F.H.
Its called bruxism and is actually quite common in young children. My two kids have chipped teeth from it. The dentists says they should grow out of it (one already has and the other does it less now)and seeing as its baby teeth the new ones will grow back fine. I would still keep an eye on it just incase and probably ask a dentist office for their opinion. (This is also a good way to search out a dentist you like by calling around for different opinions).
Most dentist see children from 3-4 years of age unless there is a problem like cavities etc. Lots of kids wont open thier mouths at 2 and will bite!
Good luck