| Root canal therapy(RCT) is the most fundamental and efficient way to cure endodontics and periapical diseases. In recent 20 years, the efficient rate of RCT is near 95% with the development of fundamental medical science research, new instruments, filling materials, preparation methods and operating microscope (OM). These developments also enlarge the range of tooth conservation and make the basis of the progress of the rehabilitation. It is very important to choose good preparation methods and instruments which have better cutting and shaping ability. The perfect RCT need the root canal shape, taper and directions holding the same after RCT. But in curved canal, something like apical zip, elbow, ledge, perforation and transportation may behappen. These may cause some bad effects such as difficulties during preparation, pain after surgery and influence the efficient rate of RCT. Recent years, with the development of light, electricity and engineering techniques, tiny sample imaging become more and more important, micro-computed tomography(Micro-CT, μCT) is one of them. It has higher resolving power and definition. It is also good for medical treatment. With the exploitation of the software, It is possible to evaluate the features of root canal preparation in 3-dimensions. Oral biomechanics is a new science and a branch of biomechanics. It is also not long applying in endodontics and periapical diseases. Oral biomechanics is a science which using the views and methods of mechanics to study oral biology. It can help us to know the functions of oral system, prelude the change, bring forward new diagnosis and treatment and also make impersonality appraise. We can know the mechanics conditions of tooth tissue in tooth rehabilitation and RCT better using oral biomechanics.Aims and methods:1. To reconstruct 3-dimension(3D) model of the first molar of human mandible and use it to analysis human molars. CT scan a mandible molar and the data was putted into Medical_ Soft in computer, then pass some courses. Put the data into matlab6.5 software to reconstruct the 3D model of the first molar.2. To reconstruct three finite element model in order to make a basis to oral biomechanics in the future.3. To scan the root canal in front of and after RCT and evaluate 3 root canal instruments and instructs the clinical works.Results:1. The three-dimension(3D) model reconstructed by CT scan data, objectively reflected the real tooth figure and the pulp cavity figure of the tooth. This model can reflect the real conditions. The data can also change to become the basis of three finite element model.2. To compare the images of CT and Micro-CT, the images of Micro-CT is more detailed. The boundary of root canal is distinctive and the root canal is also distinctive. We can see the images of root canal in the whole root.3. The images of Micro-CT can locate the second mesiobuccal canal(MB2) accurately. Accurate position can study the relationship between MB2 and other root canal. It can help us lessen the preparation time and enhance the efficient rate of RCT.4. The model can reflect the real conditions. It also can make a basis to oral biomechanics in the future.5. The Protaper take significantly less instrumentation time(P<0.05), removed more canal wall. The shaping ability is the best. Ni-Ti instruments for hand use have less cutting ability, it also cut less dentin.Conclusion:1. The three-dimension(3D) model of human molar provides an accurate model for biomechanical analysis,and can be used to put up a foundation to further research.2. The images of Micro-CT accord with actual conditions, so it can reflex the real clinical problem.3. The relationship between MB2 and other root canal. It can help us lessen... |
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