Masseter botox involves injecting botulinum toxin into the masseter muscles, the large jaw muscles used for chewing. When these muscles are overdeveloped, whether naturally or through habits like teeth grinding (bruxism) or jaw clenching, the lower face can appear square or wide. Relaxing them with botox allows the muscle to gradually reduce in size, creating a slimmer, more oval facial contour. It's also used to ease the discomfort of teeth grinding and related tension headaches. Results take one to two weeks to become visible as the muscle relaxes, with the slimming effect continuing to develop over the following weeks. Treatment typically lasts three to six months, and with repeat sessions, results can last longer as the muscle adapts.