pulp stress with different tooth movements in normal and open apex: 3D analysis using Finite element method

Orthodontic treatment outcomes are combination of advantages and disadvantage. The force implied during treatment could affect dental pulp status. Amount of changes in pulp complex depend on the types of tooth movements and whether the apex is open or not. The aim of this study is to compare the effects of different orthodontic tooth movements in two kinds of open and normal apices by 3D Finite element analysis.
Two three-dimensional Finite element models of an upper central incisor were modeled based on average dimensions. The models contained cortical and spongy bone, uniform thickness PDL of 0.25 mm and an upper central incisor. The differences between the models was the apex development which was complete in the first model and open in the second one in Solid- works 2006 and transferred to ANSYS Workbench Ver. 11.0. Different force systems to produce tipping, bodily and intrusion were applied in the tooth crown. The Von Mises stress was assessed along two defined paths.
Maximum amount of the stress along the long axis of pulp belonged to open apex by tipping movement then intrusion with normal apex and finally bodily movement in open apex samples. In evaluation as regard of stress along apical third of PDL the highest stress created by intrusion in normal apex group.
In open apex, tipping and bodily movement could induce much more stress and in normal apex the concern of root resorption by intrusion was more than other types of tooth movements.