Is there something i can do about my 4 yr old grinding teeth?

Usually Yes: Search for the true cause of the grinding, as there are many causes, and then treat the cause. At times the nasal passages can be blocked or congested due to allergy, inflammation or infection causing the patient wiggle his jaw to try to open up his airway. At times allergy itself can directly cause irritation. Some common medications for colds and cough can cause grinding as a side effect.

Mostly Normal: In fact, bruxism or teeth grinding generally is caused by unknown factors. Usually while sleeping and may be totally normal.The only complications occur if permanant teeth are physically eroded or if when older, pain occurs at the temporomandibular joint. These complications require dental interventions.

Yes: Figure out why. While this is common to do occasionally among kids, long-standing instances could adversely stress growth and developement of the chewing system. Recent studies have implicated constricted airways as an inducer...And the grinding is an attempt to open the airway and breathe easier. Something to consider if you notice any issues with breathing in your child.