The Finite Element Study On Treatment Scheme Of Cleft Palate And Lip Midfacial Hypoplasia

Cleft Palate and Lip is a common inborn heteroplasia, and is also one of the innate illnesses which has been receiving much attention from stomatologists. Children who suffer the Cleft Palate and Lip usually need repair operation of cleft palate and lip when the babies are 3~6 months or so, and after the operation, midfacial hypoplasia with different degrees often happens. With growth of the patients, the occluding, pronouncing, breathing, hairdressing and so on might be infection if the patients could't get appropriate treatments after a long period. So after the bones are mature, the patients need the therapy of the treatment operation to modify the function of nonnasality and feature. Now, the scheme design of cleft palate and lip treatment is in the phase of clinic experience.The work of this study is to numberically simulate the clinic treatment scheme of distraction osteogensis for cleft palate and lip midfacial hypoplasia illness by the definite mathod in order to provide technical guide for designing clinic treatment scheme. This includes: building up the finite element models of the complex bone fragments after LeFort I, LeFort II, LeFort III; and studying the distribution rules of the stresses and displacements of LeFort I, II, III bone fragments which loaded by a definite force and displacements traction.The method of this study is as follows. Processing the acquired spiral CT scan of craniofacial complex of midface hypoplaasia, making use of CAE software and mechanical ways to construct three-dimensional geometrical noumanal model of craniofacial aomplex whose outline is very similar to the patient's skull geomegically and simulating clinic distraction osteogenesis operation to construct 3D finite element model of LeFort I, II, III bone fragments by finite element method. Besides, the finite element model also includes the facial soft tissue such as skin etc., scarred forces and boundary conditions. After applying a definite force and displacement respectivelly on the LeFort I, II, III bone fragments (under displacement traction , the action points of Lefort III bone fragment is different from others), some conclusions can be made from numerical results of the finite element analysis as follows:â‘ When loaded by force and without added by titanic plate, the left-and- right direction displacement of LeFort I bone fragment is larger than those of LeFort II and LeFort III. Under the same condition of displacement loading, the distributing trend of displacement of all directions and von mises stress of LeFort I, II, III bone fragments are the same as those under the force loading.â‘¡The cleft palate part with titanic plate by operation, the aclinic right-and-left lateral displacement of type I become smaller, but the stresses are larger and the largest stress is at the titanic plate,so the titanic plate should has enough strength; the result of the displacements and von mises stresses of LeFort I, II, III bone fragments have no explicit change compared to those without plate, and von mises stresses of type II become smaller. The displacements of LeFort I, II, III bone fragments'vertical displacements have no influence with the plate.â‘¢When LeFort I loaded by definite forces, it can be seen that all the front of the model moves inward, and the back part moves outward; the inboard relative displacements the left and right parts of the model became smaller.â‘£When the different mechanical parameters of the soft tissue are used, the displacement values change approximately the same inverse proportion with the parameter's value.