Whereas square lower jaws are often considered a positive trait in Caucasian and many Asian men, a wide mandible can cause significant facial discordance and/or masculinization of the female face—particularly in those of East Asian descent. Even in certain men, the size of the lower jaw can cause facial disharmony—particularly when there is asymmetry.
A wide lower face can primarily be caused by enlargement of the mandible or masseter muscle.
Conversely, while a masseter muscle can be large due to congenital reasons, it can commonly be an acquired deformity. Like any muscle it increases in size with exercise. Behaviors such as repeated gum chewing, teeth clenching, or bruxism can contribute to enlargement of the muscle.
There are several jaw reduction techniques available—both surgical and non-surgical. Ideally prior to selection of a treatment, the patient is examined to determine whether the cause is due to the bone, the masseter or both. Additionally, if a treatable cause is present it should be identified.
Non-surgical techniques are essentially limited to cases in which the masseter is enlarged. A convenient method to treat an enlarged muscle is through the use of botox) injections. Botox is injected into the enlarged muscle, weakening it so it slowly becomes smaller through atrophy over several months. There is no down-time and improvement is gradual—individuals who interact with the patient may never know that a plastic surgical procedure was performed
The use of Botox for jaw reduction has been studied scientifically. Improvement is generally not seen for at least 1 – 3 months. Peak improvement occurs at months 3 to 9 with good results still observable at one year in many patients.
The procedure can result in temporary paralysis of the muscles that move the lips, a rare but acknowledged complication.
Surgical techniques are used to directly reduce the size of an enlarged mandible. Incision can be to the inside or outside of the mouth, though the internal incision is the most common because it leaves no visible scar. A burr is used to remove the outer layer of the enlarged mandible, narrowing the jaw.
Potential complications include injury to the inferior alveolar nerve which provides sensation to the lower lips and teeth.