Teeth grinding and biting your fingernails
Teeth grinding, also known as bruxism, is an unconscious movement of your teeth at night when you’re asleep. It is typically caused by problems in the alignment of the teeth, and patients with bruxism will develop jaw pain, sensibility, and it predisposes to tooth decay and cracked teeth. Fortunately, there is a solution to this problem, and you can use a nightguard to prevent this from happening.
On the other hand, biting your fingernails is something you do consciously, even though it counts as a nervous tic or a sign of anxiety. This practice does not only damages your teeth mechanically but also transfers bacteria from your fingernails into your teeth and gums. So, if you have this problem, look for any way to relieve tension with a stress ball or anything else.