Bruxism is the unconscious and involuntary grinding and clenching of teeth. Bruxism can cause discomfort including headaches, earaches, toothaches and sore facial muscles and jaw joints. The pressure from the clenching and grinding can fracture teeth and wear down enamel, making teeth especially sensitive. Many factors like an abnormal bite, stressed induced lifestyle and crooked or missing teeth can contribute to the cause of bruxism.