It's called Bruxism. I too had this one..and my dental doctor told me to wear night guard ( teeth cap ) which they customized for me.. Here is an article that may provide you more insight.. Hope it helps you. https://www.webmd.com/oral-health/guide/teeth-grinding-bruxism
Bad dream? Perhaps stress which we wont really know. Probably u can ask ur PD about it but normally its goes off on its own. But if persist, PD the way to go.
Thank You Very Much 😀
BB