Dreams about losing teeth are popularly thought to signify a lack of agency.  I started grinding my teeth in my sleep when I was 11 years old.  The urge is so strong that I have ground through or broken several devices designed to prevent it.  I dream about my teeth shattering and falling out frequently; this sensation is my most visceral repulsion.    Despite my aversion, there is nothing that can keep me from grinding my teeth from the moment I fall asleep.