An Experimental Study On Microwave On Tooth Movement And The Effect Of Periodontal Membrane In Rabbits

The malformation of occlusion corrected need a long time. How to accelerate the orthodontic tooth movement and shorten the course of treatment is a hard-work subject that many numerous scholar concentrate on study. In the current, the mechanism of orthopedic is to stimulate the alveolar bone, activating the osteoblast cells and osteoclast cells, make effective movement of orthodontic tooth and so that achieve the orthopedic purpose. Some medicine, such as prostaglandin E (PGE), cyclic adenosine monophosphate (cAMP), vitamin D (VitD), danshen root, etc, can accelerate the orthodontic tooth movement and shorten the course of treatment. But there are still many problems in using these medicines, such as the dosage, toxicity, etc. Side-effect, some physical therapy, such as direct current, ultra short wave and weak laser have been used in accelerate the orthodontic tooth movement. But these methods were still not enough satisfaction. Microwave is a kind of high frequency electromagnetic wave. It is a new physical therapy developed recently. When microwave effects in human body. It can cause high frequency vibration of H₂O molecule and dipole molecule. When microwave energy is low, it can enhance local blood circulation, accelerate localmetabolism, enhance immunization and consequently, improve local blood circulation, motivate the absorption of edema, resist inflammation and relieve pain. Using microwave irradiation to study rabbit tooth's distal movement velocity in the use of orthodontic power and the change of periodontal tissue, to provide theoretical basement for clinical orthodontic work to look for a new method of accelerate the orthodontic tooth movement. 30 white rabbits were used in the experiment. Maxillary third premolar was extracted. Six groups were divided. Namely normal control group and experimental group, the experimental group included 1d group, 3d group, 7d group, 14d group, 21d group. In the experimental group the area of right maxillary first molar was irradiated by microwave, the left wasn't irradiated. Two researches as follow were studied: (1) To observe the distance changes of the experimental tooth movement. (2) To observe the histological changes under the light microscope. The main results were as follow:1. The tooth movement distance and the velocity of the being irradiated side of the experimental group were larger than the other side. There were obvious different between each group.2. The second premolar and the first molar were occurred oblique movement. The second premolar was obvious. The distance between the first premolar and the second premolar were enlargely.3. The histological change of periodontal tissue under the light microscope.3.1 Normal control group: The periodontal membrane (PDM) fiber of the maxillary first molar became dense. The medial PDM fiber width is less obviously than thedistal, especially in the top of alveolar ridge. Medial PDM fiber is paralleled with dental long axis. The tissue distribution in PDM is normal. Accidentally, osteoclast cells were founded, osteoblast cells could be founded in the top of distal alveolar ridge.3.2 Experiment group: The vascularization reaction of the irradiated side is obvious. There is orientation in the PDM. The pyknosis is not obvious. Absorption of bone is active and it mainly occurred directly. Quantity osteoclast cells could be founded. There were more osteoblast cells and much bone tissues. Cement absorption is not found. Pulpitis inflammation cell was not distinct. In the control side, PDM arranges disordered. Pyknosis was obviously, hyaloma was occurred. Potential bone absorption was main. Osteoclast cells were distributed much. There are many inflammatory cells in dental pulp.There are the following results according the above mentioned:1. Quantitative and qualitative analysis of rabbit's tooth irradiated by microwave distal movement velocity and the change of periodontal tissue can easily be performed in rabbits and is reproducible. This experimental model could be used in any kind of experimental study about accelerating tooth movement.2. Microwave irradiating can easily increase the speed of orthodontic tooth movement effectively.3. After being irradiated by microwave, the periodontal tissue of the forced tooth changes and the remodeling of alveolar bone quickness.