Hi, yes clenching teeth hard is quite harmful in the long run. it not only harms your teeth but also applies stress on the muscles of your jaw and can lead to pain in your jaw and the joint which helps the movement of the lower jaw.
you can at times also get a headache. overtime the teeth start losing the top white structure called enamel and become sensitive.
Next Steps
visit your nearest dentist for a checkup and status of your teeth and a solution for the habit.