Temporomandibular joint disorder ( TMJ or TMD ). Pain in the muscles of the face and head can be exacerbated by clenching or grinding of the teeth. In severe cases the teeth or even porcelain crowns can become fractured. Headaches can also be triggered. Bite plate therapy can be helpful in eliminating this habit pattern during sleep. Botox injections help to relax the facial muscles and relieve the intensity of these jaw muscle contractions during the day and night for four to six months at a time. Relief of clenching and tooth grinding and slenderizing enlarged jaw muscles (masseter muscle hypertrophy) can be achieved with Botox. While Botox provides substantial relief it does not affect daily activities such as talking, chewing or swallowing. Treatment is virtually painless and takes only a few minutes.