Bruxism is defined as repetitive activity of the masticatory muscles, characterized by clenching the teeth or teeth grinding and/or by tapping and swaying. This study investigated sleep bruxism. The etiology is multifactorial: mainly central (neuropathic disorder, anxiety) but also genetic and local (posture, mouth breathing). The diagnosis is based primarily on the anamnesis and examination of dental wear and progression over time (photos and dental castings). A diagnostic guide is proposed in this article. Frequently found in children, bruxism is not always considered pathological. The severity criteria relate intensity (number of dental attrition facets) as well as the context found in children: anxiety, ventilation disorders, and fragile dental structures. Management is multidisciplinary and depends on the etiologic diagnosis.