My bracket that is bonded to a porcelain crown had fallen off 3 times during my sleep this week. the bracket is on the premolar tooth. i didn't eat anything hard, crunchy, or even chewy. what can i suggest to the dentist so it doesn't fall off again?

It is interesting that it is falling off during sleep. I wonder if you have some version of grinding or clenching of your jaw during sleep. A mouth guard that prevents damage to teeth in person who grind or clench their teeth may keep the bracket on and your premolar intact.

Trying to bond anything to a porcelain crown is extremely difficult, especially if you want to reverse the process when treatment is completed. Your dentist may want to ligate the tooth to the main wire with ligature wire.