Sleep bruxism (SB) is an unusual orofacial movement described as
a parafunction in dentistry and as a parasomnia in sleep medicine.
Since several peripheral influences could be involved in sleep-wake
regulation and the genesis of rhythmic jaw movements, the
authors have reviewed the relevant literature to facilitate understanding
of mechanisms possibly involved in SB genesis. Various
animal and human studies indicate that during either wakefulness
or anesthesia, orofacial sensory inputs (eg, from periodontium,
mucosa, and muscle) could influence jaw muscle activity.
However, the role of these sensory inputs in jaw motor activity
during sleep is unclear. Interestingly, during sleep, the jaw is usually
open due to motor suppression; tooth contact most likely
occurs in association with sleep arousal. Recent physiologic evidence
supports an association between sleep arousal and SB; a
sequential change from autonomic (cardiac) and brain cortical
activities precede SB-related jaw motor activity. This suggests that
the central and/or autonomic nervous systems, rather than peripheral
sensory factors, have a dominant role in SB genesis. However,
some peripheral sensory factors may exert an influence on SB
through their interaction with sleep-wake mechanisms. The intent
of this review is to integrate various physiologic concepts in order
to better understand the mechanisms underlying the genesis of SB.
J OROFAC PAIN 2003;17:191–213.