Medications
Certain stimulant drugs, including both prescribed and recreational drugs, are thought by some to cause the development of bruxism. However, others argue that there is insufficient evidence to draw such a conclusion. Examples may include dopamine agonists, dopamine antagonists, tricyclic antidepressants, selective serotonin reuptake inhibitors, alcohol, cocaine, and amphetamines (including those taken for medical reasons). In some reported cases where bruxism is thought to have been initiated by selective serotonin reuptake inhibitors, decreasing the dose resolved the side effect. Other sources state that reports of selective serotonin reuptake inhibitors causing bruxism are rare, or only occur with long-term use.Specific examples include levodopa (when used in the long term, as in Parkinsons disease), fluoxetine, metoclopramide, lithium, cocaine, venlafaxine, citalopram, fluvoxamine, methylenedioxyamphetamine (MDA), methylphenidate (used in attention deficit hyperactive disorder), and gamma-hydroxybutyric acid (GHB) and similar gamma-aminobutyric acid-inducing analogues such as phenibut. Bruxism can also be exacerbated by excessive consumption of caffeine, as in coffee, tea or chocolate. Bruxism has also been reported to occur commonly comorbid with drug addiction. Methylenedioxymethamphetamine (MDMA, ecstasy) has been reported to be associated with bruxism, which occurs immediately after taking the drug and for several days afterwards. Tooth wear in people who take ecstasy is also frequently much more severe than in people with bruxism not associated with ecstasy. Occlusal factors
Occlusion is defined most simply as "contacts between teeth", and is the meeting of teeth during biting and chewing. The term does not imply any disease.
According to the International Classification of Sleep Disorders revised edition (ICSD-R), the term "sleep bruxism" is the most appropriate since this type occurs during sleep specifically rather than being associated with a particular time of day, i.e., if a person with sleep bruxism were to sleep during the day and stay awake at night then the condition would not occur during the night but during the day. The ICDS-R defined sleep bruxism as "a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep", classifying it as a parasomnia. The second edition (ICSD-2) however reclassified bruxism to a "sleep related movement disorder" rather than a parasomnia. Classification by cause
Alternatively, bruxism can be divided into primary bruxism (also termed "idiopathic bruxism"), where the disorder is not related to any other medical condition, or secondary bruxism, where the disorder is associated with other medical conditions. Secondary bruxism includes iatrogenic causes, such as the side effect of prescribed medications. Another source divides the causes of bruxism into three groups, namely central or pathophysiological factors, psychosocial factors and peripheral factors. The World Health Organizations International Classification of Diseases 10th revision does not have an entry called bruxism, instead listing "tooth grinding" under somatoform disorders. To describe bruxism as a purely somatoform disorder does not reflect the mainstream, modern view of this condition (see causes).