| Crossbite is one of the common symptoms of Clinical Orthodontics. The traditionaltreatment of maxillary hypoplasia adolescent patients were press film protractionimplement. Although patients can face some degree of improvement, but at the same timewill cause the anterior teeth labial side and molars tilt adverse compensatory, thusincreasing the difficulty of post-correction.Mini implant auxiliary maxillary complex protraction is a new technology developedin recent years. There are more attention to the micro titanium plate for maxillaryprotraction than mini-implant in Previous literature. But what kind of impactbiomechanics mechanism for traction when bone sutural, literature not reported.This is the basis of this experiment to offer a scientific basis on the direction ofmaxillary protraction by establishing and using three dimensional finite elementmodel(FEM)of cranio-maxillary complex.The study is composed of four experiments as follows:Experime nt I: Mini implant auxiliary the maxillary complex three-dimensional finite element model of the protraction establishes.Objective: To establish maxillary complex, mini-plant，craniofacial skeleton sutures,including three-dimensional finite element model, and provide a platform for thesubsequent experiments. Method: Select an age of10years old person, mixed dentition,maxillary hypoplasia adolescent and record patient’s data, collection of objects. Extractedand generated data import Mimics10.1software by screening, grayscale choice,automatically extracted and manually erase the occlusal surface complexthree-dimensional finite element model. Geometric software model smoothing and entities,the maxillofacial complex CAD model. Finally, using Solidworks software to build amodel of the suture and planting mini implant, and each part of the model is imported intothe Workbench14software assembly and processing, the establishment of a themaxillofacial complex three-dimensional finite element model. Results: The mini implantauxiliary protraction maxillary complex three-dimensional finite element model.Conclusion: The established model has high geomagic and mechanical similarities toestablish a good experimental platform for subsequent experiments.Experime nt Ⅱ:Biomechanical changes of craniofacial skeleton sutures protractionwith mini implant on the craniofacial complex at different protraction force.Objective：To investigate the biomechanical changes of craniofacial skeleton suturesprotraction with mini implant on the craniofacial complex at different protractionforce.Methods： A Three-dimensional Finite Element Method (3-D FEM) ofcranio-maxillary complex of maxillary deficiency with mini-plant was established byusing reverse engineering technique. The different protraction forces from300g to800gwere applied to labial surface of the maxillary infrazygomatic crest respectively from30°with occlusal plane. Biomechanical changes on different sutures were investigated bythe analysis of finite element.Result：With the force increasing, the stress of differentpoints on craniofacial skeleton sutures was increased. The stress on craniofacial skeletonsutures were sutura pterygopalatine＞sutura temporozygomatica＞suturafrontomaxillaris＞sutura palatina transversa＞sutura zygomaticomaxillaris＞ frontozygomatic suture. The stress changes in the size were sutura pterygopalatine＞sutura temporozygomatica＞sutura frontomaxillaris＞sutura palatina transversa＞sutura zygomaticomaxillaris＞frontozygomatic suture. The results showed thatnon-uniform stress distributions existed in the same skeleton suture with the same force.Conclusions： The stress on craniofacial skeleton sutures could cause maxillarycounter-clockwise rotate and promote the development of maxillary. Non-uniform stressdistributions existed in the same skeleton suture with the same force. With the forceincreasing, the stress of different craniofacial skeleton sutures was increased. Clinical useof different traction value, to stimulate growth of skeleton sutures was different.Experime nt III: Application mini implant anchorage at different angles to the sameas the protraction force dimensional finite element analysis of craniofacial skeletonsutures stress characteristics.Objective: To study the different traction angles protraction maxillary suturebiomechanical effects. Methods: The establishment of mini implant auxiliary maxillaryprotraction on the basis of three-dimensional finite element model, under500g forces,respectively studies-60°,-45°,-30°,-15°,0°,15°,30°,45°,60°traction angle suturecharacteristics of stress distribution and displacement trends.Results: With the increasedtraction angle suture stress distribution is alike. The stress distribution more concentratedto the sutura pterygopalatine and sutura temporozygomatica.-60°to0°, the suturapterygopalatine stress distribution increases gradually, sutura pterygopalatine in the0°peak.0°to60°, the sutura pterygopalatine stress distribution reduces gradually. Suturatemporozygomatica in the-15°As the angle increases, the stress distribution is graduallyreduced. Traction angle from-60°~60°suture showed varying degreescounter-clockwise rotation of the trend. Conclusion:1.Different directions in front oftraction, the stress in the craniofacial skeleton sutures of different sizes, the most obviousto the sutura pterygopalatine and sutura temporozygomatica.2.Load angle is the same atnormal position, the same craniofacial skeleton sutures different points when under stress.3.Traction angle of0°, the sutura pterygopalatine stress distribution peak, prompted clinical this angle’s protraction is more reasonable.Experime nt IV: Mini implant implanted in different parts of the protraction stressdistribution in different three-dimensional finite element analysis.Objective: when the research planting mini implant in different parts of theprotraction craniofacial skeleton sutures biomechanical effects difference. Methods: theestablishment of mini implant auxiliary maxillary protraction on the basis ofthree-dimensional finite element model, respectively, the mini implant implanted in themaxillary infrazygomatic crest and the anterior region. Value in500g traction, occlusalplane pulling down30°to analyze the differences in suture Characteristics of stressdistribution and displacement trends. Results: Maxillary infrazygomatic crest tractionsuture stress distribution is more concentrated than anterior traction. And stress moreconcentrated in maxillofacial bone in the lower. The maxillary infrazygomatic cresttraction counterclockwise rotation trends anterior region Traction maxillary clockwiserotation trend. Conclusion:1.Regardless of the use of the front teeth area orinfrazygomatic crest planted mini implant protraction growth can stimulate maxillarysuture. And more effective in the infrazygomatic crest.2. Infrazygomatic crest traction oncounterclockwise rotation maxilla trend, prompted the treatment of patients with crossbite; the anterior area traction, clockwise rotation of the maxilla trend, prompted thetreatment of open bite of high-angle. |
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