Don't laugh - it worked for me. I had a crown put in a few years ago. The first one I swallowed in my sleep, the second one came off a few weeks later and I swallowed the third one while eating dinner.
My dentist told me that she had just read an article that said that certain individuals have an enzyme in their saliva that appears to dissolve the glue that dentists used. She felt that's what was happening to my crowns.
I jokingly said, " Why don't you use Superglue?"
She answered, "That's exactly what I'm going to use."
That crown has been in for 5 years now with no problems.
Couldn't recover it at the other end? ;-)