Day 332. I went to see the dentist and thank goodness I did. The dentist tapped on my onlay and then she picked at it and POP! It came right off. She said it would not have lasted one more day.
I am a grinder and I grinded so much and so hard I grinded my onlay off. The dentist never heard of anyone who wears a nightguard being able to grind off a crown. I told her that I have cracked all my back teeth and they all have crowns. Now I am grinding off my crowns. The natural progression.
She was able to clean off the tooth and glue my crown back on because there was no damage to the tooth. This was good news.