| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 93 === The purpose of the thesis aims at investing the stress distribution of the alveolar bones and the situation of teeth displacement during the orthodontic process, and to provide the dentists a basis for designing the orthodontic process. At the present stage, the three-dimensional stress analysis of central incisor, lateral incisor, canine, first premolar, and second premolar of mandible have finished. The thesis uses the Reverse Engineering method and Computer Aid Design method to construct the three-dimensional model of tooth and periodontal ligament, and used the cross-section of mandible which had been scanned by X-ray CT to construct three-dimensional model of mandible; then, the tooth tissue material constant is input and the mechanical analysis of finite element is proceeded.
The research analysis divides into five topics in orthodontic. The first topic discusses the influence of different model of alveolus bones to the stress distribution; the second topic is the stress analysis of using fixed appliance; the third topic is the stress analysis of using Invisalign○R; the fourth topic is the stress analysis of using moving the dental arch line; the fifth topic discusses the range of the rotational center of tooth during uncontrolled tipping. From the results, the model structure of alveolus bone affects the stress distribution and the rotational center of tooth largely. The stress concentration mainly occurs on the upper of lingual and labial of alveolus bone. Comparing the fixed appliance and Invisalign○R, both results are very similar in the situation of stress distribution of alveolus bone, the displacement amount of tooth and the location of rotational center. The value of rotational center for each tooth is between 39% and 44% for both cases. When moving the line of dental arch, since the geometry contour of the crown of canine is like a cone; hence, the setting of moving condition will produce a big influence to the stress value of alveolus bone. Combined the results each tooth displacement, the limit range of rotational center under uncontrolled tipping can be defined, and the value of rotational center of each tooth is between 33% and 47%. Finally, according to the loading and the amount of tooth displacement, the stiffness coefficient of tooth tissue for above five teeth can be calculated and offers the dentists to refer, and will serve as a basis for the future researches.
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