Bruxism into three groups, namely central or pathophysiological factors, psychosocial factors and peripheral factors. The World Health Organization's 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). The ICSD-R described three different severities of sleep bruxism, defining mild as occurring less than nightly, with no damage to teeth or psychosocial impairment; moderate as occurring nightly, with mild impairment of psychosocial functioning; and severe as occurring nightly, and with damage to
Grinding (gaming) have the potential to be rewarded in the future, and will have no reason to quit. Though grinding is used to provide a "level playing field", this effect could be achieved with any time-consuming behavior that is accessible to all and provides game advancement; The behavior need not be tedious or repetitive, as the term "grinding" generally implies. For example, in a game where advancement is gained by killing monsters, the game could provide such a huge variety of monsters and environments that no two kills are ever the same. As long as all players remained equally capable of killing