Establishment Of Animal Model For Research Of Tooth Movement In Rat

With the development of socio-economic conditions and the raise of people’s economy level, the people’s quest for beauty will be increasing, especially the appearance of facial. And with the improvement of oral health literacy, it is recognized that malocclusion largely influence not only the appearance of the maxillofacial, but also affect breathing, language, and the other functions, with the greater harm. Because of the race evolution, individual development, and change of dietary structure, the rate of malocclusion and people demanding orthodontic treatment have increased in recent years. The orthodontic treatment is that the orthodontic practitioner exert a certain degree of orthodontic force to the malposed teeth, dental arch, jaw bones or craniofacial hard and soft tissues through the appliance, to cause the alterations of periodontal tissue, jaw bones and other organizations within the physiological limits, resulting in teeth movement and guide of jaw’s normal growth and development to rebuild or restore the occlusal balance, and thus making the dentognathic system to function normally and obtain a normal appearance so that to achieve the purpose of treating the malocclusion. There are different opinions about the mechanism of causing a series of tissue remodeling and resulting in tooth movement at present, and the major of them are the bone elastic theory, the bone translation theory, the bone mechanochemical theory, the bone piezoelectric effect theory and so on. The studies of molecular biology about the bone remodeling in recent years shown that after the force exerting to the malposed teeth, it mediates to the surrounding tissue through some biochemical signals to cause the alteration of the surrounding tissue and result in tooth movement. The biochemical signals are different in different periods, and their internal mechanism are different too. Through in-depth study of the above mechanisms, the orthodontists can better control the tooth movement, protect the periodontal tissue from excessive damage, avoid some side effects, and shorten the treatment time in clinical. On this basis, It is also conducive to the development of oral clinical technology and the innovation of the clinical methods. Due to the presence of medical ethics issues, we can not conduct the series of studies in patients in clinical, so we need to establish an effective animal model to carry out these experiments and research studies.Purpose:Designing and producing compatible appliance for tooth movement, and establishing an effective animal model to settle the foundation for the subsequent experiments.Methods:The experiment was carried out on forty SPF female Wistar rats, which were8weeks old. They were randomly divided into2groups. In each group, the two central incisors were used as anchorage to move the maxillary first molars. The control group used the traditional method to install the appliance that wear the ligation wire between the first and the two molars and connect it to one end of the nickel-titanium closed-coil spring. A ligation wire was embedded to ligate the two central incisors as a whole and reinforced it with the dental adhesive agent. Then it was connect to the other end of the nickel-titanium closed-coil spring to move the maxillary first molars. The experimental group used the individual appliance. First, produce the individual tray, and then make the maxillary model of the rats. Producing the individual appliance according to the model, and then bonding them to the teeth. Then the central incisors and the first molars’individual appliance were connect through the nickel-titanium closed-coil spring to move the maxillary first molars. The drop-off rate and the fault rate of orthodontic appliances. All the results were analyzed by PASW Statistics18.Results:The movement of the maxillary first molar in the two groups were obvious. There was significant difference in drop-off rate and fault rate of orthodontic appliances. The drop-off rate and the fault rate in the group of individual orthodontic appliances was2.5%. The drop-off rate and the fault rate in the group of traditional orthodontic appliance was17.5%. The individual appliance group was significantly superior to the traditional appliance group.Conclusions:The rat experimental model of tooth movement which is established by the individual appliance is significantly better than traditional methods, and settles the foundation for the subsequent experiments which involved tooth movement in rats.