动物模型 z-bo 2020-08-08 436

　　(1) Reproduction method Choose male Beagle dogs weighing 10-15kg, and have no tooth loss, occlusal disorders, and temporomandibular joint disorders. The animals were fasted for 12 hours before the operation and could not help with water. The animals were injected with Sumenoxin at a dose of 15 mg/kg body weight, and then the oral cavity was intubated to establish venous access. Pentobarbital sodium 2 mg/kg body weight was given through the external radial intravenous access, and medicine was added as appropriate according to the specific conditions during the operation, and cefazolin sodium 2 g/mouse was given intravenously. Routinely disinfect the drape, add 1 drop of epinephrine per 5m12% lidocaine for local infiltration anesthesia. Then cut the lip and cheek gums from the first premolar to the first molar, separate the gums, first extract the first molar, and then extract the remaining teeth in turn. Trim the alveolar bone and suture the mucosa. All the premolars and first molars on the opposite side were extracted with the same method. After the operation, the cannula was removed after the dog was awake and breathing spontaneously. Cefazolin 1g was injected intramuscularly every day 3 days after operation. Feed soft food. One month after the tooth extraction, the mucosa was incised on the buccal side of the vestibular sulcus floor in the posterior mandibular area, and then layered to the lower edge of the mandible, and the periosteum was peeled upward. A 4cm rectangular osteotomy was made above the mandibular canal, and the buccal cortex was cut with a fine split drill, and both ends were completely cut off with a thin bone knife. The transverse osteotomy line was drilled with a Kirschner to retain part of the lingual cortex. Drill holes at a predetermined distance on both sides of the horizontal osteotomy line, with a distance of 8mm between the two holes, put two distraction devices in each, and securely fix them in layers and tightly suture them to completely embed them. The mandible on the other side was not treated and was the control side. During the operation, try to preserve the periosteal membrane of the osteotomy block to maintain the blood supply. Antibiotics are routinely given after surgery and soft food is given. The model animals were sacrificed on the scheduled day of termination of the experiment. Bilateral joint specimens were cut out, fixed in formaldehyde fixative solution, and then moved to formic acid decalcification, and routine tissue sectioning, HE staining, and microscopic observation.

　　(2) Characteristics of the model When the model animals were stretched 1, 3, and 6 months, the condyles and articular discs on both sides of the condyle and articular discs on both sides were observed with naked eyes and there was no obvious damage, adhesion, absorption, etc. According to histological observation under the microscope, one month later, the surfaces of the bilateral condyles of the model animals were covered with articular cartilage and the surface was smooth. The four layers of joint surface zone, proliferation zone, hypertrophy zone and calcified cartilage zone are clear. There are 5 to 8 layers of fibrocytes on the joint surface; mitotic small cells can be seen in the proliferation zone, and 3 to 5 layers of chondrocytes in the hypertrophic zone; calcification can be seen in the calcified cartilage zone.

　　(3) The previous studies of comparative medicine have proved that during mandibular traction, the mesial and distal bones are displaced by the retractor. Depending on the traction method, the direction of the mesial bones is different, but both Put pressure on the condyle. If this pressure is within the tolerance of the tissue, the joint will undergo reversible adaptive changes. If the pressure is too high, the joints will undergo irreversible changes and even cause various joint diseases. We extracted all the premolars and first molars of the bilateral mandible, and established an edentulous model of the mandible. During the process of alveolar ridge distraction osteogenesis, the control side joint did not change, but the distraction side joint had a slight reversible change. Under the same other experimental conditions on both sides, it indicates that the alveolar ridge distraction osteogenesis has an effect on the temporomandibular jaw. The joints have a certain effect. The dog’s occlusal relationship changes, the vertical distance becomes smaller, and the condyle slightly shifts backward and upward, which may cause joint changes. Secondly, after the distractor is placed, the nickel-titanium memory alloy must recover from its deformation and exert continuous pressure on the upper and lower bone segments. Especially for the lower bones, although there is no major position change under the naked eye, long-term pressure will also cause subtle changes in the muscles and joint capsules around the joints, which will affect the condyles and joint discs. Changes in the articular disc and condyle. In addition, dogs are used as experimental animals to observe joint changes. Dogs’ subjective indications such as pain cannot be recorded, and the effects of mental and psychological factors on this experiment cannot be determined. However, the dog’s spirit and diet within two weeks after tooth extraction and distractor placement All were poor and weight loss, indicating that surgical trauma and chewing discomfort have a certain impact on the dog's mood. 3 months after distraction, the surface of the condyle on the distraction side became thinner, and the collagen fibers were partially exposed. After 6 months, it basically returned to normal, indicating that the early effect of alveolar ridge distraction osteogenesis on the joint is slightly reversible .