动物造模,药效评价,牙根吸收 z-bio 2024-09-18 337

　　Root resorption is a common and difficult complication in orthodontic treatment. There are many factors that can cause root resorption, including age, gender, nutritional status, type of orthodontic appliance, magnitude of orthodontic force, orthodontic method, and treatment duration. Due to the irreversibility of root resorption, clinical studies targeting populations are mostly retrospective analyses, and animal experiments are an essential tool. Previous experimental studies have mostly used rats, while some have used rabbits and cats, but these animals have obvious shortcomings. For example, the anterior teeth of rats and rabbits grow for life, which is significantly different from that of humans. The disadvantage of using cats as a root resorption model is that cat teeth are easily affected by trauma, leading to internal resorption of teeth. Additionally, the posterior teeth and oral cavity of these experimental animals are too small, which is not conducive to the placement of orthodontic appliances. 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 at 6 months old and three at 18 months old. 6-month-old pigs choose the mandibular mammary incisor, with one side as the experimental tooth and the other side as the control tooth; 18 month old pigs choose a mandibular permanent central incisor, with one side as the experimental tooth and the other side as the control tooth. The wearer of the orthodontic appliance: The 0.012-inch nickel titanium coil spring is fixed to the second primary molar (6-month-old pig) or the first permanent molar (18 month old pig) with brass wire or ligature wire, and the force is applied once every 2 weeks, with force values of 300g and 400g, respectively. X-ray film shooting: The same technician takes the film on the same X-ray machine. Mark on the film every time it is filmed for easy measurement and statistics in the future. After taking X-rays of each animal before the experiment, orthodontic appliances were placed and X-rays were taken again before each application of force. After 45 days of force application, the animals were euthanized, and experimental and control teeth were removed. Pathological sections and scanning electron microscopy were routinely made to observe the absorption of the tooth roots.

　　Experimental results: ① X-ray display: Due to the dense bone structure of the pig mandible, long tooth roots, and significant overlap between the mammary 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 root tip of the teeth on the experimental side showed significant absorption, with an increase in the diameter of the apical foramen, while there was no root resorption on the control side Pathological section observation: There is more absorption of dental bone at the root tip of the teeth with increased force, and some areas even have no attachment of dental bone; ④ Scanning electron microscopy observation: The dental bone has been clearly absorbed, and absorption pits can be seen at the apical foramen. The apical area appears insect like.