Injections of the anti-wrinkle drug Botox can transform the appearance of people with receding chins, according to a new study by plastic surgeons.
Until now the only treatment for under-developed lower jaws, also called a weak chin, was invasive surgery – either a horseshoe-shaped chin implant, which corrects the cosmetic problem, or in more drastic cases an operation that involves sawing through the jaw and reattaching it in a more prominent position.
Many patients choose to do nothing, and commonly report low self-esteem, depression and poor quality of life.
Botox is a neurotoxin called botulinum toxin, produced by the bacterium Clostridium botulinum, the same micro-organism that causes potentially fatal botulism food poisoning.
When injected into humans in extremely small concentrations, it works by preventing signals from the nerve cells reaching muscles, therefore paralyzing them.
Botox is used medically for a wide range of conditions, from muscle problems resulting from cerebral palsy and stroke to incontinence and excessive sweating. In this pioneering new treatment, it is injected into one of the muscles in the lower part of the face, allowing the chin to move down and forward.
According to the Californian doctors trialing the treatment, the shape of the chin is not only determined by the bony projection itself, but by the muscles, principally the mentalist muscle on the leading edge of the chin, used to pout the lower lip.
A hyperactive mentalis muscle contributes to a weakened and blunted-looking chin, and Botox acts on nerves to relax muscles and prevent them from contracting.
Patients in the study were each injected with a low dose of Botox into the mentalis and were then examined about two weeks later to assess the results.
All 11 patients treated had improvements in their overall chin appearance, with a change in how much the chin projected.
The chins of the patients were more rounded after treatment, and the position of the pogonion, the most advanced part of the chin bone, moved forward.
All the patients said they were pleased with their post-treatment appearance. ‘By relaxing the muscle, Botox improved the overall chin appearance by reducing tension and altering the projection of the chin and its overall shape,’ say the researchers from the Keck School of Medicine at the University of Southern California, who report the treatment in JAMA Facial Plastic Surgery
‘This is the first analysis of the effects of Botox injection to the mentalis muscle on the position of the chin. Our results show it is effective at improving chin appearance.’
The treatment is not offered in the UK and Ash Mosahebi, professor of plastic surgery at University College London and consultant at the Royal Free Hospital, said more research would be needed. ‘An under-projected chin can lead to a sad appearance, and this novel treatment is potentially an exciting avenue,’ he added. ‘Although the numbers in this study are small, the effects seem reasonable. The only concern is that Botox may have negative effects on smiling and facial movements.
‘The gold standard for under-projected chin remains chin implants or sliding genioplasty, where the bone is cut internally and pushed forwards.’