The Three-diinensional Finite Element Analysis And Clinical Research Of Impacted Mandibular Third1molars Mesial And Upright Moving

In the treatment of malocclusion, orthodontic physicians often through pulling outteeth to obtain clearance relieve crowding with the most commonly used extraction isthe first or second premolar, and even the molar have had pulp and restorative treatmentto restore molar function. Considerations in orthodontic patients for the adolescent oryoung adult, first molar pulp and restorative treatment is influenced by many factors,orthodontic physicians make to formulate treatment plans followed the design ofpriority extracted teeth extraction principle, has severely damaged the first molar mesialand upright, mobile second, third molar, to maximize recovery with complete dentitionand masticatory function maximization. In view of the mandibular third molar onclinical near to and vertical to the impacted, mesial and upright mobile has certaindifficulty, in the basic and clinical research is less involved. This study adopts spiral CTscanning technology, engineering software modeling and finite element analysis method,through the establishment of impacted mandibular third molars and its level of supportof three-dimensional finite element model, the mesial and upright moving process ofperiodontal stress distribution finite element analysis, combined with clinical practice,for the impacted mandibular third molars clinical diagnosis, orthodontic treatment planand treatment evaluation with biomechanical and clinical reference. This thesis consistsof three chapters:The first chapter of this thesis through to a female adult volunteer patients with jawregion spiral CT scanning, accurate acquisition of image information, using Mimics,Geomagic and other related finite element software, establish the level of ambush mandibular third molars and its supporting tissue of three-dimensional finite elementmodel, and through the Ansys Workbench, solid189tetrahedron mesh division, to obtaina general model unit number217735, number of nodes is216081. The finite elementmodel with good appearance, especially for third molar teeth and their periodontalligament were fine shape simulation, and biological entity has a good geometricsimilarity, the next step for the analysis of nearly and upright movement duringperiodontal stress distribution state and laid a good foundation of model.In the second chapter, using the three-dimensional finite element model, by usingfinite element analysis software, simulation analysis in different sizes and directions foraction, mandibular third molar mesial and erect the moving process of the stressdistribution of periodontal membrane and tooth displacement state, the close andprovide a theoretical basis for the vertical move. Through the study of the main resultsof the following:1. The mandibular third molars and its supporting tissue in the neck region andapical area prone to the phenomenon of stress concentration, and the neck is the apicalarea to appear stress concentration.2. When the orthodontic force loading direction and the long axis of the toothvertical, periodontal membrane of the von Mises stress and hydrostatic pressure reachedthe maximum value.3. Mandibular third molar orthodontic force loading0.5N, the periodontal ligamenthydrostatic pressure variations in the range of5.89~12.09kPa (<16kPa); loading the1.0N orthodontic force, the periodontal ligament hydrostatic pressure variations in therange of12.16~24.17kPa.4. The mandibular third molar to the initial displacement and orthodontic force sizeand loading direction are closely related, and the teeth always have to far and buccalside rotating trend in the correction.The third chapter of the thesis through completed orthodontic correction in29 patients with a total of55third molars, the mandibular third molars clinical crownfenestration operation time and auxiliary arch, helical spring, elastic chains, molar is theaxial spring, the implant nail near and upright mobile third molar specific operationmethod, combined with a typical clinical case, expounds in detail the mandibular thirdmolars mesial and upright moving correction opportunity, operation method and skill,for mandibular third molars mesial and upright moving to provide clinical reference.The results of this study, the use of spiral CT technique and the finite elementmethod to establish the mandibular third molars and its supporting tissue ofthree-dimensional finite element model has a good geometric similarity, the mesial anderect the moving process of the stress distribution in the periodontium of simulationresults are true and reliable, while the combination of clinical examples furtherelaboration of the mandibular third molar mesial and vertical mobile treatment timingand operation points, for mandibular third molars mesial and upright movement andprovide a theoretical basis and clinical reference.