Bruxism (from the Greek βρυγμός, “gnashing of teeth”) is characterized by the grinding of the teeth and typically includes the clenching of the jaw. It is an oral parafunctional activity that occurs in most humans at some time in their lives. In most people, bruxism is mild enough not to be a health problem. While bruxism may be a diurnal or nocturnal activity, it is bruxism during sleep that causes the majority of health issues; it can even occur during short naps.
There are two main types of bruxism: one occurs during sleep (nocturnal bruxism) and one during wakefulness (awake bruxism). Dental damage may be similar in both types, but the symptoms of sleep bruxism tend to be worse on waking and improve during the course of the day, and the symptoms of awake bruxism may not be present at all on waking, and then worsen over the day. The causes of bruxism are not completely understood, but probably involve multiple factors. Awake bruxism is more common in women, whereas men and women are affected in equal proportions by sleep bruxism. Awake bruxism is thought to have different causes from sleep bruxism. Several treatments are in use, although there is little evidence of robust efficacy for any particular treatment.
Bruxism is usually detected because of the effects of the process (most commonly tooth wear and pain), rather than the process itself. The large forces that can be generated during bruxism can have detrimental effects on the components of masticatory system, namely the teeth, the periodontium and the articulation of the mandible with the skull (the temporomandibular joints). The muscles of mastication that act to move the jaw can also be affected since they are being utilized over and above of normal function.