ObjectiveThis paper aimed to simulate and compare the effect of maxillary expansion on the displacement of maxillary alveolar bone before and after alveolar bone graft.MethodsOn the established finite element model of the maxilla before bone grafting, ANSYS was used to simulate alveolar bone graft to form the model of maxilla after bone grafting. The same expansion force was applied to the two models, and the three-dimensional displacement of alveolar bone was observed and compared between them.ResultsComparison of the three-dimensional displacement showed that expansion before bone grafting was significantly larger than that after bone grafting (P<0 .05). for horizontal displacement, in the expansion group before bone grafting, the displacement was gradually decreased from anterior to posterior alveolar bone. in the expansion group after bone grafting, the displacement was gradually increased from anterior to posterior alveolar bone. displacement of noncleft side alveolar bone was significantly larger than that of cleft side alveolar bone with maxillary expansion before and after alveolar bone graft (P<0 .05). in terms of vertical displacement, the anteromedial alveolar bone moved downward and the posterolateral alveolar bone moved upward with maxillary expansion before and after alveolar bone graft. for sagittal displacement, the anteromedial alveolar bone moved forward and the posterolateral alveolar bone moved backward with maxillary expansion before alveolar bone graft. however, the movement trend was opposite with maxillary expansion after alveolar bone graft.ConclusionThe three-dimensional movement with maxillary expansion before alveolar bone graft is more obvious than that after bone grafting for patients with unilateral complete cleft lip and palate. Expander should be moved backward properly with maxillary expansion before alveolar bone graft and moved forward properly and cooperated with maxillary protraction with maxillary expansion after alveolar bone graft. Meanwhile, precaution must be taken in terms of asymmetric expansion and anterior open bite in operation.
