Bruxism is a grinding of the teeth and is usually reported to be a night activity though some children do so during the day. The masticatory muscle soreness and temporomandibular joint pain may be attributed to bruxism. The cause of bruxism is not known. Most explanations are centered around local, systemic and psychological reasons. The local theory speculates that bruxism is a reaction to an occlusal interference, high restoration or irritating dental condition. The systemic factors include intestinal parasites, subclinical nutritional deficiencies, allergies and endocrine disorders. The psychological theory claims the manifestation of personality disorder or increased stress. Children with musculoskeletal disorder (cerebral palsy) and those with mental retardation commonly grind their teeth. Treatment should begin with occlusal equilibration to remove interferences. If occlusal interference or equilibration is not successful then referral to the necessary physician to determine or treat systemic problems. If neither two steps are not successful then a mouthguard appliance can be constructed of soft plastic to protect the teeth and eliminate the grinding habit. If the habit is due to psychological factors, then refer to child development specialist.