Advice Needed – dog ruining his teeth!

My basset has separation anxiety and he is a good boy, but one issue is he gnaws at his crate metal while he is in there for the day. I end up coming home to a puddle of drool in front of the crate from him doing this. I have caught him doing it too! What can I do to help this and protect him? He has wear on his teeth from this.

Thank you in advance for your help!