Temporomandibular joint disorder (TMJ) affects the jaw joint and the muscles controlling movement. Symptoms include persistent pain, headaches, and involuntary clenching or grinding of the teeth. Botulinum toxin (Botox) is a non-surgical option that provides relief by relaxing specific muscles involved in jaw tension. Patients often ask about the resulting physical and aesthetic changes following this therapeutic procedure.
The Target Muscle in TMJ Treatment
The primary muscle targeted with Botox injections for TMJ symptom relief is the Masseter muscle. This muscle is one of the four muscles of mastication, or chewing, and is located at the angle of the jaw, connecting the cheekbone to the lower jawbone. It is a powerful muscle responsible for closing the jaw and plays a significant role in the force generated during clenching and grinding.
When Botox is precisely injected into the Masseter, the botulinum toxin temporarily blocks the nerve signals that tell the muscle to contract strongly. This reduction in contraction ability mitigates the excessive tension and spasms contributing to TMJ pain and discomfort. This relaxation breaks the cycle of chronic clenching and grinding, which often leads to headaches and jaw soreness. The goal is to weaken the muscle enough to relieve symptoms while still allowing for normal functions like chewing and speaking.
The Effect on Facial Contour
The reduction in muscle activity caused by the injection leads to a physical change in the Masseter muscle itself. When a muscle is used less frequently, it undergoes disuse atrophy, meaning the muscle fibers gradually decrease in size. Since the Masseter muscle contributes significantly to the width of the lower face, its reduction leads to a noticeable slimming of the jawline. For individuals with an enlarged or hypertrophied Masseter—often caused by chronic clenching—this atrophy can soften a square or wide jaw contour, resulting in a more tapered appearance in the lower third of the face.
This aesthetic change is not instant, as it relies on the gradual shrinking of the muscle mass. While patients may feel functional relief from clenching within days to a week, the visual contouring typically begins to become apparent around four to six weeks post-injection. The peak slimming effect is usually observed closer to the two- to three-month mark, once the muscle has had time to reduce its volume.
Duration and Reversibility of Aesthetic Changes
The effects of Botox, both therapeutic and aesthetic, are temporary because the body gradually metabolizes the neurotoxin. The duration of muscle relaxation and the corresponding facial slimming generally lasts between three and six months, depending on the dosage and individual metabolism. Factors such as the initial size and strength of the Masseter muscle and the severity of the clenching can also influence how quickly the effects wear off.
The muscle begins to regain its strength and size once the botulinum toxin’s effects fully diminish. This means that the changes in facial contour are entirely reversible if the patient chooses not to pursue maintenance injections. The timeline for complete reversibility varies, but the muscle can take several months to a year to fully regain its baseline size and function after the treatment is stopped. Many patients choose to receive follow-up injections every three to four months to maintain both symptom relief and the desired facial contour. Consistent treatment over time may allow for longer intervals between sessions, as the habit of clenching can diminish and the muscle remains smaller.