The Three-dimensional Finite Element Analysis Of Internal Fixation And Fracture Healing Process Of The Sagittal Fracture Of The Mandibular Condyle

Objective: Be based on the CT image Reverse engineering method were used toreconstruct a type II sagittal fracture of the mandibular condyle and different rigid internalfixation technologies and the fracture healing process of geometry and finite element models,to simulate the calculation under different internal fixation of mini-titanium plate stressdistribution, thus providing a theoretical basis and clinical guidance in the rigid internalfixation sagittal fracture of the mandibular condyle.Methods: Use of reverse engineering software, CAD software and finite elementsoftware were used to reconstructs the three-dimensional finite element model of themandible. Occlusal loads carried on the model, the analysis of type II sagittal fracture of themandibular condyle different fixed ways, to find out the stress distribution of different fixtures.By comparing the maximum angle and maximum displacement of fracture free in differenthealing periods, the maximum equivalent stress of titanium plate, thereby evaluate thebiomechanical effects of different methods of internal fixation.Results: The experiment established a high geometric and mechanical similaritydimensional finite element model of the cortical and cancellous bone in mandibular, based onthis model, the study establish the three dimensional finite element models of a right of thesagittal condylar fracture type Ⅱ in the different internal fixation:(1) There are30489nodes and173677units in four-hole1-form mini-titanium plate;(2) There are36711nodes and187199units in two four-hole1-form mini-titanium plates;(3) There are31427nodesand198676units in a four-hole1-form mini-titanium plate and a four-hole L-formmini-titanium plate;(4)There are41407nodes and211113units in two four-hole L-formmini-titanium plates. And also establish the three dimensional finite element models of thedifferent healing periods (fracture of the day, the4th week, the8th week and the12th week).The day of fracture, the displacement of fracture distal with four fixation are0.879mm,0.883mm,0.887mm,0.877mm; The maximum angle of fracture distal are0.038°,0.020°,0.017°,0.018°; The maximum equivalent stress of titanium plate are2297MPa,530.324MPa,897.06MPa,600.61MPa. The4th week after four internal fixation methods, thedisplacement of fracture distal are0.877mm,0.862mm,0.868mm,0.859mm; The maximumangle of fracture distal are0.039°,0.028°,0.032°,0.045°; The maximum equivalentstress of titanium plate are556.081MPa,445.17MPa,532.523MPa,468.725MPa. The8thweek after four internal fixation methods, the displacement of fracture distal are0.862mm,0.862mm,0.868mm,0.859mm; The maximum angle of fracture distal are0.028°,0.028°,0.028°,0.036°; The maximum equivalent stress of titanium plate are317.091MPa,443.71MPa,528.108MPa,465.505MPa. The12th week after four internal fixation methods,the displacement of fracture distal are0.862mm,0.862mm,0.868mm,0.859mm; Themaximum angle of fracture distal are0.025°,0.028°,0.028°,0.046°; The maximumequivalent stress of titanium plate are239.631MPa,443.294MPa,527.404MPa,463.686MPa.Conclusions: From the perspective of distribution mechanics effects, using two"a"-shaped titanium condylar fracture fixation can provide a more stable mandibular stressdistribution system, followed by a "one" shape with an "L"-shaped titanium plate combination;From the perspective of the displacement of fracture fragments, two "L"-shaped to provide astable solid titanium bits, followed two "a" shaped titanium. Regardless of fixation, fracturestress obvious faults exist, sturdy fixation methods for sagittal condylar fractures have a significant therapeutic effect.