Why do people grind their teeth? There are several causes leading to bruxism and both adults and children can experience it. Check out the different reasons why people clench their teeth. On the left hand side are the first parts of sentences, on the right are the end of the sentences. Please match the ones that complete a sentence. Bruxism - also known as grinding or clenching - is a rather common oral condition and affects children as well as adults. A patient in your dental office may not necessarily know that he or she grinds his or her teeth. Here are symptoms of grinding you can check with your patients. In this list there are some symptoms that do not have anything to do with grinding.