Three-dimensional Finite Element Analysis Of Maxillary Posterior Teeth Intrusion With Microimplant Anchorage

Objective:For the treatment of anterior teeth opening and closing,more and more orthodontists begin to use microimplant anchorage to depress the maxillary posterior teeth.At the same time,many doctors are confused about the depressed effect of microimplants placed in different locations.In this study,three dimensional finite element models of maxillary bone(cortical bone and cancellous bone),maxillary dentition,periodontal membrane,brackets,arch wire,implant nail,and transverse palatal bar were established to investigate the periodontal membrane stress distribution and tooth displacement at different implant locations when the maxillary posterior teeth were pressed down.Methods:Part 1: The three-dimensional finite element model of the microimplant was established to suppress the posterior teeth of the upper jaw.A patient was selected for opening and closing,which was arranged and leveled for a CBCT scan and saved as a DICOM file.The file was imported into Mimics20.0 software,and the preliminary 3D models of maxillary cortical bone,cancellous bone and maxillary dentition were obtained.The Geomagic Studio2012 software was used to process the model,and the materialized model of maxilla and periodontal membrane was obtained.The 3D finite element models of bracket,arch wire,implant nail,transverse palatal bar and band ring were drawn by Solid Works software,and all the models were assembled as a whole.Finally,ANSYS Workbence 19.2 was used to divide the mesh and establish a three-dimensional finite element model.Part 2: Three-dimensional finite element analysis of maxillary posterior teeth with microimplant anchorage.The implant was placed at different positions(buccal between the maxillary second premolar and the first molar,buccal between the maxillary first molar and the second molar,and palatal between the maxillary first molar and the second molar),and force was applied to the arch wire.The direction of force was directed from the arch wire to the implant nail,and the size of the force was 1.5N.Finally,the results of periodontal stress distribution and tooth displacement corresponding to the working conditions were obtained.Results:1.The three-dimensional finite element model of the treatment of anterior open bite with intruding maxillary posterior teeth by microimplant anchorage was successfully established.2.From the buccal side of the palatal implant micro kind of body down after maxillary teeth,maxillary first premolar,the second premolar and the first molar and second molar buccal,obviously when implanted into place as the second premolar and the first molar,between maxillary first premolar,the second premolar and the first molar and second molar depress volume is small,the first molar and second molar palatal root elongation in great quantities,when implanted into place as the first molar and second molar,between maxillary first premolar,the second premolar and the first molar and second molar depress volume is small,when implanted into place as the second premolar and the first molar and second molar,between the second premolar down a lot.The maxillary first premolar,second premolar,first molar,and second molar were palatally inclined,and the first premolar,first molar,and second molar were greatly depressed.When the maxillary posterior teeth were depressed by the simultaneous implantation of microimplant anchorage from buccal and palatal sides,the buccal inclination tendency of maxillary first premolar,second premolar,first molar and second molar was very small,the depressions of first premolar and second premolar were very small,while the depressions of first molar and second molar were very large.Conclusions:1.The three-dimensional nonlinear finite element model including maxillary bone(cortical bone and cancellous bone),maxillary dentit,periodontal membrane,bracket,arch wire,implant nail,and transverse palatal bar was established,which showed strong geometric similarity and was more in line with clinical practice.2.When the maxillary posterior teeth are lowered by unilateral implant anchorage of the dental arch,the maxillary first premolar,second premolar,first molar and second molar will tilt to the implant side.3.When palatal microimplant anchorage was implanted with t PA to suppress the maxillary posterior teeth,the maxillary first premolar,second premolar,first molar,second molar,buccolial and palatal inclination trend was the least,the amount of depression was obvious,and the stress on the periodontal membrane was very small.Therefore,in clinical treatment,it is more ideal to use this method to depress the maxillary posterior teeth to treat the opening and closing of anterior teeth.