All I'm trying to do is figure out the heighth of the platform I will need to build to install a new shower stall. Oh and Marlin, I said that a hole was not an option for many reasons. Number one on that list is not wanting to turn a $3,000 job into a $30,000 job.
In brief: Generally.. As far as the filling itself goes, you can eat right away with tooth colored composite fillings, but should wait at least one hour with amalgam (silver) fillings. It's always best you ask your own dentist as this can vary somewhat based upon the size and location of the filling.
1 BPA does indeed form in the mouth after some dental sealants and fillings are applied. BPA can be found in the saliva three hours after dental work is completed. It's not at all clear whether this poses a health risk.  A quick wipe and rinse of the completed dental work vastly decreases whatever risk there might be.