Botox or botulinum toxin A has a lot uses that go beyond facial wrinkle reduction. Some of these are well known and FDA-approved and others are not. One of the newer uses in plastic surgery has been in the nonsurgical management of masseter hypertrophy. While well known in the Eastern world, it is not as common in Western populations.
The muscle enlargement at the angle of the jaw gives one a square face or jaw look. In Asia, particularly Korean and Chinese populations, they have a naturally larger masseter muscles and broader bony jaw angles. When they become excessively so, which occurs in about 10 to 20% of the population, their face becomes too square or strong. This tendency appears to be a developmental or congenital one. . The incidence of masseteric hypertrophy in the Western population is unknown and is as likely to occur on just one side as it is bilateral. Many Caucasian patients have an associated history of bruxism or excessive jaw clenching which is clearly a contributing cause.
Masseteric hypertrophy can be simply and successfully treated with Botox injections. In my Indianapolis plastic surgery practice, I usually start out giving 25 units per masseter. This is relatively painless, done with a long 30 gauge needle which is introduced over the most prominent parts of the muscle near the jaw angle. The needle is introduced down to the bone where it is then retracted and injected. This makes sure that the injection is done into the muscle and not into the subcutaneous space. Usually about four or five injections are given per side based on feeling the most prominent parts of the muscle as the patient clenches.
In men and in most Asians, due to their inherently larger muscle mass, the initial injection is higher averaging 35 to 40 units. The injection methods remains the same.
In the masseter, the effects of Botox usually are felt in seven to ten days as one’s clenching and headaches are less noticeable. (if those symptoms existed beforehand) The muscle slimming effects become apparent in two to three months. It is quite surprising that the muscle mass could be reduced in such a short period of time, but I have seen it consistently occur. This improvement in facial shape is clearly evident by frontal photography as the affected sides become less square and more oval-shaped.
How long the effects of Botox last is variable. When it comes to pain relief from bruxism, I find that it lasts about the same length of time as for facial wrinkle relaxation, around four months or so. If aesthetic muscle reduction is the goal, the effects are longer and it is not necessary to re-inject until about six to nine months later.
The interesting questions are ……how long do the muscle slimming effects last once the Botox treatment stops…and are the muscle reducing effects permanent? There are no exact answers to these questions but I would find it hard to believe that maintenance injections are not necessary. I have had no bruxism patients, who over time, had their clenching cycle broken and have had a long time of relief. But I wouldn’t go so far as to say permanent.
Certainly Botox injections are much more appealing than surgical debulking of the masseter muscle or mandibular angle bony reductions. With the recent introduction of a competitive analogue to Botox, Dysport, it will be interesting to see if its effects are longer lasting as purported.
Dr. Barry Eppley