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Many patients of different ethnicities have full lower faces. One anatomic cause of a full lower and posterior face is masseteric muscle hypertrophy. The most common treatment for this aesthetic form of masticatory muscle enlargement is Botox injections. There is no doubt that Botox injections can effectively reduce the appearance of large masseter muscles and substantial clinical experience has substantiated this effect. But quantitative assessment of the amount of muscular reduction and its long-term results are less available.

In the September issue of the journal Plastic and Reconstructive Surgery an article was published entitled ‘Efficacy of Botulinum Toxin in Treating Asian Indiana Patients with Masseteric Hypertrophy: A 4-Year Follow-up Study.’ In this paper the authors prospectively evaluated fifty (50) patients who were treated for their massesteric muscle hypertrophy with 30 units per side. Half of the patients had a second treatment at 12 weeks and the other half had it repeated at 24 weeks. Photographs and ultrasounds were used to assess changes in facial contour and muscle thickness.

A 12% reduction in masseter msucle thickness was seen by the week 12. Reductions as much as 26% were seen in patients at 6 months who received two injections and maintained an avenge 24% reduction by year 4. Patients who received three injections had an average 42% reduction at week 36 and maintained an average 40% by year 4.

This study provides interesting long-term results which indicates that a few serial Botox injections spaced three months apart produced increasing amounts of muscle  reduction that were maintained long-term…without repeat injections after the initial series. These results indicate that Botox injections produce permanent masticatory muscle reduction…an outcome which has to occurred in my experience in patients who have had more than even three serial injections. Botox injections is not historically known to have permanent muscle effects either in activity or muscle size. This is the first study that demonstrates a long term muscle size reduction over years without ongoing injection treatments.

Dr. Barry Eppley

Indianapolis, Indiana

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