RESUMO
PURPOSE: To evaluate the changes in middle facial soft tissue caused by distraction osteogenesis. METHODS: A three-dimensional finite element model was established based on the simulation of a 13-year-old female with skeletal class III malocclusion. Three approaches of osteotomy, namely Le Fort I, Le Fort II and Le Fort III, were simulated and the maxillary complex was advanced by 5mm in the direction of FH plane, functional occlusal plane and functional occlusal plane with deviation of counter-clockwise 10 degrees, respectively, some premeters indicating the contour of the facial soft tissue were evaluated. RESULTS: The three kinds of osteotomy in which different levels of osteotomied maxillary complex area were advanced. Changing in detail is that the nose tip moved forward 1.25 mm, upper lip moved forward 4.9 mm, and the angle of Cm-Sn-U1 tended to increase after Le Fort I osteotomy; and nose tip moved forward 4.9 mm after Le Fort II osteotomy without increase of the angle of Cm-Sn-U1; besides changes that happened after Le Fort II osteotomy, lower eyelid moved forward 2mm after Le Fort III osteotomy. CONCLUSION: By computer surgery simulation using three-dimensional finite element model, we can obtain not only the amount of the three-dimensional change of the facial soft tissue, but also the three-dimensional effected graphics after operations.
