动物模型 z-bo 2020-08-10 487

　　(1) Reproduction method For Beagle dogs weighing 12-15 kg and aged 10-24 months, one mandible is randomly selected as the experimental side and the other side is the control side. In the experimental side device, the first and third premolar belt rings were made of stainless steel belt rings on the plaster model, and they were fixed on both ends of the spiral expander by spot welding. For the control side device, make band rings on the third and fourth premolars, respectively spot weld brackets and straight wire buccal tubes, bond the brackets on the first premolars, and connect with 0.42mm×0.61mm stainless steel square wire Each component was completely anesthetized by intravenous injection of 30g/L pentobarbital sodium at a dose of 0.6 mg/kg body weight through a dog vein, the second mandibular premolars were extracted, and the experimental side underwent alveolar septal resistance reduction, and then bilateral bonding experiments Device. From the first day after the operation, the experimental side rotates and applies the force twice a day, 1/4 turn (0.25mm) each time, and stops the force on the 14th day, and enters the retention period; the control side is in the first and fourth premolars The nickel-titanium coil spring was interposed, and the applied force was 1.96N. After that, no adjustment was made. The nickel-titanium coil spring was removed at 14 days and the ligation entered the holding period. X-ray examination and filming were performed on each side on the scheduled experiment day. When filming, the animal was taken supine position, the lower edge of the mandible was parallel to the horizontal plane, and the bite film was placed under the tongue. The model animals were sacrificed on the scheduled day of termination of the experiment. Samples of the experimental side and the control side were cut and marked and placed in formaldehyde fixative solution immediately after marking, and then moved to the compound acid decalcification solution for decalcification, along the jaws and teeth. Axial sagittal section of conventional tissues, HE staining and bone morphogenetic protein (Bone Morphogenetic Protein, BMP) McAb immunohistochemical staining, observation under a microscope; and using color pathological image immunohistochemistry measurement system, after each immunohistochemical staining The slices were used for BMP quantitative analysis.

　　(2) Model characteristics X-ray observations on the experimental side and the control side did not reveal obvious root resorption, reduction of alveolar ridge height, and loss of anchorage; the microscopic histopathological observation showed that the experimental side was on the tension side periodontal at 2 weeks The membrane is significantly widened, fibroblasts and osteoblasts are abundant, blood vessels are dilated, and there are scattered blood cells; the new lamellar bone on the side of the alveolar bone is in the shape of fingers along the traction direction, and a single layer of osteoblasts is arranged on the surface. The bone deposition line between the bone and the original alveolar bone is obvious; a layer of new cementum can be seen on the cementum side, and cementoblasts can be seen on it. The periodontal space on the pressure side is narrowed, and homogeneous hyaloid degeneration without cells is rare, mostly tissue edema and vacuole-like transformation of cells; more osteoclasts and bone resorption have been seen on the surface of the septal bone Lapse. At 3 weeks, the periodontal ligament on the tension side was slightly wider, and the cells were still abundant; the new lamellar bones on the alveolar side were interconnected in a loose mesh shape, and a large marrow cavity was visible with a layer of osteoblasts on the surface. The width of the periodontal ligament on the pressure side is slightly narrower, the cellular components increase, and the tissue edema is reduced. The original dense septal bone gradually disappears and is replaced by loose bone. At 6 and 8 weeks, the periodontal ligament on the tension side has basically returned to normal, the new bone on the alveolar side is connected into a woven shape, the trabecular bone is thick, and the calcification increases with time. The same performance is seen on the pressure side. At 2 weeks on the control side, the periodontal ligament on the tension side was widened, the cells were abundant, the blood vessels were dilated, and there were scattered blood cells; a thin layer of new bone matrix deposition zone was seen on the surface of the alveolar bone, which was lightly stained, and the bone deposition line was not obvious. Osteoblasts can be seen on the surface, and fracture lines can be seen at the bottom of the septal bone. The width of the periodontal ligament on the pressure side is narrowed, the hyaline degeneration area is larger, and bone resorption lacunas can be seen in some areas, and osteoclasts are less common. At 3 weeks, the periodontal ligament on the tension side had returned to normal, the new bone matrix on the surface of the alveolar bone had begun to calcify, osteoblasts were visible on the surface, and the bone deposition line was obvious. The width of the periodontal ligament on the pressure side is still narrow, the transparency zone has been limited, and more bone resorption lacunas can be seen on the surface of the septal bone. At 6 and 8 weeks, both the tension side and pressure side periodontal ligaments have basically returned to normal, and the new bone matrix on the surface of the alveolar bone has been calcified. The results of BMP McAb immunohistochemistry showed that BMP is mainly distributed in the periodontal ligament area in the periodontal tissues of dogs, especially in the area adjacent to the alveolar bone and cementum. The staining was strong; osteoblasts, osteoclasts, and fibroblasts The staining of cells was strongly positive; the staining intensity was stronger on the tension side than on the pressure side, and the staining of bone remodeling, especially the active area of osteogenesis, was correspondingly strongly positive.

　　(3) The basic principle of distraction osteogenesis in comparative medicine is that when the body tissue is subjected to slow and stable traction and tension, the cell proliferation and synthesis function is activated, thereby promoting tissue regeneration. This method is likely to be effective for orthodontics. The treatment has a revolutionary impact. In the process of making this model, during the 2 weeks of force application, there was an extremely significant difference between the tooth movement on the experimental side and the tooth movement on the control side, indicating that the movement speed of the first premolars on the experimental side was much higher than that of the control side, and it was not found There are other adverse reactions. BMP acts as a bone growth promoting factor. The main target cells are undifferentiated mesenchymal cells, as well as connective tissue cells such as fibroblasts. Previous studies believe that BMP is mainly involved in the body’s osteogenesis, induces differentiation of mesenchymal cells in tissues, and forms chondrocytes and bone cells. The role of BMP in inducing bone formation has been confirmed by a large number of experiments. The model replicated by this method shows that the rapid tooth movement technology of periodontal ligament distraction osteogenesis can greatly increase the movement speed of orthodontic teeth, with high osteogenesis activity, and no obvious root resorption, reduction of alveolar ridge height, and loss of anchorage. . Therefore, this model can provide a new method and new idea for clinical orthodontics. However, periodontal tissue reconstruction is a complicated process, and the regulation and influence of other growth factors (such as TGFβ, bFGF, IGF, etc.) and other factors (such as collagen and other non-collagen proteins) cannot be ignored. . Therefore, a comprehensive understanding of the synergy of various factors is of great significance for further understanding the mechanism of periodontal ligament distraction osteogenesis.