Bruxism 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. 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
Habitual aspect Italian, and Portuguese do not have a grammatical form that is specific to the habitual aspect. In the past tense, they have a form called the imperfect, which combines the past tense with the imperfective aspect; it is used to indicate that a past ongoing process was habitual or continuous. Cantonese, a Sinitic language, has a dedicated particle to express the habitual aspect, 開 "hoi1", which follows the verb. This is unlike Mandarin and some other Sinitic languages, which have no grammatical indicators of the habitual aspect, but may express habituality via circumlocution. Habitual aspect In linguistics, the aspect of