Is it common or recommended to reshape or reduce existing porcelain veneers?

The answer would really be specific to your case.  This means that if your teeth are examined and it's determined that you just need minimal reshaping, then this may be the solution.  However, after placing thousands of veneers over the past dozen years, it sounds like you would be better off, replacing your 6 veneers to exactly what you want.  Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMDSt. Louis, MO area (O'Fallon, IL)Real Self 100

It is easy to reshape porcelain veneers to a certain extent.  A slight modification many times can make a big difference.  Have a cosmetic dentist evaluate your existing veneers to be sure that you are a good candidate for reshaping.  That being said, the thickness is often difficult to alter without affecting the finish on the veneers.  Today's veneers are much thinner and more aesthetic.  It you ever have them replaced I would recommend considering eight as opposed to six.  This usually gives a much more natural appearance. Good luck.  

Typically if the veneers are 10 years old you are better off replacing them.  My suggestion would be to reshape the present veneers to your liking, then take study models and photos  of there shaped veneers.  If the polish is not satisfactory then redo the veneers to thenew shape.  If you are happy the polish of the reshaped veneers leave them until you want to replace