动物造模,牙根吸收 z-bo 2022-02-19 426

　　Root resorption is a common and difficult complication in orthodontic treatment. There are many related factors that cause root resorption, including age, gender, nutritional status, type of appliance, correction force, treatment method, and treatment course. Due to the irreversibility of tooth root resorption, clinical studies aimed at the population are mostly retrospective analysis, and animal experiments are an indispensable means. In previous experimental studies, rats were mostly used, and some people used rabbits and cats, but these types of animals have obvious shortcomings. For example, the front teeth of rats and rabbits grow for life, which is quite different from humans. The disadvantage of cats as a root resorption model is that cat teeth are easily affected by trauma to produce internal resorption of teeth, and the posterior teeth and oral cavity of these experimental animals are too small, which is not conducive to the installation of appliances. Therefore, the establishment of a mini-pig root resorption model can provide an important reference for preventing root resorption in clinical orthodontic practice.

　　Xie Yongjian and others observed the effect of different force values on root resorption. Experimental application There are 7 Chinese experimental miniature pigs, of which 4 are 6 months old and 3 are 18 months old. 6-month-old pigs choose mandibular deciduous lateral incisors, one side is experimental teeth, and the other side is control teeth; 18-month-old pigs choose mandibular permanent central incisors, one side is experimental teeth, and the other side is control teeth. The wearer of the appliance: 0.012 inch nickel-titanium spiral spring is fixed to the second deciduous molar (6-month-old pig) or the first permanent molar (18-month-old pig) with brass wire or ligation wire, and the force is applied every 2 weeks. The values are 300g and 400g respectively. X-ray filming: filming by the same technician on the same X-ray machine. Marks are made on the film every time the film is shot, which is convenient for subsequent measurement and statistics. After each animal was taken X-ray film before the start of the experiment, the appliance was placed, and X-ray film was taken again before each increase in force. The animals were sacrificed 45 days after the force was applied. The experimental teeth and the control teeth were taken out, and pathological sections and scanning electronic lenses were routinely made to observe the root absorption.

　　Experimental results: ①X-ray shows: because the bones of the mandible of pigs are relatively dense, the roots are very long, and the primary and permanent teeth are more overlapped, the images of the root tips on both sides are blurred, and it is difficult to correctly judge the location and extent of root resorption; ②Visual observation ：The apical part of the afterburner tooth on the experimental side absorbs significantly, the diameter of the apical hole increases, and there is no root resorption on the control side; ③ Pathological observation: the apical part of the afterburner tooth absorbs more cementum, and some parts are even toothless Bone attachment; ④Scanning electron microscope observation: Cementum has obviously been absorbed. Absorbed lacuna can be seen at the apical foramen, and the apex is like insects.