Bruxism is excessive grinding of the teeth and/or excessive clenching of the jaw. Bruxism is a common problem: reports of prevalence range from 8–31% in the general population. Bruxism may cause minimal symptoms, and therefore people may not be aware of the condition. Several symptoms are commonly associated with bruxism, including hypersensitive teeth, aching jaw muscles, and headaches. Bruxism may cause tooth wear, and may even cause teeth to break and dental restorations (e.g. crowns and fillings) to be repeatedly lost or damaged.