A gap in between my porcelain veneers. (photo)

Hi:One possible reason for the gap appearing after a week is bite on the back of the two front teeth.  My first suggestion is to check the bite before using a retainer to close it.  Replacing the veneers to close the gap will make the two front teeth wider than normal.Best,Dr. Maddahi

Basically porcelain veneers are used to close gaps and if you you've had your teeth shift slightly after your veneers were done, then sometimes they can be moved slightly back into a tighter alignment. Even veneers made of porcelain cannot be bonded to close the gap with a predictable long term result and a veneer made of composite could be bonded to close the gap however; the result might not be very appealing as the veneer was made to proper proportion in the first place. So in this situation I would recommend you to see your dentist without making any delay.