AIM: To investigate new bone formation of alveolar augmentation with hydroxylapatite(HA)+bone morphogenetic protein(BMP)+fibrin sealant FS(HA+BMP+FS) composite.METHODS:Bone morphogenetic protein was extracted from bovine cortical bone. Hydroxylapatite particles were combined with fibrin sealant and BMP, which is of high efficient osteoinduction, forming a new complex material. The alveolar augmentation was made with this composite. The samples were investigated 3, 6,12 and 24 weeks postoperatively, with gross observation, microscope, calculation of new bone formation, tetracycline fluorescent microscope, scanning electron microscope, backscattered electron image and X-ray energy analysis.RESULTS: 1. In experimental group, weave bone had been seen since 3 weeks postoperatively and more new bone 6 weeks postoperatively; remolded bones united and distributed to all spaces of HA particles 12～24 weeks postoperatively. In control group, no new bone appeared 3 weeks postoperatively, only some HA particles contacted base bone 6 weeks postoperatively, a little of new bone grew into HA spaces 12～24 weeks postoperatively. 2. New bone directly incorporated with HA. The quantity of calcium and phosphate are similar to HA and base bone. CONCLUSION:This composite in alveolar augmentation obviously promotes incorporation HA with base bone, speeds formation of new bone and adds amount of new bone, reconstructing a bony alveolar ridge.

Objective To investigate if anodal transcranial direct current stimulation (atDCS) of the right cerebellum improves verbal working memory in amnesic persons with mild cognitive impairment (aMCI).Methods Thirty-nine aMCI were randomly divided into an observation and a control group using a random number table.The observation group was given atDCS at 1.2 mA for 20 minutes every day for 5 days,while the control group was provid ed with fake atDCS in the same way.Before and after the treatment,both groups were tested using forward and back ward digit spans,word reading,visually cued sensorimotor tests and finger tapping.Results After the treatment,the forward and backward digit spans of the observation group had improved significantly compared with before the treatment and with the control group's improvements.Significant improvement was observed in the average backward digit span of the control group,but not in their forward digit span after the treatment.No significant differences be tween the two groups were observed in the other measurements before or after the treatment.Conclusion Direct current stimulation of the cerebellum may improve the verbal working memory deficits of aMCI.Further research should be conducted to find the mechanism.

Objective:To observe the effects of orbital bone density on the stress distribution of implant-bone surface.Methods:The 3D finite element analysis craniofacial model with eight HU values(300 -1 0 000)was established.A force of 20 N along the im-plant axis was applied on the model.The stress values and distribution were calculated and analyzed.Results:The peak of stress val-ue and displacement discreased as HU value increased.In the range of HU value 800 -1 000 HU,the peak of stress value and dis-placement of bone interface did not significantly change with the increasing of HU value.Conclusion:Orbital bone density is an im-portant factor on orbital implant failure when HU value below 800.

OBJECTIVEThis study aims to observe the effect of orbital implant lengths on stress distribution in peri-implant surfaces.

METHODSThe three-dimensional finite element analysis models of craniofacial and orbital implants with a diameter of 3.75 mm and lengths of 3, 4, 6, and 10 mm were established. A force of 20 N was applied to the models. The stress and displacement distribution under every condition were recorded and analyzed.

RESULTSThe loading direction along the implant axis and the stress concentration on the implant root were observed. The loading direction was at a 45 degree angle relative to the implant axis, and the stress concentration was located at the implant neck and the first screw thread. The maximum stress of the 3 mm implant was significantly higher than that under the other two loading directions. The maximum displacement of the four lengths exhibited no significant change. Given the same implant length, stress, and displacement, the peak of the implant axial direction was lower than that of the 45 degree direction. The loading type was an important factor influencing the stress and displacement of peri-implant bones.

CONCLUSIONThe implants of more than 4 mm length can be considered for clinical use. The implant of 3 mm length should be implanted in a region with thicker cortical bone.

Objective:To observe the effect of orbital implant shrink range on the stress distribution in bone-implant interface. Methods:The 3D finite element analysis of craniofacial and orbital implant models with the implant length of 3,4,6 and 10 mm,and with the shrink range of0.05,0.1 and 0.15 mm were established respectively.The stress in the bone-implant interface were calculat-ed and analyzed.Results:The stress increased with the increase of implant shrink range.The stress produced by the implant with 0.15 mm shrink range decreased.The stress of the implant of 10 mm was lower than that of other implants with the shrink range of 0.1 and 0.15 mm.Conclusion:The maximal implant shrink range of 0.1 mm in the model can meet the clinical requirements in orbital implant planning.

BACKGROUND:Stromal cel derived factor-1 is a smal molecular protein with a wide range of biological activity that can cause immune cel chemotaxis, and it also has a chemotactic effect on bone marrow stem cels and periodontal ligament cels.
OBJECTIVE:To investigate the effect of stromal cel derived factor-1 with different concentrations on the proliferation of bone marrow stem cels and to probe the best concentration.
METHODS:Bone marrow stem cels from beagle dogs were culturedin vitro and stimulated by different concentrations of stromal cel derived factor-1 (100, 200, 300 μg/L). MTT was used to detect the influence of stromal cel derived factor-1 on the proliferation of bone marrow stem cels so as to screen the best concentration of stromal cel derived factor-1. Then, stromal cel derived factor-1 at the best concentrations was used to intervene the bone marrow stem cels, and MTT was used again to detect the proliferation of bone marrow stem cels.
RESULTS AND CONCLUSION:Stromal cel derived factor-1 at concentrations of 100, 200, 300 μg/L could promote the proliferation of bone marrow stem cels, and the effect was more notable at 200 and 300 μg/Lbut withno significant difference. Therefore, 200 μg/L was considered to be the best concentration of stromal cel derived factor-1 for intervention of bone marrow stem cels. Compared with the blank control group, 200 μg/L stromal cel derived factor-1 could significantly promote the proliferation of bone marrow stem cels. Taken together, stromal cel derived factor-1 can promote the proliferation of bone marrow stem cels, and its best concentration is 200 μg/L.

