After having Veneers/Crowns fitted some patients argue that their teeth shifted, and that the teeth are misaligned. 

To have veneers/crowns fitted teeth are filed to a certain extent. After this procedure, the crown or veneer is fitted on your original tooth. Veneers are very thin layers that goes on the teeth, the original teeth get minimal preparation on the surface and bottom to make room for the veneers. Crowns require more preparation than veneers as they are thicker in material. However, in both cases patients keep their original tooth. The movement that stems from the original tooth, therefore, inevitably makes the veneers/crowns shift. 

There can be a lot of reasons for the teeth movement. It is skeletal problem, sometimes leaded by Periodontal Disease. Veneers/Crowns will not cause teeth movement or will not stop any movement on the teeth.