No hard and fast figures on the frequency of bruxism are available. Most people unconsciously grind or clench their teeth now and then, so the key in deciding whether someone is a bruxer is not the presence or absence of the habit, but such things as its frequency, destructiveness, social discomfort, or physical symptoms (Kydd and Daly, 1985). Moreover, over 80% of all bruxers may be unaware of the habit (Thompson, Blount, and Krumholtz, 1994), or ashamed of it, so they may dismiss evidence that they do in fact engage in self-destructive behavior. Also, it may take years for the first visible signs of worn teeth to appear; yet, often it is these signs which lead to a diagnosis of past or present bruxism. For these reasons, estimates of the prevalence of bruxism range from 5% to 100%. For the U.S. population, current estimates often settle for the 5-20% range.   A 2011 review, for instance,guesstimates the figure for the general population at 8%.

Regardless of the exact number, the figures are disturbing. At the very least, one out of twenty westerners brux. Most likely, one out of ten does. Inarguably, then, bruxism is a widespread behavioral pattern which adversely affects a significant fraction of the world's people.