Why is there discoloration under temporary crowns? (photo)

There is significant bacterial leakage under those temporary crowns.  I would contact your dentist and have them clean under the temporaries.  They can make you new ones until the permanent crowns come in, but I would try to get them permanents asap.  Good luck.  

Hi there,
There seems to be a leakage of saliva, and bacteria under the temporary crowns. This can cause staining under the temp crowns. The stain can be removed and I would recement the temp crowns with temp cement. I would get the permanent crowns placed as soon as you can.

Best of Luck,
Dr. Glosman

You have bacterial leakage under your temps. I suggest getting in with your dentist and having them remade. Your dentist will need to make sure that the teeth are cleaned very well so that this doesn't happen under your permanent crowns.