Probably just percolation of debris under the temp. veneers.  They
surely aren't bonded in place--your dentist will want to be able to
remove them easily.
    The teeth will be cleaned before the permanent veneers are put in.

Steve

"I had two veneers removed and a gingivectomy for aesthetic reasons.
Week and a half afterward it looks like the tooth behind the temp
veneer is turning black.

Any idea what causes this and what should I ask the dentist when I head

over there?

As well is this something permanent?"
________________________

Just ask your dentist the same questions you asked here.

In fact, you don't have to wait until your next appointment. Just call
his office and leave a message for him to call you back.

Best regards,
- dentaldoc