What is bruxism? Bruxism is more commonly known as 'teeth-grinding'. It is a habit which affects approximately one in ten people of all ages. Most teeth-grinding happens during sleep and can range from mild to severe. Sometimes it is only short-term, and thus relatively harmless. However, persistent teeth grinding, especially at night, can cause serious dental and jaw joint damage. It can also cause headaches, jaw muscle pain, and other health problems. What causes bruxism? T