Bruxism is the technical term for grinding and clenching of the teeth that may cause facial pain. People who grind and clench their teeth, called bruxers, unintentionally bite down too hard at inappropriate times, such as in their sleep. In addition to grinding teeth, bruxers also may bite their fingernails, pencils and chew the inside of their cheek. People usually aren’t diagnosed with bruxism until it is too late, as many people don’t realize they have the habit. Others mistakenly believe that their teeth must touch at all times. About one in three people suffer from bruxism, which can easily be treated by a dentist.