动物造模,药效评价,牙根吸收模型 z-bio 2024-07-08 456

　　Root resorption is a common and difficult to treat complication in orthodontic treatment. There are many related factors that can cause root resorption, including age, gender, nutritional status, type of orthodontic device, orthodontic force, orthodontic method, treatment course, etc. Due to the irreversibility of root resorption, clinical studies targeting populations are mostly retrospective analyses, and animal experiments are an essential means. Previous experimental studies have mostly used rats, as well as rabbits and cats, but these animals have obvious shortcomings. For example, the front teeth of rats and rabbits grow for life, which is significantly different from those of humans. The disadvantage of cats as root resorption models is that their teeth are easily affected by trauma, resulting in internal absorption of teeth. Moreover, the posterior teeth and oral cavity of these experimental animals are too small, which is not conducive to the placement of orthodontics. Therefore, establishing a small pig root resorption model can provide important reference for preventing root resorption in orthodontic clinical practice.

　　Xie Yongjian and others observed the effect of different force values on root resorption. Seven Chinese experimental miniature pigs were used in the experiment, including four pigs at 6 months old and three pigs at 18 months old. 6-month-old pigs choose mandibular deciduous incisors, with one side being the experimental tooth and the other side being the control tooth; An 18 month old pig chooses a mandibular permanent central incisor, with one side being the experimental tooth and the other side being the control tooth. The wearer of the orthodontic device: A 0.012-inch nickel titanium coil spring is fixed to the second milk molar (6-month-old pig) or the first permanent molar (18-month-old pig) with brass wire or ligation wire. The force is applied every 2 weeks, with values of 300g and 400g, respectively. X-ray shooting: taken by the same technician on the same X-ray machine. Mark the film every time it is taken for easy measurement and statistics in the future. Each animal was subjected to X-rays before the start of the experiment, and then the orthodontic device was placed. X-rays were taken again before each application of force. After 45 days of applying force, the animals were euthanized, and the experimental teeth and control teeth were taken out. Pathological sections and scanning electron microscopy were routinely made to observe the absorption of tooth roots.

　　Experimental results: ① X-ray display: Due to the dense bone structure of the pig's mandible, long tooth roots, and significant overlap of deciduous and permanent teeth, the images of the root tips on both sides are blurred, making it difficult to accurately determine the location and degree of root resorption; ② Visual observation: The experimental side showed significant absorption at the apical area of the teeth under applied force, with an increase in the diameter of the apical foramen. However, there was no root absorption on the control side Pathological section observation: There is more resorption of dental bone at the root apex of the stressed tooth, and some areas even have no attachment of dental bone; ④ Scanning electron microscopy observation: The dental bone has been clearly absorbed, with absorption pits visible at the apical foramen and a worm like appearance at the root apex.