Clenching or grinding of teeth is called bruxism and can happen intentionally or unintentionally. It can occur during daytime or nighttime. When you grind your teeth, there will be excessive stress on your muscles and structures around the jaw joint and the TMJ itself. This leads to onset or increase in the TMD symptoms. Grinding of the teeth causes the wearing of your teeth and results in loss of balance in the relation of the upper and lower teeth (occlusion).