(1-34)] and coralline hydroxyapatite (CHA) on bone regeneration of peri- implant bone defects.

METHODSTwo implant sites were prepared on both sides of tibia in 8 mongrel dogs. The bone defect was created along one bone wall of each implant site. Implants were implanted into the implant sites, then CHA was grafted into the bone defects. After surgery, the animals were randomly divided into two groups. PTH (1-34) (40 µg/kg) was used for subcutaneous injection to the experimental group for three consecutive days, meanwhile the same amount of saline was given to the control group. Half of the animals of each group were sacrificed after 4 weeks and 8 weeks respectively. Specimens were subjected to implant pull- out strength tests, X-ray picture and histological observation.

RESULTSThe bone density of bone defects in the experimental group were higher than that in the control group. No low-density images was observed between the implants and bone at 4 weeks and 8 weeks. The maximum pull-out force value of the experimental group (199.8 N, 411.5 N) was higher at 4 weeks and 8 weeks than that of the control group (100.1 N, 184.5 N) (P < 0.05). The pull-out force value of the experimental group at 4 weeks and the pull-out force value of the control group at 8 weeks were similar. The new bone trabecular around CHA of experimental group was thicker at 4 weeks. Implant surface contacted to the new bone directly without fiber. CHA granules of the experimental group at 8 weeks were fewer than that of the control group. New bone tissue of the experimental group was denser. The contact area between implant surface and new bone was wider in experimental group than in the control group.

CONCLUSIONSPTH (1-34) and CHA can promote bone regeneration of peri-implant bone defects, shorten the implants and bone healing cycle and improve the implants osseointegration.

Animals ; Bone Density ; Bone Regeneration ; drug effects ; physiology ; Ceramics ; pharmacology ; Dental Implants ; Dogs ; Hydroxyapatites ; pharmacology ; Injections, Subcutaneous ; Osseointegration ; drug effects ; physiology ; Parathyroid Hormone ; pharmacology ; Random Allocation