My porcelain dental implant crown cracked, where do I send for repair?

I'm sorry to hear that your crown cracked. I would recommend returning to the same dentist who placed the crown for an evaluation. Porcelain crowns are generally not repairable, especially for a long term fix. Usually, the crown needs to be removed and replaced with a new crown.  I hope this helps. Click save on the save button below my name, so that you may ask me more questions in the future. 

Crowns made of porcelain are generally not repairable once they have been in the mouth for some time.  Return to the dentist who made it.

You should return to the dentist that restored the implant to discuss repair, but more likely, replacement.  Repair of porcelain in the mouth is very difficult to impossible to obtain good long term results.  Usually the crown will need be removed and a new custom crown fabricated.