I agree with the previous reply. Unfortunately once the bridge breaks, there is nothing that can be done in the mouth. The entire bridge will need replacement. I would talk to your dentist about this. If it was done within the last year and you have been keeping up with...
Sending the bridge back to the lab won't change the location of the margin. If you are concerned about the way it looks, the bridge would need to be removed, the tooth needs to be prepared more and impressions for a new bridge need to be taken. I would recommend returning to your dentist to ...