BACKGROUND:Bone marrow mesenchymal stem cel s have been shown to be differentiated into periodontal ligament fibroblasts when co-cultured with periodontal ligament cel s. Existing studies have shown that estrogen has the ability to influence bone marrow regeneration. OBJECTIVE:To investigate the effects of estrogen on osteogenesis and fibroblast-related factors alkaline phosphatase, type I and III col agen in bone marrow mesenchymal stem cel s. METHODS:Bone marrow mesenchymal stem cel s isolated from Beagle dogs were treated with estrogen. Osteogenesis and fibroblast-related mRNA and protein expression of bone marrow mesenchymal stem cel s was determined by RT-PCR and western blot assay, respectively. RESULTS AND CONCLUSION:mRNA and protein expression of type I and III col agen in bone marrow mesenchymal stem cel s was upregulated fol owing estrogen treatment;especial y, in contrast with type III col agen, the changes of type I col agen were more obvious. Estrogen did not influence mRNA and protein expression of alkaline phosphatase. These findings suggest that estrogen promotes the differentiation of bone marrow mesenchymal stem cel s into fibroblasts, whereas does not impact the genes involved in parodontium mineralization.

Objective To explore the advantages and disadvantages of laparoscopic combined with colonoscopic surgery (double endoscope surgery) and open surgery in the treatment of special types of colorectal polyps. Methods The clinical data of 62 patients with special types of colorectal polyps (wide base sessile, special parts or suspected cancerous, endoscopic resection difficult or high risk) were retrospectively analyzed. Among them, 42 patients underwent double endoscope surgery (double endoscope group), and 20 patients underwent open surgery (open group). The operating time, amount of bleeding during operation, postoperative exhaust time, postoperative hospital stay and complication rate were compared between 2 groups. Results All the patients had successful resection of the polyps, and there were no operative deaths. There was no conversion to open surgery in double endoscope group. Two patients in the open group were unable to locate the lesion by the tactile sensation of the hand and then succeeded in locating by intraoperative colonoscopy. The operating time, amount of bleeding during operation, postoperative exhaust time, postoperative hospital stay and complication rate in double endoscope group were significantly lower than those in open group: (60.5 ± 25.4) min vs. (75.8 ± 20.6) min, (30.5 ± 15.8) ml vs. (55.2 ± 24.6) ml, (24.6 ± 10.5) h vs. (40.5 ± 16.8) h, (3.2 ± 1.0) d vs. (5.8 ± 2.2) d and 0 vs. 20% (4/20), and there were statistical differences (P<0.05). There was 1 case with early postoperative inflammatory bowel obstruction, 1 case with abdominal infection and 2 cases with incision infection in open group. There was no operative death in the two groups, and these patients were cured by conservative treatment. The follow-up time was 3-36 (18.6 ± 12.3) months, and all the patients survived. The patients in 2 groups had no recurrence and metastasis, no anastomotic stenosis, anastomotic leakage and other complications. Conclusions For the special types of colorectal polyps, double endoscope surgery is less invasive, with faster recovery and less complications. It is the first choice except for endoscopic resection.

Objective:To observe the effect of orbital implant load angle on the stress distribution of peri-implant surface.Methods:The 3D finite element analysis model of orbital implant with diameter of 3.75 mm and length of 6 mm was established.A force of 20 N was applied on the model at various angles.The stress distribution and displacement of the implant were recorded and analyzed.Results:Under 0°,1 0°,20°,30°,45°and 90°the maximum stress(MPa)on the peri-implant surface was 3.1 73,6.535,1 0.506,1 4.1 68, 1 8.949 and 24.755,the maximum displacement(μm)of the implant was 1 .761 ,3.654,7.665,1 1 .567,1 6.774 and 25.072,respec-tively.Conclusion:The loading angle is an important factor influencing stress and displacement of peri-implant bone.

BACKGROUND:Alveolar distraction osteogenesis is an important method for treating alveolar bone atrophy, the osteogenesis process and biomechanics play a crucial role in the fol owing implantation and repair. At present, no related experimental studies are found.
OBJECTIVE:To analyze the biomechanical and histological characteristics of alveolar distraction osteogenesis in a canine model.
METHODS:Twelve adult mongrel canines received premolars extraction and alveoloplasty in mandible to establish an atrophy alveolar model. After 3 months, a segmental alveolar osteotomy was performed in the randomly selected unilateral atrophy alveolar and two intra-osseous distractors were placed. After a 7-days latency period, the alveolar ridge was augmented at a rate of 1.0 mm/d for 5 days. After a consolidation of 1, 2, and 3 months, the canines were sacrificed and the specimens of the distracted alveolar bone were harvested for clinical, radiographic, histological and biomechanical analysis.
RESULTS AND CONCLUSION:The alveolar distractors obtained good healing with surrounding tissue. The atrophy alveolar bones were augmented for (4.80±0.50) mm and (5.12±0.47) mm by clinical and radiographic findings immediately after distraction, respectively. The bone trabeculae in the distracted chamber matured from 1 to 3 months of consolidation by histological analysis. The shearing force of alveolar distraction chamber increased from 1 to 3 months. After 3 months’ consolidation, the shearing force of distracted chamber was comparable to host bone. The histological and biomechanical property of distracted alveolar chamber is comparable to host bone after 3 months’ consolidation.